A Chronology of 

Middle Missouri Plains 

Village Sites

By Craig M. Johnson

with contributions by

Stanley A. Ahler, Herbert Haas, and Georges Bonani

Smithsonian Institution

Scholarly Press

Smithsonian Institution

Scholarly Press

smithsonian contributions to botany • number 107

Grasses of Chihuahua, 

Mexico

Yolanda Herrera Arrieta

and

Paul M. Peterson

1_S_spiciformis 2_M_tarahumara 3_M_longiligula 4_P_matri-occid... 5_M_rigida 6_F_tolucenisis 7_M_pereilema

b107_sampleCvrFigsContactshtAltOrdr3
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smithsonian contributions to botany • numb e r 1 0 7

Grasses of Chihuahua, 

Mexico

Yolanda Herrera Arrieta

and

Paul M. Peterson

WASHINGTON, D.C.

2018
ABSTRACT

Herrera Arrieta, Yolanda, and Paul M. Peterson. Grasses of Chihuahua, Mexico. Smithsonian Contributions to Botany, 

number 107, x + 380 pages, 246 figures, 1 table, 2018.—Our revision of the grasses of Chihuahua includes 385 species in 

95 genera, 15 subspecies, 29 varieties, and 4 forms. We provide keys for determination, detailed descriptions, nomenclatural synonyms, ecological information on habitat, distribution based on herbarium specimens, and illustrations for 251 

species and 8 varieties. We provide a new combination for Cenchrus polystachios subsp. setosus.

RESUMEN

Herrera Arrieta, Yolanda, and Paul M. Peterson. Grasses of Chihuahua, México. Smithsonian Contributions to Botany, 

número 107, x + 380 páginas, 246 figuras, 1 tabla, 2018.—Nuestra revisión de las gramíneas de Chihuahua incluye 385 

especies en 95 géneros, 15 subespecies, 29 variedades y 4 formas. Se proveen claves para su determinación, descripciones 

detalladas, sinónimos nomenclaturales, información ecológica del hábitat, distribución con base en ejemplares de herbario 

e ilustraciones de 251 especies y 8 variedades. Proporcionamos una nueva combinación para Cenchrus polystachios subsp. 

setosus.

This research was funded, in part, by the 

Consejo Nacional de Ciencia y Tecnología 

del Estado de Durango and 

the Instituto Politécnico Nacional.

Cover images, from left to right: Sporobolus spiciformis spikelet (Figure 235C); Muhlenbergia tarahumara habit (Figure 

178A); M. longiligula floret (Figure 162H); Poa matri-occidentalis subsp. mohinorensis ligule (Figure 207D); M. rigida

inflorescence (Figure 170C); Festuca tolucensis stylized growth form (Figure 124B); M. pereilema portion of inflorescence 

(Figure 167G). 

Published by SMITHSONIAN INSTITUTION SCHOLARLY PRESS

P.O. Box 37012, MRC 957, Washington, D.C. 20013-7012

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Compilation copyright © 2018 Smithsonian Institution

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Library of Congress Cataloging-in-Publication Data

Names: Herrera Arrieta, Yolanda, author. | Peterson, Paul M., author. | Smithsonian Institution Scholarly Press, publisher.

Title: Grasses of Chihuahua, Mexico / Yolanda Herrera Arrieta and Paul M. Peterson.

Other titles: Smithsonian contributions to botany ; number 107. 0081-024X

Description: Washington, D.C. : Smithsonian Institution Scholarly Press, 2018. | Series: Smithsonian contributions to 

botany, ISSN 0081-024X ; number 107 | Includes bibliographical references and index.

Identifiers: LCCN 2017055384

Subjects: LCSH: Grasses—Mexico—Chihuahua (State)—Identification. | Grasses—Mexico—Chihuahua (State)—

Classification.

Classification: LCC QK495.G74 H445 2018 | DDC 584/.92097216—dc23 | SUDOC SI 1.29:107

LC record available at https://lccn.loc.gov/2017055384

ISSN: 1938-2812 (online); 0081-024X (print)

Publication date (online): 10 April 2018

Ó The paper used in this publication meets the minimum requirements of the American National Standard for Permanence 

of Paper for Printed Library Materials Z39.48–1992. 
Contents

LIST OF FIGURES v

INTRODUCTION 1

Synopsis 4

Acknowledgments 4

FAMILY DESCRIPTION: POACEAE 5

KEY TO THE GRASS GENERA OF CHIHUAHUA 5

DESCRIPTIONS 15

REFERENCES 371

INDEX TO SCIENTIFIC NAMES (GRASSES) 375

Figures

1. Municipios in Chihuahua 2

2. Achnatherum curvifolium 16

3. Achnatherum eminens 17

4. Achnatherum hymenoides 18

5. Achnatherum robustum 19

6. Aegilops cylindrica 20

7. Agropyron cristatum 20

8. Agrostis exarata 22

9. Agrostis hyemalis 23

10. Agrostis scabra 24

11. Agrostis stolonifera 25

12. Alopecurus geniculatus 26

13. Andropogon gerardii 27

14. Andropogon glomeratus 28

15. Anthoxanthum odoratum 29

16. Aristida adscensionis 31

17. Aristida arizonica 33

18. Aristida divaricata 33

19. Aristida gypsophila 35

20. Aristida havardii 36

21. Aristida longespica 37

22. Aristida pansa 38

23. Aristida purpurea var. fendleriana 40

24. Aristida purpurea var. longiseta 40

25. Aristida purpurea var. nealleyi 41

26. Aristida purpurea var. perplexa 41

27. Aristida purpurea var. purpurea 42

28. Aristida purpurea var. wrightii 42

29. Aristida schiedeana var. orcuttiana 43

30. Aristida ternipes var. gentilis 45

31. Aristida ternipes var. ternipes 45

32. Arundo donax 46

33. Avena fatua 48
v i • SMITHSONIAN CONTRIBUTIONS TO BOTANY

34. Avena sativa 49

35. Avenella flexuosa 50

36. Bothriochloa barbinodis 52

37. Bothriochloa laguroides var. laguroides 53

38. Bothriochloa springfieldii 55

39. Bothriochloa wrightii 55

40. Bouteloua aristidoides var. aristidoides 59

41. Boutloua barbata var. rothrockii 61

42. Bouteloua breviseta 61

43. Bouteloua curtipendula var. caespitosa 64

44. Bouteloua curtipendula var. curtipendula 65

45. Bouteloua eludens 67

46. Bouteloua eriopoda 68

47. Bouteloua gracilis 69

48. Bouteloua hirsuta var. hirsuta 71

49. Bouteloua parryi 73

50. Bouteloua radicosa 74

51. Bouteloua ramosa 75

52. Bouteloua repens 75

53. Bouteloua simplex 77

54. Bouteloua trifida 78

55. Bouteloua uniflora 78

56. Bromus anomalus 81

57. Bromus catharticus 83

58. Bromus frondosus 84

59. Bromus japonicus 85

60. Bromus richardsonii 87

61. Bromus tectorum 87

62. Cenchrus americanus 90

63. Cenchrus ciliaris 90

64. Cenchrus clandestinus 91

65. Cenchrus echinatus 93

66. Cenchrus myosuroides 94

67. Cenchrus polystachios 95

68. Cenchrus spinifex 96

69. Chloris gayana 98

70. Chloris submutica 99

71. Chloris virgata 100

72. Cortaderia selloana 101

73. Cynodon dactylon 103

74. Dactylis glomerata 105

75. Dactyloctenium aegyptium 106

76. Dasyochloa pulchella 106

77. Deschampsia danthonioides 108

78. Deschampsia elongata 112

79. Digitaria bicornis 112

80. Digitaria californica 113

81. Digitaria ciliaris 114

82. Digitaria sanguinalis 116

83. Dinebra panicea subsp. brachiata 119

84. Diplachne fusca subsp. fusca 121

85. Disakisperma dubium 123

86. Distichlis spicata 125

87. Echinochloa colona 127
NUMBER 107 • vii

88. Echinochloa crus-galli 129

89. Echinochloa crus-pavonis 130

90. Echinochloa muricata 131

91. Echinochloa oplismenoides 132

92. Echinochloa walteri 133

93. Eleusine indica 134

94. Elymus elymoides subsp. brevifolius 138

95. Elymus trachycaulus 140

96. Enneapogon desvauxii 141

97. Eragrostis barrelieri 144

98. Eragrostis cilianensis 145

99. Eragrostis ciliaris 146

100. Eragrostis curvula 147

101. Eragrostis echinochloidea 148

102. Eragrostis erosa 149

103. Eragrostis intermedia 150

104. Eragrostis lehmanniana 151

105. Eragrostis lugens 152

106. Eragrostis mexicana subsp. mexicana 153

107. Eragrostis palmeri 154

108. Eragrostis pectinacea var. pectinacea 156

109. Eragrostis pilosa 157

110. Eragrostis secundiflora subsp. oxylepis 158

111. Eragrostis sessilispica 159

112. Eragrostis spectabilis 160

113. Eragrostis superba 161

114. Eriochloa aristida 163

115. Eriochloa contracta 164

116. Eriochloa lemmonii 165

117. Eriochloa punctata 166

118. Erioneuron avenaceum 167

119. Erioneuron nealleyi 167

120. Erioneuron pilosum 168

121. Festuca amplissima 170

122. Festuca octoflora 172

123. Festuca rubra 173

124. Festuca tolucensis 174

125. Glyceria borealis 176

126. Glyceria striata 177

127. Hackelochloa granularis 178

128. Hesperostipa neomexicana 179

129. Heteropogon contortus 180

130. Hilaria mutica 183

131. Hilaria rigida 184

132. Holcus lanatus 185

133. Hopia obtusa 186

134. Hordeum murinum 188

135. Hordeum vulgare 189

136. Imperata brevifolia 190

137. Kalinia obtusiflora 191

138. Koeleria pyramidata 192

139. Lasiacis ruscifolia 193

140. Leersia hexandra 194

141. Lolium arundinaceum 196
viii • SMITHSONIAN CONTRIBUTIONS TO BOTANY

142. Lolium multiflorum 196

143. Lolium perenne 197

144. Luziola fluitans 198

145. Melica montezumae 200

146. Melica porteri 200

147. Melinis repens 201

148. Muhlenbergia alopecuroides 211

149. Muhlenbergia uniseta, M. arenacea 213

150. Muhlenbergia arenicola 214

151. Muhlenbergia argentea, M. lucida 215

152. Muhlenbergia arizonica 216

153. Muhlenbergia asperifolia 217

154. Muhlenbergia brevis 219

155. Muhlenbergia capillipes 220

156. Muhlenbergia crispiseta, M. peruviana 222

157. Muhlenbergia depauperata 224

158. Muhlenbergia diversiglumis, M. implicata 225

159. Muhlenbergia palmeri, M. dubia 227

160. Muhlenbergia dumosa 228

161. Muhlenbergia majalcensis, M. elongata 229

162. Muhlenbergia lindheimeri, M. longiligula, M. emersleyi 231

163. Muhlenbergia flavida, M. schmitzii 234

164. Muhlenbergia fragilis 236

165. Muhlenbergia scoparia, M. gigantea 238

166. Muhlenbergia glauca, M. polycaulis 239

167. Muhlenbergia microsperma, M. pereilema 245

168. Muhlenbergia minutissima 246

169. Muhlenbergia montana 247

170. Muhlenbergia rigida, M. mucronata 250

171. Muhlenbergia pauciflora 251

172. Muhlenbergia phleoides 254

173. Muhlenbergia porteri 257

174. Muhlenbergia ramulosa 260

175. Muhlenbergia repens, M. utilis 261

176. Muhlenbergia rigens 263

177. Muhlenbergia sinuosa 268

178. Muhlenbergia tarahumara 270

179. Muhlenbergia tenuifolia 271

180. Muhlenbergia texana 273

181. Muhlenbergia torreyi 275

182. Muhlenbergia virescens 278

183. Muhlenbergia wrightii 280

184. Munroa squarrosa 281

185. Panicum hallii 286

186. Panicum hirticaule var. hirticaule 288

187. Panicum plenum 289

188. Panicum trichoides 289

189. Panicum virgatum 290

190. Paspalum convexum 293

191. Paspalum distichum 294

192. Paspalum plicatulum 295

193. Paspalum pubiflorum 296

194. Paspalum setaceum 297

195. Phalaris angusta 300
NUMBER 107 • i x

196. Phalaris aquatica 301

197. Phalaris arundinacea 301

198. Phalaris canariensis 302

199. Phalaris caroliniana 303

200. Phalaris paradoxa 304

201. Phragmites australis 306

202. Piptochaetium fimbriatum 306

203. Piptochaetium pringlei 307

204. Poa annua 310

205. Poa bigelovii 310

206. Poa fendleriana subsp. fendleriana, P. f. subsp. albescens 312

207. Poa matri-occidentalis, P. m.-o. subsp. mohinorensis 314

208. Poa pratensis 315

209. Poa strictiramea 316

210. Polypogon elongatus 318

211. Polypogon monspeliensis 318

212. Polypogon viridis 319

213. Schizachyrium cirratum 322

214. Schizachyrium sanguineum 323

215. Schizachyrium scoparium var. scoparium 324

216. Schizachyrium tenerum 325

217. Scleropogon brevifolius 326

218. Setaria leucopila 328

219. Setaria macrostachya 329

220. Setaria parviflora 330

221. Setaria pumila 331

222. Setaria viridis 332

223. Sorghastrum nutans 335

224. Sorghum bicolor 337

225. Sorghum halepense 337

226. Sphenopholis obtusata 338

227. Sporobolus airoides subsp. airoides 340

228. Sporobolus alterniflorus 341

229. Sporobolus contractus 342

230. Sporobolus cryptandrus 343

231. Sporobolus flexuosus 344

232. Sporobolus giganteus 345

233. Sporobolus indicus 346

234. Sporobolus pyramidatus 347

235. Sporobolus spiciformis 348

236. Sporobolus wrightii 349

237. Thinopyrum intermedium 351

238. Tridentopsis mutica var. mutica 355

239. Tripsacum dactyloides 357

240. Tripsacum lanceolatum 358

241. Trisetum spicatum 360

242. Triticum aestivum 363

243. Urochloa plantaginea 365

244. Zea mays subsp. mays 367

245. Zea mays subsp. mexicana 368

246. Zuloagaea bulbosa 368

Grasses of Chihuahua, Mexico

Yolanda Herrera Arrieta1 and Paul M. Peterson2*

1

 Instituto Politécnico Nacional, Centro Interdisciplinario de Investigación para el Desarrollo 

Integral Regional (CIIDIR) Unidad Durango, 

Sigma 119, Fracción 20 de Novembre II, Durango, Durango 34220, Mexico.

2

 Department of Botany, National Museum of 

Natural History, Smithsonian Institution, MRC166, P.O. Box 37012, Washington, D.C. 20013-

7012, USA. 

* Correspondence: peterson@si.edu

Manuscript received 26 October 2016; accepted 

28 March 2017.

INTRODUCTION

Chihuahua is the largest state in Mexico, occupying 12.6% of the total area, and 

is bounded by the meridians 31.78333° and 25.63333° north and 103.30000° and 

109.11667° west. Chihuahua is divided into 67 municipios [municipalities] (Figure 1, 

Table 1). The state includes portions of three natural ecoregions: the Sierra Madre Occidental (SMO) pine–oak woodlands, which contain extensive grasslands; the Chihuahuan 

Desert grassland, which is considered a center of origin and diversification for plant 

and animal species; and a smaller area west of the SMO called the Sonoron–Sinaloan 

transition subtropical dry forests (LeSueur, 1945; Olson et al., 2001). The SMO and Chihuahuan Desert regions include species that have both northern and southern affinities 

whereas the Sonoron-Sinaloan transition subtropical forests are represented by species 

with primarily southern neotropical affinities (Axelrod, 1979; Rzedowski, 1993).

Twenty-one herbaria were visited and specimens were verified before inclusion in the 

Specimens Examined sections. Specimen data provided in these sections are reproduced 

from specimen labels. The herbaria abbreviations are as follows: 

ANSM Universidad Autónoma Agraria Antonio Narro, Saltillo, Mexico

ARIZ University of Arizona, Tucson, Arizona, USA

CAN Canadian Museum of Nature, Ottawa, Ontario, Canada

CAS California Academy of Sciences, San Francisco, California, USA

CHAPA Colegio de Posgraduados, Chapingo, Mexico

CIIDIR Centro Interdisciplinario de Investigación para el Desarrollo Integral 

Regional, Instituto Politécnico Nacional, Durango, Mexico

ENCB Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, 

Mexico City, Distrito Federal, Mexico

IBUG Universidad de Guadalajara, Jalisco, Mexico

INEGI Instituto Nacional de Estadistica y Geografia, Aguascalientes, Mexico

NMC New Mexico State University, Las Cruces, New Mexico, USA

MEXU Universidad Nacional Autónoma de México, Mexico City, Distrito Federal, 

Mexico

MO Missouri Botanical Garden, St. Louis, Missouri, USA

RELC Rancho Experimental La Campana, INIFAP-SAGAR, Chihuahua, Mexico

RSA Rancho Santa Ana Botanic Garden, Claremont, California, USA

SLPM Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico

TAES S. M. Tracy Herbarium, Texas A & M University, College Station, Texas, 

USA

TEX University of Texas at Austin, Austin, Texas, USA

UACH Universidad Autónoma de Chihuahua, Chihuahua, Mexico

UACJ Universidad Autónoma de Ciudad Juárez, Ciudad Juárez, Chihuahua, 

Mexico
2 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

FIGURE 1. Location of Municipios in Chihuahua, Mexico. Municipio number is given in Table 1; color as indicated in legend represents elevation in meters. Map provided by Y. Herrera-Arrieta.
NUMBER 107 • 3

UAMIZ Universidad Autónoma Metropolitana, Mexico 

City, Distrito Federal, Mexico 

US United States National Herbarium, National 

Museum of Natural History, Smithsonian 

Institution, Washington D.C., USA

For the grasses of Cascada de Basaseachi and adjacent 

areas, Spellenberg et al. (1996) lists 85 grass species of which 25 

now occur in Muhlenbergia Schreb. Lebgue and Valerio (1986) 

included 291 grass species for Chihuahua of which 51 now occur 

in Muhlenbergia. Valdés Reyna (1977) included 314 grass species in 87 genera for Chihuahua of which 59 species now occur 

in Muhlenbergia. Our current treatment includes 385 grass species for Chihuahua of which 78 occur in Muhlenbergia. Muhlenbergia is the most diverse grass genus in Mexico, and its center 

of diversity lies within the state of Chihuahua. This is perhaps a 

reflection of the number of different habitats that are found in 

the state and the adaptive ability of the Muhlenbergia to colonize 

these habitats.

The following 68 grasses (17.7% of total) are introduced 

in Chihuahua (marked with an asterisk [*] within the description): Agropyron cristatum, Agrostis stolonifera var. palustris, 

Alopecurus geniculatus, Anthoxanthum odoratum, Arundo 

donax, Avena fatua, A. sativa, Bromus catharticus, B. japonicus, 

B. tectorum, Cenchrus americanus, C. ciliaris, C. clandestinus, 

C. echinatus, C. polystachios, Chloris gayana, Cortaderia selloana, Cynodon dactylon, Dactylis glomerata, Dactyloctenium 

aegyptium, Dichanthium annulatum, Digitaria sanguinalis, 

Echinochloa colona, E. crus-galli, Eleusine indica, E. multiflora, Elymus repens, Eragrostis barrelieri, E. cilianensis, E. ciliaris, E. curvula, E. echinochloidea, E. lehmanniana, E. pilosa, 

E. superba, Eriochloa contracta, Festuca myuros, Hackelochloa 

granularis, Heteropogon contortus, H. melanocarpus, Holcus 

lanatus, Hordeum murinum, H. vulgare, Lolium arundinaceum, 

L. multiflorum, L. perenne, Melinis repens, Panicum antidotale, 

P. dichotomiflorum, Phalaris aquatica, P. canariensis, P. paradoxa, Poa annua, Polypogon monspeliensis, P. viridis, Schismus 

arabicus, S. barbatus, Setaria adhaerens, S. pumila, S. verticillata, S. viridis, Sorghum bicolor, S. halepense, Stenotaphrum 

secundatum, Thinopyrum intermedium, Tragus berteronianus, 

Triticum aestivum, and Urochloa plantaginea. 

The following 17 species are cultivated as food for humans 

(+) or livestock (++) or as ornamentals (+++): Avena sativa (+, 

++), Bouteloua curtipendula (++), B. gracilis (++), Cenchrus 

ciliaris (++), C. clandestinus (+++), Cortaderia selloana (+++), 

Disakisperma dubium (++), Eragrostis curvula (++), E. superba

(++), Hordeum vulgare (+, ++), Lolium multiflorum (++), L. perenne (++), Panicum virgatum (++), Phalaris canariensis (++), 

Sorghum bicolor (++), Triticum aestivum (+), and Zea mays

subsp. mays (+, ++) (Esqueda Coronado et al., 2005; Saenz 

Flores et al., 2015). 

There are six endemic grass species and one subspecies 

known only from Chihuahua: Bouteloua chihuahuana, Festuca 

dichlina, Muhlenbergia argentea, M. decumbens, M. majalcensis, Poa matri-occidentalis subsp. mohinorensis, and Triniochloa laxa.

With the infusion of molecular data, the present concept 

and classification of the grasses is changing at a rapid rate. We 

follow the grass classification presented in Soreng et al. (2017a, 

2017b) and Peterson et al. (2014a, 2016, 2017), which consists 

TABLE 1. Municipios [municipalities] of Chihuahua.

Number for Number for

municipio Municipio municipio Municipio

001 Ahumada 035 Janos

002 Aldama 036 Jiménez

003 Allende 037 Juárez

004 Aquiles Serdán 038 Julimes

005 Ascensión 039 López

006 Bachíniva 040 Madera

007 Balleza 041 Maguarichi

008 Batopilas 042 Manuel 

Benavides

009 Bocoyna 043 Matachí

010 Buenaventura 044 Matamoros

011 Camargo 045 Meoqui

012 Carichí 046 Morelos

013 Casas Grandes 047 Moris

014 Coronado 048 Namiquipa

015 Coyame del Sotol 049 Nonoava

016 La Cruz 050 Nuevo Casas 

Grandes

017 Cuauhtémoc 051 Ocampo

018 Cusihuiriachi 052 Ojinaga

019 Chihuahua 053 Praxedis G. 

Guerrero

020 Chínipas 054 Riva Palacio

021 Delicias 055 Rosales

022 Belisario 056 Rosario

Domínguez

023 Galeana 057 San Francisco 

de Borja

024 Santa Isabel 058 San Francisco 

de Conchos

025 Gómez Farías 059 San Francisco 

del Oro

026 Gran Morelos 060 Santa Bárbara

027 Guachochi 061 Satevó

028 Guadalupe 062 Saucillo

029 Guadalupe y Calvo 063 Temósachic

030 Guazapares 064 El Tule

031 Guerrero 065 Urique

032 Hidalgo del Parral 066 Uruachi

033 Huejotitán 067 Valle de Zaragoza

034 Ignacio Zaragoza
4 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

of ±11,506 species in 768 genera found in 12 subfamilies, 52 

tribes, and 94 subtribes. Below we provide a synopsis of the classification for all grass genera that occur in Chihuahua.

Synopsis

The following list is a synopsis of the classification of the 

genera into subfamily, tribe, and subtribe for the grasses of Chihuahua, Mexico.

subfamily Aristidoideae

tribe Aristideae: Aristida

subfamily Arundinoideae

tribe Arundineae: Arundo

tribe Molinieae: Phragmites

subfamily Bambusoideae

tribe Bambuseae

 subtribe Guaduinae: Otatea

subfamily Chloridoideae

tribe Cynodonteae 

 subtribe Boutelouinae: Bouteloua

 subtribe Dactylocteninae: Dactyloctenium

 subtribe Eleusininae: Chloris, Cynodon, Dinebra, 

Diplachne, Disakisperma, Eleusine, 

Leptochloa

 subtribe Gouiniinae: Tridentopsis

 subtribe Hilariinae: Hilaria

 subtribe Kaliniinae: Kalinia 

 subtribe Monanthochloinae: Distichlis

 subtribe Muhlenbergiinae: Muhlenbergia

 subtribe Pappophorinae: Pappophorum, Tridens

 subtribe Scleropogoninae: Dasyochloa. 

Blepharidachne, Erioneuron, Munroa, 

Scleropogon

 subtribe Traginae: Tragus

tribe Eragrostidieae

 subtribe Cotteinae: Cottea, Enneapogon

 subtribe Eragrostidinae: Eragrostis

tribe Zoysieae

 subtribe Sporobolinae: Sporobolus

subfamily Danthonioideae

tribe Danthonieae: Cortaderia, Schismus

subfamily Oryzoideae

tribe Oryzeae

 subtribe Oryzinae: Leersia

 subtribe Zizaniinae: Luziola

subfamily Panicoideae

tribe Andropogoneae 

 subtribe Andropogoninae: Andropogon,

Bothriochloa, Dichanthium, 

Heteropogon, Schizachyrium

 subtribe Rottboelliinae: Hackelochloa

 subtribe Saccharinae: Imperata, Sorghastrum, 

Sorghum, Trachypogon

 subtribe Tripsacinae: Elionurus, Tripsacum, Zea

tribe Paniceae

 subtribe Anthephorinae: Digitaria

 subtribe Boivinellinae: Echinochloa, Lasiacis, 

Oplismenus

 subtribe Cenchrinae: Cenchrus, Setaria, 

Setariopsis, Stenotaphrum, Zuloagaea

 subtribe Melinidinae: Chaetium, Eriochloa, 

Melinis, Urochloa

 subtribe Panicinae: Panicum

tribe Paspaleae

 subtribe Paspalinae: Hopia, Paspalum

subfamily Poiodeae

tribe Bromeae: Bromus

tribe Meliceae: Glyceria, Melica, Triniochloa

tribe Poeae

 subtribe Agrostidinae: Agrostis, Calamagrostis, 

Polypogon

 subtribe Airinae: Avenella

 subtribe Alopecurinae: Alopecurus

 subtribe Anthoxanthinae: Anthoxanthum

 subtribe Aristaveninae: Deschampsia

 subtribe Aveninae: Avena, Koeleria, Peyritschia, 

Sphenopholis, Trisetum

 subtribe Dactylidinae: Dactylis

 subtribe Holcinae: Holcus

 subtribe Loliinae: Festuca, Lolium

 subtribe Phalaridinae: Phalaris

 subtribe Poinae: Poa 

tribe Stipeae: Achnatherum, Hesperostipa, Nassella, 

Piptochaetium

tribe Triticeae: Aegilops, Agropyron, Elymus, 

Hordeum, Thinopyrum, Triticum

Acknowledgments

We thank the Instituto Politécnico Nacional (SIP-20091209, 

SIP-20100879), Consejo Nacional de Ciencia y Tecnología del 

Estado de Durango, and La Comisión Nacional para el Conocimiento y Uso de la Biodiversidad (GE003) for financial support. The U.S. National Herbarium, Department of Botany, 

National Museum of Natural History, Smithsonian Institution, 

is thanked for providing YHA work space in the U.S. National 

Herbarium. We thank the National Geographic Society Committee for Research and Exploration (Grant No. 8848-10, 8087-06) 

for field and laboratory support. For financial support we thank 

the Smithsonian Institution’s Restricted Endowments Fund, the 

Scholarly Studies Program, Research Opportunities, Atherton Seidell Foundation, Biodiversity Surveys and Inventories Program, 

Small Grants Program, the Laboratory of Analytical Biology, and 

the U.S. Department of Agriculture. We also thank Konstantin 

Romaschenko and Jeffery M. Saarela for accompanying PMP on 

numerous field expeditions; Robert J. Soreng for many extended 

discussions pertinent to the manuscript, especially regarding 
NUMBER 107 • 5

nomenclature; Utah State University for permission to pay for use 

of 223 illustrations that appeared in the Flora of North America,

Volumes 24 and 25; Socorro Gonzalez Elizondo for help generating our list of cultivated grasses; and Patricia Dávila, Emmet 

J. Judziewicz, Teresa Mejia Saulés, and Ana Soriano for critical 

review and suggestions for improvement to the manuscript. 

FAMILY DESCRIPTION: POACEAE

Annual or perennial; usually terrestrial, sometimes aquatic; 

tufted, mat-forming, caespitose, pluricaespitose, or with solitary culms (flowering stems); rhizomes and stolons often welldeveloped. Culms annual or perennial, herbaceous or woody, 

usually erect or ascending, sometimes prostrate or decumbent 

for much of their length, occasionally climbing, rarely floating; 

nodes prominent, sometimes concealed by the sheaths; internodes hollow or solid, bases meristematic; branching from the 

basal nodes only or from the basal, middle, and upper nodes; 

basal branching extravaginal or intravaginal; branching from the 

upper nodes intravaginal, extravaginal, or infravaginal. Leaves

alternate, 2-ranked, each composed of a sheath and blade encircling the culm or branch; sheaths usually open, sometimes 

closed, the margins fused for all or part of their length; auricles

(lobes of tissue extending beyond the margins of the sheaths 

on either side) sometimes present; ligules usually present at the 

sheath–blade junction, particularly on the adaxial surface, abaxial ligules common in the Bambusoideae, membranous, sometimes ciliate, adaxial ligules usually present, of membranous to 

hyaline tissue, a line of hairs, or a ciliate membrane; blades usually linear to lanceolate, occasionally ovate to triangular, bases 

sometimes pseudopetiolate (having a petiole-like constriction), 

venation usually parallel, sometimes with evident cross veins, 

occasionally divergent. Inflorescences (synflorescences) usually compound, composed of simple or complex aggregations 

of primary inflorescences, aggregations paniculate, spicate, or 

racemose or of spikelike branches, often with an evident rachis

(central axis), primary inflorescences spikelets, pseudospikelets, 

or spikelet equivalents; inflorescence branches usually without 

obvious bracts. Spikelets with (0–1)2(3–6) glumes (empty bracts) 

subtending 1–60 florets, glumes and florets distichously attached 

to a rachilla (central axis); pseudospikelets with bud-subtending 

bracts below the glumes. Glumes usually with an odd number 

of veins, sometimes awned. Florets bisexual, staminate, or pistillate, usually composed of a lemma (lower bract) and palea

(upper bract), lodicules, and reproductive organs, often laterally 

or dorsally compressed, sometimes round in cross section; lemmas usually with an odd number of veins, often awned, bases 

frequently thick and hard, forming a callus, backs rounded or 

keeled over the midvein, awns usually 1(3), arising basally to 

terminally; paleas usually with 2 major veins, with 0 to many 

additional veins between the major veins, sometimes also in the 

margins, often keeled over the major veins; lodicules (0)2–3, inconspicuous, usually without veins, bases swelling at anthesis; 

stamens usually 3, sometimes 1(2) or 6+, filaments capillary, 

anthers versatile, usually all alike within a floret, sometimes 1 

or 2 evidently longer than the others; ovaries 1-loculed, with 

(1)2–3(4) styles or style branches, stigmatic region usually plumose. Fruits caryopsis, pericarp usually dry and adhering to the 

seed, sometimes fleshy or dry and separating from the seed at 

maturity or when moistened; embryos 1⁄5 as long as to almost 

equaling the caryopsis, highly differentiated with a scutellum

(absorptive organ), a shoot with leaf primordium covered by the 

coleoptile (shoot sheath), and a root covered by the coleorhiza

(root sheath); hila punctate to linear. Base chromosome number, 

x = 5, 6, 7, 9, 10, 11, 12.

KEY TO THE GRASS GENERA OF CHIHUAHUA

1. Plants generally lignified; culms height 2 m or more.

2. Culms solid or hard-walled and thick; nodes producing generally 3 branches; foliage leaves pseudopetiolate . . . Otatea

2. Culms hollow, thin-walled; nodes producing generally 2 branches; leaf blades narrow-linear, never pseudopetiolate.

3. Inflorescence an ovoid panicle, diffuse, 10–30 cm long; spikelets 3–4.7 mm long, globose, with 2 florets, 1 fertile and 

1 sterile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lasiacis

3. Inflorescence a plumose panicle, dense, 40–60 cm long; spikelets 10–15 mm long, compressed, with (2)3–9 fertile 

florets.

4. Lemma pilose with spreading hairs that are long and silky; rachilla hairless; blades strongly cordate-auriculate 

basally . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Arundo

4. Lemma glabrous; rachilla pilose with long, silky hairs; blades narrow basally . . . . . . . . . . . . . . . . . . Phragmites

1. Plants generally herbaceous; culms height less than 2 m, occasionally up to 4 m tall (in Tripsacum).

5. Spikelets unisexual, staminate appreciably different from pistillate.

6. Plants monoecious, staminate and pistillate spikelets in the same plant.

7. Staminate and pistillate spikelets in the same inflorescence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tripsacum

7. Staminate and pistillate spikelets in separate inflorescences.

8. Aquatic plants, submerged, floating leaves over water surface; plants 10–40 cm tall, perennial, stamens 6–8

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Luziola

8. Terrestrial plants; plants 100–500 cm tall, annuals, stamens 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Zea
6 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

6. Plants dioecious, staminate and pistillate spikelets in separate plants.

9. Key to pistillate plants.

10. Lemmas and reduced florets of pistillate spikelets awnless.

 11. Pistillate spikelets surrounded by a “false involucre,” formed by hardened glumes united at base; inflorescences not terminal and partially hidden by the sheath . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bouteloua

 11. Pistillate spikelets without a “false involucre”; inflorescences terminal . . . . . . . . . . . . . . . . . . Distichlis

10. Lemmas and reduced florets of pistillate spikelets conspicuously awned . . . . . . . . . . . . . . . . . . Scleropogon

9. Key to staminate plants.

12. Inflorescence a pectinate spike, with spikelets inserted at the side of the rachis; glumes obtuse to short 

acuminate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bouteloua

12. Inflorescence not pectinate; glumes long acuminate to an acute or awned apex.

 13. Glumes and lemma strongly carinate, acute, the glumes 2⁄3 as long as basal lemma; leaves clearly distichously arranged . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Distichlis

 13. Glumes and lemma not carinate, long acuminate, glumes almost as long as the basal lemmas, leaves not 

distichously arranged . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Scleropogon

5. Spikelets usually perfect, or if unisexual, then staminate spikelets not very different from the pistillate.

14. Spikelets involucrate, in groups of 2–3(5); sometimes (in Hordeum) lateral spikelets reduced to awns.

 15. Spikelets with thorns, or with an involucre of bristles or spines; awns absent.

 16. Upper glume of the lower spikelets equipped with hooked spines over the veins; involucre absent 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tragus

 16. Upper glume without spines; involucre present of spines or bristles . . . . . . . . . . . . . . . . . . . . . . . Cenchrus

 15. Spikelets without thorns and lacking an involucre of spines or bristles; awns usually present.

 17. Spikelets surrounded by “false involucres” composed of glumes united at base, the false involucre 4- to 

6-lobed.

 18. Inflorescence with short-pedicelled spikes, partially included in the upper sheaths, or false involucres whitish, lacking glands; florets pistillate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bouteloua

 18. Inflorescence a terminal, notably exserted spiciform raceme, often with blackish glands; florets perfect 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hilaria

 17. Spikelets without a “false involucre” composed of hardened glumes, united at base.

 19. Spikelets in capitate involucres, subsessile spikelets in “hardly leaved portions” of short plants (culms 

3–10 cm), hidden by wide sheaths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Munroa

 19. Spikelets not in capitate involucres, inflorescences of another form, or if in involucres, then wellexserted.

 20. Spikelets densely crowded in symmetrical spikes, disposed at both sides of the rachis; lemmas usually 

with awns 1–3 cm long.

21. Spikelets 3 per node, with 1 floret, the lateral ones pedicelled, usually reduced to awns; plants 

strictly annual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hordeum

21. Spikelets 1 to 3 per node, with 2 similar florets; plants perennial.

22. Glumes and lemmas stiff and thick, indurate to coriaceous; lemmas mostly awnless or if 

awned, then the awns to 5 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thinopyrum

22. Glumes not so stiff and thick, lemmas awned, awns 10–40 mm (2–4[10] mm long in 

E. repens) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Elymus

 20. Spikelets crowded frequently on unilateral spikes or racemes, occasionally disposed on both sides 

of the rachis (but then the inflorescence loose); lemmas with awns less than 1 cm long, sometimes 

awnless.

23. Inflorescence dimorphic; lateral spikelets staminate, 2-flowered, central spikelet 3-flowered; first 

floret perfect, short stipitate, the lateral florets staminate or sterile . . . . . . . . . . . . . . . Bouteloua

23. Inflorescences monomorphic, spikelets all 1-flowered or 2- to 3(4)-flowered, the florets 

dimorphic.

24. Spikelets 1-flowered, the central perfect, the laterals staminate or neutral; glumes oblong to 

oblong-obovate with a short terminal awn . . . . . . . . . . . . . . . . . . . . . . . . . . Muhlenbergia

24. Spikelets 2- to 3(4)-flowered, with 1 perfect floret and 1 to several staminate or sterile 

florets, long-awned or reduced to awns; glumes variably shaped, short-awned, mucronate, or 

awnless . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bouteloua
NUMBER 107 • 7

14. Spikelets not involucrate.

 25. Spikelets with 1 perfect floret, or if dioecious, plants then with 1 staminate or pistillate functional floret, additional 

reduced florets present or absent.

 26. Spikelets arranged in pairs, 1 sessile and another pedicelled, the pedicelled spikelet staminate, neutral or reduced, 

sometimes represented by only the pedicel; lower glume large and firm, enclosing the second within its margins; 

lemma of perfect florets membranous, slender, often awned.

 27. Spikelets all alike and perfect.

 28. Spikelets unawned; panicle densely silky, with long hairs surrounding the base of the spikelets. 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Imperata

 28. Spikelets awned.

 29. Rachis readily breaking up into joints; pedicel often tipped by a rudimentary spikelet; panicle often 

white-pilose, commonly with few branches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Andropogon

 29. Rachis continuous; pedicel never with a rudimentary floret; panicle yellow to golden brown, usually 

with numerous branches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sorghastrum

 27. Spikelets not all alike and perfect, the pedicellate ones (sometimes some of the sessile ones) staminate or neuter.

 30. Spikelets all awnless.

 31. Spikelets sessile, globose; lower glume ornamented, black, rough; plants annual; inflorescences 

1–2 cm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hackelochloa

 31. Spikelets sessile, not globose; lower glume never ornamented, stramineous, smooth; plants perennial; 

inflorescences 5–15 cm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Elionurus

 30. Spikelets awned, at least some of them.

 32. Awns at least (2.5)3 cm long.

 33. Pedicelled spikelets awned, perfect; sessile (to subsessile) spikelets staminate or neutral, awnless

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Trachypogon

 33. Pedicelled spikelets awnless, staminate or neutral; sessile spikelets perfect, awned.

34. Sessile spikelet dorsally compressed; callus obtuse . . . . . . . . . . . . . . . . . . . . . Dichanthium

34. Sessile spikelet cylindrical; callus enlarged, sharp, oblique . . . . . . . . . . . . . . . . Heteropogon

 32. Awns at most 2.5 cm long, or missing.

 35. Branches of the panicle numerous, freely branched, not conspicuously spiciform.

36. Pedicelled spikelets reduced, represented by a pedicel; sessile spikelet usually hispidulous

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sorghastrum

36. Pedicelled spikelets nearly the same size as sessile ones, staminate or sometimes neutral; 

sessile spikelets glabrous, hirsute or appressed-hispidulous . . . . . . . . . . . . . . . . . . Sorghum

 35. Branches of the panicle 1 to several, not branched or sparsely so, apparently spiciform.

37. Inflorescence a spike, slender, partially enclosed by a sheath in the way of spathe; pedicels and 

rachis internodes clavate, spongy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Schizachyrium

37. Inflorescence a spreading panicle, with 2 to several racemose spikes; pedicels and rachis 

internodes not clavate or spongy.

38. Rachis internodes and pedicels with a central narrow groove, hyaline and translucent; 

racemes 4 or more, digitate or subdigitate, not spatheate . . . . . . . . . . . . . Bothriochloa

38. Rachis internodes and pedicel without a central translucent groove; racemes 2 or 3, 

digitate, spatheate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Andropogon

 26. Spikelets arranged in pairs or not, if in pairs, then pedicelled spikelets not reduced, and the lower glumes not 

longer and firmer than the lemma of the perfect florets.

 39. Spikelets laterally compressed.

 40. Inflorescence of 1 or more spikes or racemes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Oplismenus

 40. Inflorescence a dense or open panicle.

 41. Leaves pubescent; florets 2, the lower perfect, awnless, the upper floret staminate with a short, 

hooked awn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Holcus

 41. Leaves glabrous; floret solitary, perfect, awned from below middle . . . . . . . . . . . . . . . . Alopecurus

 39. Spikelets dorsally compressed.

 42. Reduced floret present, placed below the fertile floret, represented by a lemma similar to the upper glume 

in size and texture (with or without palea), spikelet frequently appearing to have 3 glumes; disarticulating below the glumes (spikelets falling entire at maturity).
8 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

 43. Spikelets subtended by 1 to many bristles or flattened spines; bristles or spines forming an involucre, 

fused or not fused.

44. Bristles united at base or a little (1⁄5) above the base, forming a cup-shaped receptacle, subspherical, falling with the spikelets at maturity, thorny and hard or softly feathery . . . . . . . Cenchrus

44. Bristles totally free, persistent, usually up to 3 mm long, not falling with the spikelets at maturity, 

never feathery.

45. Sterile lemma narrower than upper glume, ovate to orbiculate, with undulate or contoured 

base and narrow apex, a bristle present below each spikelet, but this is sometimes missing 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Setariopsis

45. Sterile lemma similar to upper glume, ovate; 1 or several bristles below each spikelet, or partially missing in the panicle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Setaria

 43. Spikelets not subtended by bristles or flattened spines; bristles or flattened spines not present.

46. Inflorescence with spikelets appressed to and partially embedded in the flattened, corky rachises; 

upper glume present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stenotaphrum

46. Inflorescence not as above, or if so, then the upper glume always absent.

47. Spikelets awned.

48. Lower glume awnless.

49. Upper glume sometimes mucronate; pedicels, upper glume, and lemma with silky hairs, 

pink changing to white at maturity; weeds introduced in arid places . . . . . . . Melinis

49. Upper glume short-awned; pedicels, upper glumes and lemma scabrous and without 

silky hairs; native aquatic plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Echinochloa

48. Lower glumes awned.

50. Awns of both glumes similar sized . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chaetium

50. Awn of lower glume 3 times longer than the body of the spikelet, awn of the upper 

glume shorter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Oplismenus

47. Spikelets awnless or the upper glume sometimes mucronate.

51. Lemma of perfect floret slender and flexible, its margins extended, membranous, not 

inrolled over the palea, even when partially covering it; lower glume small or absent.

52. Inflorescences with 2 or several spiciform, spikelike branches . . . . . . . . . . Digitaria

52. Inflorescences with numerous spreading branches, paniculate.

53. Panicle spreading, dense; pedicels and spikelets with silky hairs, dense, pinkish, 

5–6 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Melinis

53. Panicle very diffuse; pedicels glabrous; upper glume and lemma sterile with 

sparsely silky hairs, appressed, 1–2 mm long . . . . . . . . . Digitaria (D. cognata)

51. Lemma of perfect floret relatively hardened, its margins rolled on the palea; lower glume 

present or absent.

54. Lower glume missing in some or all spikelets.

55. Fertile lemma often with a terminal mucro; spikelets with a thickened callus in 

a ring or cup shape at the base, dorsally compressed; back of the sterile lemma 

oriented toward the rachis of the inflorescence . . . . . . . . . . . . . . . . . Eriochloa

55. Fertile lemma usually not mucronate; spikelets without a thickened callus shaped 

as a ring or cup, in pairs or solitary, typically plano-convex; back of the upper 

glume and fertile lemma oriented toward the rachis of the inflorecence . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Paspalum

54. Lower glume present in all spikelets.

56. Dorsal side of the fertile lemma facing away from the rachis; spikelets solitary; 

fertile lemma whitish, finely wrinkled or reticulate at maturity . . . . . . Urochloa

56. Dorsal side of the fertile lemma (in most of the spikelets) turned toward the 

rachis; spikelets in pairs or solitary; fertile lemma smooth, not rough or reticulate 

(except in Zuloagaea bulbosa).

57. Primary branches of the inflorescence simple, unbranched; fertile lemma 

smooth, shiny . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Echinochloa

57. Primary branches of the inflorescence (at least some of them) branched; fertile 

lemma smooth to slightly roughened.
NUMBER 107 • 9

58. Fertile lemma and palea with a tuft of hairs at the apex; woody stems 

bamboo-like, often climbing . . . . . . . . . . . . . . . . . . . . . . . . . . . Lasiacis

58. Fertile lemma and palea without a tuft of hairs at the apex; stems herbaceous, erect.

59. Terminal inflorescences with chasmogamous spikelets flowering first, 

axillary inflorescences with clesitogamous spikelets, smaller, laterflowering; plants with leaf dimorphism, frequently producing wide 

and short basal leaves in a rosette . . . . . . . . . . . . . . . Dichanthelium

59. All inflorescences with chasmogamous spikelets, flowering at the same 

time; plants without leaf dimorphism, not producing wide and short 

basal leaves in a rosette.

60. Panicle branches 1-sided; spikelets usually subsessile; pedicels up 

to 2 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hopia

60. Panicle branches generally symmetrical; spikelets not subsessile; 

pedicels 2–20 mm long.

61. Perfect floret striate to transversely ruggose; culms with cormiform rhizomes; inflorescence branches opposite and alternate, 

never whorled; sheaths keeled . . . . . . . . . . . . . . . Zuloagaea

61. Perfect floret smooth to striate, rarely slightly ruggose; culms 

never cormose; sheaths not keeled . . . . . . . . . . . . . . Panicum

 42. Reduced floret absent, if present then the lemma dissimilar to the upper glume in size and texture; generally 

disarticulating above glumes (leaving empty glumes in mature inflorescences).

62. Spikelets with 1 or more reduced florets.

63. Inflorescence a spreading panicle; spikelets paired, golden, awned, slightly geniculate, 10–15(17) 

mm long; every spikelet accompanied by 1 or 2 sterile pedicels at the base . . . . . . . Sorghastrum

63. Inflorescence with spikelets grouped in spikes, spiciform panicles or panicles with spiciform 

branches; spikelets green to brown (the mature ones of Hordeum become golden), awns straight, 

of several sizes, without sterile pedicels at the base.

64. Inflorescence a spike or spiciform panicle, cylindrical to ovoid, with the spikelets arranged 

symmetrically around the rachis.

65. Lemma veins of the 2 lower florets conspicuous, consistently 9 in number, prolonged into 

9 plumose awns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Enneapogon

65. Lemma veins inconspicuous; awns (if present) not plumose.

66. Lemma of perfect (actually pistillate) florets with 3 awns; plant with stolons; plants 

perennial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Scleropogon

66. Lemma of perfect florets with 1 awn or awnless; plants not stoloniferous; plants often 

annual.

67. Spikelets prominently awned, arranged in groups of 3, the lateral spikelets reduced 

to awns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hordeum

67. Spikelets awnless or short-awned, 3-flowered, the 2 reduced florets never awnlike 

in shape.

68. Reduced florets sterile, shorter than perfect florets, reduced to small scale-like 

lemmas, not awned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phalaris

68. Reduced florets staminate or sterile, longer than the perfect florets, brownish, 

hirsute, awned, 1 of the awns twisted and exserted, the other short and erect 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Anthoxanthum

64. Inflorescence of 1, several, or many spikes (or spiciform racemes) digitate to racemose; spikelets arranged only on 1 side of the rachis.

69. Inflorescence branches (spikes) scattered along the main axis or sometimes solitary

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bouteloua

69. Inflorescence branches digitate, often with additional solitary branches above or below 

the verticil.

70. Lemma awned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chloris

70. Lemma awnless.
1 0 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

71. Reduced florets 1.3–1.5 mm long, truncate, bell-shaped; inflorescence branches 

generally more than 6 . . . . . . . . . . . . . . . . . . . . . . . . . . Chloris (C. submutica) 

71. Reduced florets up to 0.5 mm long, or often only the rachis present; inflorescence 

branches generally 4 or 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cynodon

62. Spikelets missing reduced florets or, if present, inconspicuous.

72. Inflorescence 1 spike, a spiciform raceme, or a panicle composed by several spikes or not 

rebranched racemes.

73. Inflorescence a single terminal spike.

74. Spikelets unilateral (on 1 side) on rachis, 2.5–3.5 mm long, awnless, solitary . . . . . . . . 

Microchloa

74. Spikelets bilateral on rachis, more than 1 cm long, largely awned, 3 per inflorescence 

node, the lateral spikelets often reduced to awns . . . . . . . . . . . . . . . . . . . . . . . . . Hordeum

73. Inflorescence composed of 2 to several spikes.

75. Glumes missing; aquatic or subaquatic plants . . . . . . . . . . . . . . . . . . . . . . . . . . Leersia

75. Glumes at least 1 present; plants usually terrestrial.

76. Upper lemma margins inrolled (appearing to clasp) over the palea margins, relatively 

thick and rigid, the apex usually obtuse . . . . . . . . . . . . . . . . . . . . . . . . . . Paspalum

76. Upper lemma margins folded over the palea margins, relatively thin and flexible, the 

apex acute or acuminate.

77. Lemma folded and consequently the spikelet appearing to be laterally compressed; 

inflorescence with 4 or 5 digitate spikes; plants notably stoloniferous . . . Cynodon

77. Lemma concave-convex and consequently the spikelet appearing dorsoventrally 

compressed, margins of the lemma conspicuously hyaline; inflorescence usually 

subdigitate; plants caespitose, stoloniferous, or rhizomatous . . . . . . . . Digitaria

72. Inflorescence a spreading or contracted panicle, sometimes spikelike, but primary branches rebranched 

(early branches very reduced and the spikelets crowded on sessile or nearly sessile glomerules).

78. Glumes and lemma awnless, the lemma sometimes mucronate.

79. Glumes as long as, or longer than, the lemma.

80. Sheaths of basal leaves folded, conspicuously compressed, carinate; plants 1 m tall or 

more . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muhlenbergia

80. Sheaths of the leaves rounded on the back, not compressed or carinate.

81. Glumes 4–10 mm long; panicle spikelike . . . . . . . . . . . . . . . . . . . Muhlenbergia

81. Glumes usually at most 4 mm long, sometimes reaching this length, but then the 

panicle open or contracted, not appearing spikelike.

82. Rachilla prolonged beyond the insertion of the palea; palea well-developed, 1⁄2

as long as the lemma, 2-veined . . . . . . . . . . . . . . . . . . . . . . . Calamagrostis

82. Rachilla usually not prolonged beyond the insertion of the palea; palea missing or reduced, veinless . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Agrostis

79. Glumes, at least the first, shorter than the lemma.

83. Lemma veins densely silky-pubescent; caryopsis ellipsoid, free from floral envelopes 

at maturity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muhlenbergia

83. Lemma veins not densely silky-pubescent; caryopsis obovate, cylindrical or somehow 

compressed, free or united to the floral envelopes at maturity.

84. Lemma 1-veined; caryopsis obovate, notably compressed, free from the floral 

envelope at maturity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sporobolus

84. Lemma 3- to 5-veined, sometimes the lateral veins inconspicuous; caryopsis cylindrical or slightly compressed, still united to the floral envelope at maturity . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muhlenbergia

78. Glumes or lemmas, or rarely both, awned.

85. Spikelets in groups of 3 at each node of the axis, the central sessile, the lateral ones in the 

form of bristles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hordeum

85. Spikelets not in groups of 3, sometimes involucres subtended by bristles.

86. Spikelets in small racemes at the nodes of a narrow and dense panicle, the racemes 

subtended by a group of bristles on 1 side, the upper spikelets of racemes naked 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muhlenbergia (M. pereilema)
NUMBER 107 • 1 1

86. Spikelets never subtended by bristles.

87. Lemma awn emerging from the back, or from the middle of the lobes of a deeply 

2-toothed apex.

88. Spikelets 6 mm or more long (without the awn), brownish or golden, accompanied at the base by 1 or 2 pedicels from missing spikelets . . . . . . Sorghastrum

88. Spikelets at least 6 mm long (without the awn), stramineous or light green, not 

accompanied by pedicels from missing spikelets.

89. Awn of glumes longer than lemma awn; spikelets disarticulating below the 

glumes and falling entire at maturity . . . . . . . . . . . . . . . . . . Polypogon

89. Glumes awnless; spikelets disarticulating above the glumes, which remains 

attached to the mature inflorescences.

90. Palea missing or reduced when present, veinless; rachilla generally not 

prolonged beyond the insertion of the palea . . . . . . . . . . . . Agrostis

90. Palea well-developed, 2-veined, 1⁄2 as long as the lemma; rachilla prolonged beyond the insertion of the palea . . . . . . . . . . Calamagrostis

87. Lemma awn emerging from an entire apex, which can be minutely 2-toothed, or 

the lemma awnless.

91. Lemma notably hardened, permanently enclosing the palea and caryopsis.

92. Lemma awn divided in 3 branches, the lateral branches sometimes less 

than 1 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aristida

92. Lemma awn not divided.

93. Palea longitudinally grooved, nearly as long as the lemma, 2-keeled; 

margins of lemma involute . . . . . . . . . . . . . . . . . . . . Piptochaetium

93. Palea flat, hidden by the convoluted margins of the lemma.

94. Palea pubescent between the veins; apex of the lemma with hairs 

not swollen at base and not forming a cylindrical crown . . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Achnatherum

94. Palea glabrous; apex of the lemma with hairs swollen at the base 

and forming a crown.

95. Apex of lemma prolonged into a smooth crown, cylindrical; 

palea 1⁄3 as long as the lemma; awn glabrous or scabrous on the 

terminal segment . . . . . . . . . . . . . . . . . . . . . . . . . . . Nassella

95. Apex of lemma glabrous; palea as long as the lemma; awn 

pilose on the terminal segment . . . . . . . . . . . . . Hesperostipa

91. Lemma not notably hardened, not permanently enclosing the palea and 

caryopsis.

96. Lemma shorter than glumes.

97. Glume awns longer than lemma awn; spikelets disarticulating below 

the glumes, so falling entire at maturity . . . . . . . . . . . . . Polypogon

97. Glume awns missing or shorter than lemma awn; spikelets disarticulating above the glumes, these persistent at maturity . . . . Muhlenbergia

96. Lemma as long as, or longer than, glumes . . . . . . . Muhlenbergia 

25. Spikelets with 2 or more perfect florets or, if unisexual, with 2 or more staminate or pistillate functional florets.

 98. Lemma with 9 or more awns or awn-shaped lobes.

 99. Awns antrorsely bearded, unequal and interspersed with awned teeth; spikelets 6- to 10-flowered, rachilla 

disarticulating between the florets; panicle usually spreading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cottea

 99. Awns forming a crown, not antrorsely bearded or plumose, but never interspersed with awned teeth; spikelets 

3- to 6-flowered, falling as a unit; panicle narrow.

 100. Spikelets 3-flowered, the first floret fertile with 9 plumose awns, equal in length . . . . . . . Enneapogon

 100. Spikelets 4- to 6-flowered, with 1 to 3 lower fertile florets; awns numerous, not plumose, unequal in 

length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pappophorum

 98. Lemma awnless or up to 3-awned.

 101. Plants robust, generally 2–8 m tall; inflorescences as large, generally plumose panicles 30–70 cm long.

 102. Lemmas glabrous; rachilla silky; the lowest floret staminate or sterile, persistent, the upper florets fertile 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phragmites
1 2 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

 102. Lemmas pilose; rachilla glabrous; the florets all alike.

 103. Leaves mostly basal, blades narrow, not cordate to clasping below; florets unisexual, the pistillate 

florets occasionally with reduced stamens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cortaderia

 103. Leaves cauline, the blades cordate to clasping below; florets perfect . . . . . . . . . . . . . . . . Arundo

 101. Plants generally less than 2 m tall; inflorescences varied in shape and length but never a plumose panicle.

 104. Spikelets sessile or subsessile; inflorescence a spike, raceme, or a spiciform panicle, the branches 

unbranched.

 105. Inflorescence a branched panicle, the spikelets placed on 1 side of the rachis of spikes or simple 

racemes (not rebranched).

 106. Inflorescence with several digitate spikes, whorled or crowded at the apex of culms.

 107. Rachis of each branch projecting beyond the spikelets as a rigid tip, 1.5–5 mm long; 

upper glume awned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dactyloctenium

 107. Rachis not projecting beyond the spikelets; upper glume unawned.

 108. Branches of the inflorescence up to 1 cm long; spikelets monoecious, with 2 or 3 

staminate florets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bouteloua 

 108. Branches of the inflorescence 1–12 cm long; spikelets with perfect and sterile florets.

 109. Lemma awnless; upper glume 3- to 7-veined, the lateral veins very close to the 

central vein; spikelets with 4–10 similar perfect florets . . . . . . . . . . Eleusine

 109. Lemma with 1 or 3 awns; upper glume 1-veined; spikelets with 1 basal perfect 

floret plus 1 or several reduced sterile florets above.

110. Lemmas lateraly compressed; the perfect lemma 1-awned . . . . Chloris

110. Lemmas dorsally compressed; the perfect lemma 3-awned Leptochloa

 106. Inflorescence with numerous slender spikes, rarely more than 1 at each node.

 111. Spikelets on pedicels at least 1⁄2 as long as the spikelet; occasionally some of the primary 

branches rebranched; spikelets never in 2 rows along 1 side of the rachis; lemma awnless.

 112. Plants with long, scaly rhizomes, 4–8 mm thick; leaf blades arcuate with the apex 

sharply pointed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Kalinia

 112. Plants without rhizomes or with short, knotty rhizomes less than 4 mm thick, often 

stout but never elongated; leaf blades straight without sharp-pointed apex . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Eragrostis

 111. Spikelets in short pedicels, arranged in 2 rows along the lower side of the rachis; primary 

branches unbranched; lemma awned or unawned.

113. Ligules 4–8(15) mm long, apex acute to attenuate, lacerate . . . . . . . . . . Diplachne

113. Ligules 0.2–8 (15) mm long, apex usually truncate to obtuse and somewhat erose.

 114. Apex of the lemmatal hairs clavicorniculate, ovate to broadly ovate; base of 

lemma often indurate and sometimes 5-veined; plants perennial; ligules 0.8–

2.2 mm long, apex erose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Disakisperma

 114. Apex of the lemmatal hairs ovate to acute, never clavicorniculate; base of 

lemma soft and always 3-veined; plants annual or perennial; ligules (0.2)0.5–

5.5(7.0) mm long, apex usually entire.

 115. Panicle branches subdigitate, inserted along the rachis usually with 2 or 

more branches per node; lemmas 1- to 3-awned or unawned; plants perennial; culms solid; ligule apex ciliate . . . . . . . . . . . . . . . . . . . . Leptochloa

 115. Panicle branches racemosely inserted along the rachis, rarely subdigitate, 

usually with a single branch per node; lemmas unawned; plants annual or 

perennial; culms solid or hollow; ligule apex never ciliate . . . . . .Dinebra

 105. Inflorescence a spike or a solitary raceme, not rebranched.

 116. Spikelets arranged on 1 side of the rachis, forming a distinctly unilateral inflorescence . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bouteloua 

 116. Spikelets arranged symmetrically, scattered on both sides of the rachis, forming a bilateral 

inflorescence.

117. Lemma with an awn or awns 1.5–10 cm long.

 118. Glumes linear to subulate, the awn 3–10 cm long . . . . . . . . . . . . . . . . . . Elymus

 118. Glumes lanceolate or ovate, awnless or the awn less than 3 cm long.
NUMBER 107 • 1 3

 119. Lemma with 3 awns 3.5–10 cm long; glumes lanceolate, membranous; spikelets with several florets, lower florets reduced usually to awns . . . . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Scleropogon (pistillate)

 119. Lemma with 1 awn up to 12 cm long; glumes ovate, coriaceous; spikelets with 

several florets, the lower ones perfect . . . . . . . . . . . . . . . . . . . . . . . Triticum

117. Lemma without awn, or the awn less than 1.5 cm long.

 120. Distal rudimentary florets 3-awned, plumose . . . . . . . . . . . . . . Blepharidachne

 120. Distal rudimentary florets 1-awned, not plumose.

 121. Inflorescence a panicle 1–2.5 cm long; spikelets in a tight capitate cluster, 

subtended by leafy bracts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dasyochloa

 121. Inflorescence a spike 1.3–45 cm long, thick and elongated; spikelets alternately arranged on opposite sides of the rachis, exserted never subtended by 

leafy bracts.

 122. Spikelets 1 to 3 at each node of the rachis; glumes subulate or setaceous 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Elymus

 122. Spikelets solitary at each node of the rachis; glumes narrowly lanceolate 

to oblong.

 123. Glume solitary, except the terminal spikelet; spikelets oriented edgewise against the rachis . . . . . . . . . . . . . . . . . . . . . . . . . . . Lolium

 123. Glumes 2; spikelets with the broad face disposed toward the rachis.

 124. Glumes lanceolate to ovate; lemmas asymmetrically keeled; 

perennial plants . . . . . . . . . . . . . . . . . . . . . . . . . . Agropyron

 124. Glumes broadly ovate; lemmas symetric; annual plants . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Triticum

 104. Spikelets pedicelled; inflorescence an open panicle, sometimes spiciform or racemose-like with branches 

rebranched.

 125. Lemma with a dorsal awn; upper glume more or less the same size or longer than the lemma.

 126. Spikelets with 3 florets, the 2 lower florets awned, staminate or sterile; the upper floret perfect, 

awnless . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Anthoxanthum

 126. Spikelets with 2 to numerous florets, lower floret perfect; upper floret(s) reduced or sterile.

127. Glumes 2 cm long or more; annual weed, introduced . . . . . . . . . . . . . . . . . . . . Avena

127. Glumes up to 1 cm long; perennial, native.

 128. Awn originating in the upper 1⁄2 or 1⁄3 of the lemma; lemmas keeled . . . . Trisetum

 128. Awn originating at the base of the lemma; lemmas rounded . . . . . Deschampsia

 125. Lemma with a terminal awn, or unawned; upper glume usually shorter than the lemma (except in 

Trisetum and Peyritschia).

 129. Lemma with 3 conspicuous veins.

130. Lemma awned; branches of the panicle simple, without secondary branches.

 131. Glumes similar in length to the spikelet; inflorescence a compound panicle; spikelets arranged radially in all directions around the rachis . . . . . . . . . . Erioneuron

 131. Glumes notably shorter than the spikelet; inflorescence a panicle of slender 

unilateral racemes; spikelets in 2 rows on the lower sides of the rachis . . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Leptochloa

130. Lemma awnless; branches of the panicle with secondary branches.

 132. Florets 1–2(3) per spikelet, typically only the lower one perfect; ligules 6–10 mm 

long, membranous; panicle narrow . . . . . . . . . . . . . . . . . . . . . . . . Muhlenbergia

 132. Florets usually more than 2 per spikelet, all perfect; ligules reduced to a row of 

hairs; panicle spreading.

 133. Lemmas glabrous or scabrous over the veins, apex entire, the veins never 

excurrent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Eragrostis

 133. Lemmas pilose along the lower 1⁄2 or over the veins, apex 3-toothed, the veins 

minutely excurrent.

134. Palea margins widened or bowed-out below; caryopses dorsoventrally 

compressed and reniform in cross section, dark brown . . . . . . . Tridens
1 4 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

134. Palea margins not widened or bowed-out below; caryopses dorsally flattened and deeply concave to folded on the dorsal or hilar surface and 

thickened toward the margin below, surface reticulate, reddish-brown 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tridentopsis

 129. Lemma with 5 or more veins, or without conspicuous veins.

 135. Rachilla extending as a bristle beyond the upper floret; spikelets with 2(3) florets; 

endosperm liquid and caryopsis soft; glumes as long or nearly as long as the spikelet.

136. Stamens 2; glumes linear, isomorphic, 1- to 3-veined; lemma awned or awnless, with 

the apex bilobed; palea narrowly enclosed by the lemma margins . . . . Peyritschia

136. Stamens 3; glumes lanceolate, ovate-lanceolate or oblanceolate, heteromorphic, 

lower glume 1- to 3-veined, upper glume 3- to 5-veined; lemma with 2 to 4 short 

awns at the apex, or entire, or 2-toothed; palea not narrowly enclosed by the margins of the lemma.

 137. Glumes longer than the lemma, equal or subequal among them; awns of the 

lemma originating in the middle or toward the base . . . . . . . . . . . . Trisetum

 137. Glumes, at least the first, shorter than the lemma; lemmas generally awnless, or 

with awns near the apex.

 138. Upper glume wider below the center; spikelets 2.5–3 mm long, disarticulating below the glumes, spikelets falling entire . . . . . . . . Sphenopholis

 138. Upper glume obovate, wider above the center; spikelets 4–5 mm long, 

disarticulating above the glumes, glumes persistent on the rachis . . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Koeleria

 135. Rachilla not extending as a bristle beyond the upper floret; spikelets with 3 or more 

florets; endosperm solid and caryopsis hardened; glumes shorter than the spikelet.

139. Glumes as long as spikelet, twice as long as the floret, unawned to sometimes 

mucronate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Schismus

139. Glumes shorter than the spikelet, generally shorter than lemmas.

 140. Plants with stolons or elongated rhizomes; florets unisexual on dioecious 

plants; plants usually less than 40 cm high.

 141. Pistillate and staminate inflorescences consisting of a single spikelet enclosed and almost concealed by the uppermost leaf sheath . . . . Distichlis

 141. Pistillate and staminate inflorescences consisiting of more than 1 spikelet, 

well-exserted above the uppermost leaf sheath.

 142. Glumes and lemmas ovate, acute to obtuse at the apex; plants with 

scaly and creeping rhizomes . . . . . Distichlis (staminate or pistillate)

 142. Glumes and lemmas lanceolate, long attenuate at the apex; plants 

without scaly rhizomes . . . . . . . . . . . . . . . Scleropogon (staminate)

 140. Plants lacking stolons and elongated rhizomes; florets perfect; plants of varying sizes.

 143. Sheaths with united margins, at least on the lower 1⁄2 or 1⁄3.

 144. Spikelets strongly compressed on dense 1-sided panicle branches; 

sheaths keeled and laterally compressed . . . . . . . . . . . . . . Dactylis

 144. Spikelets not strongly compressed on dense 1-sided panicle branches; 

sheaths terete.

 145. Lemmas 7-veined, veins almost parallel, not converging at the 

truncate or rounded apex . . . . . . . . . . . . . . . . . . . . . Glyceria

 145. Lemmas 3- to 7-veined, veins converging at the obtuse or acute 

apex, when parallel then less than 7.

 146. Upper florets empty, inrolled and reduced to a rudiment; 

glumes chartaceous or papery . . . . . . . . . . . . . . Melica

 146. Upper florets not empty or reduced to a rudiment; glumes 

usually membranous and not chartaceous or papery.

147. Spikelets awned or unawned, when awnless then at 

least 15 mm long . . . . . . . . . . . . . . . . . . . . Bromus
NUMBER 107 • 1 5

147. Spikelets awnless, generally shorter than 10 mm long 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Poa

 143. Sheaths with free margins down to the base.

 148. Lemma awned.

 149. Sheaths without auricles . . . . . . . . . . . . . . . . . . . . . . . Festuca

 149. Sheaths with auricles, the apex ciliolate . . . . . . . . . . . Lolium

 148. Lemma unawned.

 150. Lemma less than 4 mm long; plants usually less than 80 cm tall 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Poa

 150. Lemma at least 5.5 mm long; plants often greater longer than 

1 m tall.

 151. Sheaths lacking auricles . . . . . . . . . . . . . . . . . . . Festuca

 151. Sheaths with auricles, the apex ciliolate . . . . . . . Lolium 

DESCRIPTIONS

Achnatherum P. Beauv.

Perennial; tightly to loosely caespitose, sometimes short 

rhizomatous. Culms erect, not branching at the upper nodes. 

Leaves sometimes concentrated at the base; sheaths open, margins often ciliate distally; ligules hyaline to membranous, glabrous or pubescent, sometimes ciliate; blades flat, convolute, or 

involute, apex acute, flexible, basal blades not overwintering. 

Inflorescences terminal panicles, usually contracted, sometimes 2 

forming at the terminal node. Spikelets usually appressed to the 

branches, with 1 floret; disarticulation above the glumes, beneath 

the floret. Glumes exceeding the floret, usually lanceolate, 1- to 

7-veined, acute to acuminate, sometimes obtuse; florets usually 

terete, fusiform or globose, sometimes laterally compressed; lemmas smooth, usually hairy, sometimes glabrous, hairs to 6 mm 

long, usually terminating in lobes, sometimes unlobed, apex with 

a single, terminal, centric awn, awn–lemma junction evident; 

awns centric, readily deciduous to persistent, usually scabrous 

to scaberulous, sometimes hairy in whole or in part, if shorter 

than 12 mm long, usually deciduous, not or once-geniculate and 

sparsely twisted, if longer than 12 mm long, usually persistent, 

once- or twice-geniculate and twisted below, terminal segment 

usually straight, sometimes flexuous; paleas from 1⁄3 as long as 

to slightly longer than the lemmas, usually pubescent; anthers 3, 

1.5–6 mm long, sometimes penicillate. Caryopsis fusiform, not 

ribbed, style bases persistent. x = 10 or 11.

KEY TO SPECIES OF ACHNATHERUM

1. Basal blades curling with age, forming circular arcs; paleas 1⁄4–1⁄3 as long as the lemmas; panicles 7–11 cm long . . . . . . . . .

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. curvifolium

1. Basal blades straight to lax, not forming circular arcs; paleas 2⁄5–4⁄5 as long as the lemmas; panicles 5–30 cm long.

2. Lemma silky pilose, hairs 3 mm long; lemma awn deciduous, straight, never twisted, rarely geniculate, generally less than 

3 to 4 times as long as the grain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. hymenoides

2. Lemma glabrous to white-pubescent, hairs less than 1.5 mm long; lemma awn persistent, twisted and geniculate, several 

times longer than the grain.

3. Lower glume 6–8(9) mm long; inflorescence branches generally ascending or plicate; culms with 3 to 4(5) nodes 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. multinode

3. Lower glume (8)10–16 mm long; inflorescence branches open or ascending; culms with 2 to 3 nodes.

4. Inflorescence highly diffuse; lemma awn 34–68 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. eminens

4. Inflorescence a spike; lemma awn (20)23–40 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. robustum

1. Achnatherum curvifolium (Swallen) Barkworth, Phytologia 

74(1): 7. 1993. Stipa curvifolia Swallen, J. Was. Acad. Sci. 

23(10): 456. 1933.

FIGURE 2

Plants tightly caespitose, not rhizomatous. Culms 25–55 cm 

tall, 0.7–1 mm thick, glabrous; nodes 3. Basal sheaths usually puberulent, hairs 0.1–0.2 mm long, sometimes densely tomentose 

at the base, brown to gray-brown when old; collars glabrous, 

sometimes with tufts of hair on the sides, hairs to 0.5 mm; ligules 0.3–0.6 mm long, truncate, pubescent, hairs about 0.1 mm; 

blades normally valvate to involute, about 0.5 mm in diameter, 

strongly arcuate, abaxial surfaces pubescent near the base, glabrous and smooth distally, adaxial surfaces densely hairy, hairs 

to 0.2 mm. Panicles 7–11 cm long, 1–2 cm wide; branches appressed to strongly ascending, longest branches 3–4 cm. Glumes

subequal, 10–14 mm long, 0.7–0.9 mm wide; florets 6–8 mm 

long, 0.4–0.8 mm thick, fusiform, terete; calluses 1–1.5 mm 
1 6 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

long, sharp; lemmas evenly hairy, hairs at midlength 0.3–1 mm 

long, apical hairs 1–1.5 mm long, apical lobes not developed; 

awns 22–38 mm long, once-geniculate, first segment pubescent, 

hairs 1–2 mm long, gradually decreasing in length distally; paleas 2–2.3 mm long, 1⁄4–1⁄3 as long as the lemmas, glabrous; anthers about 3.5 mm long, dehiscent, not penicillate. Caryopsis

about 4 mm long, fusiform. 2n = 44.

Distribution and Habitat. Achnatherum curvifolium grows on cliffs and in disturbed, rocky, limestone habitats. It is reported from United States and northern Mexico. It is 

most readily distinguished from other species of the genus by its 

combination of curly leaves and hairy awns.

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000) and Herrera Arrieta and 

Cortés Ortiz (2010).

2. Achnatherum eminens (Cav.) Barkworth, Phytologia 74(1): 

7. 1993. Stipa eminens Cav., Icon. 5: 42, t. 467, f. 1. 1799.

FIGURE 3

Plants caespitose, short rhizomatous, bases knotty. Culms

50–100 cm tall, 0.8–1.5 mm thick, glabrous; nodes 2–3. Basal 

sheaths mostly glabrous, ciliate on the margins; collars glabrous 

on the back, usually with tufts of hair on the sides, hairs about 

0.8 mm; ligules 1–4.5 mm long, membranous, glabrous, rounded 

to acute; blades 0.7–3.5 mm wide, abaxial surfaces smooth to 

scaberulous, adaxial surfaces prominently ribbed, scaberulous 

or sparsely to densely pubescent, hairs about 0.1 mm. Panicles

20–55 cm long, 3–8 cm wide, open, often enclosed to midlength 

at anthesis; lower branches 5–8 cm long, ascending to divergent, flexuous. Lower glumes 5–12 mm long, 0.5–0.7 mm wide, 

3- to 5-veined; upper glumes 1–4 mm shorter, 3-veined; florets

4–7.5 mm long, 0.5–0.9 mm thick, fusiform, terete; calluses

1–2 mm long, sharp; lemmas evenly hairy, hairs 0.4–0.8 mm 

throughout, apical lobes not present; awns 35–70 mm long, persistent, twice-geniculate, first 2 segments scabrous, terminal segment flexuous; paleas 1–2 mm long, 1⁄3–1⁄2 as long as the lemmas, 

sparsely to moderately pubescent, apex rounded, flat; anthers

3–3.5 mm long, dehiscent, a few penicillate, hairs about 0.3 mm. 

Caryopsis about 4 mm long, fusiform. 2n = 44, 46.

Distribution and Habitat. Achnatherum eminens grows on dry, rocky slopes and valleys in the mountains; 

its range extends from the southwest United States to Mexico, 

primarily in desert scrub. It is easy to recognize because of its 

open panicle, flexuous branches, and flexuous awns. 

Specimens Examined. MEXICO. Chihuahua.

Aquiles Serdán: Between the higher and the lower parts of Aquiles Serdán, 8 Jul 1972, 1900 m, F. Chiang, T.L. Wendt & M.C. 

Johnston 8353B (MEXU). Jiménez: Sta Eulalia Mts, 12 Aug 

1885, C.G. Pringle 384 (US); E. Wilkinson s.n. (US). Matamoros: 84.6 km SE of Villa Matamoros and 1.6 km N of Ejido 

Revolución on Mex 45, 1900 m, P.M. Peterson, Annable & 

Valdés-Reyna 10875 (US). Ojinaga: 5 km sur [S] Rancho Encinillas, 30 Oct 1974, matorral micrófilo [microphyllus scrub], 

1000 m, Valdés-Reyna VR-825 (RELC).

FIGURE 2. Achnatherum curvifolium. A. Habit. B. Apex of lemma. 

C. Ligule. D. Glumes. E. Floret. F. Lemma and palea. G. Callus. 

Drawn by Cindy Roché; copyright Utah State University.
NUMBER 107 • 1 7

3. Achnatherum hymenoides (Roem. & Schult.) Barkworth, 

Phytologia 74(1): 7–8. 1993. Stipa hymenoides Roem. & 

Schult., Syst. Veg. (ed. 15 bis) 2: 339. 1817. Oryzopsis 

hymenoides (Roem. & Schult.) Ricker ex Piper, Contr. U.S. 

Natl. Herb. 11: 109. 1906.

FIGURE 4

Plants tightly caespitose, not rhizomatous. Culms 25–70 cm 

tall, 0.7–1.3 mm thick, glabrous or partly scaberulous; nodes

3–4. Sheaths glabrous or scaberulous, sometimes puberulent on the distal margins, hairs to 0.8 mm; collars glabrous, 

sometimes with tufts of hair on the sides, hairs to 1 mm; ligules 1.5–4 mm long, hyaline, glabrous, acute; blades usually 

convolute, 0.1–1 mm in diameter, abaxial surfaces smooth or 

scaberulous, adaxial surfaces pubescent. Panicles 9–20 cm long, 

8–14 cm wide; branches ascending to strongly divergent, longest 

branches 3–15 cm; pedicels paired, conspicuously divaricate, 

shorter pedicels in each pair usually at least 1⁄2 as long as the longer pedicels. Glumes subequal, 5–9 mm long, 0.8–2 mm wide, 

saccate below, puberulent, hairs about 0.1 mm long, tapering 

above midlength, apex acuminate; lower glumes 5-veined at the 

base, 3-veined at midlength; upper glumes 5- to 7-veined at the 

base; florets 3–4.5 mm long, 1–2 mm thick, obovoid; calluses

0.4–1 mm long, sharp; lemmas indurate, densely and evenly pilose, hairs 2.5–6 mm long, easily rubbed off, apex not lobed; 

awns 3–6 mm long, rapidly deciduous, not geniculate, scabrous; 

paleas subequal to the lemmas in length and texture, glabrous, 

apex pinched; anthers 1.5–2 mm long, penicillate, dehiscent, 

well-filled. Caryopsis 2–3 mm. 2n = 46, 48. 

Distribution and Habitat. Achnatherum hymenoides grows in dry, well-drained soils, primarily in the western part of the United States and northern Mexico. The roots of 

A. hymenoides are often surrounded by a rhizosheath formed 

by mucilaginous secretions to which soil particles attach. This 

rhizosheath harbors nitrogen-fixing organisms that probably 

contribute to the success of the species as a colonizer.

Specimens Examined. MEXICO. Chihuahua.

Juárez: aprox. 6 km al S del poblado [village] Samalayuca, 30 

Jul 1994, 1200 m, R. Corral, E. Pérez, A. Domínguez & F. Félix 

RCD5280 (UACJ); Near of Paso del Norte, 23 Sep 1886, C.G. 

Pringle 1053 (US).

FIGURE 3. Achnatherum eminens. A. Ligule. B. Inflorescence. 

C. Floret. D. Lemma and palea. Drawn by Cindy Roché; copyright 

Utah State University.
1 8 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

4. Achnatherum multinode (Scribn. ex Beal) Valdés-Reyna & 

Barkworth, Contr. U.S. Natl. Herb. 48: 17. 2003. Stipa multinodis Scribn. ex Beal, Grass. N. Amer. 2: 222. 1896.

Plants caespitose, not rhizomatous. Culms 60–120 cm tall, 

1.5–3.5 mm thick, erect, mostly glabrous; nodes 2–4. Basal 

sheaths mostly glabrous, distally ciliate; collars hairy, hairs 1 mm; 

ligules 0.5–3 mm; a lacerate scale, glabrous; blades 1–1.3 mm 

wide, firm, rigid, flat and involute toward the apex when mature. 

Panicles 10–20 cm long, 0.8–1.5 cm wide; branches 1–3(6) cm 

long, straight, appressed to ascending. Glumes subequal, 6–8(9) 

mm long, pale hyaline, acuminate, 1- to 3-veined, glabrous; florets 4.5–5.5 mm long, 0.6–0.9 mm thick, fusiform, terete; calluses 0.3–0.5 mm long, barbed; lemmas white-pubescent, hairs 

0.5 mm long, apical hairs to 1.5 mm; awns 20–35 mm long, persistent, twice-geniculate, first segment 3.5–8 mm long, glabrous 

to scabrous, second segment 4–5.5 mm long, terminal segment 

18–20 mm long, straight; paleas 3.5–4.6 mm long, 3⁄4 as long as 

the lemmas, hairy, hairs about 0.5 mm long, not exceeding the 

apex; anthers 2.5–3.5 mm long.

Distribution and Habitat. Achnatherum multinode grows on dry plains and hills, in open woods and forest 

clearings, and along roadsides, from the western United States to 

northern Mexico. 

Specimens Examined. MEXICO. Chihuahua.

Jiménez: Sta Eulalia Mts, Aug 1885, C.G. Pringle 385 (US), isotype; E. Wilkinson 349 (US).

5. Achnatherum robustum (Vasey) Barkworth, Phytologia 74(1): 

12. 1993. Stipa viridula var. robusta Vasey, Contr. U.S. Natl. 

Herb. 1(2): 56. 1890.

FIGURE 5

Plants caespitose, not rhizomatous. Culms 100–230 cm 

tall, 2–4.5 mm thick, mostly glabrous, often pubescent below 

the nodes, the pubescence antrorse or retrorse; nodes 4–5. Basal 

sheaths mostly glabrous, margins usually ciliate distally; collars

hairy, hairs 0.5–2 mm; ligules (1)2–4 mm; truncate, rounded, 

or obtuse, glabrous; blades 6–10 mm wide, glabrous, abaxial 

surfaces smooth, adaxial surfaces prominently ribbed, ribs 

scabrous. Panicles 15–30 cm long, 0.8–3.5 cm wide; branches

straight, appressed to ascending, lower branches 3–9 cm. Spikelets appressed to the branches. Glumes subequal, 9–11.5 mm 

long, 1–1.4 mm wide; florets 5.9–8.5 mm long, 0.9–1.2 mm 

thick, fusiform, terete; calluses 0.3–1 mm long, blunt; lemmas

evenly hairy, hairs at midlength 0.3–0.8 mm long, apical hairs 

to 1.5 mm; awns 20–32 mm long, persistent, twice-geniculate, 

scaberulous to scabrous, hairs to about 0.1 mm long, longest 

on the middle segment, terminal segment straight; paleas 3.7–

5.6 mm long, 2⁄3–3⁄4 as long as the lemmas, hairy, hairs about 

0.5 mm long, not exceeding the apex, veins terminating below 

the apex, apex rounded; anthers 4–5 mm long, dehiscent, penicillate. Caryopsis 5–6 mm. 2n = 64.

Distribution and Habitat. Achnatherum robustum grows on dry plains and hills, in open woods and forest 

FIGURE 4. Achnatherum hymenoides. A. Inflorescence. B. Inflorescence branch. C. Glumes. D. Floret. E. Callus. Drawn by Cindy 

Roché; copyright Utah State University.
NUMBER 107 • 1 9

clearings, and along roadsides, from the western United States to 

northern Mexico. 

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000) and Herrera Arrieta and 

Cortés Ortiz (2010).

Aegilops L.

Annual. Culms usually glabrous, erect or geniculate at the 

base, with 2–4(5) nodes. Sheaths open; auricles ciliate; ligules 

membranous, truncate; blades, linear to linear-lanceolate, flat, 

spreading. Inflorescence terminal, spikes, with 2–13 spikelets, 

usually with 1–3 rudimentary spikelets at the base; disarticulation either at the base of the spikes or in the rachis, the spikelets falling attached to the internodes above or below. Spikelets 

solitary at each node, 1⁄2–2(3) times the length of the internodes, 

tangential to the rachis, appressed or ascending, upper spikelet(s) 

sometimes sterile; bisexual spikelets with 2–7 florets, distal florets often sterile. Glumes ovate to rectangular, rounded on the 

back, scabrous or pubescent, with several prominent veins, midveins smooth throughout, apex truncate, denticulate, or awned, 

sometimes indurate at maturity; lemmas rounded on the back, 

apex toothed, frequently awned; paleas chartaceous, 2-keeled, 

keels ciliate; anthers 3, not penicillate; ovaries with pubescent 

apex. Caryopsis lanceolate to lanceolate-ovate. x = 7. 

Aegilops has about 23 species and is native from the Mediterranean region to central Asia, as well as in the Canary Islands; 

only 1 species occurs in Chihuahua.

6. Aegilops cylindrica Host, Icon. Descr. Gram. Austriac. 2: 6, 

pl. 7. 1802.

FIGURE 6

Culms 14–50 cm tall, erect to decumbent at the base, usually with many tillers. Sheaths with hyaline margins, sometimes 

ciliate; blades 3–15 cm long, 2–5 mm wide. Spikes 2.2–12 cm 

long, about 0.3 cm wide, narrowly cylindrical, 10–45 times longer than wide, with (2)3–8(12) bisexual spikelets; rudimentary 

spikelets absent or 1–2; disarticulation initially at the base of 

the spikes and secondarily in the rachises, the spikelets remaining attached to the internodes above. Spikelets 9–12 mm long, 

narrowly cylindrical, scabrous or pubescent, all fertile, with 3–5 

florets, lower (1)2–3 florets fertile. Glumes of lower spikelets 

awned, awns 0.2–0.5 cm; glumes of apical spikelets 7–9 mm 

long, scabrous, apex with a 3–6 cm awn usually flanked by 2 

lateral teeth; lemmas of lower spikelets 9–10 mm long, adaxial 

surfaces velutinous distally, apex mucronate or awned, awns 

0.1–0.5 cm; lemmas of apical spikelets 1-awned, awns 4–8 cm 

long, flanked by 2 teeth. Caryopsis 6–7 mm long, adhering to the 

lemmas and paleas. 2n = 28.

Distribution and Habitat. Aegilops cylindrica is a widespread weed in North America, being particularly 

troublesome in winter wheat. It usually grows in disturbed sites 

such as roadsides, fields, and along railroad tracks. It is native 

FIGURE 5. Achnatherum robustum. A. Habit. B. Ligule. C. Inflorescence. D. Floret. E. Spikelet. F. Glumes. G. Caryopsis. Drawn by 

Cindy Roché; copyright Utah State University.
2 0 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

to the Mediterranean region and central Asia and is adventive 

in other temperate countries. It is reported from Mexico only 

from specimens cultivated in an experimental station (Rancho 

La Campana); 38 years later, this species has not been collected 

again in Chihuahua. 

Specimens Examined. MEXICO. Chihuahua.

Chihuahua: Rancho Experimental La Campana, 17 May 1975, 

Jardín de Observación de zacates [grass observation garden], 

1500 m, Valdés-Reyna VR899 (RELC). 

Agropyron Gaertn.

Perennial; densely to loosely caespitose, sometimes rhizomatous. Culms geniculate or erect. Sheaths open; auricles usually 

present; ligules membranous, often erose. Inflorescences spikes, 

usually pectinate. Spikelets solitary, usually more than 3 times as 

long as the internodes, divergent or spreading from the rachis, 

with 3–16 florets; disarticulation above the glumes and beneath 

the florets. Glumes shorter than the adjacent lemmas, ovate to 

lanceolate, 1- to 5-veined, asymmetrically keeled, a secondary 

FIGURE 6. Aegilops cylindrica. A. Inflorescence. B. Spikelet, ventral view. C. Glume. Drawn by Cindy Roché; copyright Utah State 

University.

FIGURE 7. Agropyron cristatum. A. Habit. B. Ligule. C. Culm and 

inflorescence. D. Inflorescence. E. Spikelet. F. Lemma. Drawn by 

Cindy Roché; copyright Utah State University.
NUMBER 107 • 2 1

keel sometimes present on the wider side, keels glabrous or with 

hairs, hairs not tufted, apex acute and entire, sometimes awned, 

awns to 6 mm; lemmas 5- to 7-veined, asymmetrically keeled, 

acute to awned, awns to 4.5 mm; paleas from slightly shorter 

than to exceeding the lemma, bifid; anthers 3, 3–5 mm long, 

yellow. Caryopsis usually falling with the lemmas and paleas attached. x = 7.

Agropyron, it is now agreed, should be restricted to perennial species of Triticeae with keeled glumes, that is, Agropyron 

cristatum and its allies.

7. Agropyron cristatum* (L.) Gaertn., Novi Comment. Acad. 

Sci. Imp. Petrop. 14: 540. 1770.

FIGURE 7

Plants occasionally rhizomatous. Culms 25–110 cm tall, 

sometimes geniculate. Ligules to 1.5 mm; blades 1.5–6 mm wide, 

glabrous or pubescent. Spikes 1.3–10.5(15) cm long, 5–25 mm 

wide, narrowly to broadly lanceolate, rectangular, or ovate, 

sometimes tapering distally; internodes 0.7–5(8) mm long, glabrous or pilose, sometimes all more or less equal, sometimes 

short and long internodes alternating within a spike, basal internodes often longer than those at midlength. Spikelets 7–16 mm 

long, diverging at angles of 30°–95° at maturity, with 3–6(8) florets. Glumes 3–6 mm long, glabrous or with coarse hairs on the 

keels, acute, usually awned, awns 1.5–3 mm; lemmas 5–9 mm 

long, glabrous or with hairs, keeled, keels sometimes scabrous 

distally, apex acute, usually awned, awns 1–6 mm; anthers 

3–5 mm. 2n = 14, 28, 42.

Distribution and Habitat. Agropyron cristatum is native from central Europe and the eastern Mediterranean 

to Mongolia and China and is introduced in the Americas. We 

recognize a broad concept for this taxon and include A. cristatum subsp. desertorum (Fisch. ex Link) Á. Löve under this highly 

variable species. 

Specimens Examined. MEXICO. Chihuahua. 

Bocoyna: 1.1 km N of San Juanito near large lumber mill, 24 Sep 

1988, 2200 m, P.M. Peterson & Annable 5867 (ENCB, US); La 

Campana, 24 Sep 76, Jardines de Observación Forrajera [forage 

observation gardens], 1500 m, S. González 774 (RELC).

Agrostis L.

Plants usually perennial, caespitose, sometimes rhizomatous or stoloniferous. Culms usually erect. Sheaths open, usually 

smooth and glabrous; ligules membranous, smooth or scaberulous dorsally, apex truncate, obtuse, usually erose to lacerate, 

or entire; blades flat, folded, or involute, usually smooth and 

glabrous. Inflorescences terminal panicles, narrowly cylindrical 

and dense to open and diffuse; branches usually in whorls. Spikelets pedicellate, laterally compressed, lanceolate to narrowly oblong or ovate, with 1(2) florets; rachillas not prolonged beyond 

the base of the floret(s); disarticulation above the glumes, beneath the florets. Glumes 1–2(4) times longer than the lemmas, 

1(3)-veined, glabrous, usually mostly smooth, apex acuminate to 

awn-tipped; lower glumes usually 0.1–0.3 mm longer than the 

upper glumes, rarely equal; lemmas thinly membranous to hyaline, usually smooth and glabrous, sometimes scaberulous, 3- to 

5-veined, unawned or awned, awns arising from near the lemma 

bases to near the apex, usually geniculate, sometimes straight; 

paleas absent or minute to subequal to the lemmas, usually thin, 

veins not or only weakly developed; anthers 3, not penicillate; 

styles 2, free to the base, white; ovaries glabrous. Caryopsis with 

a hard, soft, or liquid endosperm. x = 7.

KEY TO SPECIES OF AGROSTIS

1. Prostrate herbs with decumbent culms, stoloniferous; palea evident, 2-veined, at least 1⁄2 of the lemma length . . . . . . . . . . .

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. stolonifera var. palustris

1. Erect herbs, culms not forming stolons; palea absent or minute, reduced to a small scale, rarely longer than 1⁄3 of the lemma 

length.

2. Panicle narrow, laxly cylindrical or spiciform, 5–10 times longer than wide, the branches erect or ascending . . . . A. exarata

2. Panicle highly branched, diffuse, almost as long as wide at maturity, the branches spread.

3. Culms 30–40(50) cm tall; spikelets 1.5–1.7 mm long; glumes 1.2–2.3 mm long . . . . . . . . . . . . . . . . . . . A. hyemalis

3. Culms 60–100 cm tall; spikelets 2–3.1 mm long; glumes 2–2.6(3) mm long.

4. Rhizomatous plants; blades basal and cauline; anthers 1–1.3 mm; caryopsis 1–1.2 mm long, endosperm solid 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. subrepens

4. Caespitose plants; blades mostly basal; anthers 0.4–0.8 mm; caryopsis 0.9–1.4 mm long, endosperm liquid . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. scabra

8. Agrostis exarata Trin., Gram. Unifl. Sesquif﻿l. 207. 1824.

FIGURE 8

Perennial; usually caespitose, sometimes rhizomatous, not 

stoloniferous. Culms 8–100 cm tall, erect or decumbent at base, 

sometimes rooting at the lower nodes, with (2)3–6 nodes. Leaves 

mostly cauline; sheaths smooth or slightly scabrous; ligules 

(1)1.7–8 mm long, dorsal surfaces scabrous, apex truncate to obtuse, lacerate to erose; blades 4–15 cm long, 2–7 mm wide, flat. 

Panicles (3)5–30 cm long, 0.5–4 cm wide, contracted, spikelike, 

oblong, or lanceolate, usually dense, rarely more open, sometimes 

interrupted near base, bases usually exserted, rarely enclosed by 
2 2 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

the upper sheaths at maturity, lowest node with 1–5 branches; 

branches scabrous, ascending to appressed, spikelet-bearing to or 

near the base, usually hidden by the spikelets, spikelets crowded, 

lower branches 1–2(4) cm; pedicels 0.2–4.3 mm. Spikelets lanceolate to narrowly ovate, greenish to purplish. Glumes subequal 

to equal, 1.5–3.5 mm long, scabrous on the midvein and sometimes on the back, 1(3)-veined, acute, elongate-acuminate, with 

an awn-like tip to 1 mm; callus hairs to 0.3 mm long, sparse 

to abundant; lemmas 1.2–2.2 mm long, smooth, translucent to 

opaque, 5-veined, veins prominent distally or obscure throughout, apex acute, entire or toothed, teeth no more than 0.12 mm 

long, unawned or awned from above midlength, awns to 3.5 mm 

long, straight or geniculate; paleas absent or to 0.5 mm; anthers 

3, 0.3–0.6 mm. Caryopsis 0.9–1.2 mm; endosperm solid or soft. 

2n = 28, 42, 56.

Distribution and Habitat. Agrostis exarata is 

common and widely distributed in western North America, usually growing in moist ground in open woodlands, river valleys, 

tidal marshes, and swamp and lake margins; it also grows in 

dry habitats such as grasslands and shrublands. It extends from 

Alaska into Mexico.

Specimens Examined. MEXICO. Chihuahua. 

E of Rancho El Willy, 8 Jun 1998, J. Spencer 687 (US). Guachochi: 12.4 km S of Cusarare on road to Guachochi, 25 Sep 1988, 

pine forest, 2400 m, P.M. Peterson & Annable 5889 (ENCB, US); 

SW of Cusarare at brink of Cascada de Cusarare, 22 Jul 1973, 

pine–oak, Bye 43178 (MEXU). Ocampo: Basaseachic Falls, 6 Jul 

1936, LeSueur Mex-0101 (US); Parque Nacional “Cascada de 

Basaseachic,” ca. 130 air km W of Cuauhtemoc, along river at 

base of falls, 25 Abr [Apr] 1987, 1600 m, Spellenberg, Muldavin 

& R. Corral 9056 (MEXU, NMC); Parque Nacional “Cascada 

de Basaseachic,” ca. 100 m upstream from the top of the falls 

along the Rio Basaseachic, 17 Jun 1993, 2000 m, Spellenberg, 

L. Brouillet & E. Ulaszek 11885 (NMC); Parque Nacional “Cascada de Basaseachic,” near river at bottom of falls, 26 Abr 1985, 

1570 m, Spellenberg, Soreng & R. Corral 8022 (MEXU, NMC).

9. Agrostis hyemalis (Walter) Britton, Sterns & Poggenb., Prelim. Cat. 68. 1888. Cornucopiae hyemalis Walter, Fl. Carol. 

73. 1788.

FIGURE 9

Perennial or facultative annual; caespitose, not rhizomatous 

or stoloniferous. Culms 15–82 cm tall, erect, with (3)4–7 nodes. 

Leaves cauline and basal; sheaths smooth; ligules (0.7)1.2–4 mm 

long, dorsal surfaces scabrous, apex usually rounded to truncate, 

sometimes acute, lacerate-erose; blades 3–10 cm long, 1–2 mm 

wide, flat, becoming involute, or folded. Panicles (5)10–25(36) 

cm long, (3)4–24 cm wide, broadly ovate, often nearly as wide 

as long, diffuse, the whole panicle often detaching at base when 

mature, forming a tumbleweed, bases often enclosed by the 

upper sheaths, lowest node with (3)5–11 branches; branches 

scabrous, capillary, flexible, wide-spreading, branching in the 

distal 1⁄4, spikelets strongly clustered at the branch tips, lower 

branches 5–15 cm; pedicels 0.1–2.5(3.5) mm. Spikelets ovate to 

FIGURE 8. Agrostis exarata. A. Habit. B. Inflorescence. C. Inflorescence. D. Inflorescence. E. Spikelet. F. Spikelet. G. Floret, dorsal view. H. Floret, ventral view. I. Floret, dorsal view. J. Anthers. 

Drawn by Sandy Long; copyright Utah State University.
NUMBER 107 • 2 3

narrowly ovate, greenish or purplish. Glumes subequal, 1–2 mm 

long, 1-veined, keeled, keels scabrous, sometimes the body also 

scabrous toward the apex, acute to acuminate; callus hairs to 

0.2 mm long, sparse; lemmas 0.8–1.2 mm long, scaberulous, 

translucent to opaque, 5-veined, veins obscure or prominent 

distally, apex usually obtuse, sometimes acute, entire, unawned; 

paleas absent or to 0.2 mm and thin; anthers 3, 0.2–0.5 mm. 

Caryopsis 0.7–1 mm. 2n = 28.

Distribution and Habitat. Agrostis hyemalis 

is most abundant along roadsides and in open pastures, scrub, 

and rocky areas. It is centered in the southeastern United States 

to the Caribbean, Mexico, and Ecuador.

Specimens Examined. MEXICO. Chihuahua.

Batopilas: Rancho Byarly, Sierra Charuco, 17–25 Apr 1948, 

1700 m, Gentry 8027 (US); Yamuco, 1 mi E of hwy N of Rio 

Urique crossing towards Basihuare and Creel, 6 Sep 2008, P.M. 

Peterson & J.M. Saarela 22059 (US). Bocoyna: 2 km de San 

Juanito rumbo [course] a Bocoyna, 14 Aug 76, bosque de pino 

[pine forest], 2446 m, S. González & J.M. Peña 649 (RELC). 

Carichi: Sánchez, 12 Oct 1910, Hitchcock 7680 (US). Chihuahua: Rancho el Peñasco km 150 carr. [hwy] Chihuahua–Cd. 

Juárez, 9 Aug 1979, pastizal mediano abierto [mostly open 

grassland], M. Siqueiros 340 (MEXU). Guerrero: On road between Tomochic and Basaseachic, 20 mi E of jct with road S 

to San Juanito, 1.8 mi W of Agua Caliente, 5 Oct 1986, 2000 

m, Spellenberg, Soreng, R. Corral & T. Lebgue 8677 (NMC). 

Madera: Vicinity of Madera, 27 May–7 Jun 1908, E. Palmer 263

(US). Ocampo: Near Mirador Cascada Basaseachic, 7 Sep 2008, 

rocky forested slopes with Pinus, 2022 m, P.M. Peterson & J.M. 

Saarela 22080 (US).

10. Agrostis scabra Willd., Sp. Pl. 1(1): 370. 1797.

FIGURE 10

Perennial or annual; caespitose. Culms (7.5)15–90 cm tall, 

erect, nodes usually 1–3. Leaves mostly basal, basal leaves usually persistent; sheaths usually smooth, sometimes scaberulous; 

ligules 0.7–5 mm long, dorsal surfaces scabrous, apex usually 

rounded, sometimes truncate or acute, erose-ciliolate to lacerate; 

blades 4–14 cm long, 1–2 mm wide, basal blades mostly involute, cauline blades mostly flat. Panicles (4)8–25(50) cm long, 

0.5–20 cm wide, broadly ovate, often nearly as wide as long, 

diffuse, the whole panicle often detaching at base when mature, 

forming a tumbleweed, exserted from the upper sheaths, lowest node with (1)2–7(12) branches; branches scabrous, capillary, 

flexible, wide-spreading, readily visible, branching beyond midlength, spikelets somewhat distant, not crowded, lower branches 

4–12 cm; pedicels 0.4–9.6 mm. Spikelets lanceolate, greenish 

purple, frequently purple when mature. Glumes unequal, 1.8–

3.4 mm long, lanceolate, 1-veined, keels scabrous at least toward 

the apex, apex acuminate; callus hairs to 0.2 mm long, sparse; 

lemmas 1.4–2 mm long, scabrous to scaberulous or smooth, 

translucent to opaque, 5-veined, veins prominent, apex acute to 

obtuse, usually entire, sometimes minutely toothed, awned or 

awnless from below midlength, awns 0.2–3 mm long, exceeding 

FIGURE 9. Agrostis hyemalis. A. Habit. B. Inflorescence. C. Inflorescence branch. D. Spikelet. E. Floret. F. Floret, dorsal view. 

G. Floret, ventral view. Drawn by Sandy Long; copyright Utah State 

University.
2 4 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

the lemma apex by up to 2.5 mm long, geniculate or straight, 

persistent; paleas absent or to 0.2 mm; anthers 3, 0.4–0.8 mm 

long, usually shed at anthesis. Caryopsis 0.9–1.4 mm; endosperm liquid. 2n = 42.

Distribution and Habitat. Agrostis scabra 

grows in grasslands, meadows, shrublands, woodlands, marshes, 

and stream and lake margins as well as disturbed sites such as 

roadsides, ditches, and abandoned pastures. It occurs in the 

southeastern United States to Mexico; it is also native to the Pacific coast from Kamchatka to Japan and Korea and has been 

introduced elsewhere (Harvey, 2007).

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: Yamuco at 1 km E of Hwy towards Basihuare and 

Creel, N of Rio Urique crossing, 26 Aug 2003, slopes with pines 

and oaks, 1891 m, P.M. Peterson & P. Catalán 17553 (US); 

Rancho Byarly Sierra Charuco, 17–25 Abril [April] 1948, pine–

oak forest, 5000–5800 ft, H. Scott 8027 (MEXU). Bocoyna: 

1.1 km N of San Juanito near large lumber mill, 24 Sep 1988, 

2200 m, P.M. Peterson & Annable 5864b (US); Arroyo Rituchi, 

12 Sep 2003, Bye & col. 32281, 31881 (US). Guachochi: carr. 

[hwy] Guachochic–Creel km 20, 24 Sep 1981, bosque escleroaciculifolio [narrow-leaved sclerophyllous forest], R. Fierros 

1611 (MEXU); Creel, 2 Aug 1977, suelo húmedo & rocoso 

[moist and rocky soil], 2350 m, matorral de juniperos [juniper 

scrub], 2240 m, A. Benítez 2181 (CIIDIR, MEXU). Guadalupe y 

Calvo: near Cumbre Mohinora, 13 Sep 2006, 3300 m, P.M. Peterson 20044, F.Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, 

US). Ocampo: Basaseachi a 21 km al S de San Juanito & a 9 km 

al N de Creel, 16 Sep 1983, bosque de pino−encino [pineoak 

forest], 2150 m, Tenorio & R. Torres 4365 (MEXU); Parque 

Nacional Cascada de Basaseachic, 5 Aug 1994, 1950 m, C. Yen 

& E. Estrada 2861 (NMC); Parque Nacional “Cascada de Basaseachic,” 25 Abr 1986, 1700 m, Spellenberg, Soreng, R. Corral & T. Lebgue 8428 (MEXU, NMC). Temosachi: Nabogame, 

25 Mar 1988, pine–oak–cypress, 1800 m, Laferr. 1419 (MEXU). 

Urique: Cuiteco, ranchito en la cañada [glen] a 5 km de San Rafael, 21 Sep 2002, Tenorio, G. Morales & J. Rodríguez 21977, 

21987 (US).

11. Agrostis stolonifera L. var. palustris* (Huds.) Farw.

FIGURE 11

Perennial; caespitose, stoloniferous. Culms 8–40 cm tall, 

smooth, geniculately ascending, or decumbent, rooting from 

lower nodes. Sheaths glabrous; ligule 1–6 mm long, an eciliate 

membrane, obtuse; blades 1–10 cm long, 0.5–5 mm wide, surface ribbed, scaberulous, apex acuminate. Panicle 1–13 cm long, 

0.4–2.5 cm wide, open, or contracted, linear, lanceolate or oblong, continuous or interrupted, dense or loose; primary panicle 

branches whorled at most nodes, scabrous. Spikelets 2–3 mm 

long, solitary, terete, lanceolate, or oblong, laterally compressed, 

fertile spikelets pedicelled, pedicels filiform, 0.5–2 mm long, 

FIGURE 10. Agrostis scabra. A. Habit. B. Habit, dwarf form. C. 

Inflorescence. D. Inflorescence branch. E. Spikelet. F. Floret with 

caryopsis. G. Lemma, side view. H. Lemma, dorsal view. Drawn by 

Sandy Long; copyright Utah State University.
NUMBER 107 • 2 5

comprising 1 fertile floret, disarticulating below each fertile 

floret. Glumes exceeding florets, persistent, similar, firmer than 

lemma, shiny, 1-keeled, 1-veined, lanceolate; lemma 1.5–2.3 mm 

long, elliptic to oblong, hyaline, 5-veined, apex obtuse; callus 

pubescent; palea 1.0–1.8 mm long, 2-veined, oblong, apex obtuse; anthers 3, 1–1.5 mm. Caryopsis with adherent pericarp, 

ellipsoid, isodiametric, biconvex, estipitate, smooth.

Distribution and Habitat. Agrostis stolonifera var. palustris grows on saline soils; there exists a collection 

from humid depressions in gypsum areas. Native in Eurasia, it is 

introduced as forrage in America, north of Mexico. 

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000).

12. Agrostis subrepens (Hitchc.) Hitchc., N. Amer. Fl. 17(7): 

525. 1937. 

Perennial; with delicate rhizomes. Culms 60–100 cm tall, 

erect, glabrous, with 2–4 nodes, the superior node near the middle of the culm. Sheaths glabrous; ligule 1–2 mm; blades 3–5 cm 

long, 1–1.3(1.8) mm wide, inrolled, scabrous, slender, apex hard 

and acute, superior blades above 1⁄2 culm. Panicle 12–18(22) cm 

long, 5–10 cm wide, open, pyramidal, axis glabrous, and the 

branches lightly scaberulous, slender, widely spread, on verticils 

or 1–2 per node, verticils 2–4 cm apart, lower branches 5–8 cm. 

Spikelets 2.5–2.8 mm long, brown to purple, grouped along the 

superior part of branches. Glumes 2.5–2.8 mm long, acuminate, 

scarcely scabrous along the keel; lemmas 1.8–2 mm long, hyaline, veinless, entire, obtuse to apiculate, awnless, callus scarcely 

pilous; palea rudimentary; anthers 3, 1–1.3 mm long, yellow. 

Caryopsis 1–1.2 mm long, ovate, flat, hard, brown. 

Distribution and Habitat. Agrostis subrepens 

grows in meadows and stream margins in Mexico and South 

America.

Specimens Examined. MEXICO. Chihuahua. 

Base of Sierra Madre, 28 Sep 1887, C.G. Pringle 1420 (US), holotype. Casas Grandes: W of Casas Grandes, just S of Hernández, 18 Sep 1960, 7000 ft, Reeder, C. Reeder & Soderstrom 

3535 (US). Madera: Chuichupa, Aug–Sep 1936–37, LeSueur 

087, 0198 (US); near Col. García, 1 Aug 1899, E.W. Nelson 

6195 (US).

Alopecurus L.

Annual or perennial; sometimes short rhizomatous, caespitose or occasionally the culms solitary. Culms erect or decumbent, occasionally cormlike at the base; nodes glabrous. Leaves 

inserted mostly on the lower 1⁄2 of the culms; sheaths open; ligules 

truncate to acute, membranous, dorsally puberulent or glabrous, 

entire to lacerate; blades flat or involute, glabrous or scabrous, 

those of the uppermost leaves sometimes short or absent. Inflorescences terminal spikelike, capitate to cylindrical; disarticulation below the glumes. Spikelets pedicellate, strongly laterally 

compressed, with 1 floret; rachilla prolongations absent. Glumes 

equaling or exceeding the florets, membranous or coriaceous, 

free or connate basally to more than 1⁄2 their length, 3-veined, 

FIGURE 11. Agrostis stolonifera. A. Habit. B. Inflorescence. C. Inflorescence. D. Spikelet. E. floret. Drawn by Sandy Long; copyright 

Utah State University.
2 6 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

keeled, keels ciliate, at least basally, apex obtuse to acute or 

shortly awned; calluses blunt, glabrous; lemmas membranous, 

margins often connate basally to 1⁄2 their length, keeled, indistinctly 3- to 5-veined, apex truncate to acute, awned dorsally, 

awns arising from just above the base to about midpoint, geniculate or straight; paleas absent or greatly reduced; lodicules 

absent; anthers 3; ovaries glabrous; styles fused, with 2 branches. 

Caryopsis glabrous. x = 7. 

13. Alopecurus geniculatus* L., Sp. Pl. 1: 60. 1753.

FIGURE 12

Perennial; caespitose. Culms (5)10–60 cm tall, erect or decumbent, rooting at the nodes. Ligules 2–5 mm long, obtuse; blades 

2–12 cm long, 1–4(7) mm wide; upper sheaths somewhat inflated. 

Panicles 1.5–7 cm long, 4–8 mm wide. Glumes 1.9–3.5 mm long, 

connate at the base, membranous, pubescent, keels not winged, 

ciliate, apex obtuse, parallel, often purplish; lemmas 2.5–3 mm 

long, connate in the lower 1⁄2, glabrous or with a few scattered 

hairs at the apex, apex truncate to obtuse, awns 3.5–5(6) mm 

long, geniculate, exceeding the lemmas by (1.2)2–4 mm; anthers 

(0.9)1.4–2.2 mm long, yellow. Caryopsis 1–1.5 mm. 2n = 28.

Distribution and Habitat. Alopecurus geniculatus is native to Eurasia and parts of North America, growing in 

shallow water, ditches, open wet meadows, shores, and stream 

banks from the lowland to montane zones. It has been naturalized in eastern North America.

Specimens Examined. MEXICO. Chihuahua. 

Bocoyna: 1.1 km N of San Juanito near large lumber mill, 24 Sep 

1988, 2200 m, P.M. Peterson & Annable 5870 (ENCB, US). 

Chihuahua: Bajio del Rancho Experimental La Campana, Aug 

1958, Pastizal [pastureland], F. Martínez 117 (RELC, US).

Andropogon L.

Annual or perennial; usually caespitose, sometimes rhizomatous. Culms 20–310 cm tall, erect, much-branched distally. 

Leaves not aromatic; ligules membranous, sometimes ciliate; 

blades linear, flat, folded, or convolute. Inflorescences terminal 

and axillary or a false panicle; inflorescence units 1–600 per 

culm; peduncles initially concealed by the subtending sheaths, 

sometimes exserted beyond the sheaths at maturity, with (1)2–

5(13) spikes; spikes not reflexed at maturity, axes slender, terete 

to flattened, not longitudinally grooved, usually conspicuously 

pubescent, with spikelets in heterogamous sessile-pedicellate 

pairs (the terminal spikelets sometimes in triplets of 1 sessile and 

2 pedicellate spikelets), apex of the internodes neither cupulate 

nor fimbriate; disarticulation in the spikes below the sessile spikelets. Sessile spikelets bisexual, awned, with short, blunt calluses; 

lower glumes 2-keeled, flat or concave, usually veinless between 

the keels, sometimes 2- to 9-veined; anthers 1 or 3(2). Pedicels 

usually longer than 3 mm long, similar to the rame internodes in 

shape, length, and pubescence color, not fused to the rame axes. 

Pedicellate spikelets usually vestigial or absent, sometimes welldeveloped and staminate. x = 10. 

Andropogon is a cosmopolitan genus of tropical and temperate zones, comprising 122 species (Kellogg, 2015). The genus needs 

to be intensively studied since it has been found to be paraphyletic 

(Skendzic et al., 2007) or monophyletic (Estep et al., 2014).

KEY TO SPECIES OF ANDROPOGON

1. Annual; upper glume of the sessile spikelets largely awned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. fastigiatus

1. Perennial; upper glume of the sessile spikelets unawned.

2. Sessile spikelet 3–4 mm long; hairs of rachis and pedicels much longer than on the sessile spikelets; inflorescence very 

branched, each branch with 2 to 3 spikes; pedicellate spikelets rudimentary, 1–2 mm long . . . . . . . . . . . A. glomeratus

2. Sessile spikelets (4)6–10 mm long; inflorescence simple, with 3 to 6 spikes; pedicellate spikelets 5–7 mm long, similar to 

the sessile, unawned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. gerardii

FIGURE 12. Alopecurus geniculatus. A. Culm and Inflorescence. 

B. Spikelet. C. Lemma, lateral view. D. Stamen. Drawn by Cindy 

Roché; copyright Utah State University.
NUMBER 107 • 2 7

14. Andropogon fastigiatus Sw., Prodr. 26. 1788. Diectomis fastigiata (Sw.) P. Beauv., Ess. Agrostogr. 132, 160. 1812. 

Annual; caespitose. Culms 30–200 cm tall. Leaves generally cauline, sheaths inconspicuously carinate at the apex; ligula 5–11 mm long, glabrous, decurrent, conspicuously veined; 

blades 15–35 cm long, 1–3 mm wide, scabrous or puberulent, 

flat, apex acuminate; inflorescences numerous, partly enclosed 

in the sheaths, narrow, spikes 1 per peduncle, 3–5 cm long, rachis internodes claviform; sessile spikelets 4–5 mm long, callus 

markedly oblique, pilose, hairs 2–3 mm; lower glume deep and 

narrowly sulcate, membranous, veinless, pilose between keels, 

unawned, upper glume carinate, navicular, largely awned, awn 

10–20 mm long, divergent, not twisted on the superior half, 

geniculate; anthers 3, 1.5–1.8 mm; pediceled spikelets 7–8 mm 

long, sterile; lower glume conspicuously enlarged, flattened, with 

awn 6–10 mm long, geniculate with a twisted column. 2n = 20. 

Distribution and Habitat. Andropogon fastigiatus grows in grasslands and pine forests. It is known from 

Mexico to South America.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: Parque Nacional Barranca del Cobre, 3.2 km S of La 

Bufa on road to Batopilas, tropical forest, 1050 m, P.M. Peterson, Annable & Valdés-Reyna 10860 (CIIDIR, US); Parque Nacional Barranca del Cobre, 6.7 km NE of Batopilas along the 

Río Batopilas at the Arroyo de Santiago, 690 m, P.M. Peterson, 

Annable & Valdés-Reyna 10855 (US). Guachochi: 7.4 km SW 

of La Bufa and 15 km NE of Batopilas, 920 m, thorn scrub vegetation, 20 Sep 1991, P.M. Peterson, Annable & Valdés-Reyna 

10847 (US); Parque Nacional Barranca del Cobre, 3.8 km NE of 

La Bufa and 9.6 km S of Kirare, 1240 m, P.M. Peterson, Annable 

& Valdés-Reyna 10834 (US).

15. Andropogon gerardii Vitman, Summa Pl. 6: 16. 1792.

FIGURE 13

Plants often forming large clumps; rhizomes, if present, with 

internodes shorter than 2 cm. Culms 1–3 m tall, often glaucous. 

Sheaths glabrous or pilose; ligules 0.4–2.5 mm; blades 5–50 cm 

long, (2)5–10 mm wide, usually pilose adaxially, at least near the 

collar. Inflorescence units usually only terminal; peduncles with 

2–6(10) spikes; spikes 5–11 cm long, exserted at maturity, usually purplish, sometimes yellowish; internodes sparsely to densely 

pubescent, hairs 2.2–4.2 mm long, usually white, rarely yellowish. 

Sessile spikelets 5–11 mm long, scabrous; awns 8–25 mm; anthers 

3, 2.5–4.5 mm. Pedicellate spikelets 3.5–12 mm long, usually welldeveloped and staminate. 2n = 20, 40, 60 (usually), 70, 80, 90.

Distribution and Habitat. Andropogon gerardii grows in prairies, meadows, and generally dry soils. It is a 

widespread species, extending from southern Canada to Mexico

Specimens Examined. MEXICO. Chihuahua. Chihuahua: km 2064 carr [hwy] Chih.–V. Ahumada, 21 Oct 1954, 

1100 m, Hern.-Xol. & C.Tapia N-26 (US); Juárez: Sand dunes, 

10–20 Oct 1935, LeSueur Mex-061 (US); aprox. 6 km al S del 

poblado [village] Samalayuca, 9 Sep 1995, en arenas profundas 

[deep sands], 1200 m, R. Corral & P. Olivas RCD6315 (UACJ). 

FIGURE 13. Andropogon gerardii. A. Habit. B. Ligule. C. Spikelet 

pair. Drawn by Linda Ann Vorobik and Hana Pazdírková; copyright Utah State University.
2 8 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Matamoros: 19.3 km S of Villa Matamoros on Mex 45 to Durango, 3 Oct 1989, 1910 m, P.M. Peterson & R.M. King 8256 (US).

16. Andropogon glomeratus (Walter) Britton, Sterns & Poggenb., 

Prelim. Cat. 67. 1888.

FIGURE 14

Plants caespitose, upper portion dense, oblong to oblanceolate 

or obpyramidal. Culms 20–250 cm; internodes green, sometimes 

glaucous; branches mostly erect, straight. Sheaths usually scabrous, 

sometimes smooth; ligules 0.6–2.2 mm long, sometimes ciliate, cilia 

to 0.9 mm; blades 13–109 cm long, 2.9–9.5 mm wide, glabrous or 

sparsely to densely pubescent, hairs usually spreading, rarely appressed. Inflorescence units 10–600 per culm; subtending sheaths 

(2.0)2.9–4.4(6.5) cm long, (1.5)2.3–3.4(4.4) mm wide; peduncles 

(1)6–14(60) mm long, with 2(4) spikes; spikes (1)1.7–2.5(3.5) cm 

long, exserted or not at maturity, pubescence sparse basally and 

increasing in density distally within each internode. Sessile spikelets 3–5 mm; callus hairs 1–2.5 mm; keels of lower glumes sometimes scabrous below midlength, usually scabrous distally; awns 

6–19 mm; anthers 1(3), 0.5–1.5 mm long, yellow, red, or purple. 

Pedicellate spikelets vestigial or absent, sterile. 2n = 20.

Distribution and Habitat. This species has 

five varieties; only Andropogon glomeratus var. pumilus (Vasey) 

Vasey occurs in Chihuahua. It is weedy and grows in disturbed 

wet or moist sites. It is abundant and widespread, extending 

from the southern United States through Central America to 

northern South America.

Specimens Examined. MEXICO. Chihuahua. Rio 

Bonito hot country, 26 Aug 1936, H. LeSueur 0100 (US). Galeana: Cerro Angostura Springs, 2.4 mi, by Mexico Highway 10, 

N of Angostura, 8 Oct 1982, F.W. Reichenbacher 1310 (ARIZ).

Anthoxanthum L.

Annual or perennial; densely to loosely caespitose, sometimes 

rhizomatous; fragrant. Culms 4–100 cm tall, erect or geniculate, 

sometimes branched; internodes hollow. Leaves cauline or basally 

concentrated, glabrous or softly hairy; sheaths open, auricles absent or present; ligules membranous, sometimes shortly ciliate or 

somewhat erose; blades flat or rolled, glabrous or sparsely hairy. 

Inflorescences open or contracted panicles, sometimes spikelike. 

Spikelets pedicellate or sessile, 2.5–10 mm long, laterally compressed, stramineous to brown at maturity, with 3(4) florets, lowest 2 florets usually staminate or sterile, sometimes reduced to 

dorsally compressed lemmas, subequal to or exceeding the distal 

floret, distal floret bisexual; rachilla not prolonged beyond the 

base of the distal floret; disarticulation above the glumes, the 

florets falling together. Glumes unequal or subequal, equaling 

or exceeding the florets, lanceolate to ovate, glabrous or pilose, 

keeled; calluses blunt, glabrous or hairy; lowest 2 florets: lemmas strongly compressed, 3-veined, strigose, hairs brown, apex 

bilobed, unawned or dorsally awned; distal florets: lemmas somewhat indurate, glabrous or with hairs, shiny, inconspicuously 

3- to 7-veined, unawned; paleas 1-veined, enclosed by the lemmas; lodicules 2 or absent; anthers 2 or 3. Caryopses shorter than 

the lemma, concealed at maturity, tightly enclosed in the floret; 

hila less than 1⁄3 the length of the caryopses, oval. x = 5. 

Anthoxanthum is a cool-season genus of about 50 species 

that grow in cool-temperate and arctic regions throughout the 

world. There are seven species in North America, five of which 

are native, and only one introduced in Chihuahua (Allred & 

Barkworth, 2007). 

17. Anthoxanthum odoratum* L., Sp. Pl. 28. 1753.

FIGURE 15

Plants perennial. Culms (10)25–60 (100) cm tall, erect, simple or sparingly branched. Auricles 0.5–1 mm long, pilose-ciliate, 

sometimes absent; ligules 2–7 mm long, truncate; blades 1–31 cm 

FIGURE 14. Andropogon glomeratus. A. Inflorescence. B. Ligule. 

Drawn by Linda Ann Vorobik and Hana Pazdírková; copyright 

Utah State University.
NUMBER 107 • 2 9

long, 3–10 mm wide. Panicles (3)4–14 cm long, the spikelets congested; lowermost branches 10–25 mm; pedicels 0.5–1 mm long, 

pubescent. Spikelets 6–10 mm; lower glumes 3–4 mm long, upper 

glumes 8–10 mm; 2 lowest florets sterile, 34 mm long, awn of the 

first lemma 2–4 mm long, awn of the second lemma 4–9 mm long, 

equaling or only slightly exceeding the upper glumes; bisexual florets 1–2.5 mm; anthers 2, (2.9)3.5–4.8(5.5) mm. 2n = 10, 20.

Distribution and Habitat. Anthoxanthum 

odoratum is native to southern Europe. In North America, it 

grows in meadows, pastures, grassy beaches, old hay fields, 

wasteplaces, and openings in coniferous forests (occasionally in 

dense shade) or as a weed in lawns. It is known from North 

America in Canada, the United States, and Mexico in Chiapas, 

Chihuahua, Coahuila, Distrito Federal, Durango, Hidalgo, 

México, and Oaxaca and in Central America, South America, 

and the Caribbean. 

Specimens Examined. MEXICO. Chihuahua. 

Reported in Herrera Arrieta and Cortés Ortiz (2010).

Aristida L.

Plants usually perennial; herbaceous, usually caespitose, 

occasionally rhizomatous. Culms 10–150 cm long, not woody, 

sometimes branched above the base; internodes usually pithfilled, sometimes hollow. Leaves sometimes predominantly basal, 

sometimes predominantly cauline; sheaths open; auricles lacking; 

ligules of hairs or very shortly membranous and long-ciliate, the 

2 types generally indistinguishable. Inflorescences terminal, usually panicles, sometimes racemes, occasionally spikes; primary 

branches without axillary pulvini and usually appressed to ascending, or with axillary pulvini and ascending to strongly divergent or divaricate. Spikelets with 1 floret; rachillas not prolonged 

beyond the florets; disarticulation above the glumes. Glumes 

often longer than the florets, thin, usually 1- to 3-veined, acute 

to acuminate; florets terete or weakly laterally compressed; calluses well-developed, hirsute; lemmas fusiform, 3-veined, convolute, usually glabrous or scaberulous, usually enclosing the palea 

at maturity, usually with 3 terminal awns, lateral awns reduced 

or obsolete in some species, lemma apex sometimes narrowed 

to a straight or twisted beak below the awns; awns ascending 

to spreading, usually straight, bases sometimes twisted together 

into a column or the bases of the individual awns coiled, twisted, 

or otherwise contorted, occasionally disarticulating at maturity; 

paleas shorter than the lemmas, 2-veined, occasionally absent; 

anthers 1 or 3. Caryopsis fusiform. x = 11, 12.

Aristida is a tropical to warm-temperate genus of 304 species (Kellogg, 2015).

FIGURE 15. Anthoxanthum odoratum. A. Habit. B. Ligule. C. Inflorescence. 

D. Spikelet. E. Sterile floret. F. Sterile floret. G. Fertile floret. Drawn by Linda 

Ann Vorobik and Hana Pazdírková; copyright Utah State University.
3 0 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

KEY TO SPECIES OF ARISTIDA

1. Lateral awns of the lemma markedly reduced, generally less than 1⁄3 as long as the central awn.

2. Sheaths collar densely pilose, with hairs conspicuously cobwebby and tangled, often deflexed at maturity . . . . . . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. gypsophila

2. Sheaths collar with hairs straight or somehow tangled, but not conspicuously cobwebby, generally extended.

3. Lemma narrowing to slightly keeled, usually with an untwisted beak . . . . . . . . . . . . . . . . . . . . . . . . . . . A. ternipes

3. Lemma terminating in a twisted, awn-like beak 4–6.5 mm long. 

4. Panicles open, all the primary branches with axillary pulvini; branches naked at the base . . . . . . . A. schiedeana

4. Panicles closed, contracted, none of the primary branches (except occasionally the inferior ones) with axillary 

pulvini, then branches tightly appressed to the main axis.

5. Lemmas 18–22(25) mm long; panicle sparsely flowered; spikelets 3–12 in total, 2(4) per branch . . . . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. spanospicula

5. Lemmas smaller, 10–13 mm long; panicle densely flowered, more than 16 spikelets per branch . . . . . A. eludens

1. Lateral awns of the lemma well-developed, at least 1⁄3 as long as the central awn.

6. Lemma involute, sulcate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. gibbosa

6. Lemma convolute, never sulcate.

7. Lemma beak lacking or sparsely developed; annual.

8. Lower glumes shorter than upper ones; lateral awns equal to central awn . . . . . . . . . . . . . . . . . . A. adscensionis

8. Glumes equal sized; lateral awns shorter than central awn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. longespica

7. Lemma beak well-developed, the twisted part 1–9 mm long, sometimes straight; perennial.

9. Glumes markedly unequal in size, the lower less than 3⁄4 as long as the upper; beak less than 2 mm long, or missing.

10. Lemma 7–12 mm long, awns subequal, (7)10–25 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. pansa

10. Lemma 10–15 mm long, awns equal, 20–56(65) mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. purpurea

9. Glumes equal to subequal in size, the lower at least 3⁄4 as long as the upper; beak twisted (occasionally straight in 

A. havardii), 2–9 mm long.

11. Panicle usually completely open, the primary branches widely divergent with axillary pulvini.

 12. Lemma beak twisted 5–9 mm long; lemma 10–12 mm long; central awn 10–20 mm long, lateral awns 

3–7 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. laxa

 12. Lemma beak twisted 0.5–4 mm long; lemma 7–9 mm long; central awn 8–20 mm long, lateral awns almost 

equal to the central.

13. Spikelets divergent from twigs, the pedicels with axillary pulvini; primary branches 2–6 cm long; 

plants delicate, 20–40 cm tall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. havardii

13. Spikelets and twigs plicate along the primary branches, the pedicels lacking axillary pulvini; primary 

branches 5–13 cm long; plants robust, 25–75 cm tall . . . . . . . . . . . . . . . . . . . . . . . . . A. divaricata

11. Panicle narrow and contracted, at least in the distal part, the branches strongly ascending, occasionally having 

axillary pulvini, but only in 1–2 proximal branches.

 14. Lemma 7.5–9 mm long, the awns unequal, the central one 16–35 mm long, the lateral ones 13–25 mm 

long; inflorescence densely flowered, the florets overlapping . . . . . . . . . . . . . . . . . . . . . . . . . A. appressa

 14. Lemma 10–14 mm long, equal awns, 15–20 mm long; inflorescence loosely flowered, the florets not overlapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. arizonica

18. Aristida adscensionis L., Sp. Pl. 1: 82. 1753.

FIGURE 16

Plants short- to long-lived annuals. Culms (3)10–50(80) 

cm tall, often highly branched above the base. Leaves cauline, 

glabrous; sheaths shorter than the internodes, not disintegrating 

into threadlike fibers; ligules 0.4–1 mm long; blades 2–14 cm 

long, 1–2.5 mm wide, flat to involute. Inflorescences panicles, 

5–15(20) cm long, 0.5–3 cm wide, often interrupted below; 

nodes glabrous or with straight, less than 0.5 mm hairs; primary 

branches 1–4 cm long, erect to ascending, without axillary pulvini, with 3–8 spikelets. Spikelets crowded. Glumes unequal, 

1-veined, acuminate; lower glumes 4–8 mm; upper glumes 

6–11 mm long; calluses 0.5–0.8 mm long; lemmas 6–9 mm 

long, slightly keeled, midveins scabrous, junction with the awns 

not evident; awns not disarticulating at maturity, flattened and 

straight to somewhat curved at base, central rib flanked by 

equally wide pale wings; central awns 7–15(20) mm long; lateral 

awns somewhat shorter, occasionally only 1–2 mm long; anthers 

3, 0.3–0.7 mm long. 2n = 22.

Distribution and Habitat. Aristida adscensionis grows in waste ground, along roadsides, and on degraded 

rangelands and dry hillsides, often in sandy soils. It is associated 

with woodland, prairie, and desert shrub communities. Its range 
NUMBER 107 • 3 1

extends from the United States south through Mexico and Central America to South America.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 10 km al S de Moctezuma, 30 Jul 1994, 1200 m, 

R. Corral, E. Pérez, A. Domínguez & F. Félix RCD5348 (UACJ); 

Arroyo del Nido Valley, 8.2 mi by dirt road, S of Mexico Highway 10, near Arroyo Plan del Alamos, 8 Oct 1982, grassland, 

1300 m, F.W. Reichenbacher 1326 (ARIZ). Aldama: 26 (rd) mi 

NE of Aldama along Hwy 16 near El Morrion, 15 Sep 1972, 

1100 m, J. Henrickson 7562 (NMC); San Diego de Alcalá, 20 

Aug 1996, 1200 m, E. Estrada & C. Yen 5692 (NMC); Aldama, 

24 Aug 1978, matorral [scrub], 1250 m, Rodríguez, Molinar 25

(MEXU); Baños de San Diego, 1.8 km E of San Diego de Alcalá, ca 16 km NE of jct of local road with 45, 14 Oct 1986, 

1200 m, B. Neson & L. Vorobik 5512 (MEXU). Allende: Valle 

de Allende, entrada a la población [entrance to population], 13 

Sep 1970, 1550 m, L.M. Villarreal 3662 (ENCB); 6 km al NW 

de Valle de Allende a un lado de la carr. [side of hwy] 45, 5 Sep 

1976, pastizal [pastureland], 1670 m, E. Aldrete s/n (MEXU). 

Buenaventura: Buenaventura, 9 Sep 1975, 1850 m, J. Passini 

& M.F. Robert 6582 (ENCB). Camargo: vicinity of Colina, SW 

of Camargo, 6 Sep 1967, 4000 ft, Reeder & C. Reeder 4867

(ARIZ, ENCB); 23 mi S of La Perla, 6 mi E of Ojinaga–Cd. 

Camargo Hwy on road to Jaco, 18 Sep 1971, grassland, 1350 

ft, J. Henrickson 8447 (MEXU); km 2 carret. [hwy] Camargo–

Chih, 29 Sep 1995, orilla de camino [roadside], 1240 m, Ing. 

González 91 (MEXU). Casas Grandes: Arroyo Los Nogales 20 

km, al S de Col. Juárez, 23 Sep 1982, 1450 m, Tenorio 1600 & 

Romero de T. (ENCB); Tapiecitas, Casas Gdes. a Col. Juárez a 

la derecha [to the right], 19 Abr [Apr] 2000, pastizal, G. Gómez 

25, 28 (MEXU). Chinipas: Sierra Saguarivo, 1.3 mi W of Curahui, 9 Sep 2008, 1001 m, P.M. Peterson & J.M. Saarela 22175 

(US). Chihuahua: Rancho Experimental La Campana, 16 Oct 

1980, pastizal, 1500 m, A. Melgoza 623 (CIIDIR); entre [between] el Peñón & Minas Las Margaritas, Chihuahua, 29 Jul 

1976, 1400 m, S. González & J.M. Peña 330 (ENCB); Plains 

near Chihuahua, 3 Sep 1935, LeSueur Mex-03 (US); Aug 1885, 

C.G. Pringle 390 (US); 5 mi SW of Chihuahua on road to Cuauhtémoc, 6 Oct 1959, pastizal, 1463 m, Soderstrom 899 (US); La 

Campana Experimental Station and Rancho El Arco Iris, about 

81–84 km along the Pan American hwy to Chihuahua City, Sep 

1977, 1500 m, J.K. Meents W.H. Moir 101 (ENCB); Oct 1977, 

J.K. Meents & W.H. Moir 79 (NMC); La Campana, 4 km E 

carr. Panamericana, 6 Sep 1973, 1570 m, Valdés-Reyna VR96 (ENCB, RELC); La Campana, Potrero El Plan, 1 km E carr. 

Panamericana, 10 Sep 1973, 1570 m, Valdés-Reyna VR-155

(ENCB); Hacienda Sta Gertrudis, criadero [hatchery] número 2 

caballería Ejercito Nacional [national army cavalry], 21 Sep 55, 

1650 m, Hern.-Xol. & V. Mathus N-1992 (RELC). La campana: 

Potrero el Bajío; 11 km Ote [W], carr. Panamericana, 13 Sep 

73, pastizal halófito [halophyte pastureland], 1480 m, ValdésReyna VR-247 (RELC); La Campana: Potrero El Plan; 1 km 

Ote. Carr. Panamericana, pastizal mediano abierto [mostly open 

pastureland], 1570 m, Valdés-Reyna VR-155 (RELC). Delicias: 

7 mi S of Delicias along Hwy 45, 24 Sep 1972, 1250 m, Henr. 

7992 (NMC). Gómez Farías: Laguna de Babicora, 15 km al SO 

[SW] de San Jose de Babicora, 26 Aug 1994, 2250 m, C. Yen 

& E. Estrada 3367 (NMC). Guachochi: Camino Guachochi–

Creel, 0.5 km antes del entronque [before the junction] a la Bufa, 

24 Sep 1981, bosque esclerófilo caducifolio [deciduous sclerophyllous forest], 2700 m, M.E. Siqueiros 1633, 1643 (MEXU); 

stepy ledges and cliffs above the river at Basiguare, a few mi 

off Creel–Río Urique, 19 Oct 1977, 1900 m, Bye & W.A.Weber 

8330 (MEXU). Guerrero: Miñaca, 13 Oct 1910, Hitchcock 753, 

7755 (US); S of Mesa Colorado, on S side of Arroyo Ancho, 

28 Aug 1978, pinyon woodlands, 2100 m, Bye 8926 (MEXU, 

US). Janos: Chihuahua–Sonora border, Rancho Carretas, 28 Aug 

1939, 1620 m, L. H. Harvey 1635 (ENCB, US). Jiménez: 8 mi 

N of Jiménez of Mex 45, 30 Aug 1971, 4400 ft, L. H. Harvey 

8895 (ENCB); El Hugo, Torreoncitos, 13 Aug 2010, terrenos de 

cultivo [farmland], 1355 m, D. Ramírez & M.L. Juárez 3375

(CIIDIR). Juárez: km 32 Juárez–Chih., 13 Oct 1997, matorral 

FIGURE 16. Aristida adscensionis. A. Habit. B. Glumes. C. Lemma. 

Drawn by Linda Ann Vorobik and Andy Sudkamp; copyright Utah 

State University.
3 2 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

de gobernadora [governor’s scrub], I. Enríquez, S. Ordoñez & 

J. Leyva IEA5 (UACJ). Madera: Paraje Sirupa, ejido Cebollitas, 

16 Oct 1990, bosque de encino [oak forest], 1200 m, A. Benítez 

2907 (CIIDIR). Meoqui: Entre Julimes & Felipe Ángeles, 30 Jul 

1976, 1310 m, S. González & J.M. Peña 377 (ENCB). Nuevo 

Casas Grandes: 27.4 km S of Nuevo Casa Grandes on Mex 2, 

28 Sep 1989, oak woods, 1585 m, P.M. Peterson & R.M. King 

8143 (ENCB, US). Riva Palacio: Col. Cumbres de Majalca, 33.8 

km W of Mex 45, N of Chihuahua City, 7 Sep 1989, pine forest, 

2190 m, P.M. Peterson, Annable & Y. Herrera 7943 (ENCB, 

US). Saucillo: Mancomún El Pajarito Dominguero 18 km de las 

Varas, 10 Oct 1995, Matorral, 1280 m, Fierros 109 (MEXU); 

Rancho El Salvador, 10 Oct 1995, matorral, 1300 m, Fierros 

116 (MEXU). Temosachi: Nabogame, 27 Aug 1989, forest pine–

oak, 1800 m, Laferr. 2303 (MEXU).

19. Aristida appressa Vasey, Contr. U.S. Natl. Herb. 1(8): 282. 

1893.

Perennial; mat-forming. Culms 30–105 cm tall, erect, simple, slightly branched from the proximal nodes, glabrous. Leaves 

basal and cauline, straight or curved, not spirally inrolled with 

age; sheaths glabrous; blades 10–35 cm long, 1–3 mm wide, flat 

or plicate, puberulent and frequently with long hairs sparse adaxially, near the base. Panicle 10–25(30) cm long, narrow, densely 

flowered, the spikelets overlapping, erect, sometimes inclinate; 

branches 5–10 cm long, appressed, scabrous, with spikelets to the 

base, appressed or occasionally open. Spikelets appressed; glumes 

acute or short-awned, the awn 1–2 mm long, 1-veined, lower 

glumes (7)9–11 mm long, upper glumes 9–13 mm long, a little 

longer than the lower; lemmas 7.5–9 mm long, convolute, scabrous toward the apex, lemma beak 2–4 mm long, twisted, not 

articulate, awns 3, straight to divergent, the central 16–35 mm 

long, the lateral 13–25 mm long; anthers 1.3–2.3 mm long. 

Distribution and Habitat. Aristida appressa

grows in grasslands in oak and desert shrub communities. Its 

range extends from Mexico to Central America.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: km 10 del entronque [junction] a Casas Grandes 

carr. [hwy] Chih–Cd. Juárez, 8 Aug 1979, pastizal [pastureland], 

1525 m, Serrato 270 (MEXU). Balleza: 43.5 km W of Balleza 

and 51.6 km E of Guachochi, 18 Sep 1991, bosque de pino [pine 

forest], 2320 m, P.M. Peterson, Annable & Valdés-Reyna 10762

(CIIDIR, US); 56.4 km W of Balleza and 38.7 km E of Guachochi, 18 Sep 1991, pinyon woodlands, 2480 m, P.M. Peterson, 

Annable & Valdés-Reyna 10771 (CIIDIR, US). Batopilas: SW 

Chihuahua, Aug 1885, E. Palmer 5 (US); Yamuco at 1 km E of 

Hwy towards Basihuare and Creel, N of Rio Urique crossing, 

26 Aug 2003, slopes with pine–oaks, 1891 m, P.M. Peterson & 

Catalán 17540 (US). Bocoyna: Sánchez, 12 Oct 1910, Hitchcock 

7709 (US); S of San Ignacio Arareco near Creel airstrip, 9 Aug 

1972, pine–oak forest, 7200 ft, Bye 2698 (MEXU). Buenaventura: Buenaventura, 28 Sep 1981, pastizal, 1460 m, A. Baray 

1699 (MEXU); Ejido El Apache, 28 Sep 1981, pastizal, 1460 m, 

A. Baray 1713 (MEXU). Cuauhtémoc: Rancho Las Carretas, 

acceso [access] de Chihuahua hacia [toward] Namiquipa, desviar en [divert in] “campo 73” a la izquierda terac. [left dirt road] 

12 km, 7 Oct 2000, Bosque de encino–pino [oak–pine forest], 

G. Gómez 206 (MEXU). Guachochi: Just south of Napuchis, 

2 Sep 2003, grassland, 2162 m, P.M. Peterson & P. Catalán 

17662 (US); Cusarare, at Km 24 south of Creel, 17 Sep 1973, 

pine–oak forest, Bye 5170 (MEXU). Guerrero: 24 mi SW of 

La Junta on road to Creel, 2270 m, P.M. Peterson & Annable 

9611 (US); 40.3 km W of La Junta on road to Parque Nacional 

Cascada de Basaseachic, 29 Sep 1989, 2390 m, P.M. Peterson 

& R.M. King 8189 (US); Tomochi, 2 km alrededor del poblado 

[around the village], 24 Sep 1997, bosque de pino, 2100 m, 

M.A. Vergara 146 (MEXU); carr. la Junta–San Juanito, 17 km. 

22 Sep 1997, 2290 m, B. Tah V. 17 (MEXU). Janos: Chihuahua–Sonora border, Rancho Carretas, 26 Aug 1939, 1450 m, 

L. H. Harvey 1593 (ENCB). Madera: Mesa del Yerbanís, ejido 

El Largo, 12 Oct 1990, bosque de encino, 1900 m, O. Bravo 

1846 (CIIDIR, MEXU); Col. García, 2 Sep 1990, pastizal, 2240 

m, A. Benítez 2193 (CIIDIR). Matamoros: 84.6 km SE of Villa 

Matamoros and 1.6 km N of Ejido Revolución on Mex 45, 22 

Sep 1991, 1900 m, P.M. Peterson, Annable & Valdés-Reyna 

10872 (US). Riva Palacio: Col. Cumbres de Majalca, 33.8 km W 

of Mex 45, N of Chihuahua City, 7 Sep 1989, pine forest, 2190 

m, P.M. Peterson, Annable & Y. Herrera 7952 (ENCB, US).

20. Aristida arizonica Vasey, Bull. Torrey Bot. Club 13(2): 27. 

1886.

FIGURE 17

Perennial; usually caespitose, occasionally with rhizomes. 

Culms 30–80(100) cm long, erect, unbranched. Leaves mostly 

basal; sheaths usually longer than the internodes, mostly glabrous, throat sometimes with hairs, not disintegrating into 

threadlike fibers; collars glabrous or with hairs at the sides; 

ligules 0.2–0.4 mm long; blades 10–25(30) cm long, 1–3 mm 

wide, usually flat, often curling like wood shavings when mature, glabrous. Inflorescences spikelike panicles, 10–25 cm long, 

1–3 cm wide, loosely flowered, the spikelets not overlapping; 

nodes glabrous or with straight, about 0.5 mm, hairs; primary 

branches 2–6 cm long, appressed, without axillary pulvini, with 

2–8 spikelets. Glumes 10–15(18) mm long, brownish, acuminate 

to awned, awns to 3 mm; lower glumes slightly shorter than to 

equaling the upper glumes, 1- to 2-veined; calluses 1–1.8 mm; 

lemmas 12–18 mm long, glabrous, rarely sparsely pilose, terminating in a 3–6 mm twisted column, junction with the awns not 

conspicuous; awns 20–35 mm long, straight to curved basally, 

ascending distally, not disarticulating at maturity; central awns 

20–35 mm; lateral awns slightly shorter than the central awns; 

anthers 3, 1.3–1.9 mm long. 2n = 22.

Distribution and Habitat. Aristida arizonica

grows in pine, pine–oak, and pinyon–juniper woodlands from 

the southwestern United States to southern Mexico. It may be 

confused with A. purpurea var. nealleyi but differs in having flat, 

curly leaf blades and longer awns.
NUMBER 107 • 3 3

Specimens Examined. MEXICO. Chihuahua. 

Bocoyna: Sánchez, 12 Oct 1910, Hitchcock 7717 (US). Guachochi: km 70 carr. [hwy] Balleza–Guachochi, 24 Sep 1981, 

bosque esclerófilo caducifolio [deciduous sclerophyllous forest], 

2650 m, M.E. Siqueiros 1597 (MEXU). Guadalupe y Calvo: Rio 

Verde Crossing, 21 mi SW of El Vergel on hwy 24, 14 Sep 2006, 

2330–2360 m, P.M. Peterson 20073, F. Sánchez Alvarado & 

E.P. Gómez Ruíz (CIIDIR, US). Guerrero: Miñaca, 13 Oct 1910, 

Hitchcock 7752, 7764 (US); 78 km de la Junta a Basaseachic, 

10 Oct 1981, bosque esclerófilo caducifolio, 1230 m, R. Fierros 1699 (MEXU). Hidalgo del Parral: 14 mi E of Parral, 6 Sep 

1967, 5300 ft, Reeder & C. Reeder 4878 (ARIZ, ENCB). Ignacio Zaragoza: Ejido de León, Ignacio Zaragoza, 12 Sep 1975, 

2100 m, J. Passini & M.F. Robert 6731 (ENCB). Madera: Chuhichupa, Aug–Sept 1936, LeSueur Mex 0113 (MEXU, US). Matamoros: 19.3 km S of Villa Matamoros on hwy 45 to Durango, 

27 Sep 1988, grassland, 1800 m, P.M. Peterson & Annable 5986

(ENCB, US).

21. Aristida divaricata Humb. & Bonpl. ex Willd., Enum. Pl. 

1: 99. 1809.

FIGURE 18

Perennial; caespitose. Culms 25–70 cm tall, erect or prostrate, unbranched or sparingly branched. Leaves tending to be 

basal; sheaths longer than the internodes, glabrous except at the 

summit; collars densely pilose; ligules 0.5–1 mm long; blades 

5–20 cm long, 1–2 mm wide, flat to loosely involute, glabrous. 

Inflorescences paniculate, 10–30 cm long, 6–25 cm wide, peduncles flattened and easily broken; rachis nodes glabrous or 

with hairs, hairs to 0.5 mm; primary branches 5–13 cm long, 

stiffly divaricate to reflexed, with axillary pulvini, usually naked 

on the basal 1⁄2; secondary branches usually well-developed. 

Spikelets overlapping, usually appressed, sometimes divergent 

and the pedicels with axillary pulvini. Glumes 8–12 mm long, 

1-veined, acuminate or shortly awned, awns to 4 mm; calluses 

about 0.5 mm; lemmas 8–13 mm long, the terminal 2–3 mm 

with 4 or more twists when mature, narrowing to 0.1–0.2 mm 

wide just below the awns, junction with the awns not evident; 

awns (7)10–20 mm long, not disarticulating at maturity; central 

awns almost straight to curved at the base, ascending to somewhat divergent distally; lateral awns slightly thinner and from 

FIGURE 17. Aristida arizonica. A. Inflorescence. B. Spikelet. Drawn 

by Linda Ann Vorobik and Andy Sudkamp; copyright Utah State 

University.

FIGURE 18. Aristida divaricata. A. Habit. Drawn by Linda Ann 

Vorobik and Andy Sudkamp; copyright Utah State University.
3 4 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

much to slightly shorter than the central awns, ascending to divergent; anthers 3, 0.8–1 mm long. Caryopsis 8–10 mm long, 

light brown. 2n = 22.

Distribution and Habitat. Aristida divaricata

grows on dry hills and plains, especially in pinyon–juniper–

grassland zones, from the southwestern United States through 

Mexico to Guatemala. It occasionally intergrades with A. havardii, but that species has lemma beaks that are straight or 

have only 1–2 twists, shorter primary branches, usually no secondary branches, and pedicels that more frequently have axillary pulvini so the spikelets are more frequently divergent than 

in A. divaricata.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 5 km al N de Flores Magón, 30 Jul 1994, 1200 m, 

R. Corral, E. Pérez, A. Domínguez & F. Félix RCD5380 (UACJ);

aprox. 25 km al N del poblado [village] Flores Magón, 7 Oct 

1995, 1140 m, R. Corral, P. Olivas & J.O. Torres RCD6469

(UACJ). Aldama: Aldama, 24 Aug 1978, 1250 m. Molinar-Baray 

26 (MEXU). Balleza: 56.4 km W of Parral on road to Balleza 

and 35.5 km S of Balleza on MEX 432, near Corral de Duarte, 

18 Sep 1991, bosque de pino–encino [pine–oak forest], 2210 m, 

P.M. Peterson, Annable & Valdés-Reyna 10719 (CIIDIR, US); 

7.4 km W of Balleza on road to Guachochi, 18 Sep 1991, matorral xerófilo [xerophilous scrub], P.M. Peterson, Annable & 

Valdés-Reyna 10740 (CIIDIR, US); 10 mi SW of El Ojito, 12 

Sep 2006, 1902 m, P.M. Peterson 20019, F. Sánchez Alvarado 

& E.P. Gómez Ruíz (CIIDIR, US). Batopilas: Yamuco, 1 mi E 

of hwy N of Rio Urique crossing, towards Basihuare and Creel, 

6 Sep 2008, slopes with pines and oaks, 1890 m, P.M. Peterson 

& J.M. Saarela 22064, 22065 (US); entre [between] Kirare & la 

Bufa, 18 Jul 1984, selva baja caducifolia [low deciduous forest], 

600–1000 m, Tenorio et al 6584 (MEXU). Bocoyna: Sánchez, 

along the railway 12 Oct 1910, Hitchcock 7730 (US). Chihuahua: La Campana Experimental Station and Rancho El Arco 

Iris, about 81–84 km, Sep 1977, 1500 m, J.K. Meents & W.H. 

Moir 81, 89 (ENCB), 75 (NMC); Rocky hills near Chihuahua, 

13 Aug 1885, C.G. Pringle 387 (US); Mts W of Chihuahua, 20 

Oct 1935, LeSueur Mex-068 (US); La Campana: Potrero El Plan 

1 km Pte. Carr. [hwy] Panamericana, 10 Sep 73, pastizal [pastureland], 1570 m, Valdés-Reyna VR-156 (RELC). Coyame: 21 

km SW of Coyame on the Chihuahua Hwy on SE, flank of Sierra 

de la Escodida, 22 Oct 1972, Isotál, 1400 m, T.L. Wendt, F. Chiang & M.C. Johnston 9842 (MEXU). Cuauhtémoc: 21 km W of 

Cuauhtemoc, on Hwy 16, 23 Aug 1990, 2000 m, P.M. Peterson 

& Annable 9600 (US). Gral. Trias: 2.8 mi W of General Trias on 

Rte. 16, 21 Aug 1979, 1780 m, W.L. Wagner & J.C. Solomon 

4336 (MEXU). Gómez Farías: Laguna de Babicora, 15 km al SO 

[SW] de San Jose de Babicora, 26 Aug 1994, 2250 m, C. Yen & 

E. Estrada 3451 (NMC).Guachochi: 1–2 km S of Rio Osichi and 

Rio Basihuare jct., 1 Sep 2003, slopes with oaks and pines, 1600 

m, P.M. Peterson & P. Catalán 17635 (US). Guerrero: Miñaca, 

13 Oct 1910, Hitchcock 7754, 7761 (US); carr. La Junta–San 

Juanito, 17 km, 22 Sep 1997, 2290 m, B. Tah V. 4 (MEXU). 

Ignacio Zaragoza: 20.3 km NE of Ignacio Zaragoza on Mex 23, 

28 Sep 1989, pine woods, 2400 m, P.M. Peterson & R.M. King 

8155 (ENCB, US). Manuel Benavides: 1 mi E of Pozo de Villa 

along road from Ojinaga to Castillon, via La Mula, Trincheras, 

Piramide and San Salvador, 10–12 Aug 1941, I.M. Johnston 

8177 (MEXU). Matamoros: 18.2 km SE of Villa Matamoros on 

Mex 45 to Durango, 1780 m, P.M. Peterson, Annable & ValdésReyna 10867 (US); 19.3 km S of Villa Matamoros on hwy 45 

to Durango, 3 Oct 1989, grassland, 1910 m, P.M. Peterson & 

R.M. King 8254 (US). Namiquipa: Rancho Las Carretas, acceso 

de [access from] Chihuahua hacia [toward] Namiquipa, 10 Oct 

2000, bosque de pino–encino, G. Gómez 237 (MEXU), 2100 

m; Rancho Tepehuanes, acceso de Chihuahua hacia Namiquipa, 

11 Oct 2000, pastizal, G. Gómez 303,313 (MEXU); Rancho 

Aguja, acceso de Chihuahua hacia Namiquipa, 13 Oct 2000, 

pastizal, G. Gómez 327 (MEXU).

22. Aristida eludens Allred & Valdés-Reyna, Novon 5: 209–

222. 1995.

Perennial; mat-forming. Culms 35–65(80) cm tall, erect, 

branched from the base, glabrous. Sheaths glabrous or scaberulous, rounded, collar with a lock of hairs at the edges, occasionally 

with a row of small hairs dorsally crossing ; ligule 0.2–0.3 mm 

long, a ring of hairs; blades 12–35 cm long, 1–1.5 mm wide, flat 

or partially plicate when young, inrolled when mature, glabrous 

or scaberulous. Panicle 10–22 cm long, 1–2 cm wide, with more 

than 16 spikelets, narrow, contracted, nodes glabrous; branches 

5–9 cm long, divaricate, erect, appressed to the main axis, spikelets from the base. Spikelets appressed, occasionally present in 

the inferior axils. Glumes glabrous, brown, subequal, 1-veined, 

8–13 mm long, the apex acute and often with a mucro; lemma 

10–13 mm long, glabrous, mottled, awn beak 3–5 mm long, 

twisted, central awn 5–10 mm long, geniculate, not twisted, lateral awns highly reduced, erect, 0.1–3 mm long, callus 0.5–1 mm 

long, with stiff hairs to 1 mm; paleas completely enclosed by 

the lemma, hyaline; anthers 0.8–1 mm long. Caryopses 6–8 mm 

long, fusiform, brown. 

Distribution and Habitat. Aristida eludens 

grows on grasslands over calcareous soils. It is known from 

Mexico in Chihuahua, Coahuila, Durango, Guanajuato, Nuevo 

León, Oaxaca, Querétaro, and San Luis Potosí.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: Yamuco at 1 km E of Hwy towards Basihuare and 

Creel, N of Rio Urique crossing, 26 Aug 2003, bosque de pino 

[pine forest], 1891 m, P.M. Peterson & P. Catalán 17536 (US). 

23. Aristida gibbosa (Nees) Kunth, Enum. Pl. 1: 189. 1833. 

Chaetaria gibbosa Nees, Fl. Bras. Enum. Pl. 2: 383. 1829.

Perennial; caespitose. Culms 50–95 cm tall, erect, simple, 

glabrous. Basal leaves markedly spirally inrolled when mature, 

cauline generally straight or curved; sheaths glabrous; blades 

15–25 cm long, 1–2 mm wide, flat, plicate near the apex, glabrous abaxially, densely puberulent occasionally with spaced 

hairs adaxially. Panicle 10–30 cm long, narrow but somewhat 

open, branches ascending, scabrous, with spikelets from the base, 
NUMBER 107 • 3 5

pedicels ascending. Glumes 1-veined, the lower 7.5–9.5 mm 

long, scabrous on the keel, shortly awned, the upper 7–8 mm 

long, glabrous, acuminate; lemma 6–7.6 mm long, involute, conspicuously sulcate, glabrous, awn beak 1–4 mm long, twisted, 

not articulate, awns 3, erect to divergent, the central 9–14 mm 

long, the lateral 6–12 mm long; callus 0.2–0.4 mm long, obtuse, 

pillose, the hairs 0.5–0.7 mm long; anthers 1.6–2.3 mm long. 

Distribution and Habitat. Aristida gibbosa 

ranges from Mexico to Central America, South America, and 

the Caribbean.

Specimens Examined. MEXICO. Chihuahua. Guachochi: 24.6 km W of Guachochi and 0.6 km S of 

Rocheachi, 2340 m, P.M. Peterson, Annable & Valdés-Reyna 

10793 (US). Uruachi: Guazaremos, Río Mayo, 26 Sep 1935, 

Gentry 1873 (US).

24. Aristida gypsophila Beetle, Phytologia 49(1): 36–37. 1981.

FIGURE 19

Perennial. Culms 45–80 cm tall, erect, usually unbranched. 

Leaves basal and cauline; sheaths longer than the internodes, 

glabrous except at the summit; collars densely pilose, hairs 

1–3 mm long, cobwebby and tangled, often deflexed; ligules 

less than 0.5 mm long; blades 5–15 cm long, about 0.5 mm 

wide, usually involute, occasionally loosely folded, glabrous, 

light green. Inflorescences paniculate, 12–20 cm long, 2–8 cm 

wide; primary branches 2–5 cm long, erect to horizontal, with 

or without axillary pulvini, with 1–5 spikelets. Spikelets appressed or with axillary pulvini and spreading. Glumes 6–10(12) 

mm long, equal or the lower glumes slightly shorter, 1-veined, 

brownish; calluses about 0.5 mm; lemmas (6)7–14(16) mm 

long, mostly smooth, mottled, terminating in a 2–4 mm long, 

usually twisted, scabrous beak; central awns 5–10 mm long, 

sharply curved at the base, spreading distally; lateral awns absent or to 3 mm long, erect; anthers 3, about 1.5 mm long, 

brown. Caryopsis 5–8 mm long.

Distribution and Habitat. Aristida gypsophila grows on rocky limestone or gypsum hills in thorn scrub communities of the Chihuahuan Desert, almost always growing in 

the protection of shrubs. It is very similar to A. pansa, which differs in having 3 well-developed awns and being, usually, shorter 

in stature. Both species have involute blades with a characteristic 

tuft of cobwebby hairs at the collar. 

There exist three recognized forms of this species, and two 

are present in Chihuahua.

FIGURE 19. Aristida gypsophila. A. Culm and inflorescence. B. Sheath, collar, 

and blade. C. Spikelet. Drawn by Linda Ann Vorobik and Andy Sudkamp; copyright Utah State University.
3 6 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

KEY TO FORMS OF ARISTIDA GYPSOPHILA

1. Axillary pulvini absent; panicle contracted . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. gypsophila fo. diffussa

1. Axillary pulvini present; panicle branches extended, at least the primary ones . . . . . . . . A. gypsophila fo. gypsophiloides

Aristida gypsophila fo. diffussa Allred & Valdés-Reyna, Brittonia 49(1): 65. 1997.

Known only from Mexico (Chihuahua, San Luis Potosí).

Specimens Examined. MEXICO. Chihuahua. 

Jiménez: Sierra Las Pampas, N end of the sierra along dirt rd 

from Las Pampas to jct with rd to Camargo, 23 Sep 1992, matorral xerófilo [xerophilous scrub], 1400 m, Allred & ValdésReyna 5815 (NMC).

Aristida gypsophila fo. gypsophiloides Allred & Valdés-Reyna, 

Brittonia 49(1): 65. 1997.

Known from the Unites States to Mexico in Chihuahua, 

Coahuila, and San Luis Potosí.

Specimens Examined. MEXICO. Chihuahua. 

Jiménez: Sierra Las Pampas, N end of the sierra, from Las Pampas to Camargo, 6.2 mi SE of jct, 23 Sep 1992, matorral xerófilo [xerophilous scrub], 1370 m, Allred & Valdés-Reyna 5804

(NMC) Holotipo; Sierra Las Pampas, N end of the sierra along 

dirt rd from Las Pampas to jct with rd to Camargo, 23 Sep 1992, 

matorral xerófilo, 1400 m, Allred & Valdés-Reyna 5810, 5812

(NMC); N end of Sierrra Las Pampas, 11.5 km NW of Las Pampas on rd to Camargo, 24 Aug 1972, Chiang & A. Lott 8805

(MEXU).

25. Aristida havardii Vasey, Bull. Torrey Bot. Club 13(2): 

27.1886.

FIGURE 20

Perennial; caespitose. Culms 15–40 cm tall, slender, usually erect, occasionally decumbent, often tightly clustered into 

hemispheric clumps, unbranched. Leaves mostly basal; sheaths 

longer than the internodes, glabrous except at the summit; collars densely pilose; ligules 0.5–1 mm long; blades 5–20 cm long, 

1–2 mm wide, flat to loosely involute, glabrous. Inflorescences 

paniculate, 8–18 cm long, 4–12 cm wide, peduncles often flattened and easily broken; rachis nodes glabrous or with straight, 

less than 0.3 mm, hairs; primary branches 2–6 cm long, stiffly 

divaricate to reflexed, with axillary pulvini, usually naked on the 

lower 1⁄2; secondary branches usually absent. Spikelets usually divergent, pedicels usually with axillary pulvini. Glumes 8–12 mm 

long, 1-veined, acuminate or awned, awns to 4 mm long; calluses 

about 0.5 mm long; lemmas 8–13 mm long, glabrous, smooth 

or scabrous, terminal 2–3 mm straight or with 1–2 twists, narrowing to 0.1–0.2 mm wide, junction with the awns not evident; 

awns (7)10–22 mm long, not disarticulating at maturity, from almost straight to somewhat curved basally, ascending to divergent 

distally; lateral awns slightly shorter and thinner than the central 

awns; anthers 3, 0.8–1 mm long. Caryopsis 8–10 mm long, light 

brown. 2n = 22.

Distribution and Habitat. Aristida havardii

grows on dry hills and plains in desert grassland to pinyon–

juniper zones, and in sandy to rocky ground, from the southwestern United States to northern Mexico. It occasionally intergrades 

with A. divaricata, but that species differs in having more twisted 

lemma beaks, longer primary branches, well-developed secondary branches, and, usually, appressed spikelets.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 1 km al Pte Sueco; carr. [hwy] Sueco–Buenaventura, 

FIGURE 20. Aristida havardii. A. Habit. B. Glumes. C. Lemma. 

Drawn by Linda Ann Vorobik and Andy Sudkamp; copyright Utah 

State University.
NUMBER 107 • 3 7

23 Oct 74, pastizal [pastureland], 1300 m, Valdés-Reyna VR726a (RELC); 7 km W carr. Sueco–Buenaventura, 23 Oct 1974, 

pastizal, 1300 m, Valdés-Reyna & M.L. Yeomans VR-726

(ENCB); 10 km W carr. Sueco–Buenaventura, 23 Oct 1974, pastizal, 1300 m, Valdés-Reyna & M.L. Yeomans VR-726 (ENCB). 

Aldama: Aldama, 24 Aug 1978, matorral [scrub], 1250 m, 

Molinar-Baray 26b (MEXU); km 50 carr. Chihuahua–Ojinaga, 

24 Aug 1978, matorral, 1250 m, R. Gutiérrez 19 (MEXU). 

Casas Grandes: Sur de Colmenas, 23 Oct 74, Matorral de Prosopis–Acacia, 1250 m, Valdés-Reyna VR-745 (RELC). Chihuahua: 6 km al S de Chihuahua, carr. Chihuahua–Delicias, 17 Aug 

1996, 1450 m, E. Estrada & C. Yen 5431 (NMC); Sacramento, 

21 Jul 1976, pastizal, 1570 m, Gómez-Blanco 34 (MEXU). San 

Francisco del Oro: 21 km W of Parral and approx. 3.2 km N 

on dirt road to Torrencillo, 26 Sep 1988, grassland, 2000 m, 

P.M. Peterson & Annable 5967 (ENCB). Janos: Chihuahua–Sonora Border, Rancho Carretas, 26 Aug 1939, L. H. Harvey 1602

(US). Madera: Laguna de Babicora, Ejido Año de Hidalgo, 15 

Sep 1994, 2300 m, T. Lebgue, G. Quintana & E. Estrada 3763

(NMC). Namiquipa: Rio Santa Clara Valley. 3.1 mi, by dirt road 

to San Lorenzo, N of Ortega.10 Oct 1982, grassland, 1350 m, 

F.W. Reichenbacher1373 (ARIZ).

26. Aristida laxa Cav., Icon. 5: 44–45, t. 470, f. 1. 1799.

Perennial; with strong roots. Culms 40–60(100) cm tall, erect, 

simple. Leaves basal and cauline, persistent and spirally twisted 

with age; sheaths glabrous; blades 1–30 cm long, 2–2.5 mm wide, 

flat toward the base, involute toward the apex, glabrous abaxially, with long hairs adaxially. Panicles 20–35 cm long, pyramidal, 

open, branches long, spreading to inclinate, scabrous, branched 

below the half, naked at the base; pedicels appressed. Spikelets 

2.3–2.6 mm including the awns. Glumes subequal, 1-veined, the 

lower 9–12 mm long, scabrous, narrow-apiculate, brown, the 

upper 10–12 mm long, glabrous; lemma 10–12 mm long, convolute, glabrous, apiculate, beak awn 5–9 mm long, twisted, not 

articulate, awns 3, straight, the central 10–20 mm long, the laterals 3–7 mm long; anthers 1.2–1.6 mm long. 2n = 44. 

Distribution and Habitat. Aristida laxa

grows on open areas of the pine and oaks forests. It is known 

from Mexico. There are three varieties of this species; in Mexico, 

Aristida laxa var. laxa is found.

Specimens Examined. MEXICO. Chihuahua. 

Namiquipa: at Rancho Teseachic, Mar 1974, rocky hills, A.A. 

Beetle M-3274 (MEXU). Guachochi: 21.8 km al SW de la desviación a [deviation to] La Bufa, 22 km al S de Humira, 17 Sep 

1983, bosque de pino–encino [pine–oak forest], 2070 m, R. Torres et al. 3675 (MEXU).

27. Aristida longespica Poir., Encycl. Suppl. 1: 452. 1810.

FIGURE 21

Annual. Culms 15–65 cm long, erect to spreading, often 

geniculate-based, sometimes nearly prostrate, usually muchbranched. Leaves cauline; sheaths shorter than the internodes, 

not disintegrating into threadlike fibers at maturity, glabrous 

or sparsely pilose, hairs on the throat sometimes to 5 mm; collars glabrous; ligules about 0.5 mm long; blades 5–14 cm long, 

1–2 mm wide, flat to loosely involute, light green. Inflorescences 

usually paniculate, occasionally racemose or spicate, 6–22 cm 

long, 1–4(6) cm wide; nodes glabrous or with straight hairs, 

hairs to 0.3 mm; primary branches 1–4 cm long, appressed to 

erect, rarely somewhat spreading distally, without axillary pulvini, with 2–5 spikelets per branch. Spikelets widely spaced to 

crowded. Glumes subequal, 2–11 mm long, 1-veined, acuminate, 

unawned or awned, awns to 1 mm; calluses less than 1 mm; lemmas 2.5–10 mm long, gray to dark purplish-brown, often horizontally banded or mottled, scabrous-hirsute or glabrous, not 

beaked, apex only slightly narrowed, junction with the awns not 

evident; awns usually unequal, terete and curving up to 100° at 

the base, erect to reflexed distally, not disarticulating at maturity; 

central awns 1–27 mm; lateral awns absent or to 18 mm long, 

shorter than the central awns; anthers 1 and 0.2–0.3 mm long, 

or 3 and 3–4 mm long. Caryopsis 3–4 mm long, light brown.

Distribution and Habitat. Aristida longespica

grows along roadsides and in waste places, sandy fields, and 

clearings in pine and oak woods of southern Ontario and the 

eastern and central United States to Mexico. 

Specimens Examined. MEXICO. Chihuahua. 

Chinipas: Sierra Saguarivo, 1.3 mi W of Curahui, 9 Sep 2008, 

tropical deciduous forest, 1001 m, P.M. Peterson & J.M. Saarela 

22150 (US); 2.1 mi W of Curahui on road towards Saguarivo, 

1328 m, open woods with pines and oaks, 9 Sep 2008, P.M. 

Peterson & J.M. Saarela 22158 (US).

FIGURE 21. Aristida longespica. A. Inflorescence. B. Spikelet. 

Drawn by Linda Ann Vorobik and Andy Sudkamp; copyright Utah 

State University.
3 8 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

28. Aristida pansa Wooton & Standl., Contr. U.S. Natl. Herb. 

16: 112. 1913.

FIGURE 22

Perennial; caespitose. Culms 20–60(75) cm tall, erect, unbranched. Leaves basal and cauline; sheaths usually longer than 

the internodes, glabrous except at the summit; collars densely 

pilose, hairs 1–3 mm long, cobwebby and tangled, often deflexed; ligules less than 0.5 mm long; blades 4–28 cm long, less 

than 1 mm wide, usually involute, infrequently flat, usually arcuate, abaxial surfaces glabrous, adaxial surfaces glabrous or 

puberulent near the base, scabrous or puberulent distally. Inflorescences paniculate, 10–20 cm long, 3–10(12) cm wide; rachis 

nodes usually glabrous, sometimes with straight, less than 0.3 

mm, hairs; primary branches 2–11 cm long, stiffly ascending to 

spreading, with axillary pulvini; secondary branches and pedicels with or without pulvini; terminal spikelets often divergent. 

Spikelets clustered on the distal 1⁄2 of the branches. Glumes equal 

or subequal, 1-veined, acuminate or awned, awns to 6 mm long, 

brownish; lower glumes 5–10 mm; upper glumes 6–12 mm; calluses 0.5–1 mm; lemmas 7–13 mm long, terminating in an obscure, narrow beak 1–4 mm long, 0.1–0.2 mm wide, junction 

with the base of the awns not evident; awns 6–15 mm long, not 

disarticulating at maturity, central and lateral awns similar in 

length and thickness, spreading to horizontal; anthers 3, 1–3 mm 

long, brown. Caryopsis 6–8 mm long, tan.

Distribution and Habitat. Aristida pansa

grows in desert scrub, commonly in the Chihuahuan Desert of 

the southwestern United States and Mexico, but its ecological 

range extends into the lower juniper zones and its geographic 

range to southern Mexico. It has been confused with A. purpurea var. perplexa, which differs in having reddish glumes of 

unequal length and longer ascending awns.

KEY TO FORMS OF ARISTIDA PANSA

1. Axillary pulvini present only on primary branches of the panicle; secondary branches and spikelets appressed to the primary 

branches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. pansa fo. pansa

1. Axillary pulvini present on all branches and pedicels; spikelets widely spreading from the branches . . . . A. pansa fo. dissita

Aristada pansa fo. dissita (I. M. Johnston) Allred & ValdésReyna, Brittonia 49(1): 62. 1997. Aristida dissita I. M. 

Johnston, J. Arnold Arbor. 24(4): 401–402. 1943.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: km 5 on road to Casas Grandes from hwy to Cd. 

Juárez, 19 Sep 1955, matorral xerófilo [xerophilous scrub], 1350 

m, Hern.-Xol 1916 (NMC). Chihuahua: Hills and plains near 

Chihuahua, 13 Oct 1885, C.G. Pringle 388 (US) Isotype; km 

1773 carr. [hwy] a Cd. Juárez, 15 Sep 55, pradera con encinos 

dispersos [meadow with scattered oaks], 1500 m, Hern.-Xol 

& V. Mathus N-1800 (RELC). Guachochi: Flat rock outcrops 

at Napuchis, 2 Sep 2003, grassland, 2140 m, P.M. Peterson & 

P. Catalán 17675 (US). Jiménez: along hwy 45 from Jiménez to 

Parral, 7.2 mi W of Jiménez, 23 Sep 1992, matorral xerófilo, 

1350 m, Allred & Valdés-Reyna 5824 (NMC). Juárez: 5 km 

Norte de Samalayuca, 24 Oct 74, Zona de medanos-dunas [dune 

area], 1730 m, Valdés-Reyna VR-776 (RELC).

Aristida pansa Wooton & Standl. fo. pansa

Specimens Examined. MEXICO. Chihuahua. 

Aldama: Aldama, 24 Aug 1978, matorral [scrub], 1250 m, Molinar, Baray 26c (MEXU); 10.9 (rd) mi NE of Aldama along 

Hwy 16, 14 Sep 1972, matorral, 4200 ft, J. Henrickson 7500

(MEXU). Ahumada: ca 23 (air) mi ENE of Villa Ahumanda in 

NW canyon of Sierra de la Alcaparra NE of Rancho El Palmar, 

12 Sep 1973, matorral, 3800 ft, J. Henrickson 12882 (MEXU). 

FIGURE 22. Aristida pansa. A. Habit. B. Spikelet. Drawn by Linda 

Ann Vorobik and Andy Sudkamp; copyright Utah State University.
NUMBER 107 • 3 9

Camargo: E Chihuahua, 4 mi SE of Mesteñas, road from Jaco, 

to Mesteñas (vía Honorato, Victoria and San Francisco), 5 Oct 

1941, 1380 m, R. Stewart & I.M. Johnson 2016 (US); 7 mi S of 

Camargo, 22 Oct 1957, matorral xeróflio [xerophilous scrub], 

1300 m, Gould 7946 (NMC). Chihuahua: La Campana Experimental Station and Rancho El Arco Iris, about 81–84 km along 

the Pan American hwy, Sep 1977, 1500 m, J.K. Meents & W.H. 

Moir 7 (ENCB); Arenal del 45, 12 km E of La Campana, 28 Sep 

1973, 1400 m, Valdés-Reyna VR-368 (ENCB); km 14 N of Cd. 

Chihuahua, 15 Sep 1955, Hern.-Xol N-1752, N-1755 (ENCB, 

US); 6 km ESE of Rancho Chupaderos in the W part of the Sierritas del Rosario, 29 Aug 1972, matorral, 1575 m, F. Chiang, 

T. Wendt & M.C. Johnston 8987 (MEXU). Jiménez: 13 km al S 

of Jiménez, 30 Jul 1939, 1460 m, L. H. Harvey 1344 (ENCB). 

Juárez: 5 km al N de Samalayuca, Ciudad Juárez, 24 Oct 1974, 

1270 m, Valdés-Reyna VR-776 (ENCB). Madera: Laguna de 

Babicora, Ejido Año de Hidalgo, 15 Sep 1994, 2300 m, Quintana, Lebgue & Estrada 3764 (NMC).

29. Aristida purpurea Nutt., Trans. Amer. Philos. Soc., n.s., 5: 

145. 1837.

Perennial; densely caespitose, without rhizomes. Culms 

10–100 cm long, erect to ascending, usually unbranched. Leaves 

mostly basal or mostly cauline; sheaths shorter or longer than 

the internodes, glabrous, not disintegrating into threadlike fibers 

at maturity; collars glabrous, or sparsely pilose at the sides with 

straight hairs; ligules less than 0.5 mm long; blades 4–25 cm long, 

1–1.5 mm wide, tightly involute to flat, usually glabrous, sometimes scaberulous abaxially, gray-green, lax to curled at maturity. 

Inflorescences usually sparingly branched panicles, occasionally 

racemes, 3–30 cm long, 2–12 cm wide, with 2 or more spikelets per node; nodes glabrous or with straight, about 0.5 mm, 

hairs; primary branches 3–6 cm long, appressed to divaricate, 

varying sometimes within a panicle, stiff to flexible, bases appressed or abruptly spreading, usually without axillary pulvini. 

Spikelets divergent or appressed, with or without axillary pulvini. Glumes usually unequal, sometimes subequal, light to dark 

brown or purplish, glabrous, smooth or scaberulous, 1(2)-veined, 

acuminate, unawned or awned, awns to 1 mm; lower glumes 

4–12 mm; upper glumes 7–25 mm; calluses 0.5–1.8 mm; lemmas 

6–16 mm long, glabrous, scaberulous, or tuberculate, whitish 

to purplish, apex 0.1–0.8 mm wide, not beaked or the beak less 

than 3 mm long, junction with the awns not conspicuous; awns 

(8)13–140 mm long, ascending to divaricate, not disarticulating 

at maturity; central awns thicker than the lateral awns; lateral 

awns (8)13–140 mm long, usually subequal to the central awns, 

occasionally less than 1⁄3 as long as the central awns; anthers 3, 

0.7–2 mm long. Caryopsis 6–14 mm long. 2n = 22, 44, 66, 88.

Aristida purpurea is composed of several intergrading 

varieties.

KEY TO VARIETIES OF ARISTIDA PURPUREA

1. Lower or all primary panicle branches stiff, divergent to divaricate from the base, with axillary pulvini; awns 1.3–3 cm long 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. purpurea var. perplexa

1. Primary panicle branches appressed or ascending at the base, sometimes drooping distally, without axillary pulvini; awns 

0.8–14.0 cm long.

2. Awns 3.5–10 cm long.

3. Lemmas apex 0.1–0.3 mm wide; awns 3.5–6 cm long, 0.1–0.2(0.3) mm wide at the base; upper glumes usually less 

than 1.6 cm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. purpurea var. purpurea

3. Lemma apex 0.3–0.8 mm wide; awns 4–10 cm long, 0.2–0.5 mm wide at the base; upper glumes 1.4–2.5 cm long 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. purpurea var. longiseta

2. Awns 0.8–3.5 cm long.

4. Summit of lemma mostly less than 0.2 mm wide, often with a prominent narrowed beak; awns delicate, mostly less 

than 0.2 mm wide at the base.

5. Panicle branches and pedicels erect, stiff, occasionally spreading . . . . . . . . . . . . . . . . . A. purpurea var. nealleyi

5. Panicle branches and pedicels drooping to flexuous in an S or U shape . . . . . . . . . . . A. purpurea var. purpurea

4. Summit of lemma mostly wider than 0.2 mm long, usually without a beak or the beak indefinite; awns stout, mostly 

0.2 mm or more wide at the base.

6. Mature panicle branches and pedicels flexible, lax or drooping distally . . . . . . . . . . . A. purpurea var. purpurea

6. Mature panicle branches and pedicels usually stiff, straight. 

7. Panicles usually 3–15 cm long; blades 4–10 cm long, generally basal . . . . . . . . . A. purpurea var. fendleriana

7. Panicles usually 15–30 cm long; blades 10–25 cm long, generally cauline . . . . . . . . . . A. purpurea var. wrightii

Aristida purpurea var. fendleriana (Steud.) Vasey, Rep. U.S. 

Natl. Herb. 3(1): 46. 1892.

FIGURE 23

Cited from Unites States and Mexico: Baja California, Chihuahua, Coahuila, Nuevo León, and San Luis Potosí. Samples 

not seen during the present revision.

Aristida purpurea var. longiseta (Steud.) Vasey, Rep. U.S. Geogr. 

Surv., Wheeler 6: 286. 1878.

FIGURE 24

Cited from Canada, Unites States, and north Mexico.

Specimens Examined. MEXICO. Chihuahua. Ahumada: 10 km al W de Sueco, carr. [hwy] 
4 0 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Sueco–Buenaventura, 14 Jun 1974, 1300 m, Valdés-Reyna & 

C. Hernández VR-538 (ENCB); 10 km al SE de Moctezuma, 30 

Jul 1994, 1200 m, R. Corral, E. Pérez, A. Domínguez & F. Félix 

RCD5361 (UACJ). Ascensión: Por la carr. a Palomas, justo al 

N del entronque con [just north of junction with] la carr. a 

casas Grandes, 11 Jun 2005, 1183 m, R. Corral, M. Vargas & 

H. Gutiérrez RCD7138 (UACJ). Chihuahua: Plains near Chihuahua, 8 Oct 1885, C.G. Pringle 473 (MEXU, US); La Campana, Potrero La Sierra, 1 km Ote. [W] Carr. Panamericana, 

10 Sep 73, pastizal [pastureland], 1570 m, Valdés-Reyna VR157 (RELC). Encinillas, 15 Feb 78, pastizal, A. Melgoza 415

(RELC). El Plan, Rancho Experimental La Campana, 19 Abr 

[Apr] 83, pastizal, G. Melgoza 76 (RELC).

Aristida purpurea var. nealleyi (Vasey) Allred, Brittonia 36(4): 

391. 1984. Aristida stricta var. nealleyi Vasey, Contr. U.S. 

Natl. Herb. 1(2): 55. 1890.

Aristida glauca (Nees) Walp.

FIGURE 25

Cited from Unites States to Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Camargo: In arroyo 50 km N of Jiménez, 1 Aug 1939, 1270 m,

L. H. Harvey 1372 (US); 10 km N of Cd. Camargo, 7 Aug 

1939, L. H. Harvey 1418 (US). Chihuahua. Chihuahua, 20 

Aug 1935, LeSueur Mex-09 (US); Rancho Experimental La 

Campana, 82 kms al N de Chihuahua, 26 Aug 1978, 1500 m, 

C.A. Fernández s.n. (ENCB); 16.7 mi W of hwy 45 on road 

up Los Prietos Canyon, 18 Oct 1992, 2120 m, bosque de pino 

[pine forest], 2120 m, P.M. Peterson & Annable 12597 (US); La 

Campana; 1 km carr. [hwy] Panamericana, 5 Sep 1973, 1570 

m, Valdés-Reyna s.n. (ENCB). Jiménez: 39 mi N of Ceballos on 

Mex 49, 31 Mar 1971, 3950 ft, W.E. Harmon, Cox & Dunn 

5433 (ENCB); 50 km al S de Jiménez, 15 Aug 2010, 1442 m, 

D. Ramírez & M.L. Juárez 3414 (CIIDIR); 13 km al S of Jiménez, 30 Jul 1939, 1460 m, L. H. Harvey 1345 (US); Sta Eulalia 

Mts, 8 Sep 1885, C.G. Pringle 389 (US); Sierra de Sta Eulalia, 

2 km N of San Antonio, 16 Aug 1939, L. H. Harvey 1514 (US). 

Juárez: 116 mi N of Gallego, Chih., 18 Jul 1975, 4100 ft, Wallace, LeDux & Dunn 115 (ENCB). Meoqui: Meoqui, 6 Aug 

1936, LeSueur 0120 (US).

FIGURE 23. Aristida purpurea var. fendleriana. A. Habit. B. Spikelet. Drawn by Linda Ann Vorobik and Andy Sudkamp; copyright 

Utah State University.

FIGURE 24. Aristida purpurea var. longiseta. A. Spikelet. B. Glumes. 

C. Lemma. Drawn by Linda Ann Vorobik and Andy Sudkamp; 

copyright Utah State University.
NUMBER 107 • 4 1

Aristida purpurea var. perplexa Allred & Valdés-Reyna, Novon 

5(3): 217–221, f. 6. 1995.

FIGURE 26

Cited from Unites States to Mexico in Chihuahua, Coahuila, and San Luis Potosí (Espejo Serna et al., 2000). Samples 

not seen during the present revision.

Aristida purpurea Nutt. var. purpurea.

Aristida roemeriana Scheele.

FIGURE 27

Cited from Unites States to Mexico and Caribbean Islands.

Specimens Examined. MEXICO. Chihuahua. Aldama: Santo Domingo, 50 km SW of Coyame of Mex 16 between 

Presidio, Texas and Chihuahua, 22 Sep 1988, 1400 m, P.M. Petereson & Annable 5756, 5757 (ENCB, US). Ascensión: Por la 

carr. a [by the highway to] Palomas, justo al N del entronque con 

[just north of the junction with] la carr. a Casas Grandes, 11 Jun 

2005, 1183 m, R. Corral, M. Vargas & H. Gutiérrez RCD7131

(UACJ). Balleza: 24.9 km SE of Balleza and 22.5 km N of hwy 

24, W of Parral, 26 Sep 1988, grassland, 1900 m, P.M. Peterson & Annable 5954 (ENCB, US). Chihuahua: Chihuahua, 3 Sep 

1935, LeSueur Mex-019 (US). Coyame: 13.5 km N of Ojinaga–

Chihuahua Hwy, on road to Acebuche, Murciél and Socorro, 11 

Jun 1973, 1050 m, M.C. Johnston, T. Wendt & F.Chiang 11274

(MEXU). Guachochi: Just N of Guachochi (1 km), 26 Sep 1988, 

pine forest, 2500 m, P.M. Peterson & Annable 5916 (ENCB, US). 

Hidalgo del parral: 14 mi E of Parral, 6 Sep 1967, Reeder & 

C. Reeder 4878, 4892 (ARIZ). Jiménez: Reserva de la Biosfera 

de Mapimí, dunas de arena [sand dunes] La Soledad, 9 Jul 1997, 

matorral xerófilo [xerophilous scrub], 1140 m, A. García 2696

(CIIDIR); Reserva de la Biosfera, presón La Soledad, 3 Sep 1997, 

matorral xerófilo, 1100 m, A. García 2819 (CIIDIR). Julimes: 

S slope and top of Sierra del Roque, NNE of Julimes, approach 

from Mina Las Playas via Rancho El Saucito, 19 Jun 1973, matorral, 1500–2000 m, M.C. Johnston, T. Wendt & F.Chiang 11382

(MEXU). Matamoros: 84.6 km SE of Villa Matamoros and 

1.6 km N of Ejido Revolución on Mex 45, 1900 m, P.M. Peterson, Annable & Valdés-Reyna 10873 (US). Valle de Zaragoza: 

58 km N of Parral on Mex 24 towards Chihuahua, 14 Sep 1989, 

grassland, 1500 m, P.M. Peterson & Annable 8100 (ENCB, US).

Aristida purpurea var. wrightii (Nash) Allred, Brittonia 36(4): 393. 

1984. Aristida wrightii Nash, Fl. S.E. U.S. 116, 1327. 1903.

FIGURE 28

Cited from Unites States to Mexico (Espejo Serna et al., 

2000).

FIGURE 25. Aristida purpurea var. nealleyi. A. Inflorescence. 

B. Spikelet. Drawn by Linda Ann Vorobik and Andy Sudkamp; 

copyright Utah State University.

FIGURE 26. Aristida purpurea var. perplexa. A. Inflorescence. 

B. Spikelet. Drawn by Linda Ann Vorobik and Andy Sudkamp; 

copyright Utah State University.
4 2 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: ca 23 (air) mi ENE of Villa Ahumanda in NW canyon of Sierra de la Alcaparra NE of Rancho El Palmar, 12 Sep 

1973, matorral [scrub], 1250 m, J. Henrickson 12824 (MEXU). 

Aldama: 0.4 mi below (W of) Mina Cerro Verde along Arroyo 

La Cristina, on road to Chorreras (9.1 mi); N of W part of Ejido 

Chorreras, 22 Mar 1975, 1160 m, T.Wendt, E.& J. Lott 747

(ENCB, MEXU); Cañón Pedregoso, SW peak of range, ca. 6 air 

mi. ESE of Ejido Chorreras, 21 Mar 1975, canyon dry scrub, 

1500 m, T.Wendt & E. J. Lott 715 (MEXU); 19 km N of Aldama, on the road to Coyame, 9 Jul 1972, 1300 m, F. Chiang, 

T. Wendt & M.C. Johnston 8361 (MEXU). Ascensión: A few km 

S of Rancho El Norteño and due E of the S end of Sierra de Moscos, 18 Aug 1972, 1250 m, F.Chiang, T. Wendt & M.C. Johnston 8694A (MEXU). Bocoyna: Moist llano [flat] SW of Creel 

near San Ignacio, 17 Oct 1977, on dry slope marginal to the 

llano, Bye & W.A. Weber 8278 (MEXU). Coyame: Base (E) of 

N and of Sierra del Cuchillo Parado where crossed by Ojinaga–

Cd. Chihuahua highway 60 km W of Ojinaga, 21 Oct 1972, 

matorral, 925 m, F.Chiang, T. Wendt & M.C. Johnston 9770

(MEXU); 10 km NE of Coyame on the Ojinaga highway, 22 Oct 

1972, matorral, 1050 m, T. Wendt, F.Chiang & M.C. Johnston 

9818 (MEXU). Guadalupe: Sierra San Martín de Borracho, approached from the abandoned Rancho Carrizozo on the N side, 

15 Jun 1973, Izotal, 1500–2195 m, M.C. Johnston, T. Wendt & 

F.Chiang 11341-A (MEXU). Ojinaga: 15 mi S of Ojinaga, on 

road towards La Perla, Cd. Camargo, 17 Sep 1971, matorral, 

4100 ft, J. Henrickson 6818 (MEXU).

30. Aristida schiedeana Trin. & Rupr., Sp. Gram. Stipac. 120–

121. 1842.

Perennial; caespitose. Culms 30–120 cm tall, erect, unbranched. Leaves basal and cauline, pale green, sometimes 

glaucous; sheaths longer or shorter than the internodes, glabrous except at the summit; collars densely to sparsely pilose or 

glabrous; ligules less than 0.5 mm long; blades 8–30 cm long, 

1–2 mm wide, usually flat, often curled at maturity. Inflorescences 

paniculate, 10–30 cm long, (4)8–26 cm wide; rachis nodes with 

straight hairs, hairs to 0.8 mm long; primary branches 6–16 cm 

long, abruptly spreading to divaricate, stiff to lax, with axillary 

FIGURE 27. Aristida purpurea var. purpurea. A. Habit. B. Spikelet. 

Drawn by Linda Ann Vorobik and Andy Sudkamp; copyright Utah 

State University.

FIGURE 28. Aristida purpurea var. wrightii

A. Spikelet. Drawn by Linda Ann Vorobik 

and Andy Sudkamp; copyright Utah State 

University.
NUMBER 107 • 4 3

pulvini, usually not spikelet-bearing below midlength. Spikelets appressed, rarely spreading. Glumes 1(3)-veined, brown or 

purple at maturity, acuminate; lower glumes 6–13 mm; upper 

glumes equaling or to 4 mm shorter than the lower glumes; calluses 0.8–1.2 mm long; lemmas 10–15(17) mm long, terminating in a strongly twisted, 2–4 mm awn-like beak, junction with 

the awns not conspicuous; awns not disarticulating at maturity; 

central awns 5–12 mm long, markedly bent near the base; lateral 

awns absent or to 1(3) mm long, erect; anthers 1.2–2.2 mm long, 

brownish. Caryopsis 6–8 mm long. 2n = 22, 44.

Distribution and Habitat. Aristida schiedeana

grows on rocky slopes and plains, generally in pinyon–juniper, 

oak, or ponderosa pine communities. It has two recognized varieties in Mexico; only the A. schiedeana var. orcuttiana is found 

in Chihuahua.

Aristada schiedeana var. orcuttiana (Vasey) Allred & ValdésReyna, Novon 5(3): 217. 1995.

FIGURE 29

Cited from the southwestern United States and northern 

Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 43.5 km W of Balleza and 51.6 km E of Guachochi, 

18 Sep 1991, 2320 m, P.M. Peterson, Annable & Valdés-Reyna 

10754, 10757 (CIIDIR, US). Batopilas: between La Bufa and 

Quirirem on N side of Barranca de Batopilas, 10 Oct 1973, oak 

forest, 4500 ft, Bye 5373 (MEXU); Yamuco at 1 km E of Hwy 

towards Basihuare and Creel, N of Rio Urique crossing, 26 Aug 

2003, bosque de pino [pine forest], P.M. Peterson & P. Catalán 17547 (US). Bocoyna: Cabecera de la cañada de Recogoata, 

22 Sep 1997, bosque de pino–encino [pine–oak forest], 2400 m, 

B. Tah V. 31 (MEXU); Sánchez, 12 Oct 1910, Hitchcock 7671

(US). Chihuahua: 32 km W of hwy 45 towards Benito Juárez, 

17 Oct 1992, pinyon woodlands, 2110 m, P.M. Peterson & 

Annable 12553 (US); La Campana, Potrero La Sierra, 4 km W 

carr. [hwy] Panamericana, 5 Sep 1973, 1700 m, Valdés-Reyna 

VR-89, VR-148 (ENCB); Base de la Sierra de La Campana, 

80 km al N de Chihuahua, 19 Oct 1974, 1700 m, Rzedowski 

32332 (ENCB); near Chihuahua, 24 Aug 1885, C.G. Pringle 

486 (US); Mts NW of Chihuahua, 30 Jul 1936, LeSueur 0145

(US); La Campana: Potrero La Sierra; 4 km Pte. carr. Panamericana, 5 Sep 1973, pastizal amacollado con encino [grass pasture 

with oaks], 1700 m, Valdés-Reyna VR-89 (RELC). Guachochi: 

West of Munérachi, 7 Sep 2003, bosque tropical [tropical forest], 1200 m, P.M. Peterson & P. Catalán 17714 (US); 1–2 km 

south of Rio Osichi and Rio Basihuare jct, 1 Sep 2003, oak forest, 1600 m, P.M. Peterson & P. Catalán 17645 (US); 39.2 km S 

of Creel on road to Batopilas at the Barranca El Cobre, 10 Sep 

1989, oak forest, 1930 m, P.M. Peterson, Annable & Y. Herrera 

8027 (ENCB, US); Parque Nacional Barranca del Cobre, 3.8 km 

NE of La Bufa and 9.6 km S of Kirare, 1240 m, P.M. Peterson, 

Annable & Valdés-Reyna 10832 (US); Cusarare, S of Creel, 14 

Sep 1973, pastizal [pastureland], Bye 5042 (MEXU); 2 km W 

of Rio Corareáchi and E of Osichi, 30 Aug 2003, bosque de 

pino, 1960 m, P.M. Peterson & P. Catalán 17622 (US). Guerrero: Miñaca, 13 Oct 1910, Hitchcock 7763 (US); km 19 carr. la 

Junta San Juanito, 22 Sep 1997, 2300 m, B. Tah V. 24 (MEXU); 

km 193 carr. Chihuahua–Hermosillo, 24 Sep 1997, 2200 m, 

M.A. Vergara 170 (MEXU); km 202 carr. Chihuahua–Madera, 

8 Aug 1981, bosque esclero-aciculifolio [narrow-leaved sclerophyllous forest], R. Fierros 1483 (MEXU); 32.3 km SW of La 

Junta on road to Creel, 10 Sep 1989, pine forest, 2310 m, P.M. 

Peterson, Annable & Y. Herrera 7989 (ENCB, US); 33.7 mi W 

of La Junta on road to Parque Nacional Cascada Basaseachic, 

30 Sep 1989, 2260 m, P.M. Peterson & R.M. King 8206 (US); 

Camino Guachochic–Creel, 5 km antes del entronque [before the 

junction] a la Bufa, 24 Sep 1981, Bosque esclerófilo caducifolio 

[deciduous sclerophyllous forest], 2700 m, M.E. Siqueiros 1623 

(MEXU). Janos: Chihuahua–Sonora Border, Rancho Carretas, 

30 Aug 1939, grassland, 1460 m, L. H. Harvey 1638 (ENCB, 

US). Jiménez: Sta Eulalia Mts, 10 Sep 1885, C.G. Pringle 386

(ENCB); Sta. Eulalia Mts, 10 Sep 1885, 1280 m, E. Wilkinson 4, 

343 (US). Juárez: On rocky north-facing mountain slope, Sierra 

Mula, just W of Juarez, 24 Oct 1959, Correll 23306-A (ENCB, 

US). Madera: Mesa del Yerbanís, ejido El Largo, 12 Oct 1990, 

bosque de Quercus, 1900 m, O. Bravo 1828a (CIIDIR); km 

202, carr. Chihuahua–Madera, 21 Aug 1981, bosque escleroaciculifolio, M.E. Siqueiros 1483 (MEXU). Matachi: SW of 

Matachi; on slope on NW side of ridge near km 9.7 on Matachi–

Cocomorachi road, 29 Aug 1978, pine–oak forest, 1900 m, Bye 

FIGURE 29. Aristida schiedeana var. orcuttiana. A. Inflorescence. 

B. Lemma. Drawn by Linda Ann Vorobik and Andy Sudkamp; 

copyright Utah State University.
4 4 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

9010, 9007 (MEXU). Ocampo: Parque Nacional “Cascada de 

Basaseachic,” near top of falls, 22 Sep 1994, 2000 m, Spellenberg, Corral & Estrada 12080 (NMC); Parque Nacional “Cascada de Basaseachic,” at overlook ca. 1 km airline S of Cascada, 

3 Oct 1986, 2100 m, Spellenberg, Soreng, R. Corral & T. Lebgue 8648 (NMC); Parque Nacional “Cascada de Basaseachic,” 

on ridge top SE side of canyon of Rio Candamena leading to 

falls, 4 Oct 1986, 1800 m, Spellenberg, Soreng, R. Corral & 

T. Lebgue 8719 (NMC). Riva Palacio: Arroyo del Nido, Sierra 

del Nido, 3.6 mi by dirt road, southwest of Rancho El Nido, 

8 Oct 1982, pine–oak woodland, 1700 m, F.W. Reichenbacher 

1315 (ARIZ); Col. Cumbres de Majalca, 33.8 km W of Mex 45, 

N of Chihuahua City, 7 Sep 1989, pine forest, 2190 m, P.M. Peterson, Annable & Y. Herrera 7972 (ENCB, US). San Francisco 

del Oro: Ejido Corral de Duarte, 21 Sep 1981, bosque escleroaciculifolio, E. Blanco 1557 (MEXU).

31. Aristida spanospicula Allred, Valdés-Reyna & Sánchez-Ken, 

Novon 5: 209–222. 1995.

Perennial; mat-forming. Culms 25–50(66) cm tall, ascending, slender, not branched above the base, glabrous. Sheaths 

glabrous or sparsely pilose, ligula 0.5 mm long, a ring of hairs; 

blades 14–25 cm long, 1.5–2 mm wide, flat to plicate, inrolled 

when mature, glabrous to puberulent, green pale, the margins 

hardened. Panicles 10–22 cm long, 1–2 cm wide, with spaced 

spikelets, 3–12 in total, 2(4) on each branch, widely spaced, with 

capillary pedicels. Glumes 9–15 mm long, subequal, brown, 

1-veined, glabrous; lemma 18–22(25) mm long, convolutes, glabrous, awns 1–3, the central 10–20 mm long, the laterals when 

present no longer than 0.5 mm; callus 0.6–0.8 mm long, obtuse; 

stamens 1.7–2 mm long, brown. 

Distribution and Habitat. Aristida spanospicula grows in pine–oak forests and occurs in Mexico in Chihuahua, Durango, and Sonora.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: Yamuco, 1 mi E of hwy N of Rio Urique crossing, 

towards Basihuare and Creel, 6 Sep 2008, slopes with pines and 

oaks, 1890 m, P.M. Peterson & J.M. Saarela 22075 (US); bajada 

[descent] a Batopilas, 25 sep 1981, bosque esclero-caducifolio 

[deciduous sclerophyllus forest], 2100 m, R. Fierros 1641 

(MEXU) Bocoyna: at Cuesta Prieta, along road from San Juanito to Creel, 3.1 mi S of San Juanito, 22 Sep 1992, 2400 m, 

K.W. Allred & Valdés-Reyna 5787 (NMC). Casas Grandes: 

W of Casas Grandes, 3 mi W of Cuesta Blanca, 4 Sep 1958, 

Reeder & C. Reeder 3214 (ARIZ, US). Cusihuiriachi: Rancho 

El Coronel, 2 Sep 1981, bosque esclero-aciculifolio [narrowleaved sclerophyllous forest], 2500 m, Loya & Méndez 1523

(MEXU). Guachochi: Cusarare, south of Creel, 14 Sep 1973, 

pastizal [pastureland], Bye 5047 (MEXU); km 85 carr. [hwy] 

Balleza–Guachochi, 24 Sep 1981, bosque esclerófilo caducifolio, 

2300 m, M.E. Siqueiros 1601 (MEXU). Guerrero: Between Cd. 

Guerrero and Creel, Mar 1974, 2200 m, A.A. Beetle M-3323

(MEXU). Madera: Chuhichupa, Aug–Sep 1936, LeSueur Mex0112 (MEXU). Namiquipa: Rancho Teseachic, potrero Palmillas 

[palm pasture], Cerro falda [hillside] del Saucito, 30 Jun 1971, 

pastizal con encino [pastureland with oak], P. Pérez 21 (MEXU).

32. Aristida ternipes Cav., Icon. 5: 46. 1799.

Perennial; caespitose. Culms 25–120 cm tall, wiry, erect to 

sprawling, unbranched. Leaves basal and cauline; sheaths usually 

longer than the internodes, glabrous; collars glabrous or strigillose; ligules less than 0.5 mm; blades 5–40 cm long, 1–2.5 mm 

wide, flat to folded, straight to lax at maturity, adaxial surfaces 

with scattered 1.5–3 mm hairs near the ligule. Inflorescences paniculate, 15–40 cm long, (8)10–35(45) mm wide; rachis nodes 

glabrous or strigillose; primary branches 5–25 cm long, remote, 

stiffly ascending to divaricate, with axillary pulvini, usually naked 

near the base; secondary branches and pedicels usually appressed. 

Spikelets usually congested. Glumes subequal, 9–15 mm long, 

1-veined, acuminate; calluses 1–1.2 mm; lemmas 9–15 mm long, 

smooth to tuberculate-scabrous, narrowing to slightly keeled, usually not twisted, 0.1–0.2 mm wide apex, junction with the awns 

not evident; awns unequal or almost equal, not disarticulating at 

maturity; central awns 8–25(30) mm long, straight to arcuate at 

the base; lateral awns absent or to 23 mm; anthers 3, 1.2–2.4 mm. 

Caryopsis 6–8 mm long, light brownish. 2n = 22, 24.

Two varieties from this species are recognized in Mexico, 

both in Chihuahua.

KEY TO VARIETIES OF ARISTIDA TERNIPES

1. Lateral awns 2–23 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. ternipes var. gentilis

1. Lateral awns 0–2 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. ternipes var. ternipes

Aristida ternipes var. gentilis (Henrard) Allred, Phytologia 77: 

412. 1995. Aristida gentilis Henrard, Meded. Rijks-Herb. 

54:196. 1926.

A. hamulosa Henrard, A. ternipes var. hamulosa (Henrard) Trent.

FIGURE 30

Distribution and Habitat. Aristida ternipes var. gentilis grows in grasslands and desert scrub and 

ranges from the United States to Mexico, Guatemala, and 

Honduras. 

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: Gallegos, 2 Oct 1958, G. Neville J. 22485 (MEXU). 

Aldama: 19 km N of Aldama, on the road to Coyame, 9 Jul 1972, 

1300 m, F.Chiang, T. Wendt & M.C. Johnston 8360 (MEXU); 

13.3 (rd) mi NE of Aldama along Chihuahua Hwy 16, 14 Sep 

1972, Larrea scrub, 1400 m, J. Henrickson 7520 (ARIZ). Allende: Carr. [hwy] 45 Parral–Torreón, 20 km al N del Poblado 

[village] Río Florido, Chih., 15 Sep 1970, 1850 m, E. Estrada 

4107 (ENCB). Batopilas: Batopilas, 25 Sep 1981, selva baja caducifolia [low deciduous forest], 530 m, R. Fierros 1662, 1684
NUMBER 107 • 4 5

(MEXU). Bocoyna: Barrancas del Cobre, camino a Río Urique 

por Estación Divisadero, 16 Aug 1975, bosque bajo de leguminosas [low legume forest], 1875 m, S. González 718 (RELC). Chihuahua: 5 mi SW of Chihuahua on road to Cuauhtémoc, 6 Oct 

1959, 1463 m, Soderstrom 895 (US); La Campana Experimental 

Station and Rancho El Arco Iris, 81–84 km along Pan American 

Hwy to Chihuahua City, Oct 1977, 1500 m, J.K. Meents & W.H. 

Moir 103 (NMC); La Campana; bajío [shallows] 12 km Ote. [W] 

carr. Panamericana, 13 Sep 1973, pastizal halófito [halophyte pastureland], 1450 m, Valdés-Reyna VR-242 (RELC); km 1773 carr. 

a Cd. Juárez, 15 Sep 55, pradera con encinos dispersos[meadow 

with scattered oaks], 1500 m, Hern.-Xol & V. Mathus N-1838, 

N-1840 (RELC); La Campana, 1 km Pte. Carr. Panamericana, 

31 Aug 1973, pastizal, 1570 m, Valdés-Reyna VR-199, VR-34

(RELC); S. González 282 (RELC); Chihuahua, 3 Aug 1978, 

pastizal, 1450 m, Molinar-Delgadillo 13 (MEXU); km 52 carr. 

Chihuahua–Juárez, 3 Aug 1978, pastizal, 1450 m, I.D. Enriquez 8

(MEXU); carr. Chihuahua–Cuauhtémoc, 27 Abr [Apr] 1981, pastizal, E. Blanco 1242 (MEXU); Sacramento, 21 Jul 1976, pastizal, 

1570 m, Gómez-Blanco 32 (MEXU); 19 km N of Aldama, on the 

road to Coyame, 9 Jul 1972, 1300 m, F.Chiang, T. Wendt & M.C. 

Johnston 8360 (MEXU). Guachochi: 2 km W of Rio Corareáchi and E of Osichi, 30 Aug 2003, bosque de pino [pine forest], 

1960 m, P.M. Peterson & P. Catalán 17622A (US); Camino Guachochi–Creel, 5 km del entronque [junction] a la Bufa, 24 Sep 

1981, bosque sclero-caducifolio [deciduous sclerophyllus forest], 2700 m, M.E. Siqueiros 1635 (MEXU). Hidalgo del Parral: 

14 mi E of Parral, 6 Sep 1967, 5300 ft, Reeder & C. Reeder 4880

(ARIZ, ENCB, US). Janos: near San Pedro River, Mexican boundary line, 18 Jun 1892, E.A. Mearns 355 (US); km 5 carr. Janos–

Agua Prieta, 13 Jun 1981, matorral [scrub], 1830 m, I. Enríquez 

& Jaramillo 1321 (MEXU). Jiménez: LBJ’s Rancho Las Pampas, 

ca. 13 km SE of the min ranch house (Acebuches), 27 Aug 1972, 

pastizal, 1450 m, M.C. Johnston, T. Wendt & F.Chiang 8950

(MEXU). La Cruz: La Paz microwave relay station, 26 km W of 

Camargo, 8 Jul 1972, top of basalt-capped hill overlooking Río 

Conchos, 1400 m, F.Chiang, T. Wendt & M.C. Johnston 8329? 

(MEXU). Madera: Laguna de Babicora, alrededores [surroundings] de Nicolas Bravo, 18 Aug 1994, 2200 m, Quintana, Lebgue & Estrada 3133 (NMC). Manuel Benavides: Entre [between] 

Manuel Benavides & Pocitos, 2 Aug 1975, Ladera de cerro con 

pastizal [hillside with pasture], 1342 m, S. González 455 (RELC); 

69 (rd) mi S of Ojinaga along Hwy 18 (Ojinaga–C. Camargo), 17 

Sep 1972, pastizal, 1500 m, J. Henrickson 7717 (MEXU); 71⁄2 mi 

S Piramide, 11 Aug 1941, I.M. Johnston 8108 (MEXU). 

Aristida ternipes var. ternipes

FIGURE 31

Distribution and Habitat. Aristida ternipes 

var. ternipes grows in grasslands, desert scrub, and oak forests. 

It ranges from the United States to Mexico, South America, and 

the Caribean Islands.

Specimens Examined. MEXICO. Chihuahua. Aldama: 13.3 (rd) mi NE of Aldama along Chihuahua Hwy 16, 

14 Sep 1972, 1400 m, J. Henrickson 7520 (NMC). Batopilas: 

SW Chihuahua, Aug 1885, E. Palmer 115, 161 (US). Chinipas: 

Sierra Saguarivo, 1.3 mi W of Curahui, 9 Sep 2008, tropical deciduous forest, 1001 m, P.M. Peterson & J.M. Saarela 22153, 

22154 (US). Chihuahua: La Campana Experimental Station and 

Rancho El Arco Iris, about 81–84 km along the Pan American 

hwy to Chihuahua City, Sep 1977, 1500 m, J.K. Meents & W.H. 

FIGURE 30. Aristida ternipes var. gentilis. A. Inflorescence branch. 

B. Lemma. Drawn by Linda Ann Vorobik and Andy Sudkamp; 

copyright Utah State University.

FIGURE 31. Aristida ternipes var. ternipes. A. Habit. Drawn by 

Linda Ann Vorobik and Andy Sudkamp; copyright Utah State 

University.
4 6 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Moir 78 (ENCB); Rocky hills near Chihuahua, 13 Aug 1885, 

C.G. Pringle 387-B (US); 25 km W of Chihuahua, 20 Aug 1939, 

pastizal [pastureland], 1635 m, L. H. Harvey 1544 (US). Guachochi: 7.4 km SW of La Bufa and 15 km NE of Batopilas, 920 

m, thorn scrub vegetation, 20 Sep 1991, P.M. Peterson, Annable 

& Valdés-Reyna 10850 (US). Janos: Chihuahua–Sonora border, 

Rancho Carretas, 27 Aug 1939, bosque de encino [oak forest], 

1780 m, L. H. Harvey 1633 (US); La Campana Experimental 

Station and Rancho El Arco Iris, 81–84 km along Pan American Hwy to Chihuahua City, Oct 1977, J.K. Meents & W.H. 

Moir 71, 74 (NMC). Jiménez: Sierra de Sta Eulalia, 2 km N of 

San Antonio, 16 Aug 1939, L. H. Harvey 1498 (US); 8 mi N 

of Jiménez on Mex. 45, 30 Aug 1971, 4400 ft, L. H. Harvey 

8894 (ENCB). Madera: Paraje Sirupa, ejido Cebadilla de Dolores, 24 Ag 1990, matorral de Juniperus [juniper scrub], 1220 m, 

A. Benítez 1931 (CIIDIR). Meoqui: Meoqui, 24 Aug 1935, 

LeSueur Mex-038 (US). Satevo: Parral–Chihuahua road, 19 km 

N of Rio San Pedro, 8 Aug 1939, matorral xerófilo [xerophilic 

scrub], 1375 m, L. H. Harvey 1426 (US). Valle de Zaragoza: 58 

km N of Parral on Mex 24 towards Chihuahua, 14 Sep 1989, 

grassland, 1500 m, P.M. Peterson & Annable 8099 (ENCB, US).

Arundo L.

Perennial; rhizomatous, rhizomes short, usually more than 

1 cm thick. Culms 2–10 m tall, 1–3.5 cm thick, usually erect, 

occasionally pendant from cliffs; nodes glabrous; internodes hollow. Leaves cauline, conspicuously distichous, glabrous; sheaths 

open, longer than the internodes; ligules membranous, shortly 

ciliate; blades flat or folded, margins scabrous. Panicles terminal, 

plumose, silvery to purplish. Spikelets laterally compressed, with 

1 to several florets; rachilla internodes glabrous; disarticulation 

above the glumes and between the florets. Glumes longer than 

the florets, 3- to 5-veined; lemmas pilose, hairs not papillosebased, 3- to 7-veined, apex entire or minutely awned; paleas 

shorter than the lemmas, 2-veined; anthers 3. x = 12.

Arundo, a genus of three species, grows throughout the 

tropical and warm-temperate regions of the world. Only one 

species has been introduced to the Western Hemisphere.

33. Arundo donax* L., Sp. Pl. 1: 81. 1753.

FIGURE 32

Culms (2)3–10 m tall, in large tussocks or hedges. Leaves 

distichous; ligules 0.4–1 mm long; blades 30–100 cm long, 

2–7(9) cm wide, cordate to clasping below, light to dark brown 

area at the base. Panicles 30–60 cm long, to 30 cm wide. 

Spikelets 10–15 mm long, with 2–4 florets. Glumes subequal, 

as long as the spikelets, thin, brownish or purplish, 3-veined, 

long-acuminate; lemmas 8–12 mm long, 3- to 5-veined, pilose, 

hairs 4–9 mm long, apex bifid, midvein ending into a delicate 

awn; paleas 3–5 mm long, pilose at the base; anthers 2–3 mm 

long. Caryopsis 3–4 mm long, oblong, light brown. 2n = 24, 

100, 110.

FIGURE 32. Arundo donax. A. Culm and inflorescence. B. Rhizome. C. Spikelet. D. Floret. Drawn by Linda Ann Vorobik and 

Hana Pazdírková; copyright Utah State University.
NUMBER 107 • 4 7

Distribution and Habitat. Arundo donax

grows in the southern half of the contiguous United States and 

throughout Mexico, being found along ditches, culverts, and 

roadsides where water accumulates. It is grown for its ornamental value of tall, leafy culms and large panicles.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: 14.5 km N of Batopilas on road to La Bufa, 12 Sep 

1989, 850 m, P.M. Peterson, Annable & Y. Herrera 8062

(ENCB, US); Barranca de Batopilas, vicinity of La Bufa, Nov 

1973, Bye 3949, 9614 (MEXU); 20 km de Batopilas, pequeña 

cañada a orilla de la carr. sobre la barranca [small glen to side 

of road on the canyon] del Río Batopilas, 30 Abr [Apr] 1980, 

F.S. Montaño & M.A. Martínez s/n (MEXU); SW of Chihuahua, 

Aug–Nov 1885, E. Palmer 51A (US); Barranca de Batopillas, 

near Creel–La Bufa road, 9 Jun 1963, margin of riverbed, 850 

m, S. Felger & R. Russell 8081 (ARIZ). Bocoyna: Barrancas del 

Cobre, camino a Alto Río Urique por Estación Divisadero, 15 

Aug 1976, bosque bajo espinoso [thorny low forest], 1975 m, 

S. González & J.M. Peña 715 (RELC). Delicias: About 14 mi S 

of Las Delicias, 4 Oct 1953, cultivated valley, 1220 m, Reeder, 

C. Reeder 2614 (MEXU). Juárez: Ciudad Juárez, a lo largo 

[along] de la “Asequia Madre” entre [between] la Av. Américas 

& Paseo Triunfo de la República, 29 Sep 1995, 1140 m, R. Corral, P. Olivas & L.M. Barraza RCD6413 (UACJ); Ciudad Juárez 

a lo largo de la “Asequia Madre” al N del fracc. Rincones de 

San Marcos, 13 Oct 1995, 1140 m, R. Corral, P. Olivas & L.M. 

Barraza RCD6545 (UACJ); Ciudad Juárez a lo largo [along] 

de la “Asequia Madre” desde la intersección de las calles [from 

the intersection of streets] Mejía & Santos Degollado, hasta el 

túnel bajo [until the tunnel under] el Viaducto Díaz Ordaz, 3 Jun 

1995, 1140 m, R. Corral & L.M. Barraza RCD6113 (UACJ). 

Madera: Near Chuhichupa in the Sierra Madres, 3 Sep 1899, 

bosque de encino [oak forest], 2240 m, C.H.T. Townsend & 

C.M. Barben 399 (NMC). Práxedis G. Guerrero: aprox. 3 km 

al NW del Porvenir, por la carr. [hwy] Juárez–Porvenir, a los 

lados de cultivo de algodón [near cultivated cotton], 8 Sep 1994, 

1090 m, R. Corral, Bye, A. Domínguez, K. Chico & P. Yañez 

RCD5413 (UACJ). Uruachi: Rio Mayo between Moris and San 

Bernardo. 25 Sep 1991, 500 m, along the banks of the river, 

P. Jenkins 91-79 (ARIZ).

Avena L.

Annual or perennial. Culms 8–200 cm tall, erect or decumbent. Sheaths open; auricles absent; ligules membranous; blades 

usually flat, sometimes involute, lax. Inflorescences as panicles, 

diffuse, sometimes 1-sided. Spikelets 15–50 mm long, laterally 

compressed, with 1–6(8) florets; rachillas not prolonged beyond 

the uppermost floret; disarticulation above the glumes, usually 

also between the florets, or cultivated forms not disarticulating. 

Glumes usually exceeding the florets, membranous, glabrous, 3-

to 11-veined, acute; calluses rounded to pointed, with or without 

hairs; lemmas usually indurate and enclosing the caryopsis at 

maturity, 5- to 9-veined, often with twisted, strigose hairs below 

midlength, apex dentate to bifid or biaristate, awns (if present) 

dorsal, usually once-geniculate and strongly twisted in the basal 

portion; paleas bifid or entire, ciliate on the keels; lodicules 2, 

free, glabrous, toothed or not toothed; anthers 3; ovaries hairy. 

Caryopsis terete, ventrally grooved, pubescent. x = 7. 

Distribution and Habitat. Avena, a genus of 

29 species, is native to temperate and cold regions of Europe, 

North Africa, and central Asia; it has become nearly cosmopolitan through the cultivation of cereal oats and the inadvertent 

introduction of the weedy species.

KEY TO SPECIES OF AVENA

1. Lemma conspicuously pubescent dorsally, the awn geniculate and twisted; spikelets usually with 3 florets; lodicules without lateral lobes or teeth; weeds of cultived areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. fatua

1. Lemma glabrous or sparsely pubescent at the base, the awn straight or weakly twisted and weakly geniculate; spikelets 

with 2 florets; lodicules with a small terminal tooth or lobe below the center; plants cultivated, rarely persistent . . . . . .

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. sativa

34. Avena fatua* L., Sp. Pl. 1: 80. 1753.

FIGURE 33

Annual. Culms 8–160 cm long, prostrate to erect when 

young, becoming erect at maturity. Sheaths of the basal leaves 

with scattered hairs, distal sheaths glabrous; ligules 4–6 mm 

long, acute; blades 10–45 cm long, 3–15 mm wide, scaberulous. Panicles 7–40 cm long, 5–20 cm wide, nodding. Spikelets 

18–32 mm long, with 2(3) florets; disarticulation beneath each 

floret; disarticulation scars round to ovate or triangular. Glumes 

subequal, 18–32 mm long, 9- to 11-veined; calluses bearded, 

hairs to 1⁄4 the length of the lemmas; lemmas 14–22 mm long, 

usually densely strigose below midlength, varying to sparsely 

strigose or glabrous, veins not excurrent beyond the apex, apex 

usually bifid, teeth 0.3–1.5 mm long, awns 23–42 mm long, arising in the middle 1⁄3 of the lemmas; lodicules without lobes on the 

wings; anthers about 3 mm long. 2n = 42.

Distribution and Habitat. Avena fatua is native to Europe and central Asia. It is known as a weed in most 

temperate regions of the world; in some parts of Canada and the 

United States it is considered a noxious weed.

Specimens Examined. MEXICO. Chihuahua.

Ascensión: alrededores del cruce del río [near river crossing] 

Casas Grandes con la carr. [hwy] Juárez–Ascensión, 11 Jun 

2005, 1180 m, R. Corral, M. Vargas & H. Gutiérrez RCD7150

(UACJ).
4 8 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

FIGURE 33. Avena fatua. A. Habit. B. Ligule. C. Inflorescence. D. Spikelet. E. Floret. F. disarticulation scar. Drawn by Cindy Roché; copyright Utah State University.
NUMBER 107 • 4 9

35. Avena sativa* L., Sp. Pl. 1: 79. 1753.

FIGURE 34

Annual. Culms 40–180 cm tall, prostrate to erect when 

young, becoming erect at maturity. Sheaths smooth or scaberulous; ligules 3–8 mm long, acute; blades 8–45 cm long, 3–14 

(25) mm wide, scaberulous. Panicles (6)20–40 cm long, 5–15 cm 

wide, nodding. Spikelets(18)25–32 mm (to 50 mm in naked 

oats), with 1–2 florets (to 7 in naked oats); disarticulation not 

occurring, the florets remaining attached even when mature.

Glumes subequal, (18)20–32 mm long, 9- to 11-veined; calluses 

glabrous; lemmas 14–18 mm long, usually indurate (membranous in naked oats), usually glabrous, sometimes sparsely strigose, apex erose to dentate, longest teeth 0.2–0.5 mm long, awns 

usually absent, 15–30 mm when present, arising in the middle 1⁄3, 

straight or weakly twisted and weakly geniculate; lodicules with 

a lobe or tooth on the wings, this sometimes very small; anthers 

(1.7)3–4.3 mm long. 2n = 42.

Distribution and Habitat. Avena sativa, a native of Eurasia, is widely cultivated in cool, temperate regions of 

the world, including North America. Several forms are grown, 

of which the most distinctive are naked oats. These differ from 

typical forms as indicated in the description and in having caryopses that fall.

Specimens Examined. MEXICO. Chihuahua. 

Bocoyna: 1.1 km N of San Juanito near large lumber mill, 24 Sep 

1988, 2200 m, P.M. Peterson & Annable 5868 (ENCB, US); 

20 km S of San Juanito on road to Creel and 3 km S of Bocoyna, 

24 Sep 1988, pine forest, 2200 m, P.M. Peterson & Annable 

5874 (ENCB, US). Chihuahua: La Campana; Potrero El Plan, 

4 km Ote [W], carr. [hwy] Panamericana, 5 Sep 1973, lotes producción de semilla [seed-production lots], 1500 m, Valdés-Reyna 

VR-92 (RELC). Matamoros: 19.3 km S of Villa Matamoros on 

Hwy 45 to Durango, 3 Oct 1989, grassland, 1910 m, P.M. Peterson & R.M. King 8251 (US). Práxedis G. Guerrero: a 2 km del 

poblado [village] Práxedis G. Guerrero (San Ignacio), Rancho 

Escuela de la Univ. Autónoma de Ciudad Juárez, 5 May 1995, 

maleza de acequia [weed of ditch], 1090 m, R. Corral, Bye, 

A. Domínguez, K. Chico & A. Soutyrine RCD6079 (UACJ); 

Rancho Escuela, 16 Aug 1997, I. Enriquez, S. Ordoñez, L. Sushii, S. Carrasco, A. Perales & N. Loya IEA8 (UACJ). Temosachi: Nabogame, 22 Jun 1988, 1800 m, Laferr. 1366 (ARIZ).

Avenella (Bluff & Fingerh.) Drejer

Plants usually perennial, sometimes annual; caespitose or 

tufted. Culms hollow, erect. Leaves usually mainly basal, often 

forming a dense tuft; sheaths open; auricles absent; ligules membranous, decurrent, rounded to acuminate; blades often all or 

almost all tightly rolled or folded and some flat, sometimes most 

flat, others rolled or folded. Inflorescences terminal panicles, 

open or contracted; disarticulation above the glumes, beneath 

the florets. Spikelets with 2(3) florets in all or almost all spikelets, florets usually bisexual, sometimes viviparous; rachillas 

FIGURE 34. Avena sativa. A. Habit. B. Ligule. C. Spikelet. D. Floret. 

Drawn by Cindy Roché; copyright Utah State University.
5 0 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

hairy, usually prolonged more than 0.5 mm beyond the base 

of the distal floret, sometimes terminating in a highly reduced 

floret. Glumes subequal to unequal, usually exceeding the adjacent florets, often exceeding all florets, 1- to 3-veined, acute 

to acuminate; calluses antrorsely strigose; lemmas obscurely 

(3)5- to 7-veined, rounded over the back, apex truncate-erose 

to 2–4-toothed, awned, awns usually attached on the lower 1⁄2

of the lemmas, occasionally subapical, straight to strongly geniculate, slightly to strongly twisted proximally, straight distally; 

paleas shorter than the lemmas, 2-keeled, keels often scabrous; 

lodicules 2, lanceolate to ovate-lanceolate, usually entire; anthers 

3; ovaries glabrous; styles 2. Caryopsis oblong; embryos about 1⁄4

the length of the caryopsis. x = 7.

Avenella, a segregate of Deschampsia includes one species 

widely distributed in America. It grows in cool, damp habitats 

throughout the world.

36. Avenella flexuosa (L.) Drejer, Fl. Excurs. Hafn. 32. 1838. 

Aira flexuosa L., Sp. Pl. 1: 65. 1753. Deschampsia flexuosa

(L.) Trin., Mém. Acad. Imp. Sci. Saint-Pétersbourg, Sér. 6, 

Sci. Math., Seconde Pt. Sci. Nat. 1: 66. 1836.

FIGURE 35

Perennial; densely caespitose. Culms 30–80 cm long, erect 

or geniculate at the base, usually with 2 nodes. Leaves mostly 

basal, sometimes forming a basal tuft; sheaths smooth, glabrous; 

ligules 1.5–3.6 mm long, rounded to acute; blades 12–25 cm 

long, strongly rolled, 0.3–0.5 mm in diameter, abaxial surfaces 

smooth or scaberulous, glabrous or hairy, often scaberulous or 

hairy proximally and essentially smooth and glabrous distally, 

adaxial surfaces scabrous, flag leaf blades 5–8 cm. Panicles 

5–15 cm long, (2)4–12 cm wide, narrow to open, often nodding; branches ascending to spreading, flexuous, smooth or scaberulous. Spikelets 4–7 mm long, ovate or U-shaped. Glumes 

exceeded by or subequal to the adjacent florets, 1-veined, acute; 

lower glumes 2.7–4.5 mm long; upper glumes 3.5–5 mm long; 

callus hairs to 1 mm long; lemmas 3.3–5 mm long, scaberulous or puberulent, hairs to 0.1 mm long, apex acute, erose to 

4-toothed, awns 3.7–7 mm long, attached near the base of the 

lemma, strongly geniculate, geniculation below the lemma apex, 

distal segment 2.5–4.5 mm long, pale; anthers 2–3 mm long. 

2n = 14, 26, 28, 32, 42.

Distribution and Habitat. Avenella flexuosa 

grows on dry, often rocky, slopes and in woods and thickets, 

often in disturbed sites. It is primarily eastern in distribution, 

with records from west of the Great Lakes and Appalachians 

probably being introductions. It is also known from Mexico, 

Central America, South America, Borneo, the Philippines, and 

New Zealand.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: 38 km W of hwy 45 on road towards Benito Juárez, 

17 Oct 1992, pinyon woodlands, 2230 m, P.M. Peterson & 

Annable 12575 (US). Cuauhtémoc: 21 km W of Cuauhtemoc, 

on Hwy 16, 23 Aug 1990, 2000 m, P.M. Peterson & Annable 

9591 (US). Gómez Farías: Laguna de Babicora,18 Aug 1994, 

2150 m, T. Lebgue & E. Estrada 3324 (NMC). Guadalupe y 

Calvo: on summit of Sierra Mohinora, 10,000–10,300 ft, conifer 

forest, 16–17 Oct 1959, Correl & Gentry 23179 (ENCB, US); 

near Cumbre Mohinora, 13 Sep 2006, 3300 m, P.M. Peterson 

20039, F. Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, US). 

Ocampo: Parque Nacional “Cascada de Basaseachic,” 25 Abr 

[Apr] 1986, 1700 m, Spellenberg, Soreng, R. Corral & T. Lebgue 

8474 (NMC).

FIGURE 35. Avenella flexuosa. A. Habit. B. Spikelet. C. Florets. 

Drawn by Cindy Roché; copyright Utah State University.
NUMBER 107 • 5 1

Blepharidachne Hack.

Perennial, rarely annual; caespitose, from a knotty base, 

often mat-forming. Culms often decumbent and rooting at the 

lower nodes, frequently branched above the bases, forming short 

spur shoots at the ends of long internodes; internodes minutely 

pubescent. Leaves clustered at the bases of the primary and spur 

shoots; basal sheaths shorter than the internodes; ligules of hairs 

or absent; blades linear to triangular, convolute to conduplicate, 

or flat to plicate, sharp, those of the upper leaves usually exceeding the inflorescences. Inflorescences terminal, compact panicles, 

exserted or partially included in the upper sheath(s). Spikelets 

laterally compressed, subsessile or pedicellate, with 4 florets per 

spikelet; disarticulation above the glumes but not between the 

florets. Glumes subequal to each other and the lowest lemma, 

rounded or weakly keeled, 1-veined, awn-tipped or unawned; 

lowest 2 florets in each spikelet staminate or sterile; third floret 

pistillate or bisexual; lemmas rounded on the back, 3-veined, 

mostly glabrous but pilose across the bases and on the margins, 

strongly 3-lobed, lateral lobes wider than the central lobes, all 

lobes ciliate on 1 or both margins, lower lemmas slightly shorter 

to slightly longer than the lemmas; lodicules absent; anthers 2 or 

3 (rarely 1); style branches 2. Distal florets rudimentary, 3-awned, 

plumose, or hairy. Caryopsis laterally compressed. x = 7. 

The four species of Blepharidachne are restricted to the Americas, growing in arid and semi-arid regions of the United States, 

Mexico, and Argentina. One species occurs in our study area.

37. Blepharidachne bigelovii (S. Watson) Hack., Monogr. Phan. 

6: 261. 1889.

Plants caespitose, from a firm, often knotty base. Culms 

6–20 cm tall, freely branched at and above the bases. Sheaths usually with a tuft of hairs on either side of the collars, often puberulent on the backs; ligules to 0.3 mm long; blades 1–2 cm long, 

less than 1 mm wide, involute, convolute to conduplicate, firm, 

harshly puberulent, stiffly arcuate, lower blades deciduous. Panicles 15–30 mm long, 10–15 mm wide, exserted or partially included in the upper 2, subopposite, subtending sheaths; rachises 

and branches puberulent. Spikelets 5–7 mm long; glumes nearly 

equal to the lowest lemmas in the spikelets, exceeded by the distal 

f﻿lorets, thin, translucent, smooth or the vein scaberulous, subacute; 

lower glumes 5–6 mm long; upper glumes about 6 mm long; lowest 

florets staminate, 4–5 mm long; second florets sterile, about 5 mm 

long, lateral lobes 1–3 mm long; paleas of lowest 2 florets reduced, 

membranous; third florets pistillate, third lemmas 5.5–6 mm long, 

lateral lobes 3–4.5 mm long, awned, central awns 2.5–3 mm long; 

paleas of third florets slightly longer than the lemmas; anthers 2(1), 

1.2–1.5 mm long. Caryopsis 1.5–2 mm long. 2n = 14.

Distribution and Habitat. Blepharidachne 

bigelovii grows on rocky slopes in western Texas and adjacent 

areas of New Mexico and in Coahuila and Zacatecas, Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Juárez: 5 km SW of Cd. Juárez in the extreme N end of Sierra 

Juárez, 17 Apr 1992, matorral de gobernadora-lechuguilla 

[governor’s lechuguilla scrub], 1250 m, Spellenberg & J. Bacon 

10992 (CIIDIR, NMC). 

Bothriochloa Kuntze

Perennial; caespitose or stoloniferous. Culms with pithy internodes. Leaves basal or cauline, not aromatic; sheaths open; auricles absent; ligules membranous, sometimes also ciliate; blades 

usually flat, convolute in the bud. Inflorescences terminal, panicles 

of subdigitate to racemosely arranged branches, each branch with 

(1)2 to many rames, branches not subtended by modified leaves; 

rames with spikelets in heterogamous sessile-pedicellate pairs, internodes with a translucent, longitudinal groove, often villous on 

the margins; disarticulation in the rames, beneath the sessile spikelets. Spikelets dorsally compressed; sessile spikelets with 2 florets; 

lower glumes rounded, several-veined, sometimes with a dorsal 

pit, margins clasping the upper glume; upper glumes somewhat 

keeled, 3-veined; lower florets hyaline scales, unawned; upper florets bisexual; upper lemmas with a midvein that usually extends 

into a twisted, geniculate awn, occasionally unawned; anthers 3. 

Pedicels similar to the internodes. Pedicellate spikelets reduced or 

well-developed, sterile or staminate, unawned. Caryopsis lanceolate to oblong, somewhat flattened; hila punctate, basal; embryos 

about 1⁄2 as long as the caryopsis. x = 10.

Bothriochloa is a genus of about 35 species that grow in tropical to warm-temperate regions. Nine are native to North America.

KEY TO SPECIES OF BOTHRIOCHLOA

1. Axis of the inflorescence (rachis) much shorter than racemes; racemes 2–8 per inflorescence; culms 1–2 mm thick in the 

inferior 1⁄2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. springfieldii

1. Axis of the inflorescence (rachis) 1–2 times as long as the racemes; racemes (8)10–40 per inflorescence; culms generally 

(1.5)2–4 mm thick near the base. 

2. Inferior racemes generally longer than the panicle axis, the panicle flabelate.

3. Pedicellate spikelets similar in size and shape to the sessile; lower glumes with a punctiform glandular pit; blades 

slender 3–4 mm wide; inflorescence bearing 3–7 racemes; plants 20–100 cm tall . . . . . . . . . . . . . . . . . . B. wrightii

3. Pedicellate spikelets shorter and/or narrower than the sessile; lower glume lacking a glandular pit in all spikelets; 

blades 4–8 mm wide; inflorescence bearing 10–20 racemes; plants 50–150 cm tall . . . . . . . . . . . . . . . B. barbinodis

2. Inferior racemes generally shorter than the panicle axis, the panicle oblong.

4. Sessile spikelets 4–6 mm long, with a glandular pit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. perforata

4. Sessile spikelets 4(5) mm long, lacking a glandular pit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. laguroides
5 2 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

38. Bothriochloa barbinodis (Lag.) Herter, Revista Sudamer. 

Bot. 6(5–6): 135. 1940. Andropogon barbinodis Lag., Gen. 

Sp. Pl. 3. 1816.

FIGURE 36

Culms 60–120 cm tall, rarely more than 2 mm thick, erect, 

geniculate at the base, often branched at maturity, not glaucous 

below the nodes; nodes hirsute, the hairs 3–4 mm long, mostly 

erect to ascending, tan or off-white. Leaves cauline; ligules 

1–2 mm long, often erose; blades 20–30 cm long, 2–7 mm wide, 

not glaucous, glabrous or sparingly pilose near the throat. Panicles 5–14(20) cm on the larger shoots, oblong to somewhat fanshaped, silvery-white; rachises 5–10 cm long, straight, exserted 

or partially included in the sheath, with numerous branches; 

branches 4–9 cm long, erect, with several rames; rame internodes 

with a membranous groove wider than the margins, margins 

densely pilose, longest hairs 3–7 mm long, concentrated distally. 

Sessile spikelets 4.5–7.3 mm; lower glumes short pilose, with or 

without a dorsal pit; awns 20–35 mm; anthers 0.5–1 mm long, 

often remaining within the spikelet. Pedicellate spikelets 3–4 mm 

long, narrowly lanceolate, sterile. 2n = 180.

Distribution and Habitat. Bothriochloa barbinodis is a common species, at 500–1,200 m, along roadsides, 

drainage ways, and gravelly slopes in desert grasslands from the 

southwestern United States through Mexico and Central America to Bolivia and Argentina.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 29.4 mi N of Gallego, Sierra Gallego, 18 Jul 1975, 

4500 ft, Wallace, Dunn 183 (ENCB); 52.4 mi N of Gallego, Sierra Gallego, 18 Jul 1975, 4500 ft, Wallace, Dunn 167 (ENCB); 

12 km al N de Flores Magón, 7 Oct 1995, 1180 m, R. Corral, 

P. Olivas & J.O. Torres RCD6485 (UACJ). Ascensión: a orillas 

de la carr. [banks of hwy] # 2 Juárez–Janos, km 128, 11 Aug 

1996, P. Olivas , R. Rivas & I. Enríquez POS816 (UACJ); por la 

carr. a Palomas, justo al N del entronque con [just north of the 

junction with] la carr. a Casas Grandes, 11 Jun 2005, 1183 m, 

R. Corral, M. Vargas & H. Gutiérrez RCD7130 (UACJ). Batopilas: SW Chihuahua, Aug 1885, pastizal [pastureland], 1800 m, 

E. Palmer 2 (US). Balleza: 7.4 km W of Balleza on road to Guachochi, 18 Sep 1991, huizachal, 1990 m, P.M. Peterson, Annable 

& Valdés-Reyna 10739 (CIIDIR, US). Buenaventura: km 11 S 

Buenaventura, 23 Oct 1954, Hernández-X & C. Tapia N-161

(US). Camargo: Arroyo 20 km S of Cd. Camargo, 2 Aug 1939, 

1220 m, L. H. Harvey 1382 (US); 6 mi W of Piloncillo, rd from 

Jimenez to Camargo, 24 Sep 1938, I.M. Johnston 7879 (US). 

Casas Grandes: near Casas Grandes, 30 Aug 1899, 2000 m, 

E.W. Nelson 6342 (US). Chihuahua: Chihuahua, 14 Oct 1910, 

FIGURE 36. Bothriochloa barbinodis. A. Habit. B. Node. C. Sessile 

and pedicellate spikelets. Drawn by Linda Ann Vorobik and Hana 

Pazdírková; copyright Utah State University.
NUMBER 107 • 5 3

Hitchcock 7798 (US); Rancho Experimental La Campana, 23 

Oct 1980, pastizal, 1640 m, A. Melgoza 638 (CIIDIR); hills and 

plains near Chihuahua, 23 Aug 1885, pastizal, 1900 m, C.G. 

Pringle 491(US); km 1773 Carr. a Cd. Juárez, 15 Sep 55, pastizal, 1500 m, Hern.-Xol. & V. Mathus N-1813, N-1832 (US); 

km 28 Cd. Chihuahua–Cd. Cuauhtémoc, 27 Oct 1954, pastizal, 

1600 m, Hern.-Xol. & C. Tapia N-287 (US); km 20 Cd. Cuauhtémoc de Cd. Chihuahua, 27 Oct 1954, pastizal, 1500 m, 

Hern.-Xol. & C. Tapia N-258 (US); km 14 Cd. Cuauhtémoc de 

Cd. Chihuahua, 15 Sep 1955, pastizal, 1400 m, Hern.-Xol. & 

V. Mathus N-1785 (US); 6 Oct 1959, Soderstrom 904 (US). El 

Tule: 19.3 km SE of Balleza towards Parral, 26 Sep 1988, oak 

woods, 1800 m, P.M. Peterson & Annable 5944 (ENCB, US). 

Guerrero: railroad NW of San Isidro, Sierra Madre Occidental, 

18 Sep 1934, 1990-2010 m, Pennell 18987 (US). Guadalupe: 

NE Chihuahua, vicinity of Rancho El Pino, ca 10 km, SE of Sierra Rica, 23 Sep 1942, bosque de encino [oak forest], 1100 m, 

R. Stewart 2410 (US). Janos: Chihuahua–Sonora border, Rancho Carretas, 27 Aug 1939, bosque de encino, 1780 m, L. H. 

Harvey 1615 (US). Juárez: aprox. 7 km al N del poblado [village] de Samalayuca, a los lados [roadside] de la carr., 30 Jul 

1994, 1200 m, R. Corral, E. Pérez, A. Domínguez & F. Félix 

RCD5292 (UACJ); km 32 Juárez–Chih., 13 Oct 1997, matorral de gobernadora [governor’s scrub], I. Enríquez, S. Ordoñez 

& J. Leyva IEA1 (UACJ). Ocampo: Ca 1 km W of W boundary of Parque Nacional “Cascada de Basaseachic,” 15 km from 

the Cahuisori–Ocampo road on the road to Candamena, 4.3 km 

below Cruz Verde, 23 Sep 1994, 1570 m, Spellenberg, Corral & 

Estrada 12169 (NMC). Riva Palacio: Arroyo del Nido, 1.2 mi 

by dirt road, E Rancho El Nido, 8 Oct 1982, grassland, 1400 m, 

F.W. Reichenbacher 1325 (ARIZ).

39. Bothriochloa laguroides (DC.) Herter, Revista Sudamer. Bot. 

6(5–6): 135. 1940. Andropogon laguroides Cat., Pl. Horta 

Mons. 78. 1813.

FIGURE 37

Culms 35–115(130) cm tall, usually less than 2 mm thick, 

erect or geniculate at the base, branched at maturity; nodes 

short hirsute with erect hairs, or glabrous. Leaves usually basal 

to sometimes cauline on robust plants, usually glaucous; ligules 

1–3 mm; blades 5–25 cm long, 2–7 mm wide, flat to folded, 

mostly glabrous. Panicles 4–12(14) cm long, narrowly oblong or 

lanceolate, silvery-white or light tan; rachises 4–8 cm long, with 

more than 10 branches; branches 1–5.5 cm long, erect-appressed, 

rarely with axillary pulvini, lower branches shorter than the rachises, usually with more than 1 rame; rame internodes with a 

FIGURE 37. Bothriochloa laguroides var. laguroides. A. Habit. B. Inflorescence 

branch. Drawn by Linda Ann Vorobik and Hana Pazdírková; copyright Utah State 

University.
5 4 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

groove wider than the margins, margins copiously hairy, hairs 

3–9 mm long, at least somewhat obscuring the spikelets. Sessile spikelets 2.5–4.5 mm long, ovate, somewhat glaucous, apex 

blunt; lower glumes glabrous or hirtellous, rarely with a dorsal 

pit; awns 8–16 mm; anthers 0.6–1.4 mm. Pedicellate spikelets 

1.5–2.5(3.5) mm long, shorter than the sessile spikelets, sterile. 

2n = 60.

Distribution and Habitat. Bothriochloa laguroides grows in well-drained soils of grasslands, prairies, roadsides, river bottoms, and woodlands, often on limestone, usually 

at 20–2100 m. It has two varieties; Bothriochloa laguroides var. 

torreyana (Steud.) M. Marchi & Longhi-Wagner is found in 

Chihuahua.

Bothriochloa laguroides has been confused with Bothriochloa saccharoides (Sw.) Rydb., a more southern species that differs from B. laguroides in having pilose leaves, a narrow central 

groove in the internodes and pedicels, and panicle branches with 

axillary pulvini.

Specimens Examined. MEXICO. Chihuahua.

Aldama: Santo Domingo, 50 km SW of Coyame of Mex 16 between Presidio, Texas and Chihuahua, 22 Sep 1988, 1400 m, 

P.M. Peterson & Annable 5759 (ENCB, US). Bocoyna: 24.7 mi 

N of San Juanito on road towards Cuauhtemoc, 5 Sep 2008, 

2233 m, P.M. Peterson & J.M. Saarela 22037 (US). Camargo: 

Arroyo 20 km S of Cd. Camargo, 2 Aug 1939, 1220 m, L. H. 

Harvey 1389 (ENCB). Casas Grandes: Valle de Las Cuevas al S 

del Ejido Ignacio Zaragoza, 25 Sep 1982, 1760 m, Tenorio 1709 

& Romero de Terreros (ENCB, MEXU). Cuauhtémoc: 21 km W 

of Cuauhtemoc, on Hwy 16, 23 Aug 1990, 2000 m, P.M. Peterson & Annable 9593 (US). Ignacio Zaragoza: 10 mi N of Ignacio 

Zaragoza, 8 Abr 1977, 7800ft, Dunn, Torke, Bennett & Wieder 

22637 (ENCB). Madera: Paraje Sirupa, ejido Cebollitas, 16 Oct 

1990, bosque de encino [oak forest], 1200 m, O. Bravo 1917

(CIIDIR). San Francisco del Oro: 21 km W of Parral and approx. 

3.2 km N on dirt road to Torrencillo, 26 Sep 1988, grassland, 

2000 m, P.M. Peterson & Annable 5966 (ENCB, US).

40. Bothriochloa perforata (Trin. ex E. Fourn.) Herter, Revista 

Sudamer. Bot. 6(5–6): 135. 1940. Andropogon perforatus 

Trin. ex E. Fourn., Mexic. Pl. 2: 59. 1886. Bothriochloa barbinodis var. perforata (Trin. ex E. Fourn.) Gould, Southw. 

Naturalist 3: 212. 1959.

Perennial plants, densely tufted. Culms 50–100 cm tall, geniculate at base, nodes plicate-pubescent to short barbed. Sheaths 

glabrous; ligules 2–3 mm long, membranous, blades 17–30 cm 

long, 2–4 mm wide, attenuate to the apex, flatened, glabrous or 

sparsely pilose adaxially; inflorescences 5–10 cm long, oblong, 

subtended by the superior sheath, racemes 4–8, 5–7 cm long, 

pseudo-digitate, agglomerate in a short rachis, straight, union 

of the rachis and pedicels densely long-viloses; sessile spikelets 

4–6 mm long, bisexual, short pilose at base; lower glumes 4–6 mm 

long, scarce-pilose, with a pit at central part, upper glumes glabrous; bisexual lemmas 2.3–2.6 mm long, awn 18–25 mm long, 

geniculate, twisted below; pedicelate spikelets 3.8–4 mm long, 

steriles, with only 1 floral wrap, unawned, coriaceous. 

Distribution and Habitat. Bothriochloa perforata grows in pine forests, oak–juniper forests, desert scrub, 

and grasslands at elevations of 2,150–2,616 m. Known from 

United States, Mexico, and South America.

Specimens Examined. MEXICO. Chihuahua. 

Jiménez: carr. [hwy] 45 Parral-Torreón, 20 km al N de Río 

Florido, 15 Sep 1970, 1850 m, L.Ma. Villarreal 3690 (ENCB).

41. Bothriochloa springfieldii (Gould) Parodi, Gram. Bonaer. 

(ed. 5): 120. 1958.

FIGURE 38

Culms 30–80 cm long, erect, unbranched; nodes prominently bearded, hairs 3–7 mm long, spreading, silvery-white. 

Leaves mostly basal; ligules 1–2.5 mm long; blades 5–30 cm 

long, 2–3(5) mm wide, flat to folded, glabrous or sparsely hirsute 

adaxially, pilose near the throat. Panicles 4–9 cm long, oblong to 

fan-shaped; rachises 1–5 cm long, with 2–9 branches; branches 

4–8 cm long, longer than the rachises, with 1(2) rames; rame 

internodes with a membranous groove wider than the margins, 

margins densely white-villous, hairs 5–10 mm long, obscuring 

the sessile spikelets. Sessile spikelets 5.5–8.5 mm long, lanceolate; lower glumes densely short-pilose on the lower 1⁄2, sometimes with a dorsal pit; awns 18–26 mm long; anthers 1–1.5 mm 

long. Pedicellate spikelets 3.5–5.5 mm long, sterile. 2n = 120.

Distribution and Habitat. Bothriochloa 

springfieldii grows in rocky uplands, ravines, plains, sandy areas, 

and roadsides from southern Utah to western Texas and Mexico 

at 900–2,500 m and, as a disjunct, in northwest Louisiana. It differs from B. barbinodis in its less robust habit, narrower blades, 

longer nodal hairs, and fewer, more hairy panicle branches

Specimens Examined. MEXICO. Chihuahua.

Ahumada: 28 km al sur [S] de Samalayuca, 21 Oct 74, pastizal 

halófito [halophyte grassland], 1400 m, Valdés-Reyna VR-793 

(RELC). Chihuahua: La Campana; 1 km Pte. Carr. [hwy] Panamericana, 14 Sep 73, Pastizal mediano abierto [mostly open 

grassland], 1570 m, Valdés-Reyna VR-274 (RELC). Cusihuiriachi: Río Papigochi 40 km de Cuahutémoc, carr. Cuahutémoc–

Ocampo, 8 Aug 1975, pastizal mediano abierto, 2100 m, J.M. 

Peña JMP-84 (RELC).

42. Bothriochloa wrightii (Hack.) Henrard, Blumea 4(3): 520. 

1941. Andropogon wrightii Hack., Flora 68(8): 139. 1885.

FIGURE 39

Culms to 70 cm long, erect, sparingly branched; nodes glabrous or hirsute, hairs about 1 mm. Leaves cauline, glaucous; 

ligules 1–2 mm; blades 15–25 cm long, 3–7 mm wide, glabrous. 

Panicles 5–6 cm long, oblong to fan-shaped; rachises 1–3 cm 

long, with 4–5 branches; branches 4–6 cm long, lacking axillary 

pulvini, with 1 raceme; raceme internodes with stiff, 1–3 mm 
NUMBER 107 • 5 5

FIGURE 38. Bothriochloa springfieldii. 

A. Habit. B. Node. C. Sessile and pedicellate spikelets. Drawn by Linda Ann Vorobik and Hana Pazdírková; copyright Utah 

State University.

FIGURE 39. Bothriochloa wrightii. A. Habit. B. Culm and inflorescence. C. Inflorescence branch. Drawn by Linda Ann Vorobik and 

Hana Pazdírková; copyright Utah State University.
5 6 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

marginal hairs. Sessile spikelets 5.5–7 mm long, lanceolateelliptic; lower glumes glabrous, usually without a dorsal glandular pit; awns 10–15 mm long, twisted, once-geniculate; anthers 

about 3 mm. Pedicellate spikelets staminate, subequal to the sessile spikelets. 2n = 120.

Distribution and Habitat. Bothriochloa 

wrightii grows in rocky grasslands and shrubby slopes of the pine–

oak woodlands of southern Arizona, New Mexico, Texas, and 

northern Mexico at 1,200–1,800 m. It was last collected in the 

United States in 1930. It differs from B. barbinodis in its glaucous 

foliage, short, fan-shaped panicles, and large, pedicellate spikelets.

Specimens Examined. MEXICO. Chihuahua.

Buenaventura: km 11 S Buenaventura, 23 Oct 1954, Hern.-Xol. 

& C. Tapia N-164, 215 (US); J. Passini & M.F. Robert 6580

(ENCB). Cuauhtémoc: Between Chihuahua City and Cuauhtémoc, 15 Oct 1954, 1750 m, R.G. Reeves, J. Morrow & R.Q. 

Landers s.n. (ARIZ). Cusihuiriachi: Mesas near Cusihuiriachic, 

27 Aug 1887, C.G. Pringle 1409 (US). Chihuahua: Chihuahua, 

14 Oct 1886, C.G. Pringle 1122 (US). Ignacio Zaragoza: 17.9 

mi N of Ignacio Zaragoza, 8 Apr 1977, 7000 ft, Dunn, Bennett, 

Torke & Wieder 22647 (ENCB). Namiquipa: Tepehuanes, pastizal amacollado [grass pasture], 2200 m, G. Gómez s/n (RELC).

Bouteloua Lag.

Annual or perennial; synoecious; habit various, caespitose, stoloniferous, or rhizomatous. Leaves usually mostly 

basal; sheaths open; ligules of hairs, membranous, sometimes 

ciliate. Inflorescences terminal, panicles of 1–80 solitary, spikelike branches, exceeding the upper leaves; branches not woody, 

1-sided, usually racemose on elongate rachises, sometimes digitate or subdigitate, with 1–130 sessile to subsessile spikelets in 

2 rows, axes terminating in a spikelet or extending beyond the 

base of the distal spikelet. Spikelets closely imbricate, appressed 

to pectinate, laterally compressed or terete, with 1–2(3) florets, 

lowest floret in each spikelet bisexual, distal florets staminate 

or sterile; disarticulation at the base of the branches or above 

the glumes. Glumes unequal or subequal, 1 or both glumes 

equaled or exceeded by the distal floret, 1-veined, acute or acuminate, sometimes shortly awned; lower glumes usually shorter 

than the lowest floret; lemmas of lowest florets entire, 2-, 3-, or 

4-lobed, 3-veined, veins usually extended into 3 short awns; paleas of lowest florets 2-veined, veins sometimes excurrent; distal 

floret(s) staminate or sterile, similar to the lowest floret in shape, 

size, and venation to sterile and reduced to an awn column with 

well-developed awns or to a flabellate scale. x = 10. 

Bouteloua, a genus of the Western Hemisphere with its 

center of diversity in Mexico, has 60 species (Herrera Arrieta et 

al., 2004, 2008; Peterson et al., 2015). There are 26 species of 

Bouteloua in Chihuahua, all native. Several species are important forage grasses, and some are important constituents of the 

native Mexican grasslands. Two that are particularly important 

in Mexico and Chihuahua are B. curtipendula and B. gracilis. 

These were major constituents of the shortgrass prairie that once 

covered the drier portions of the Great Plains. Both are excellent 

forage species. 

KEY TO SPECIES OF BOUTELOUA

1. Unisexual spikelets on dioecious or monoecious plants; pistillate spikelets different in form and size to the staminate . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. dactyloides

1. Bisexual spikelets, all similar in form and size.

2. Spikelets 3 per spike (branch); central spikelet shortly-stipitate, 3-flowered, first floret bisexual, the laterals staminate.

3. Culms generally more than 15 cm tall; blades 3–12 cm long; lateral spikelets well-developed, staminate . . . . . B. erecta

3. Culms less than 15 cm tall; blades 1–5 cm long; lateral spikelets reduced rarely staminate but with reduced lemmas

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. diversispicula

2. Spikelets (1)2 to several per spike (branch); or with 1 to 2 (3) rudiments, these sometimes represented by an awn.

4. Spikes falling when mature, bearing 1–12 spikelets; spikelets persistent on the spikes.

5. Inflorescence branches (spikes) mostly with 1 spikelet alone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. uniflora

5. Inflorescence branches (spikes) with 2–22 spikelets.

6. Spikes 20–80 per culm, if less than 15, then the spikes less than 1 cm long.

7. Spikes 9–25(35) per culm, 8–10 mm long, bearing 2–6 spikelets; central awn of the rudiment 2.5–5 mm long 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. warnockii

7. Spikes 20–80 per culm, 10–30 mm long, bearing 2–13(20) spikelets; central awn of the rudiment 5–10 mm 

long.

8. Culms with 4–7 nodes; upper glumes 3.5–5.5 mm long; inflorescences both terminal and axillary, the 

terminal bearing 5–13 spikelets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. media

8. Culms with 1 or 2(3) nodes; upper glumes 5.5–8 mm long; inflorescences only terminal, bearing 2–6 

spikelets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. curtipendula

6. Spikes 1–15 per culm, if up to 20 then more than 1 cm long.

9. Annual plants; rudimentary florets tipically reduced to a cylindrical column with 3 awns, these 5–8 mm long; 

spikelets appressed to the branch axis, widely spaced along the inflorescense rachis . . . . . . B. aristidoides
NUMBER 107 • 5 7

9. Perennial plants; rudimentary florets well-developed, staminate or neutral, when 3-awned the awns of variable sizes; spikelets appressed or spreading from the branch axis, not widely separated from each other.

10. Spikes bearing 2–5 spikelets; upper glume hairy.

11. Inflorescence 7–15 cm long; spikelets 4–6.5 mm long; lower glume 3⁄4 as long as the upper glume; 

awns of rudimentary floret 1–3 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. eludens

11. Inflorescence 3–6 cm long; spikelets 7–10 mm long; lower glume 1⁄2 as long as the upper glume; awns 

of rudimentary floret 7–10 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. chihuahuana

10. Spikes bearing 5–20 spikelets; upper glabrous or hairy.

12. Leaf blades involute along entire length, apically rigid and spine-like, densely lanate-pubescent 

adaxially and glabrous at maturity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. johnstonii

12. Leaf blades flat, at least the proximal 1⁄2, the distal 1⁄2 often involute at maturity, the apex never rigid 

or spine-like, glabrous, hirsute or bearing papillose hairs adaxially. 

13. Rachis of spikes and upper glume dorsally hairy; spikes 3–8, 7–10 mm long . . . . . . . . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. chondrosioides

13. Rachis of spikes and upper glume glabrous to scabrous; spikes 5–12, 15–40 mm long.

14. Spikes 2–5(7) cm long with (9)12–22 spikelets, inserted to near the apex of the spike . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. williamsii

14. Spikes 1.5–3.0 cm long with 5–12 spikelets, inserted on the lower 1⁄2–3⁄4 of the spike.

15. Plants with well-developed rhizomes, hard and knotty; spikelets 9–13 mm long . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. radicosa

15. Plants without rhizomes; spikelets 6–9 mm long . . . . . . . . . . . . . . . . . . . . . . B. repens

4. Spikes persistent, bearing 20–60 spikelets; spikelets deciduous from the spikes.

16. Inflorescence of a single unilateral spike.

 17. Annual plants, generally small, 7–23 (35) cm tall; few-leaved . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. simplex

 17. Perennial plants, generally greater than 25 cm tall; many-leaved.

 18. Spike rachis prolonged 2–10 mm beyond the insertion of the distal spikelet, ending in a semi-rigid needle; 

upper glumes with papillose-based hairs, at least in some spikelets.

 19. Blades 1.5–5 cm long, evidently distichous, rigid, distributed homogeneously along the culm; plants 

generally glabrous, except pubescent on the adaxial surface of the leaf blade; spikelets 3–3.5 mm 

wide, the rachis prolonged 2–5 mm beyond the distal spikelet . . . . . . . . . . . . . . . . . . . . B. breviseta

 19. Blades 5–18 cm long, not distichous; plants hirsute; spikes 6–9 mm wide, the rachis prolonged 5–10 

mm beyond the distal spikelet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. hirsuta

 18. Spike rachis not extending beyond the distal spikelet insertion; upper glume pubescent or glabrous.

 20. A single spike per culm; rachis of spike and upper glume glabrous to scabrous, the rachis clearly 

arched . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. scorpioides

 20. 1–3(4) spikes per culm; rachis of spike and upper glume pilose or hirsute, often with long papillosebased hairs, the rachis straight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. gracilis

16. Inflorescence of 2 or more unilateral spikes.

 21. Upper glumes (at least in some spikelets) hirsute with papillose-based hairs.

 22. Spike rachis prolonged 2–10 mm beyond the distal spikelet insertion.

 23. Blades 1.5–5 cm long, evidently distichous, rigid, distributed homogeneously along the culm; plants 

generally glabrous, except pubescent on the adaxial surface of the leaf blade; spikelets 3–3.5 mm 

wide, the rachis prolonged 2–5 mm beyond the distal spikelet . . . . . . . . . . . . . . . . . . . . B. breviseta

 23. Blades 5–18 cm long, not distichous; plants hirsute; spikes 6–9 mm wide, the rachis prolonged 5–10 

mm beyond the distal spikelet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. hirsuta

 22. Spike rachis not prolonged beyond the distal spikelet insertion.

 24. Lemma 3.5–4 mm long; spikes 3–8, 1–3 cm long; plants caespitose or stoloniferous, never rhizomatous 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. parryi

 24. Lemma 4–5.5 mm long; spikes 2 or 3(6), 1.3–5(7) cm long; plants subrhizomatous . . . . . B. gracilis

 21. Upper glumes glabrous or pubescent but the hairs never papillose-based.

 25. Culm internodes lanose-pubescent, at least below; base of rachis and branches lanose-pubescent . . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. eriopoda

 25. Culm internodes glabrous; base of rachis and branches glabrous.

 26. Annual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. barbata
5 8 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

 26. Perennial.

27. Inflorescence with 2 or 3(4) spikes.

28. Culms conspicuously branched, geniculate, usually with 4 to 5 nodes, bearded on the branche 

axiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. ramosa

28. Culms never branched, erect, usually with 1 or 2(3) nodes, glabrous on the branch axils . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. gracilis

27. Inflorescence with 3–30 spikes.

29. Plants rhizomatous to subrhizomatous.

30. Spikelets 3–4.5 mm long; plants strongly rhizomatous . . . . . . . . . . . . . . B. karwinskii

30. Spikelets 5–6.5 mm long; plants subrhizomatous.

31. Lemma of bisexual floret glabrous to scaberulous with 3 awns; spikelets inserted on 

rachis in zigzag fashion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. trifida

31. Lemma of bisexual floret pubescent at the base with a single awn; spikelets inserted 

on rachis in straight or arched fashion . . . . . . . . . . . . . . . . . . . . . . . . . . . B. gracilis

29. Plants not rhizomatous.

32. Lemma of bisexual floret glabrous to scaberulous with 3 awns; spikelets inserted on 

rachis in zigzag fashion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. trifida

32. Lemma of bisexual floret pubescent at the base with a single awn; spikelets inserted on 

rachis in straight or arched fashion.

33. Lemma of bisexual floret bearded below and pilose on the veins, hairs 0.5–0.8 mm 

long; spikes 2 or 3(6), 1.3–5(7) cm long bearing 40–80 spikelets . . . . . . . B. gracilis

33. Lemma of bisexual floret slightly pubescent below, at least on the basal margins and 

not pilose on the veins; spikes (2)4–9(11), 1–3 cm long, bearing 20–55 spikelets . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. barbata

43. Bouteloua aristidoides (Kunth) Griseb., Fl. Brit. W. I. 537. 

1864. Dinebra aristidoides Kunth, Nov. Gen. Sp. (quarto 

ed.) 1: 171. 1815.

FIGURE 40

Annual; tufted. Culms 4–60 cm tall, outer culms of a tuft 

decumbent, sometimes geniculate, branched at the lower nodes. 

Ligules 0.2–0.5 mm long, membranous, lacerate or ciliate; 

blades 2–5(9) cm long, 0.7–2 mm wide, flat or folded, adaxial 

surfaces sometimes with papillose-based hairs, margins usually 

with papillose-based hairs near the ligules. Panicles 2.5–10.5 cm 

long, with (1)4–15 widely spaced branches; branches 5–45 mm 

long, deciduous, densely pubescent (at least basally), with 2–10 

spikelets per branch, the spikelets appressed, axes extending 

2–10 mm beyond the base of the terminal spikelets, apex entire; 

disarticulation at the base of the branches, the break forming a 

sharp tip. Spikelets appressed. Proximal spikelet on each branch 

with 1 floret; lower glumes 1.5–3.5 mm long, glabrous, narrow 

to subulate; upper glumes 5.5–6.2 mm long, densely pubescent, 

at least on the basal 1⁄2; lemmas 5.8–6 mm long, acuminate, unawned; lowest paleas almost as long as the lemmas, bifid, glabrous; rachillas prolonged beyond the florets for about 0.5 mm. 

Distal spikelets with 1 bisexual and 1 rudimentary floret; glumes 

unequal, glabrous, minutely scabrous on the keels; narrowly 

acute or acuminate; lower glumes 1.5–2 mm; upper glumes 5–6 

mm long, glabrous or sparsely pubescent basally, often divergent; lowest lemmas 6–8 mm long, veins pubescent, lateral veins 

excurrent as short (to 1 mm) awns, acuminate, midvein extended 

into a setaceous tip or a short awn; lowest paleas 5–7 mm long, 

bifid, veins often excurrent as short awns; anthers about 2.5 mm 

long, yellow or yellow and red; distal florets reduced to a pubescent, 3-awned, awn column, awns 2–7 mm long, exserted. 

Caryopsis 2.5–3 mm long. 2n = 40 

There are two varieties; only the typical variety grows in 

Chihuahua.

Distribution and Habitat. Bouteloua aristidoides var. aristidoides grows in dry mesas, plains, and washes 

from near sea level to about 2,000 m. Its range extends from 

California to west Texas and Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: SW Chihuahua, Aug 1885, E. Palmer 51 (US). Buenaventura:7 km al S de Buenaventura, 5 Sep 76, pastizal con 

[pastureland with] Opuntia, 1574 m, A. Melgoza 348 (RELC). 

Camargo: Low ridge 1 mi SW of Mesteñas, 5 Oct 1941, 1380 m, 

R. Stewart & I.M. Johnston 2022 (US); Vicinity of Colina, SW of 

Carmargo, 6 Sep 1967, Reeder & C. Reeder 4865 (ARIZ-4893, 

US); Road from Camargo to Mesteñas, 11 mi NE of Camargo, 24 

Sep 1938, I.M. Johnston 7904 (US); Sierra de los Organos, 8 Sep 

1937, LeSueur 0163 (US). Casas Grandes: near Casas Grandes, 

30 Aug 1899, E.W. Nelson 6329 (US). Chihuahua: near Chihuahua, 18 Sep 1885, C.G. Pringle 477 (US); 26 Aug 1939, L. H. 

Harvey 1599 (US); La Campana: potrero [paddock] El Plan, 

4 km Ote. [W] carr. [hwy] Panamericana, 6 Sep 73, lotes productores de semilla [seed-production lots], 1500 m, Valdés-Reyna 

VR-116 (RELC). Coyame: 1 mi W of Cuchillo Parado along Rio 

Conchos, 17 Sep 1971, clay margins of Rio Conchos,1560 m, 

J. Henrickson 6769 (ARIZ). Hidalgo del Parral: Just S of Parral, 

2 Oct 1959, Soderstrom 831 (US). Jiménez: San Pedro Conchos, 
NUMBER 107 • 5 9

16 Aug 1939, F. Shreve 9070 (US); Sierra de Sta Eulalia, 18 Aug 

1939, L. H. Harvey 1526 (US); Banks of the Río Florido, Cd. 

Jiménez, 28 Jul 1939, L. H. Harvey 1323 (US); 33 mi SE of Jiménez, 27 Sep 1963, Reeder & C. Reeder 3614 (ARIZ); Costado 

del Rio Florido, Torreoncitos, 4 Aug 2010, 1330 m, D. Noya & 

M.L. Juárez 3407 (CIIDIR). Juárez: carr. No. 2 Juárez–Janos, km 

42, 11 Aug 1996, matorral de médanos [scrub dunes], 1250 m, 

P. Olivas, R. Rivas & I. Enríquez POS786 (UACJ); 23 km al S 

del poblado [village] de Samalayuca, por la carr. Panamericana, 

9 Sep 1995, 1250 m, R. Corral & P. Olivas RCD6344 (UACJ). 

Manuel Benavides: E Chihuahua, vicinity of Pirámide, 11 Aug 

1941, I.M. Johnston 8117 (US). Meoqui: Meoqui, 24 Aug 1935, 

LeSueur Mex-029 (US).

44. Bouteloua barbata Lag.,Varied. Ci. 2(4): 141. 1805.

Annual or short-lived perennial; tufted, sometimes with 

stolons. Culms 1–75 cm tall, prostrate, decumbent, or erect, 

sometimes rooting at the lower nodes; lower internodes glabrous. Leaves basal or cauline; sheaths usually glabrous, except for tufts of long hairs on either side of the collars; ligules 

0.5–2 mm long, membranous, ciliate; blades 0.5–10 cm long, 

0.7–4 mm wide, adaxial surfaces usually sparsely pubescent 

with a few papillose-based hairs basally. Panicles 0.7–25 cm 

long, with (2)4–9(11) branches; branches 10–30 mm long, 

persistent, straight to arcuate, glabrous, scaberulous, or with 

papillose-based hairs, with 20–55 spikelets, axes terminating 

in a well-developed spikelet; disarticulation above the glumes. 

Spikelets 2.5–5 mm long, pectinate, with 1 bisexual and 2 rudimentary florets; glumes unequal, glabrous, sometimes scaberulous, apex sometimes shortly bilobed, acuminate or mucronate; 

lower glumes 0.7–1.5 mm; upper glumes 1.5–2.5 mm long, glabrous, scabrous, or strigose, hairs not papillose-based; lowest 

lemmas 1.7–4 mm long, densely pilose, at least on the margins, 

3-awned, awns 0.5–3 mm long, central awns flanked by 2 membranous lobes; lowest paleas 1.5–4 mm long, pubescent on the 

margins, 4-lobed, 2-awned, awns 1–2 mm; anthers 0.4–0.7 mm; 

rachilla internodes subtending second florets terminating in a 

dense tuft of hairs; second florets rudimentary, 1.5–4 mm long, 

2-lobed, lobes rounded, 3-awned, awns 0.5–4 mm long; rachilla 

internodes subtending third florets with glabrous or puberulent 

apex; third florets rudimentary, flabellate, unawned. Caryopsis 

to 1 mm. 2n = 20.

Distribution and Habitat. Bouteloua barbata

extends from the southwestern United States to southern Mexico. There are three varieties of B. barbata; two of them grow in 

Chihuahua.

FIGURE 40. Bouteloua aristidoides var. aristidoides. A. Habit. B. Spikelet. C. Inflorescence branch. 

D. Fertile lemma. E. Sterile lemma. Drawn by Linda Ann Vorobik and Cindy Roché; copyright Utah 

State University.
6 0 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

KEY TO VARIETIES OF BOUTELOUA BARBATA

1. Annual; culms usually decumbent and geniculate, occasionally rooting at the lower nodes; ligule a hairy fringe 0.5–1 mm 

long with glabrous auricles; anthers yellow-reddish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. barbata var. barbata

1. Plants short-lived perennials; culms erect from the base; ligule a hairy fringe 1–2 mm long with pubescent auricles; anthers 

orange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. barbata var. rothrockii

Bouteloua barbata var. barbata

Distribution and Habitat. Bouteloua barbata

var. barbata grows in loose sands, rocky slopes, and washes, 

often on disturbed soils, usually at elevations below 2,000 m. Its 

range extends from the southwestern United States to northern 

Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: Villa Ahumada, 10–20 Oct 1935, LeSueur Mex-065

(US); aprox. 25 km al N del poblado [village] Flores Magón, 7 

Oct 1995, 1140 m, R. Corral, P. Olivas & J.O. Torres RCD6480

(UACJ); Al N cerca [near] de Villa Ahumada, 25 Oct 54, duna 

de pastos [dune pasture], 1100 m, Hern.-Xol. & C. Tapia N-173

(RELC, US); 1 km al N del rancho Santa Fé, 18 Oct 74, matorral micrófilo [microphytic scrub], 1400 m, Valdés-Reyna VR-652

(RELC). Buenaventura: km 11 San Buenaventura–El Carmen, 23 

Oct 1954, Hern.-Xol. & Tapia N-134 (US); 7 km al S de Buenaventura, 5 Sep 76, Pastizal con [pastureland with] Opuntia, 

1574 m, A. Melgoza 548 (RELC). Camargo: 20 km S of Cd. 

Camargo, 2 Aug 1939, L. H. Harvey 1386 (US); E Chihuahua, 

4.5 mi NW of San Francisco, road from Jaco to Mesteñas, 5 Oct 

1941, matorral xerófilo [xerophilous scrub] , 1400 m, R. Stewart 

& I.M. Johnston 2010 (US); Vicinity of Colina SW of Camargo, 6 

Sep 1967, Reeder & C. Reeder 4866 (ARIZ, US). Casas Grandes: 

alredfedores del pueblo [around the village], 28 Aug 2013, 

30°11ʹ58.7′′N, 108°02ʹ13.3′′W [30.19964°N, 108.03694°W], 

pastizal con dominancia de anuales [pastureland with annuals 

dominant], E. Mata Ortiz s.n. (UACH). Chihuahua: near Chihuahua, 23 Aug 1885, C.G. Pringle 490 (US); Hitchcock 7782 (US); 

5 mi SW of Chihuahua on road to Cuauhtémoc, 6 Oct 1959, 

grassland, 1463 m, Soderstrom 905 (US); Hacienda Santa Gertrudis, criadero [hatchery] número 2 caballería Ejercito Nacional 

[national army cavalry], 21 sep 55, 1650 m, Hern.-Xol. & V. Mathus N-1996 (US); La Campana, Potrero del Plan, 4 km Ote. [W] 

carr. [hwy] Panamericana, 6 Sep 73, lotes producción de semilla 

[seed-production lots], 1500 m, Valdés-Reyna VR-117 (RELC). 

Gran Morelos: km 20 Cd. Cuauhtemoc de Cd. Chihuahua, 27 

Oct 1954, pastizal, 1500 m, Hern.-Xol. & C. Tapia N-257 (US). 

Hidalgo del Parral: 2 mi E S of Parral on road to Cd. Juarez, 

3 Oct 1959, Soderstrom 859 (US). Janos: Chihuahua–Sonora 

Border, Rancho Carretas, 26 Aug 1939, 1460 m, L. H. Harvey 

1598 (US). Jiménez: Sierra de Santa Eulalia, 18 Aug 1939, L. H. 

Harvey 1525 (US); Banks of the Río Florido, Cd. Jiménez, 28 

Jul 1939, L. H. Harvey 1319 (US); 33 mi SE of Jiménez, 27 Sep 

1963, Reeder & C. Reeder 3616 (ARIZ); Reserva de la Biosfera 

de Mapimí, dunas de arena [sand dunes] La Soledad, 9 Jul 1997, 

matorral xerófilo, 1140 m, A. García 2703 (CIIDIR); Reserva de 

la Biosfera de Mapimí, rancho La Soledad, 9 Jul 1997, matorral 

xerófilo, 1113 m, A. García 2640 (CIIDIR); Reserva de la Biosfera de Mapimí, laguna Palomas, 31 Oct 1998, matorral xerófilo, 

1055 m, A. García 3177 (CIIDIR); El Hugo, Torreoncitos, 13 

Aug 2010, terrenos de cultivo [farmland], 1355 m, D. Ramírez 

& M.L. Juárez 3379 (CIIDIR). Juárez: 1 km al S de Carr. Fed. 

No. 2 en el km 25, matorral de dunas arenosas [sand dune scrub] 

(Izotal con mesquite), 29 Aug 1997, 1150 m, A. Aquino AA78

(UACJ); Parque “El Chamizal”, 7 Sep 1995, maleza de prados 

& canales de riego [meadow grass and irrigation channels], 

1120 m, R. Corral RCD6291 (UACJ); carr. No. 2 Juárez–Janos, 

km 42, 11 Aug 1996, matorral de médanos [ditch scrub], 1250 

m, P. Olivas, R. Rivas & I. Enríquez POS792 (UACJ); a orillas 

[roadside] de la Carr. No 2 Juárez–Janos, km 128, 11 Aug 1996, 

P. Olivas, R. Rivas e I. Enríquez POS812 (UACJ); al W de Sierra 

Juárez, 1 km al W de El Parabién, 27 Aug 1997, matorral de 

dunas arenosas, Izotal con mesquite, 1200 m, A. Aquino AA54

(UACJ). Meoqui: along hwy 45, SE of city of Chihuahua, in town 

of Meoqui, 25 Sep 2004, matorral xerófilo, 1140 m, R.M. King 

& R.M. Garvey 13466 (CIIDIR). Ojinaga: E Chihuahua, 5.5 mi S 

of Ojinaga, road from Ojinaga S to Alamos Chapo, 9 Aug 1941, 

matorral xerófilo, 1100 m, I.M. Johnston 8006 (US).

Bouteloua barbata var. rothrockii (Vasey) Gould, Ann. Missouri 

Bot. Gard. 66(3): 403. 1979.

FIGURE 41

Distribution and Habitat. Bouteloua barbata

var. rothrockii grows on dry slopes and sandy flats, mostly at 

750–1,700 m. It grows throughout the southwestern United 

States and Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Janos: Chihuahua–Sonora Border, Rancho Carretas, 30 Aug 

1939, 1460 m, L. H. Harvey 1642 (US). Reeder, C. Reeder & 

Soderstrom 3491 (US).

45. Bouteloua breviseta Vasey, Contr. U.S. Natl. Herb. 1(2): 58. 

1890.

FIGURE 42

Perennial; sometimes caespitose, sometimes rhizomatous, rhizomes 1–3 mm thick, short or elongate, scaly. Culms 

20–40 cm tall, erect, somewhat woody at the base, branching 

at the base and, in late fall, sometimes at the aerial nodes; nodes 

usually 4–5; internodes glabrous, distal portions of the lower internodes with a thick, white, chalky bloom. Ligules 0.1–0.2 mm 

long, of hairs; blades 1–4(7) cm long, 0.5–2 mm wide, flat basally, involute and arcuate to reflexed distally. Panicles 2–4 cm 
NUMBER 107 • 6 1

long, with 1–3(4) branches; branches 15–37 mm long, persistent, 

straight to slightly arcuate, mostly appressed, stramineous, with 

30–45 spikelets, branches terminating in a reduced, needlelike, 

2–5 mm spikelet; disarticulation above the glumes.Spikelets pectinate, with 1 bisexual floret and 1–2 rudimentary florets; glumes 

acute to acuminate, glabrous or sparsely short-hairy, hairs not 

papillose-based; lower glumes 2–2.5 mm; upper glumes 2–3.5 

mm; lowest lemmas 2.5–4 mm long, sparsely to densely hairy, 

3-awned, awns slightly shorter than the lemma bodies, central 

awns flanked by 2 membranous lobes; lowest paleas about 4.5 

mm long, mostly or completely glabrous, sometimes puberulent 

distally, acute to acuminate, unawned, veins not excurrent; second florets about 4.5 mm long, 3-awned, awns 3–5 mm long; 

rachilla internodes subtending second florets with densely pubescent apex; third florets, if present, flabellate scales, 1-awned. 

Caryopsis 1–1.2 mm long, about 0.4 mm wide. 2n = 20.

Distribution and Habitat. Bouteloua breviseta

is locally abundant on gypsum soils in southeastern New Mexico 

and Texas. It also grows in the state of Chihuahua, Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Coyame: km 100 carr. [hwy] Chihuahua–Ojinaga, 18 Oct 74, 

matorral [scrub] de lechugilla, 1650 m, Valdés-Reyna VR-718

(RELC). Ahumada: Médanos de Samalayuca, 26 Oct 73, suelo 

muy arenoso [very sandy soil], Valdés-Reyna VR-446 (RELC). Jiménez: Sta Eulalia Mts., C.G. Pringle 414 (US); E. Wilkinson s.n.

(US); 31 mi SW of Jimenez, 16 Sep 1939, C.H. Muller 3329 (US).

46. Bouteloua chihuahuana (M. C. Johnston) Columbus, Aliso 

14(3): 227. 1996. Bouteloua rigidiseta (Steud.) Hitchc. var. 

chihuahuana M. C. Johnston, Southw. Naturalist 27: 29. 

1982.

Perennial. Culms 40–50 cm tall, slender, weak, in small 

mats. Sheaths glabrous to slightly scabrous; ligule 0.5 mm long, 

a ciliate ring; blades 6–17 cm long, 1–2 mm wide, involute, 

apiculate, glabrous to scaberulous, especially over the margins, 

FIGURE 41. Bouteloua barbata var. rothrockii. A. Habit. B. Spikelet. C. Lower lemma. D. Lower palea. Drawn by Linda Ann Vorobik 

and Cindy Roché; copyright Utah State University.

FIGURE 42. Bouteloua breviseta. A. Habit. B. Glumes. C. Lower 

floret. Drawn by Linda Ann Vorobik and Cindy Roché; copyright 

Utah State University.
6 2 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

occasionally with sparse pubescence adaxially. Inflorescence 

3–6 cm long, bearing 2–8 spikes of 0.8–1.6 mm long including 

the awns, erect or ascending, deciduous at maturity, rachis glabrous, bearing 2–5 spikelets; rachis flaccid, never bifurcate or trifurcate at the apex. Spikelets 5–7 mm long, permanently inserted 

into the spikes; glumes unequal, lower glumes 3–4 mm long, 

very narrow, acuminate, sparsely pubescent at the base to glabrous, upper glumes 6–8 mm long, acuminate, scabrous-ciliate 

on the main vein to the base; lemma 5–7 mm long including 

the awns, sparsely pubescent on the veins; paleas of equal size, 

as long as the lemma body, glabrous; anthers 2.5–3 mm long, 

white-yellowish; rudimentary florets 1 to 2, lemma of the rudimentary floret 7–9 mm long, reduced to 3 awns flattened, strong, 

scabrous, exceding the awns of the fertile lemma, alternate with 

intermediate awned lobes; second rudimentary floret similar to 

the first but smaller. 

Distribution and Habitat. Bouteloua chihuahuana is endemic to Chihuahua and grows in desert scrublands 

at 1,500 m. 

Specimens Examined. MEXICO. Chihuahua. 

Camargo: Northern end of Sierra de Las Pampas, 11.5 km NW 

of Las Pampas on road to Cd. Camargo, M.C. Johnston & F. Chiang 8811 (MEXU); Allred 5820 (ANSM) Sierra de las Pampas, 

near Cd. Camargo, K.W. Allred, T. Columbus & Valdés-Reyna 

5820 (ANSM, RSA); Sierra de las Pampas, 11.5 km of Las Pampas, on road to Cd. Camargo, T. Columbus 2289 (RSA).

47. Bouteloua chondrosioides (Kunth) Benth. ex S. Watson, 

Proc. Amer. Acad. Arts 18: 179. 1883. Dinebra chondrosioides Kunth, Nov. Gen. Sp. (quarto ed.) 1: 173, t. 53. 1815.

Perennial; caespitose, without rhizomes or stolons. 

Culms (10)30–60 cm tall, erect, unbranched. Leaves mostly 

basal; sheaths mostly glabrous, margins often long-ciliate distally; ligules 0.3–0.6 mm long, of hairs; blades 1–10 cm long, 

1–2.5(3) mm wide, flat, glaucous, bases with papillose-based 

hairs on the margins, similar hairs sometimes present on either 

or both surfaces. Panicles 2.5–6 cm long, with 3–8(10) branches; 

branches (8)10–15 mm long, densely pubescent, with 8–12 

spikelets, axes extending to 5 mm beyond the base of the terminal spikelets, apex entire; disarticulation at the base of the 

branches. Spikelets appressed, all alike, 7–7.5 mm long, with 1 

bisexual and 1 rudimentary floret; glumes evidently hairy; lower 

glumes 2.5–4.5 mm long; upper glumes 4.5–6.5 mm long; lowest 

lemmas 4.7–6.2 mm long, hairy distally, 3-lobed, lobes unawned 

or shortly awned; lowest paleas 5–7.2 mm long, pubescent along 

the veins and on the margins, bifid, veins excurrent as short 

awns; anthers 2.8–4 mm long, yellow; upper florets rudimentary, glabrous, 3-awned, awns scabrous, sometimes arising from 

a short but evident awn column, central awns sometimes with a 

membranous margin, awns scabrous. Caryopsis about 2.5 mm 

long, about 0.9 mm wide. 2n = 20, 22, 40.

Distribution and Habitat. Bouteloua chondrosioides grows on dry, rocky slopes and grassy plateaus at 

200–2,500 m. Its range extends from southern Arizona and 

western Texas to Costa Rica. It resembles B. eludens in having 

pubescent panicle branches, but B. eludens usually has 12–16 

branches 5–11 mm long with 2–6 spikelets whereas B. chrondrosoides usually has 3–8 branches 10–15 mm long with 8–12 

spikelets per branch.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 24.9 km SE of Balleza and 22.5 km N of hwy 24, W 

of Parral, 26 Sep 1988, grassland, 1900 m, P.M. Peterson & 

Annable 5955 (ENCB, US); 7.4 km W of Balleza on road to 

Guachochi, 18 Sep 1991, huizachal, 1660 m, P.M. Peterson, 

Annable & Valdés-Reyna 10731 (CIIDIR, US); 56.4 km W of 

Parral on road to Balleza and 35.5 km S of Balleza on Mex 432, 

near Corral de Duarte, 18 Sep 1991, pinyon–oak communities, 2210 m, P.M. Peterson, Annable & Valdés-Reyna 10716

(CIIDIR, US); 10 mi SW of El Ojito, 12 Sep 2006, 1902 m, 

P.M. Peterson 20029, F. Sánchez Alvarado & E.P. Gómez Ruíz 

(CIIDIR, US).. Bocoyna: 1.1 km N of San Juanito near large 

lumber mill, 24 Sep 1988, 2200 m, P.M. Peterson & Annable 

5864 (US). Buenaventura: 6 mi E of San Buenaventura, 2 Sep 

1958, Reeder & C. Reeder 3197 (US); Casas Grandes: At first 

mt range SE Nuevo Casas Grandes, ca 12 mi SE of town on 

Hwy to Buenaventura, 30 Aug 1986, Spellenberg & R. Corral 8581 (NMC). Chihuahua: 87.7 km N of Parral on Mex 

24 towards Chihuahua, 14 Sep 1989, 1620 m, P.M. Peterson, 

Annable & Y. Herrera 8107 (US); 25 km W of Chihuahua, 

20 Aug 1939, L. H. Harvey 1541 (US); 12 mi N of Chihuahua, 16 Sep 1960, grassland, 1554 m, Reeder, C. Reeder & 

Soderstrom 3480, 3481 (ARIZ, US); near Chihuahua, 21 Aug 

1885, C.G. Pringle 410 (US); 25 km W of Chihuahua, 20 Aug 

1939, 1615 m, L. H. Harvey 1541 (US); Rancho Experimental La Campana, 15 Oct 1981, pastizal [pastureland], 1500 m, 

G. Melgoza s.n. (CIIDIR); 87 km N Chihuahua 1 km S Arco Iris 

on Hwy 45, 5 Oct 1986, Spellenberg, Soreng & R. Corral 8904

(NMC); La Campana, potrero [paddock] La Sierra, 1 km Ote. 

[W], carr. [hwy] Panamericana, 11 Aug 1976, pastizal, 1500 

m, Valdés-Reyna VR-58 (RELC); km 1773 carr. a Juárez, 15 

Sep 55, pastizal con encinos [pastureland with oaks], 1500 m, 

Hern.-Xol. & V. Mathus N-1829 (RELC). Hidalgo del Parral: 

Just S of Parral, 2 Oct 1959, Soderstrom 829 (US); NE edge of 

Parral, 30 Sep 1959, Correll 22666 (US); 3 mi E of Parral, 13 

Sep 1960, Reeder, C. Reeder & Soderstrom 3456 (ARIZ-4839, 

US); About 8 mi S of Parral, 7 Oct 1966, Reeder & C. Reeder 

4620 (ARIZ, US); About 10 mi W of Parral, on road to El Vergel, 7 Oct 1966, Reeder & C. Reeder 4621-Bis (ARIZ); 4609

(US). Janos: 2 km W of Carretas, 21 Aug 1939, L. H. Harvey 

1562 (US); Jiménez: Sta Eulalia plains,17 Sep 1885, Wilkinson 

53 (US); Sta Eulalia pass between Velandena and Cristomines, 

29 Aug 1948, W. Hewitt 350 (US). Matamoros: 7 mi S of Villa 

Matamoros, 8 Oct 1966, Reeder & C. Reeder 4622 (ARIZ, 

US); 19.3 km S of Villa Matamoros on Mex 45 to Durango, 

3 Oct 1989, 1910 m, P.M. Peterson & R.M. King 8262 (US). 

Riva Palacio: Nuevo Majalca, approx. 14.5 km W of Hwy 45, 

N of Chihuahua, 22 Sep 1988, 1700 m, P.M. Peterson & Annable 5768 (US).
NUMBER 107 • 6 3

48. Bouteloua curtipendula (Michx.) Torr., Explor. Red River 

Louisiana 300. 1853. Chloris curtipendula Michx., Fl. Bor.-

Amer. 1: 59. 1803.

Panicles 13–30 cm long, secund, with (12)30–80 reflexed 

branches; branches (5)10–30(40) mm long, deciduous, with 

(1)2–7(15) spikelets, axes terminating 3–5 mm beyond the base 

of the terminal spikelets, apex entire; disarticulation at the base 

of the branches. Spikelets 6–8 mm long, appressed, all alike, with 

1 bisexual floret and 1–2 sterile, rudimentary florets; glumes unequal, glabrous or scabrous; lower glumes 2.5–6 mm long, 1⁄2 or 

more as long as the upper glumes; upper glumes 5.5–8 mm; lowest lemmas 3–6.5 mm long, glabrous or scabrous-strigose, often 

minutely rugose, acute or inconspicuously 3-lobed, 3-veined, 

veins usually excurrent as short mucros or awns to 6 mm; central 

mucros or awns not flanked by membranous lobes; lowest paleas acute, unawned; anthers 1.5–3.5 mm long, yellow, orange, 

red, or purple; distal floret(s) 0.4–3.5 mm long, sterile, variable, 

usually a glabrous lemma having a short membranous base, no 

palea, and 3 unequally developed awns, central awns 1.5–7 mm. 

2n = (20), 40, 41–103.

Bouteloua curtipendula is a common, often dominant or codominant species in open grasslands and wetlands of the drier 

portions of the central grasslands of North America. It is highly 

regarded as a forage species and is also an attractive ornamental. Its range extends from United States, Mexico, and Central 

America to western South America.

KEY TO VARIETIES OF BOUTELOUA CURTIPENDULA

1. Plants forming small mats, with rhizomes or stolons.

2. Rhizomatous plants, lacking stolons; culms erect and stiff; blades 5–7(8) mm wide, flat, green-bluish, with pubescence of 

papillose base; inflorescence with 40–70 spikelets; spikelets typically purple; anthers red or orange-reddish . . . . . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. curtipendula var. curtipendula

2. Stoloniferous plants or the culms slender and decumbent, with inferior nodes rooted, rhizomes missing; blades 2–4 mm 

wide, relatively large and slender, inrolled at the base; inflorescence bearing 4–9 spikes; spikelets stramineous to light 

brown; anthers yellow or orange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. curtipendula var. tenuis

1. Plants generally forming large mats, lacking stolons or rhizomes; culms erect; blades 3–5 mm wide, thick and stiff; inflorescence with 30–80 spikes; spikelets plumbeous, stramineous, or green colored with purple spots; anthers yellowish or orange 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. curtipendula var. caespitosa

Bouteloua curtipendula var. caespitosa Gould & Kapadia, Brittonia 16(2): 203, f. 43. 1964.

FIGURE 43

Distribution and Habitat. Bouteloua curtipendula var. caespitosa grows in grasslands, xerophyl scrubs, 

oak and pine forests, and tropical deciduous forests at 1,500–

2,450 m. It ranges from United States and Mexico to Central 

and South America.

Specimens Examined. MEXICO. Chihuahua. Aldama: NE of Aldama along Chihuahua hwy 16, 14 Sep 1972, 

1360 m, J. Henrickson 7514 (US); Aldama, Sitio 27, Torreño 

# 3, 2 Sep 2015, 29°04′45′′N, 105°45′49′′W [29.07917°N, 

105.76361°W], matorral subinerme [mostly unarmed scrub] 

con Fouquieria splendens, Tecoma stans, Acacia neovernicosa & 

Cassia wislizenii, 1380 m, J. Santos & A. Olivas 528 (CIIDIR, 

UACH). Allende: 20 mi N from Parral to Jiménez on hwy 45, 21 

Jul 2006, grassland, 1750 m, K.R. Adams & N. Martínez 059-

2006 (CIIDIR). Balleza: 56.4 km W of Parral on road to Balleza 

and 35.5 km S of Balleza on Mex 432, near Corral de Duarte, 

18 Sep 1991, 2210 m, P.M. Peterson, Annable & Valdés-Reyna 

10725 (CIIDIR, US). Batopilas: SW Chihuahua, Aug 1885, 

E. Palmer 206 (US). Buenaventura: km 11 San Buenaventura–

El Carmen, 23 Oct 1954, Hern.-Xol. & Tapia N-152 (US). Camargo: 20 km S of Cd. Camargo, 2 Aug 1939, 1220 m, L. H. 

Harvey 1384 (US); Sitio 17, Rancho Epigmenia, 25 Aug 2015, 

27°46′37.7′′N, 104°09′10.8′′W [27.62833°N, 104.15306W], 

matorral desértico [desert scrub] con Yucca carnerosana, 1627 

m, J. Santos & A. Olivas s.n. (CIIDIR, UACH). Casas Grandes: 

Col. Juarez, Sierra Madre Occidental, 21 Sep 1934, Pennell 

19054 (US). Chihuahua: near Chihuahua, 3 Sep 1935, LeSueur 

Mex-024 (US); Hitchcock 7797 (US); hills and plains near Chihuahua, 27 Aug 1885, C.G. Pringle 408 (US); vicinity of Chihuahua, 27 Apr 1908, E. Palmer 114 (US); km 1773 carr. [hwy] 

Juárez, 15 Sep 55, pastizal [pastureland], Hern.-Xol. & V. Mathus N-1833 (US); 6.1 mi W of hwy 45 on dirt road towards 

Santa Clara, 18 Oct 1992, bosque de encino [oak forest], 1640 

m, P.M. Peterson & Annable 12582 (US); Rancho La Campana, 

potreros del lado W [paddocks on W side], km 80 autopista Chihuahua–Cd. Juárez, 25 Nov 1994, pastizal natural, 1590 m, Y. 

Herrera & M.E. Siqueiros 1343 (CIIDIR). Cuahutémoc: 9.7 kms 

al N del entronque [junction] de carrs. 28 & 16, 10 Aug 1976, 

vegetación riparia [riparian vegetation], J.M. Peña JMP-140

(RELC). General Trías: km 43 Cd. Chihuahua–Cd. Cuahutémoc, 27 Oct 54, pastizal, 1600 m, Hern.-Xol. & C. Tapia N-304

(RELC). Guerrero: Miñaca, 13 Oct 1910, Hitchc. 7739 (US). 

Janos: San Luis Mts, Mexican boundary line, 19 Jul 1892, E.A. 

Mearns 520 (US); Chihuahua–Sonora Border, Rancho Carretas, 

29 Aug 1939, 1460 m, L. H. Harvey 1611 (US). Jiménez: Sta 

Eulalia plains, 15 Sep 1885, E. Wilkinson 64 (US); Sta Eulalia 

pass between Velandena and Cristomines, 29 Aug 1948, W. 

Hewitt 349 (US); El Hugo, Torreoncitos, 13 Aug 2010, matorral de Prosopis sp., 1355 m, D. Ramírez & M.L. Juárez 3395

(CIIDIR). Juárez: S of Samalayuca, autopista Chih.–Cd. Juarez, 
6 4 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

9 Oct 1997, M.E. Siqueiros 4475 (US); parte alta de la Sierra 

de Samalayuca, 50 km al S de Cd. Juárez, 9 Sep 1995, 1300 m, 

R. Corral & P. Olivas RCD6365 (UACJ); Sierra de Samalayuca, 

13 Oct 1997, pastizal, I. Enríquez, S. Ordoñez & J. Leyva IEA17

(UACJ); Sierra del Presidio, área de Samalayuca, 1 Sep 1999, pastizal, I. Enríquez & P. Olivas IE050 (UACJ); km 5 desviación 

[deviation] a Nvo. Casas Grandes de la carr. a Juárez, 19 Sep 55, 

pastizal, 1600 m, Hern.-Xol. & V. Mathus N-1912 (RELC, US); 

camino a Presidio, 2 km de la carr. Panamericana, 24 Oct 74, 

matorral micrófilo [microphytic scrub], 1400 m, Valdés-Reyna 

VR-766 (RELC). Madera: El agua caliente [hot water], predio 

particular [private property] El Chorrito, 17 Oct 1990, bosque de 

encino, 2350 m, A. Benítez 2924 (CIIDIR). Ocampo: Parque Nacional “Cascada de Basaseachic,” in a canyon along Rio Basaseachi leading to falls, 4 Oct 1986, 1800 m, Spellenberg, Soreng, 

R. Corral & T. Lebgue 8820 (NMC), Temosachi: Nobogame, 

8 Sep 1987, 1800 m, Reeder, C. Reeder & Laferr. 1046 (NMC).

Bouteloua curtipendula (Michx.) Torr. var. curtipendula.

FIGURE 44

Distribution and Habitat. Bouteloua curtipendula var. curtipendula grows in grasslands, scrub communities, and Taxodium gallery at 1,750–2,300 m. It ranges from 

Canada and the United States to Mexico in Chihuahua, Coahuila, Distrito Federal, Nuevo León, Puebla, and Tamaulipas.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 10 km al S de Moctezuma, 30 Jul 1994, 1200 m, 

R. Corral, E. Pérez, A. Domínguez & F. Félix RCD5367

(UACJ); 32 km SW de Villa Ahumada, cerca [near] del rancho 

Santo Domingo rumbo [course] a Casas Grandes, 22 Oct 54, 

1100 m, Hern.-Xol. & C. Tapia N-91 (RELC). Balleza: 10 mi 

SW of El Ojito, 12 Sep 2006, 1902 m, P.M. Peterson 20016, 

F. Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, US). Chihuahua: Rancho Experimental La Campana, 16 Oct 1980, pastizal 

[pastureland], 1640 m, A. Melgoza 647 (CIIDIR); La Campana; 

1 km Pte. carr. [hwy] Panamericana, 18 Sep 73, pastizal mediano 

abierto [mostly open grassland], 1500 m, Valdés-Reyna VR-309, 

VR-97 (RELC); km 1319 carr. Juárez, 12 Sep 55, pastizal, 1900 

m, Hern.-Xol. N-1726 (RELC). Guachochi: Río Osichi Canyon 

at jct of Río Basihuare, up Río Osichi Canyon, 31 Aug 2003, 

bosque de encino [oak forest], 1650 m, P.M. Peterson & P. Catalán 17625 (CIIDIR, US). Madera: Paraje Sirupa, ejido Cebollitas, 16 Oct 1990, bosque de encino, 1200 m, O. Bravo 1926

(CIIDIR).

FIGURE 43. Bouteloua curtipendula var. caespitosa. A. Habit. B. Spikelet. C. Fertile 

lower lemma. D. Sterile upper lemma. Drawn by Linda Ann Vorobik and Cindy Roché; 

copyright Utah State University.
NUMBER 107 • 6 5

Bouteloua curtipendula var. tenuis Gould & Kapadia, Brittonia 

16(2): 201, f. 42. 1964.

Distribution and Habitat. Bouteloua curtipendula var. tenuis grows in grasslands and scrub of Larrea 

tridentata at 1,980–2,500 m. In Mexico it occurs in Aguascalientes, Chiapas, Chihuahua, Coahuila, Distrito Federal, Durango, 

Guanajuato, Jalisco, Michoacán, Morelos, Nuevo León, Oaxaca, Puebla, Querétaro, San Luis Potosí, Tamaulipas, Tlaxcala, 

Veracruz, and Zacatecas.

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000) and Herrera Arrieta et 

al. (2004).

49. Bouteloua dactyloides (Nutt.) Columbus, Aliso 18(1): 63. 

1999. Sesleria dactyloides Nutt., Gen. N. Amer. Pl. 1: 65. 

1818. Buchloë dactyloides (Nutt.) Engelm., Trans. Acad. 

Sci. St. Louis 1: 432, pl. 12 & 14, f. 1–17. 1859. Bulbilis 

dactyloides (Nutt.) Raf. ex Kuntze, Revis. Gen. Pl. 2: 763. 

1891.

Perennial; usually dioecious; strongly stoloniferous, sometimes mat-forming. Culms 1–30 cm tall, erect, solid, mostly unbranched, those of the pistillate inflorescences much shorter than 

those of the staminate inflorescences; nodes mostly glabrous. 

Leaves basally tufted, not clustered or strongly distichous; sheaths 

open, rounded, often sparsely pilose near the collar; ligules membranous or of hairs; blades usually flat basally, curling when dry, 

glabrous or sparsely pilose, apex involute. Staminate inflorescences terminal, usually exceeding the upper leaves, panicles 

of 1–3(4) racemosely arranged, unilateral, pectinate branches; 

branches not enclosed at maturity, spikelets densely crowded 

in 2 rows. Staminate spikelets with 2 florets; glumes unequal, 

glabrous, 1- or 2-veined; lemmas 3-veined, glabrous, unawned; 

anthers brownish to red or orange. Pistillate inflorescences terminal, panicles, partially hidden within bracteate sheaths; branches 

2–3(4), 2.5–4.5 mm long, bur-like, with 3–5(7) spikelets; disarticulation at the base of the panicle branches. Pistillate spikelets 

with 1 floret, almost completely enclosed by the upper glumes; 

lower glumes irregular and reduced; branch axes and lower portion of upper glumes globose, white, indurate, terminating in 3 

awn-like teeth; lemmas firmly membranous, glabrous, 3-veined, 

unawned or shortly 3-awned. 2n = 20, 40, 56, 60. 

Distribution and Habitat. Bouteloua dactyloides is a common grass in the central plains of North America. It is usually dioecious, infrequently monoecious, and rarely 

synoecious.

FIGURE 44. Bouteloua curtipendula var. curtipendula. A. Habit. B. Ligule. C. Inflorescence branch. Drawn by Linda Ann Vorobik and Cindy Roché; copyright Utah 

State University.
6 6 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Specimens Examined. MEXICO. Chihuahua. Allende: Pueblito, orilla de una laguna [shore of lagoon], 23 Jul 

1988, P.L. Mata Fierro s/n (MEXU). Chihuahua: Rancho experimental La Campana, 16 Oct 1980, pastizal [pastureland], 1500 

m, A. Melgoza 619 (CIIDIR); La Campana, Potrero del Plan, 

1 km al SE carr. [hwy] Panamericana, 11 Sep 73, pastizal, 1500 

m, Valdés-Reyna VR-207 (RELC). Cuauhtémoc: 21 km W of Cuauhtemoc, on Hwy 16, 23 Aug 1990, 2000 m, P.M. Peterson & 

Annable 9588 (US). Cusihuiriáchi: Laguna Grande, 10 Aug 1975, 

vegetación riparia [riparian vegetation], 1950 m, J.M. Peña JMP135 (RELC); Laguna Mexicanos, 29 Aug 1977, 2030 m, BlancoGómez 05/77 (MEXU). Jiménez: 10 km E of Cd. Jimenez, 31 Jul 

1939, L. H. Harvey 1346 (US); About 2 mi SW of Jiménez, 6 Oct 

1966, Reeder & C. Reeder 4606 (ARIZ, US). Temosachi: about 

25 mi S of Natachic, in a depression in grassland, 9 Jul 1950, 

Reeder, C. Reeder & Goodding 1243 (ARIZ, ENCB, MEXU).

50. Bouteloua diversispicula Columbus, Aliso 18(1): 63. 1999. 

Cathestecum brevifolium Swallen., J. Wash. Acad. Sci. 

27(12): 500. 1937.

Perennial; polygamous or dioecious; caespitose, forming 

dense, small clumps, stoloniferous, stolons thin, internodes to 

10(12) cm long, straight or only slightly arching. Culms 5–15 cm 

tall, erect or geniculate. Leaves primarily basal; lower sheaths 

densely villous basally, mostly glabrous or sparsely pilose distally, throats densely ciliate; blades 1–5 cm long, 1–2 mm wide, 

stiff, flat to involute, abaxial surfaces glabrous, adaxial surfaces scabrous and pilose, margins scabrous. Panicles with 3–10 

branches; branches divergent, dimorphic, with staminate or bisexual spikelets, spikelets usually reddish or purple. Staminate 

branches with all spikelets similar; lower glumes to 1 mm long, 

often reduced to a scale, 0- to 1-veined; upper glumes 1⁄2–2⁄3 as 

long as the spikelets, narrowly lanceolate, usually glabrous, veins 

sometimes sparsely pilose, glumes of the lateral spikelets about 

2.5 mm long, acute or acuminate, those of the central spikelets 

about 3 mm long, minutely lobed and mucronate; lowest lemmas to 3 mm long, sparsely pilose, with short lobes, mucronate 

between the lobes; distal lemmas to 2.5 mm long, similar to the 

lowest lemmas but with deeper lobes; anthers 0.7–2 mm. Bisexual branches: lateral spikelets poorly developed, lower glumes to 

1 mm long, upper glumes to 2.5 mm long, veins pilose, florets 

greatly reduced, sometimes just a cluster of awns, sterile (rarely 

staminate); central spikelets with glumes similar to those of the 

lateral spikelets; lowest florets pistillate, lemmas about 3 mm 

long, scabrous, lobed, lobes about 1⁄4 as long as the lemmas, 

awned from the sinuses, awns slightly exceeding the lobes; distal 

florets staminate or sterile, about 2.5 mm long, deeply lobed, 

awned from the sinuses, awns exceeding the lobes by 1–3 mm. 

2n = 20, 40, 60, and 80.

Distribution and Habitat. Bouteloua diversispicula extends from Arizona, to Mexico, El Salvador, and 

Honduras. 

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: SW Chihuahua, Aug 1885, E. Palmer 66 (US). Ojinaga: 

Ca. 9 km of Ojinaga on the Hwy to Chihuahua City, 20 Oct 1972, 

matorral desertico [desert scrub] 820 m, F. Chiang, T. Wendt & 

M.C. Johnston 9723 (MEXU).

51. Bouteloua eludens Griffiths, Contr. U.S. Natl. Herb.14(3): 

401, pl. 78–80a. 1912.

FIGURE 45

Perennial; without rhizomes or stolons. Culms 20–60 cm 

tall, unbranched. Leaves mostly basal; sheaths glabrous or 

sparsely ciliate near the throat, basal sheaths papery, becoming 

pale; ligules to 0.5 mm long, of hairs; blades to 15 cm long, 

1–1.5(3) mm wide, flat, lower leaves variously hirsute or scabrous, upper leaves glabrous, with scabrous margins. Panicles 

6–10 cm long, with (8)12–16(20) branches; branches 5–11 mm 

long, deciduous, pubescent, with (2)4–6 spikelets, axes extending about 5 mm beyond the terminal spikelets, apex entire; disarticulation at the base of the branches. Spikelets appressed, all 

alike, with 1–2 bisexual florets and 1 rudimentary floret; glumes 

silvery-hirsute over and between the veins, at least basally, apex 

acute, acuminate, or shortly awned; lower glumes 5–6 mm long; 

upper glumes 6–7 mm long, sericeous over the veins and elsewhere, hairs about 0.5 mm long, apex mucronate; lowest florets 

bisexual, pistillate, or staminate; lowest lemmas 6–7 mm long, 

pubescent between the veins and over the midveins, midveins 

excurrent into acuminate or setaceous lobes about the same 

length as the lateral lobes, not flanked by membranous lobes, 

lateral veins excurrent from the lateral lobes for 0.5–2 mm; lowest paleas as long as the lemmas, pubescent, acute to acuminate, 

unawned; second florets usually staminate, pistillate, or bisexual 

(rarely rudimentary); second lemmas 8–10 mm long; usually 

well-developed, pubescent, lateral veins extended into 0.5–4 mm 

awns, midveins extended into a flattened awn 1–5 mm long; second paleas as long as the second lemmas, pubescent, usually with 

2 short awns; third florets, if present, pubescent, variable, resembling the second floret, a 3-awned structure with 2 membranous 

scales, or a prolongation of the rachilla. Caryopsis about 5 mm 

long, about 1.5 mm wide. 2n = 20.

Distribution and Habitat. Bouteloua eludens

grows on dry, rocky slopes and rolling desert flats at 1200–1800 

m. It is known from Cochise, Santa Cruz, and eastern Pima 

counties in Arizona, adjacent portions of New Mexico, and to 

Chihuahua and Sonora, Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Reported in Beetle,(1977), Espejo Serna et al. (2000), and Herrera Arrieta and Cortés Ortiz (2010).

52. Bouteloua erecta (Vasey & Hack.) Columbus, Aliso 18(1): 

63. 1999. Cathestecum erectum Vasey & Hack., Bull. Torrey Bot. Club 11: 37. 1884.

Perennial; polygamous; caespitose, forming dense, small 

clumps, stoloniferous, stolons thin, internodes 15–40 cm long, 

strongly arching. Culms 10–30 cm tall, erect or geniculate, 

glabrous. Leaves primarily basal; lower sheaths overlapping, 
NUMBER 107 • 6 7

densely villous basally, throats pilose; upper sheaths not overlapping, glabrous; ligules about 0.3 mm long; blades 3–12 cm long, 

1–1.5 mm wide, involute or flat, glabrous abaxially, scabrous 

and sparsely pilose adaxially, hairs to 2 mm. Panicles with 5–7 

branches; branches about 5 mm long, dimorphic, staminate or 

bisexual, the 2 forms sometimes on different plants, sometimes 

mixed within a panicle, spikelets of 1 form all staminate, bisexual form with pistillate (sometimes bisexual) central spikelets 

and well-developed staminate or sterile lateral spikelets, spikelets 

frequently pale green. Staminate branches: all spikelets similar; 

lower glumes about 1 mm; upper glumes glabrous or almost so, 

those of the lateral spikelets about 3 mm long, those of the central spikelets about 4 mm; lemmas similar, about 3 mm long, 

glabrous, irregularly lobed, unawned, sometimes mucronate. Bisexual branches: glumes villous; lateral spikelets with staminate 

or sterile florets; lemmas of lateral spikelets about 3 mm long, 

glabrous or sparsely pubescent, irregularly lobed, awned from 

the sinuses, awns hispid, equaling or occasionally exceeding the 

lobes; anthers 1.7–2.3 mm long; central spikelets with the lowest 

floret pistillate, distal florets staminate or sterile; lowest lemmas 

glabrous or sparsely pubescent, lobed, lobes about 1⁄3 as long as 

the lemmas, awned from the sinuses, awns glabrous, subequal to 

the lobes or the central awns slightly longer; distal florets similar to those of the lateral florets, awns 1–2 mm longer than the 

lobes. 2n = 20.

Distribution and Habitat. Bouteloua erecta

grows on dry hills in the Great Bend region of western Texas and 

in northern Mexico. It ranges from United States and northern 

Mexico to Central America.

Specimens Examined. MEXICO. Chihuahua. 

Bocoyna: Creel, along airstrip southeast of Creel, 16 Jul 1972, 

grass in dry part of field, 7240 ft, Bye 2344 (MEXU). Guachochi: 16.4 km SW of La Bufa and 6.4 km NE of Batopilas, 710 

m, P.M. Peterson, Annable & Valdés-Reyna 10852 (US). Ojinaga: 10 mi S of Ojinaga, road from Ojinaga south to Alamos 

Chapo, 9,10 Aug 1941, ravine in low hills, I.M. Johnston 8018

(MEXU); 17.5 km S of Ojinaga on Chih. Hwy 18, 21 Oct 1990, 

1100 m, Spellenberg, M. Mahrt & L. Rayburn 10741 (MEXU).

FIGURE 45. Bouteloua eludens. A. Habit. B. Spikelet. C. Fertile lemma. Drawn by 

Linda Ann Vorobik and Cindy Roché; copyright Utah State University.
6 8 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

53. Bouteloua eriopoda (Torr.) Torr., Pacif. Railr. Rep. 4(5): 155. 

1856. Chondrosum eriopodum Torr., Not. Milit. Reconn. 

154. 1848.

FIGURE 46

Perennial; often short rhizomatous, stoloniferous, stolons 

long, densely woolly pubescent. Culms 20–60(75) cm long, 

wiry, decumbent, rooting at the lower nodes; lower internodes 

densely woolly pubescent. Sheaths mostly glabrous or sparsely 

pilose, usually pilose near the ligules; ligules 0.1–0.4 mm long, 

of hairs; blades 2.5–6 cm long, 0.5–2 mm wide, scabrous adaxially, margins with papillose-based hairs basally. Panicles (1)2–

16 cm long, with (1)2–8 branches; branches 14–50 mm long, 

persistent, densely woolly pubescent basally, with 8–18 spikelets, axes terminating in entire, sometimes scarious apex; disarticulation above the glumes. Spikelets pectinate, with 1 bisexual 

floret and 1 rudimentary floret; glumes unequal, smooth or 

scabrous; lower glumes 2–4.5 mm; upper glumes 4.5–8(9) mm 

long, glabrous, scabrous, or with hairs, hairs to 0.5 mm long, not 

papillose-based; lower lemmas 4–7 mm long, pubescent basally, 

glabrous or sparsely puberulent distally, acuminate, central awns 

0.5–4 mm long, lateral awns absent or shorter than 1 mm long; 

lower paleas acuminate, unawned; anthers 1.5–3 mm long, yellow to orange; rachilla segment to second florets about 2 mm 

long, with a distal tuft of hairs; upper florets rudimentary, an 

awn column terminating in 3 awns, the awns 4–9 mm long. 

Caryopsis 2.5–3 mm long. 2n = 20, 21, 28.

Distribution and Habitat. Boutloua eriopoda

grows on dry plains, foothills, and open forested slopes, often in 

desert shrublands, and also in waste ground. It is usually found 

between 1,000–1,800 m but extends to 2,500 m. Once a dominant in much of its range, under heavy grazing B. eriopoda persists only where protected by shrubs or cacti because it is highly 

palatable. Its range extends from the southwestern United States 

to northern Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 2 mi N of Gallego, 16 Sep 1960, Reeder, C. Reeder 

& Soderstrom 3492 (ARIZ, US); Villa Ahumada flats, 10–20 Oct 

1935, LeSueur Mex-066 (US). Camargo: 6 mi W of Piloncillo, rd 

from Jimenez to Camargo, 23–24 Sep 1938, I.M. Johnston 7875

(US); 16 mi SE of Camargo, 3 Sep 1967, Reeder & C. Reeder 

4842 (ARIZ); E Chihuahua, 4.5 mi NW of San Francisco, rd 

from Jaco to Mesteñas (via Honorato, Victoria & San Francisco), 

5 Oct 1941, R. Stewart & I.M. Johston 2012 (US); rd from Camargo NE of Mesteñas, 40 mi NE of Camargo, 25 Sep 1938, I.M. 

Johnston 7937 (US); 2 mi S of Rancho San Fernando, 40 mi NE 

of Camargo, 25 Sep 1938, F. Shreve 8896 (US); Rancho Mesteñas, 20 km S La Perla, 20 Oct 1996, 1450 m, C.Yen & E. Estrada 

6821 (NMC). Chihuahua: Chihuahua, 14 Oct 1910, Hitchcock 

7794 (US); Hills and plains near Chihuahua, 31 Aug 1885, C.G. 

Pringle 411 (US); Rancho La Presa, 21 Oct 1954, 1100 m, Hern.-

Xol. & C.Tapia N-62 (US); Rancho Experimental La Campana, 

16 Oct 1980, pastizal [pastureland], 1500 m, A. Melgoza 649

(CIIDIR); Rancho La Campana, potreros del lado W [paddocks 

on W side], km 80 autopista Chihuahua–Cd. Juárez, 25 Nov 

1994, pastizal natural, 1590 m, Y. Herrera & M.E. Siqueiros 

1340 (CIIDIR); 35 km norte de Chih., carr. [hwy] Chih.–Cd. 

Juarez, 24 Oct 1997, 1400 m, C. Yen & E. Estrada 9031 (NMC); 

La Campana, Potrero La Sierra, 1 km Pte., carr. Panamericana, 

31 Aug 1975, pastizal, 1500 m, Valdés-Reyna VR-53 (RELC); 

L. Suáres & M. Valencia s/n (RELC). Jiménez: Sierra de los Organos, 8 Sep 1937, LeSueur 0162 (US); About 5 mi SW of Jiménez, 

6 Oct 1966, Reeder & C. Reeder 4608 (ARIZ). Juárez: km 5 

desviación [deviation] a Nvo. Casas Grandes de la carr. a Juárez, 

19 Sep 1955, pastizal, 1600 m, Hern.-Xol. & V. Mathus N-1922

(US); km 16 al S de Cd. Juárez, carr. Juárez–Cd. Chihuahua, 20 

Oct 1954, Hern.-Xol. & C. Tapia N-2 (US); Sierra de Samalayuca, 13 Oct 1997, pastizal, I. Enríquez, S. Ordoñez & J. Leyva 

IEA18 (UACJ); parte S de la Sierra de Samalayuca, aprox. 50 km 

al S de Cd. Juárez, 9 Sep 1995, 1300 m, R. Corral & P. Olivas 

RCD6364 (UACJ); 3 mi S of Samalayuca, 4 Nov 1957, 1300 m, 

31.3, 106.5, R.V. Moran s.n. (ARIZ). Manuel Benavides: 1 mi 

E of Pozo de Villa, along rd from Ojinaga to Castillon, vía La 

Mula, Trincheras, Pirámide and San Salvador, 10 Aug 1941, I.M. 

Johnston 8176 (US). Ojinaga: E Chihuahua, Sierra del Virulento, 

2–3 mi E of Rancho Virulento, about 65 mi S of Ojinaga, 11 Aug 

1941, I.M. Johnston 8085 (US).

FIGURE 46. Bouteloua eriopoda. A. Habit. B. Spikelet. C. Upper 

floret. D. Lower lemma. Drawn by Linda Ann Vorobik and Cindy 

Roché; copyright Utah State University.
NUMBER 107 • 6 9

54. Bouteloua gracilis (Kunth) Lag. ex Griffiths, Contr. U.S. 

Natl. Herb. 14: 375. 1912. Chondrosum gracile Kunth, 

Nov. Gen. Sp. (quarto ed.) 1: 176. t. 58. 1815.

FIGURE 47

Perennial; usually densely caespitose, often with short, stout 

rhizomes. Culms 24–70 cm tall, not woody basally, erect, geniculate, or decumbent and rooting at the lower nodes, not branched 

from the aerial nodes; nodes usually 2–3, glabrous or puberulent; 

lower internodes glabrous. Leaves mainly basal; sheaths glabrous 

or sparsely hirsute; ligules 0.1–0.4 mm long, of hairs, often with 

marginal tufts of long hairs; blades 2–12(19) cm long, 0.5–2.5 mm 

wide, flat to involute at maturity, hairs usually present basally. 

Panicles 0.5(12.5) cm long with 1–3(6) branches, these racemosely 

inserted on the rachis; branches 13–50(75) mm long, persistent, 

arcuate, scabrous, without papillose-based hairs, with 40–130 

spikelets, terminating in a spikelet; disarticulation above the 

glumes. Spikelets pectinate, with 1 bisexual and 1 rudimentary floret; glumes mostly glabrous or scabrous, midveins sometimes with 

papillose-based hairs; lower glumes 1.5–3.5 mm; upper glumes 

3.5–6 mm; lowest lemmas 3.5–6 mm long, pubescent at least basally, 5-lobed, central and lateral lobes veined and awned, awns 

1–3 mm long, central awns flanked by 2 membranous lobes; lower 

paleas about 5 mm long, shallowly bilobed, veins excurrent for 

less than 1 mm; rachilla internodes subtending second florets with 

a distal tuft of hairs; anthers 1.7–2.9 mm long, yellow or purple; 

upper florets sterile, 0.9–3 mm long, lobed almost to the base, lobes 

rounded, 3-awned, awns 1–3 mm, equal. Caryopsis 2.5–3 mm 

long, about 0.5 mm wide. 2n = 20, 28, 35, 40, 42, 60, 61, 77, 84.

Distribution and Habitat. Bouteloua gracilis

grows in pure stands in mixed prairie associations and disturbed 

habitats, usually on rocky or clay soils and mainly at elevations 

of 300–3000 m. Its native range extends from Canada to central 

Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 10 km al Nte.[N] de Sueco, 18 Oct 74, matorral micrófilo [microphytic scrub], 1400 m, Valdés-Reyna VR-648 (RELC). 

Aldama: 26 (rd) mi NE of Aldama along Hwy 16 near El Morrion, 15 Sep 1972, 1400 m, J. Henrickson 7565 (NMC); km 38 

Villa Aldama–Hormigas, 31 Oct 54, pastizal [pastureland], 1150 

m., Hern.-Xol. & C. Tapia N-529 (RELC). Balleza: 56.4 km W 

of Parral on road to Balleza and 35.5 km S of Balleza on MEX 

432, near Corral de Duarte, 18 Sep 1991, bosque de pino–encino 

[pine–oak forest], 2210 m, P.M. Peterson, Annable & ValdésReyna 10710 (CIIDIR, US). Batopilas: SW Chihuahua, Aug 1885, 

E. Palmer 24 (US). Bocoyna: Sánchez, 12 Oct 1910, Hitchcock 

7716 (US). Camargo: 6 mi W of Piloncillo, rd from Jimenez to 

Camargo, 24 Sep 1938, I.M. Johnston 7878 (US); Sierra de los 

Organos, 8 Sep 1937, LeSueur 0166 (US). Carichi: Mojarachic, 5 

Sep 1938, I.W. Knobloch 5651 (US). Casas Grandes: Near Casas 

Grandes, 30 Aug 1899, E.W. Nelson 6330 (US); Col. Juarez, Sierra 

Madre Occidental, 21 Sep 1934, Pennell 19053 (US); 1.6 mi NE 

Col. Juarez SW Casas Grandes, 30Aug 1986, 2000 m, Spellenberg 

& R. Corral 8585 (NMC). Chihuahua: Chihuhaua, 14 Oct 1910, 

Hitchcock 7799 (US); hills and plains near Chihuahua, 23 Aug 

1885, C.G. Pringle 407 (US); 6.1 mi W of hwy 45 on dirt road towards Santa Clara, 18 Oct 1992, bosque de encino, 1640 m, P.M. 

Peterson & Annable 12583 (US); Rancho La Campana, potreros 

del lado W [paddocks W side], km 80 autopista Chihuahua–Cd. 

Juárez, 25 Nov 1994, pastizal natural, 1590 m, Y. Herrera & M.E. 

Siqueiros 1342 (CIIDIR); Rancho Experimental La Campana, 16 

Oct 1980, pastizal, 1640 m, A. Melgoza 626 (CIIDIR); 6 km al S de 

Chihuahua, carr. [hwy] Chihuahua–Delicias, 17 Aug 1996, E. Estrada & C. Yen 5407 (NMC); Rancho Gallego, Estación Sueco, 

14 Sep 1999, pastizal, I. Enríquez & P. Olivas IE055 (UACJ); La 

Campana, Potrero El Bajío, 1 km Ote. [W], carr. Panamericana, 

13 Sep 73, pastizal, 1500 m, Valdés-Reyna VR-241(RELC). Cuahutémoc: 6–7 km al N, entronque [junction] carrs. 28 & 16, 10 

Aug 1976, ruderal, 2100 m, J.M. Peña JMP-138 (RELC); 21 km 

W of Cuauhtemoc, on Hwy 16, 23 Aug 1990, 2000 m, P.M. Peterson & Annable 9596 (US); 5.6 mi N of Cuahutémoc on Mex 

23, 14 Sep 1989, 2120 m, P.M. Peterson & R.M. King 8109 (US). 

Guadalupe: NE Chihuahua, vicinity of Rancho El Pino, ca 10 km 

SE of Sierra Rica, 23 Sep 1942, R. Stewart 2408 (US). Guerrero: 

FIGURE 47. Bouteloua gracilis. A. Habit. B. Ligule. C. Glumes. 

D. Florets. E. Lower floret. Drawn by Linda Ann Vorobik and 

Cindy Roché; copyright Utah State University.
7 0 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

railroad NW of San Isidro, Sierra Madre Occidental, 18 Sep 1934, 

Pennell 18985 (US); 38.6 km SW of La Junta and approx. 70.8 

km N of Creel at p. Arroyo Ancho crossing, 21 km marker, 24 Sep 

1988, pine woods, 2200 m, P.M. Peterson & Annable 5856 (US); 

Miñaca, 13 Oct 1910, Hitchcock 7746 (US); carr. La Junta–San 

Juanito, 17 km, 22 Sep 1997, bosque de encino, 2290 m, B. Tah 

V. 9 (CIIDIR). Hidalgo del Parral: NE edge of Parral, 30 Sep 

1959, D.S. Correl 22660 (ENCB); 10 mi W of Parral on road to 

El Vergel, 7 Oct 1966, Reeder & C. Reeder 4621 (ARIZ); 3 mi E 

of Parral, 13 Sep 1960, Reeder & C. Reeder 3455 (ARIZ-3456, 

US). Janos: Chihuahua–Sonora Border, Rancho Carretas, 29 Aug 

1939, 1460 m, L. H. Harvey 1597 (US). Guerrero: Barranca 

Colorada, Sierra Gazachic, 35 km S of Miñaca, 2500 m, Pennell 

18980 (US). Gran Morelos: 4 mi E of General Trias, 14 Sep 1960, 

Reeder, C. Reeder & Soderstrom 3464 (ARIZ, US). Janos: Mexican boundary line near White Water, 11 Sep 1893, E.A. Mearns 

2301 (US). Jiménez: Sta Eulalia plains, 15 Sep 1885, Wilkinson 

63 (US). Madera: along railroad N of Madera, Sierra Madre Occidental, 19 Sep 1934, Pennell 18998 (US); near Col. Garcia in the 

Sierra Madre, 15 Aug 1899, C.H.T. Townsend & C.M. Barber 

257 (US). Proximidad a la col. Chuichupa, 1 Sep 1990, bosquete 

de junípero [juniper grove], 2240 m, A. Benítez 2163 (CIIDIR); 

Laguna de Babicora, Ejido Año de Hidalgo, 15 Sep 1994, 2300 m, 

Quintana, Lebgue & Estrada 3305 (NMC). Manuel Benavides: 

E Chihuahua, 2 mi W of Pozo de Villa, along rd from Ojinaga to 

Castillon, vía La Mula, Trincheras, Pirámide and San Salvador, 10 

Aug 1941, I.M. Johnston 8165 (US). Ocampo: Parque Nacional 

“Cascada de Basaseachic,” near top of falls, 22 Sep 1994, 2000 

m, Spellenberg, Corral & Estrada 12099 (NMC); Col. Cumbres 

de Majalca, 33.8 km W of Mex 45, N of Chihuahua City, 7 Sep 

1989, pine forest, 2190 m, P.M. Peterson, Annable & Y. Herrera 

7959 (US). Práxedis G. Guerrero (San Ignacio): a 2 km al S del 

poblado del mismo nombre [town of the same name], Rancho Escuela de la Univ. Autónoma de Cd. Juárez, 18 Mar 1995, 1090 m, 

R. Corral, P. Olivas & E. Pérez RCD6043 (UACJ). Riva Palacio: 

Majalca, 18–20 Aug 1935, LeSueur Mex-017 (US); Riva Palacio: 

Majalca (Pilares), 11 Aug 1939, L. H. Harvey 1462 (US). Col. 

Cumbres de Majalca, approx. 32.2 km W of hwy 45 N of Chihuahua, 22 Sep 1988, pine woods, 1800 m, P.M. Peterson & Annable 

5804 (ENCB, US). San Francisco del Oro: 21 km W of Parral 

and approx. 3.2 km N on dirt road to Torrencillo, 26 Sep 1988, 

grassland, 2000 m, P.M. Peterson & Annable 5965 (ENCB, US).

55. Bouteloua hirsuta Lag., Varied. Ci. 2(4): 141. 1805.

Perennial; densely or loosely caespitose, occasionally stoloniferous. Culms 15–75 cm tall, erect or decumbent, sometimes branched basally, sometimes branched aerially, nodes 

3–6, internodes glabrous or sparsely to densely pubescent with 

papillose-based hairs. Leaves basal or mainly cauline; sheaths 

mostly glabrous, finely scabrous, or pubescent, pilose near the 

ligules; ligules 0.2–0.5 mm long, of hairs; blades 1–30 cm long, 

1–2.5 mm wide, flat to involute, papillose-based hairs often 

present on both surfaces, usually present on the bases of the 

margins. Panicles usually with 0.7–18 cm rachises bearing 1–6 

branches, the branches sometimes digitate; branches 10–40 mm 

long, persistent, straight, with 20–50 spikelets, axes extending 

5–10 mm beyond base of the terminal spikelets; disarticulation 

above the glumes. Spikelets pectinate, green to dark purple, 

with 1 bisexual floret and 1–2 rudimentary florets; glumes acuminate or awn-tipped; lower glumes 1.4–3.5 mm long; upper 

glumes 3–6 mm long, midveins with papillose-based hairs; lowest lemmas 2–4.5 mm long, pubescent, 1- to 3-awned, central 

(or only) awns 0.2–2.5 mm long, not flanked by membranous 

lobes, lateral lobes acuminate, unawned or with awns no longer than the central awn; lower paleas ovate, unawned; anthers 

2–3.4 mm long, cream or yellow; rachilla internodes subtending 

second florets glabrous or pubescent, sometimes with a distal 

tuft of hairs; second lemmas 0.5–2 mm long, bilobed, 3-awned, 

awns 2–4(6) mm; third lemmas, if present, minute, membranous 

scales, glabrous. Caryopsis 1.5–2.6 mm long. 2n = 20, 40, 50, 

60; numerous diploid numbers also reported.

Bouteloua hirsuta is a widespread species with two varieties.

KEY TO VARIETIES OF BOUTELOUA HIRSUTA

1. Culms glabrous below the nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. hirsuta var. hirsuta

1. Culms hispidulous with papillose-based hairs below the nodes . . . . . . . . . . . . . . . . . . . . . . . . . . B. hirsuta var. glandulosa

Bouteloua hirsuta var. glandulosa (Cerv.) Gould, J. Arnold 

Arbor. 60(2):320. 1979. Erucaria glandulosa Cerv., Naturaleza 1: 347. 1870.

Distribution and Habitat. Bouteloua hirsuta var. glandulosa grows in grasslands and thorn scrublands 

at 2,100 m. It occurs in the United States, Mexico, and Central 

America.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 10 mi SW of El Ojito, 12 Sep 2006, 1902 m, P.M. Peterson 20027, F. Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, 

US). Chihuahua: 25 km W of Chihuahua, 20 Aug 1939, L.H. 

Harvey 1540 (US).

Bouteloua hirsuta var. hirsuta.

Bouteloua hirsuta var. palmeri Vasey ex Beal.

FIGURE 48

Distribution and Habitat. Bouteloua hirsuta

Lag. var. hirsuta grows in open grasslands, desert scrub, and 

oak–pine forests at 1,800–2,370 m. It occurs in Canada, the 

United States, and Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 10 km al S de Moctezuma, 30 Jul 1994, 1200 m, 

R. Corral, E. Pérez, A. Domínguez & F. Félix RCD5364

(UACJ); km 1891 carr. [hwy] Juárez, sur [S] de Gallegos, 1 Dic 
NUMBER 107 • 7 1

54, 1400 m, Hern.-Xol. & C. Tapia N-1158 (RELC); 4 km al 

S de Estación Fernández, 10 Aug 1975, bosque de pino–encino 

[pine–oak forest], J.M. Peña JMP-124 (RELC). Aldama: 13.3 

(rd) mi NE of Aldama along Chihuahua Hwy 16, 14 Sep 1972, 

1400 m, J. Henrickson 7519 (NMC). Camargo: Sierra de los 

Organos, 8 Sep 1937, LeSueur 0165 (US). Casas Grandes: El 

Alamito, Col. Cuauhtémoc, 12 Aug 1999, P. Olivas, R. Rivas, 

I. Enríquez & A. Márquez POS 839 (UACJ). Chinipas: Saguarivo, 53 mi N of Alamos, 9 Sep 2008, slopes with oaks and 

pines, 1540 m, P.M. Peterson & J.M. Saarela 22126 (US). Chihuahua: Chihuahua, 14 Oct 1910, Hitchcock 7795 (US); Rancho La Campana, potreros del lado W [paddocks on W side], 

km 80 autopista Chihuahua–Cd. Juárez, 25 Nov 1994, pastizal 

natural [natural pasture], 1590 m, Y. Herrera & M.E. Siqueiros 

1341 (CIIDIR). km 52 Chihuahua–Juárez, 3 Aug 1978, pastizal, 

1450 m, Enríquez-Delgadillo 26 (CIIDIR); hills and plains near 

Chihuahua, Aug 1885, C.G. Pringle 409 (US); La Campana, 

Potrero La Sierra, 1 km Pte. carr. [hwy] Panamericana, 31 Aug 

1973, pastizal, 1500 m, Valdés-Reyna VR-52 (RELC). Guachochi: NW of Norogachic, ca. 3 road miles; airport near locality 

called Achiachic, 23 Aug 1978, bosque de pino, 2500 m, Bye 

8761 (MEXU). 1–2 km S of Río Osichi and Río Basihuare jct, 

1 Sep 2003, bosque de Quercus–Pinus, 1600 m, P.M. Peterson 

& P. Catalán 17644 (CIIDIR, US); 9 mi S of Guachochi at edge 

of Barranca Rio Verde, 1 km along trail descending into canyon, 

6 Oct 2000, bosque de pino, 2470 m, P.M. Peterson & J. Cayouette 15378 (US). Guerrero: 32.3 km SW of La Junta on road to 

Creel, 10 Sep 1989, pine forest, 2310 m, P.M. Peterson, Annable & Y. Herrera 7986 (ENCB, US); km 91 Yeporema–San José 

Babicora, al N de Vicente Guerrero, 29 Oct 1954, Hern.-Xol. & 

C. Tapia N-415 (US); S of Mesa Colorada, on S side of Arroyo 

Ancho, 28 Aug 1954, Bye 8925 (US). Janos: Chihuahua–Sonora 

Border, Rancho Carretas, 27 Aug 1939, 1460 m, L. H. Harvey 

1632 (US); Rancho El Carrizo, 30 Sep 1982, 1600 m, pastizal 

mediano abierto [mostly open grassland], P. Rojas s.n. (CIIDIR). 

Jiménez: Sta Eulalia Mts, E. Wilkinson 347 (US). Madera: between Col. García and Pratt’s Rancho below Pacheco, 22–24 

Aug 1899, E.W. Nelson 6246 (US); Mesa del Yerbaníz, ejido El 

Largo, 12 Oct 1990, bosque de encino, 1900 m, O. Bravo 1833

(CIIDIR); La Tinaja, ejido El Largo, 29 Aug 1990, encino–pino, 

1840 m, O. Bravo 1349 (CIIDIR). Manuel Benavides: Entre 

[between] Manuel Benavides & Pocitos, 2 Aug 1976, pastizal 

en ladera de cerro [pasture on hillside], 1342 m, S. González 

& J.M. Peña 454 (RELC). Matachic: SW of Matachic on slope 

on NW side of ridge near km 9.7 on Matachic–Cocomoarachic 

road, 29Aug 1978, pine–oak, 1900 m, Bye 9003 (US). Ocampo: 

Ca 1 km W of W boundary of Parque Nacional “Cascada de 

Basaseachic,” 13.5 km from the Cahuisori–Ocampo road on 

the road to Candamena, 3 km below Cruz Verde, 23 Sep 1994, 

1680 m, Spellenberg, Corral & Estrada 12154 (NMC); Parque 

Nacional “Cascada de Basaseachic,” 200 m upstream from the 

top of the falls along the Rio Basaseachi, 11 Nov 1989, 2000 m, 

Spellenberg, R. Corral, J Brunt & L. Huenneke 10078 (NMC). 

Riva Palacio: Majalca, 18–20 Aug 1935, LeSueur Mex-020 (US).

56. Bouteloua johnstonii Swallen, Proc. Biol. Soc. Wash. 56: 79. 

1943.

Perennial; densely caespitose, rhizomatous. Culms 10–

30(45) cm tall, strongly based. Leaves basal; sheaths glabrous, 

margins hyaline; ligule 0.5 mm long, a fringe of hairs, leaf blades 

5–12 cm long, 1–2 mm wide, curved, involute for entire length, 

apically rigid and spine-like, densely lanate-pubescent adaxially 

and glabrous at maturity. Panicle axis 7–10 cm long, tip subulate, composed of 6–12 unilateral branches, branches 8–15 mm 

long, 5–10 mm wide, bearing 7–11 appressed spikelets, sessile. 

Spikelets 5–9 mm long, cuneate, laterally compressed, falling entire; glumes unequal, glabrous, often purplish, lanceolate, apex 

acute to setaceously attenuate, thinner than fertile lemma, membranous, 1-keeled, 1-veined, lateral veins absent, lower glume 

FIGURE 48. Bouteloua hirsuta var. hirsuta. A. Habit. B. Glumes 

C. Florets. Drawn by Linda Ann Vorobik and Cindy Roché; copyright Utah State University.
7 2 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

3–4 mm long, upper glume 5–7 mm; lemma 5–7 mm long, ovate, 

keeled, 3-veined, apex lobulate, 3-awned, awns 2–3 mm long, 

subequal, central awn among 2 lobes; palea 4–4.2 mm long, glabrous; anthers 2–2.2 mm long, yellowish, filaments pubescent; 

apical sterile florets 1–2, rudimentary, sterile lemma 3-awned, 

awns 2–3 mm. Caryopsis 2–2.2 mm long, yellow, oblong-elipsoid. 

Distribution and Habitat. Bouteloua johnstonii is an endemic species in the north of Mexico that grows in 

gypsum and calcium soils in scrub communities and grasslands. 

It occurs in the states of Chihuahua and Coahuila.

Specimens Examined. MEXICO. Chihuahua. Chihuahua: Camargo: Sitio 17B, Rancho Epigmenia, 

25 Aug 2015, 27°46′37.7′′N, 104°09′10.8′′W [27.77722°N, 

104.15306°W], matorral desértico con [desert scrub with] 

Yucca carnerosana, 1627 m, J. Santos & A. Olivas s.n. (CIIDIR, 

UACH).

57. Bouteloua karwinskii (E. Fourn.) Griffiths, Contr. U.S. Natl. 

Herb. 14(3): 394. 1912.

Perennial; rhizomatous. Culms 20–55 cm tall, erect, branched 

from the base, internodes glabrous. Sheaths shorter than internodes, glabrous, marginally cilate, with some large hairs over the 

throat; ligule 0.3 mm long, a ciliate ring; blades 3–9 cm long, 

1–2 mm wide, flat, scabrous, loosely pilose on the adaxial surface, curved. Panicle 1.5–5(8) cm long, conformed by 3–6 persistent spikes (branches), branches 1–1.8 cm long, spaced out and 

almost erect, containing 16–32 spikelets. Spikelets 3–3.5(4) mm 

long, disarticulating over the glumes; glumes unequal, glabrous, 

sparsely pubescent over the keel, lower glumes 1.5–2 mm long, 

narrow, acuminate, upper glumes 2–2.5 mm long, wider than 

the lower glume; lemma of the bisexual floret 2.5–3.2 mm long, 

sparsely plicate-pubescent over the veins and the base, the lateral 

veins excurrent into strong awns, awns 1–1.5 mm long, not exceeding the acute apex of the lemma. Rudimentary florets (1)2, 

lemma of the first rudimentary floret 1 mm long with 3 veins 

prolonged into awns of 1.5 mm long, second rudimentary floret 

1 mm long including the 3 scabrous awns, rachilla glabrous at the 

base of the rudimentary floret. Caryopsis 0.7–1 mm long, light 

yellow to brown when mature, narrowly elliptic. 2n = 20. 

Distribution and Habitat. Bouteloua karwinskii grows on grasslands and scrub communities over gypsum 

soils. It is an endemic species in Mexico known from Coahuila, 

Nuevo León, San Luis Potosí, and Zacatecas and now found in 

Chihuahua. 

Specimens Examined. MEXICO. Chihuahua. 

Aldama: Sitio 27B, Torreño # 3, 2 Sep 2015, 29°04′45′′N, 

105°45′49′′W [29.07917°N, 105.76361°W], matorral subinerme [mostly unarmed scrub] con Fouquieria splendens, Tecoma 

stans, Acacia neovernicosa & Cassia wislizenii, 1380 m, J. Santos & A. Olivas 528B (CIIDIR, UACH).

58. Bouteloua media (E. Fourn.) Gould & Kapadia, Brittonia 

16(2): 196, f. 35. 1964. Atheropogon medius E. Fourn., 

Mexic. Pl. 2: 139. 1886.

Perennial; caespitose, basally nudose. Culms 80–200 cm 

tall, erect, with 4–7 nodes purple, simple, occasionally branched 

on the superior nodes. Sheaths scabrous or papillose-hirsute, 

sparsely pilose on the margins and near the throat; ligules 0.5–

0.7 mm long, membranous, minutely ciliate; blades 30–45 cm 

long, 4–6(9) mm wide, flat, scabrous or papillose-hirsute. Inflorescence 20–25 cm long, terminal and axillary, branches 

20–40, 1–2 cm long, inclined, deciduous when mature, bearing 

7–13(20) spikelets, rachis scabrous, spikelets congested; axillary 

inflorescences shorter than the nodes, placed below the terminal node, with thinner axes, short, with fewer number of spikelets per branch. Spikelets 5–6 mm long, some abortive, inserted 

in the spikes; glumes unequal, lower glumes 3.8–4.5 mm long, 

narrow, acute, attenuate or setaceous, with membranous base, 

scabrous to pubescent on the keel, upper glumes 4.5–5.5 mm 

long, widely lanceolate, acute to acuminate, sparsely pilous to 

scabrous on the keel; lemmas of the bisexual floret 5–5.5 mm 

long, scabrous to puberulent, 3-veined,veins excurrent into 3 

short awns, scabrous; paleas equal in size about as long as the 

lemma, minutely pubescent; anthers 2.8–3.5 mm long, yellow or 

orange; rudimentary florets 1–2, sterile, lemma of the first floret rudimentary, 3–3.5 mm long, membranous, 5-awned, awns 

4–5 mm long, scabrous, central awn 5–10 mm long, strong and 

scabrous; lemmas of the second floret when present 2.5–3 mm 

long. Caryopsis 2.2–2.5 mm long, slender, yellow, ovoid to narrowly elliptic. 2n = 20.

Distribution and Habitat. Bouteloua media 

grows in grasslands, scrub communities, and, less commonly, 

tropical forest. It ranges from Mexico to Central America and 

South America.

Specimens Examined. MEXICO. Chihuahua.

Guachochi: West of Munérachi, 7 Sep 2003, matorral espinoso 

[thorny scrub], 1200 m, P.M. Peterson & P. Catalán 17711

(US). Guadalupe: NE Chihuahua, vicinity of Rancho El Pino, 

ca 10 km SE of Sierra Rica, 23 Sep 1942, R. Stewart 2406 (US). 

59. Bouteloua parryi (E. Fourn.) Griffiths, Contr. U.S. Natl. 

Herb.14(3): 381, f. 37, pl. 73. 1912. Chondrosum parryi

E. Fourn., Mexic. Pl. 2: 150. 1886. 

FIGURE 49

Annual or short-lived perennial; tufted, sometimes stoloniferous. Culms 20–60 cm tall, erect or somewhat geniculate at the 

base. Leaves mostly basal; sheaths pubescent, usually with tufts 

of long hairs on either side of the collar; ligules 0.1–0.5 mm long, 

of hairs; blades 1–3 cm long, 1–2.5 mm wide, margins and usually both surfaces with papillose-based hairs. Panicles 2.5–10 cm 

long, with 4-8 branches; branches 20–35 mm long, persistent, 

with papillose-based hairs, with 40–65 spikelets, branches terminating in a spikelet; disarticulation above the glumes. Spikelets pectinate, with 1 bisexual floret and 2 rudimentary florets; 

glumes unequal; lower glumes about 2 mm long, glabrous or 

sparsely pubescent at the base, mucronate; upper glumes 3–4 mm 

long, keels with papillose-based hairs, apex bilobed, awned from 
NUMBER 107 • 7 3

between the teeth, awns to 0.7 mm long; lowest lemmas 3–4 mm 

long, pilose or villous proximally, 3-awned, awns 2–3 mm 

long, central awns flanked by 2 membranous lobes; lowest paleas about 2.5 mm long, 4-lobed, 2-awned; anthers 1.8–2 mm 

long, yellow; rachilla internodes subtending second florets with 

densely pubescent apex; second florets lobed nearly to the base, 

lobes ovate, awns 2–4 mm long, exceeding those of the lowest 

lemmas, third florets minute scales, glabrous, unawned or with a 

single awn. Caryopsis 1.3–1.5 mm long. 2n = 20.

Distribution and Habitat. Bouteloua parryi grows on sandy slopes and flats at elevations from near sea 

level to 2,000 m. Its range extends from the southwestern United 

States to central Mexico; only Bouteloua parryi var. parryi occurs in Chihuahua.

Specimens Examined. MEXICO. Chihuahua.

Casas Grandes: 1.6 mi NE Col. Juarez SW Casas Grandes, 

30 Aug 1986, Spellenberg & R. Corral 8586 (NMC). Chihuahua: km 153 Chihuahua–Sueco, 6 Oct 77, pastizal [pastureland], 

1570 m, A. Melgoza-Peña-Martín s/n (RELC). Ojinaga: 5 km al 

Pte. del Rancho Escobillas, 30 Oct 74, pastizal, Valdés-Reyna 

VR-828 (RELC).

60. Bouteloua radicosa (E. Fourn.) Griffiths, Contr. U.S. 

Natl. Herb. 14: 411, t. 81. 1912. Atheropogon radicosus

E. Fourn., Mexic. Pl. 2: 140. 1886.

FIGURE 50

Perennial; with a dense, hard, knotty base, rhizomatous, rhizomes 2–3 mm thick, with pale cataphylls, internodes 4–5 mm 

long. Culms (40)60–80 cm tall, erect, straight, unbranched. 

Sheaths strongly striate; ligules 0.5–1 mm long, of hairs; blades 

mostly basal, short and firm, 2–3 mm wide, bases with papillosebased hairs on the margins. Panicles 10–15 cm long, usually 

with 7–12 branches; branches (15)20–30 mm long, deciduous, 

with 8–11 spikelets, apex entire; disarticulation at the base of 

the branches. Spikelets 9–13 mm long, appressed, all alike, with 

2 florets, lowest floret bisexual, upper florets pistillate, bisexual, 

or staminate; glumes acuminate, glabrous; lower glumes about 

4 mm; upper glumes 5–6 mm; lowest lemmas 7–8 mm long, 

smooth, often shortly trilobed, 3-awned, awns excurrent from 

the lobes, central awns 2–3 mm long, not flanked by membranous lobes, lateral awns about 1 mm; lower paleas 6–7 mm long, 

unawned, sometimes mucronate; upper lemmas 9–10 mm long, 

central awns 6–8 mm long, lateral awns 5–6 mm; upper paleas 

similar to the lower paleas. Caryopsis 4–5 mm long, 0.75–1 mm 

wide. 2n = 60.

Distribution and Habitat. Bouteloua radicosa grows on dry, rocky slopes at 1,000–3,000 m, from Arizona 

and southern New Mexico to southern Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: SW Chihuahua, Aug 1885, E. Palmer 115-A (US). 

Casas Grandes: Casas Grandes, 25 Aug 1899, E.W. Nelson 6305

(US); 18 mi W of Col. Juárez, 2073 m, Reeder & C. Reeder 3205

(US). Guachochi: Parque Nacional Barranca del Cobre, 3.8 km 

FIGURE 49. Bouteloua parryi. A. Habit. B. Spikelet. C. Lower 

lemma. Drawn by Linda Ann Vorobik and Cindy Roché; copyright 

Utah State University.
7 4 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

NE of La Bufa and 9.6 km S of Kirare, 1240 m, P.M. Peterson, 

Annable & Valdés-Reyna10836 (US). Guerrero: near Guerrero, 

11 Sep 1887, C.G. Pringle 1436 (US). Janos: Chihuahua–Sonora 

Border, Rancho Carretas, 26 Aug 1939, 1460 m, L. H. Harvey 1612 (US). Madera: near Col. Garcia in the Sierra Madre, 

5 Aug 1899, C.H.T. Townsend & C.M. Barber 226 (NMC, US); 

between Col. García and Pratt’s Rancho below Pacheco, 22–24 

Aug 1899, E.W. Nelson 6258 (US); Mesa del Yerbanís, ejido El 

Largo, 12 Oct 1990, bosque de encino [oak forest], 1900 m, 

O. Bravo 1858 (CIIDIR). Ocampo: Ca 1 km W of W boundary of Parque Nacional “Cascada de Basaseachic,” 15 km from 

the Cahuisori–Ocampo road on the road to Candamena, 4.3 km 

below Cruz Verde, 23 Sep 1994, 1570 m, Spellenberg, Corral & 

Estrada 12168 (NMC).

61. Bouteloua ramosa Scribn. ex Vasey, U.S.D.A. Div. Bot. Bull. 

12(1): t. 44. 1890.

FIGURE 51

Perennial; densely caespitose, bases hard, knotty, without 

rhizomes or stolons. Culms 25–60 cm tall, numerous, somewhat woody at the base, geniculate, branching profusely from 

the lower nodes; nodes usually 4–5; lower internodes glabrous, 

without a conspicuous, white, chalky bloom. Ligules 0.1–0.2 mm 

long, of hairs; blades 2–7 cm long, 1–2 mm wide, mostly flat but 

the tips involute. Panicles 1–3(5) cm long, with 1–3(4) branches; 

branches 10–35 mm long, persistent, ascending to widely divergent, becoming arcuate, dark, with 24-45(64) spikelets, branches 

terminating in a reduced, needlelike, 2–5 mm spikelet; disarticulation above the glumes Spikelets with 1 bisexual floret and 

1–2 rudimentary florets; glumes acute to acuminate, glabrous 

or sparsely short-hairy, hairs not papillose-based; lower glumes 

2–2.5 mm long; upper glumes 2–3.5 mm long; lowest lemmas 

2.5–4 mm long, sparsely to densely hairy, 3-awned, awns slightly 

shorter than the lemma bodies, central awns flanked by 2 membranous lobes; lowest paleas about 4.5 mm long, mostly glabrous, sometimes puberulent distally, acute to acuminate, veins 

not excurrent, unawned; second florets about 4.5 mm long, 

3-awned, awns 3–5 mm long; rachilla internodes subtending 

second florets with densely pubescent apex; third florets, if present, flabellate scales, 1-awned. Caryopsis 1–1.2 mm long, about 

0.4 mm wide. 2n = 40.

Distribution and Habitat. Bouteloua ramosa

is locally common on rocky limestone slopes and flats among 

shrubs and Agave lecheguilla. Its range extends from the Trans 

Pecos region of western Texas to adjacent northern Mexico, particularly in the Chihuahuan Desert.

FIGURE 50. Bouteloua radicosa. A. Habit. B. Leaf blade with 

papillose-based hairs. C. Lemma. Drawn by Linda Ann Vorobik and 

Cindy Roché; copyright Utah State University.
NUMBER 107 • 7 5

Specimens Examined. MEXICO. Chihuahua. Jiménez: Sta. Eulalia Mts., Pringle 414 (US); 50 km al S de Jiménez, 15 Aug 2010, 1442 m, D. Ramírez & M.L. Juárez 3417

(CIIDIR); 13 km S of Cd. Jimenez, 30 Jul 1939, L. H. Harvey 

1339 (US).

62. Bouteloua repens (Kunth) Scribn. & Merr., Bull. Div. Agrostol. U.S.D.A. 4: 9, 1897. Dinebra repens Kunth, Nov. Gen. 

Sp. (quarto ed.) 1: 172, t. 52. 1815.

FIGURE 52

Perennial; caespitose, usually not dense, hard, or knotty, 

without rhizomes or stolons. Culms 15–65 cm tall, erect, geniculate, or decumbent, sometimes rooting at the lower nodes, 

usually branching from the aerial nodes. Sheaths glabrous 

or pubescent; ligules 0.2–0.3 mm long, membranous, ciliate; 

blades 5–20 cm long, 1–5 mm wide, bases with papillose-based 

hairs on the margins, both surfaces glabrous or pubescent. Panicles 4–14 cm long, with (3)7–12 branches; branches 10–20 mm 

long, with 2–8 spikelets, extending 4–6 mm beyond the base of 

the terminal spikelets, apex entire; disarticulation at the base of 

the branches. Spikelets 6–9 mm long, appressed, all alike, with 

FIGURE 51. Bouteloua ramosa. A. Habit. B. Glumes. C. Lower 

lemma. D. Lower palea. Drawn by Linda Ann Vorobik and Cindy 

Roché; copyright Utah State University.

FIGURE 52. Bouteloua repens. A. Habit. B. Spikelet. C. Lemma. 

D. Palea. Drawn by Linda Ann Vorobik and Cindy Roché; copyright Utah State University.
7 6 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

1 bisexual and 1 staminate (rarely rudimentary) floret; glumes 

glabrous, veins scabrous or strigose; lower glumes 4–7 mm 

long; upper glumes 4–9 mm long, mostly glabrous, sometimes 

scabrous or strigose over the veins, apex acute, unawned or 

awn-tipped, awns about 1 mm; lowest lemmas 4.5–8 mm long, 

usually glabrous, rarely pubescent basally, 3-awned, awns wide 

basally, central awns slightly longer than the lateral awns, 

often flanked by 2 membranous 0.5–1.5 mm long lobes; lowest 

paleas 6–8 mm long, bilobed, often shortly 2-awned; anthers 

3–5.5 mm long, usually orange or yellow, occasionally red or 

purple; second lemmas 5.5–7 mm long, glabrous, 3-awned, 

central awns 4–10 mm long, often flanked by membranous 

lobes, lateral awns 2–10 mm long; second paleas 4–7 mm long; 

anthers less than those of the lowest florets; rachillas prolonged 

beyond the second florets as a short bristle. Caryopsis 3–4 mm 

long. 2n = 20, 40, 60.

Distribution and Habitat. Bouteloua repens

grows in open, usually hilly terrain on many soil types, from 

sandy ocean shores to montane slopes, reaching elevations of 

2,500 m. Its native range extends from the southwestern United 

States to Mexico and Central America to Colombia and Venezuela; it also occurs in the Caribbean Islands.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: SW Chihuahua, Aug 1885, E. Palmer 65 (US); Yamuco 

at 1 km E of Hwy towards Basihuare and Creel, N of Rio Urique 

crossing, 26 Aug 2003, bosque de pino–encino [pine–oak forest], 1891 m, P.M. Peterson & P. Catalán 17534 (US). Madera: 

Paraje Sirupa, ejido Cebadilla de Dolores, 24 Aug 1990, bosque 

de encino, 1220 m, O. Bravo 1262 (CIIDIR). 

63. Bouteloua scorpioides Lag., Gen. Sp. Pl. 5. 1816.

Perennial; mat-forming. Culms 10–20(30) cm tall, erect, 

few branched at the base. Leaves basal; sheaths glabrous, with 

hyaline margins, throats pilose with a tuft of hairs of 1–3 mm; 

ligules 0.5–1 mm long; blades 2.5–13 cm long, involute, filiform, recurved or flexuous. Inflorescence 1 spike, 2.5–4(5) cm 

long, unilateral, arched-recurved, persistent, insert in culm 

apex, bearing 35–90 spikelets. Spikelets 5–7 mm long, with 1

bisexual floret and 2 rudimentary, disarticulation above glumes; 

glumes subacute, glabrous, greenish or with purple spots, the 

lower 2–3 mm long, narrow, the second 4–7 mm; lemmas of the 

bisexual floret 3.5–5.5 mm long, basally bearded and densely pilose over the margins and veins of the inferior 1⁄2, veins excurrent 

in strong awns, 1.5–2 mm the central, 1–1.5 mm the lateral; anthers 3 mm long, orange; first rudimentary floret 5.5–6 mm long, 

3-awned, awns 1.5–4 mm long, with a basal tuft of hairs. Caryopses 1.8–2.4 mm long, yellow to brown, angulose-triangular. 

2n = 20. 

Distribution and Habitat. Bouteloua scorpioides grows in grassland, desert scrub, and pine–oak forests 

at 1,800–2,570 m. Its range extends into Mexico in Chihuahua, Distrito Federal, Durango, Guanajuato, Hidalgo, Jalisco, 

México, Morelos, Oaxaca, Puebla, Querétaro, San Luis Potosí, 

Tamaulipas, Tlaxcala, and Zacatecas.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: Encinillas, 13 Sep 1906, D. Griffiths 8527 (US); 

Campero, 30 Aug 1906, D. Griffiths 8462 (US).

64. Bouteloua simplex Lag., Varied. Ci. 2(4): 141. 1805.

Bouteloua procumbens (P. Durand) Griffiths.

FIGURE 53

Annual. Culms 3–35 cm tall, usually decumbent, occasionally erect, rarely branching; internodes glabrous. Sheaths 

smooth, deeply striate; ligules 0.1–0.2 mm long, of short hairs, 

sometimes with a few papillose-based hairs on either side; blades 

2–8 cm long, 0.5–1.5 mm wide, flat to involute, adaxial surfaces mostly glabrous, often pilose basally. Panicles usually with 

only 1 branch (terminating the culm), or with 2–4 branches and 

subdigitate; branches 10–25(40) mm long, persistent, straight, 

arcuate, or circular, with 30–80 spikelets, axes terminating in a 

reduced spikelet; disarticulation above the glumes. Spikelets pectinate, with 1 bisexual floret and 1–2 rudimentary florets; glumes 

glabrous, sometimes scabrous distally, acute or acuminate; lower 

glumes 1.5–2.5 mm long; upper glumes 3.5–5 mm long; lowest lemmas 2.5–3.5 mm long, pilose over the veins, 3-awned, 

awns stout and flattened, central awns 1–2 mm long, flanked by 

2 membranous lobes, lateral awns shorter than the central awns; 

lowest paleas obovate, unawned; rachilla internodes subtending 

second floret with densely pubescent apex; second floret reduced 

to an awn column with 3 awns of 5–6 mm; third floret, if present, flabellate scales. 2n = 20.

Distribution and Habitat. Bouteloua simplex

grows on rocky, open slopes in grassy and open shrub vegetation at 1,200–2,500 m. Its native range extends from the southwestern United States through Mexico and Central America to 

western South America.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 43.5 km W of Balleza and 51.6 km E of Guachochi, 

18 Sep 1991, 2320 m, P.M. Peterson, Annable & Valdés-Reyna 

10761 (CIIDIR); 69.2 km al E de Guachochi and 25.7 km W of 

Balleza, 26 Sep 1988, 2100 m, P.M. Peterson & Annable 5939

(US). Batopilas: SW Chihuahua, Aug 1885, E. Palmer 3 (US). 

Chihuahua: La Campana, Potrero El Bajío, Ote. [W] carr. [hwy] 

Panamericana, 13 Sep 73, pastizal halófito [halophyte grassland], 1480 m, Valdés-Reyna VR-244, VR-320 (RELC). Gómez 

Farías: Laguna de Babicora,18 Aug 1994, 2150 m, T. Lebgue 

& E. Estrada 3490 (NMC). Guachochi: 12.4 km S of Cusarare 

on road to Guachochi, 25 Sep 1988, pine forest, 2400 m, P.M. 

Peterson & Annable 5893 (US); flat rock at Napuchis, 2 Sep 

2003, pastizal [pastureland], 2140 m, P.M. Peterson & P. Catalán 17671 (CIIDIR, US). Guerrero: near Guerrero, 8 Sep 1887, 

C.G. Pringle 1434 (US); 35.4 km SW of La Junta and approx.74 

km N of Creel, 24 Sep 1988, 2200 m, P.M. Peterson & Annable 

5832(US). Hidalgo del Parral: 5.5 mi NW of Parral, 2 Oct 1959, 

Correll & Gentry 22705 (US). Madera: 3 km al NE de Madera, 

5 Oct 74, bosque de pino [pine forest], 2100 m, Valdés-Reyna 

& L.C. Fierro VR-685 (RELC). Riva Palacio: Col. Cumbres de 
NUMBER 107 • 7 7

Majalca, 33.8 km W of Mex 45, N of Chihuahua City, 7 Sep 

1989, pinyon forest, 2190 m, P.M. Peterson, Annable & Y. Herrera 7951 (ENCB, US).

65. Bouteloua trifida Thurb., Proc. Amer. Acad. Arts 18. 177. 

1883.

FIGURE 54

Perennial; caespitose, older plants occasionally short rhizomatous. Culms 5–40 cm tall, slender, wiry, erect or slightly 

geniculate at the lower nodes; lower internodes glabrous, shorter 

than those above. Leaves mostly basal; sheaths glabrous, sometimes scaberulous, becoming flat, persistent; ligules 0.2–0.5 mm 

long, of hairs; blades 0.7–8 cm long, 0.5–1.5(2) mm wide, scaberulous, margins often with papillose-based hairs basally. Panicles 3–9 cm long, with 2–7 branches; branches 7–25 mm long, 

persistent, spreading, ascending, or appressed, straight to slightly 

arcuate, with 8–24(32) spikelets, axes terminating in a spikelet; 

disarticulation above the glumes. Spikelets appressed to pectinate, reddish-purple; with 1 bisexual floret and 1 rudimentary 

floret; glumes bilobed; lower glumes 1.7–3.4 mm long, slightly 

shorter than the upper glumes, veins excurrent to 0.6 mm; 

upper glumes 1.9–4 mm long, glabrous or pubescent, hairs not 

papillose-based, veins excurrent to 1 mm; lower lemmas 1.2–

2.2 mm long, glabrous, sparsely appressed-pubescent along the 

veins or densely appressed-pubescent for much of their length 

and on the margins, trilobed, lobes veined, tapering into 3 awns, 

awns 2.2–6.6 mm long, central awns not flanked by membranous lobes; anthers 0.2–0.4 mm long, yellow; rachilla internodes 

glabrous; upper florets glabrous, 3-awned, awns equal, 2–7 mm. 

Caryopsis 0.8–1.5 mm long, 0.3–0.6 mm wide. 2n = 20.

Distribution and Habitat. Bouteloua trifida

grows on dry open plains, shrubby hills, and rocky slopes at 

2,200–2,500 m. Its range extends from the southwestern United 

States to central Mexico. It is a drought-resistant species that is 

sometimes confused with B. barbata, but that species is annual, 

with the central awn flanked by 2 membranous lobes and the 

lowest paleas 4-lobed and 2-awned.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: near Chihuahua, 25 Aug 1885, C.G. Pringle 412

(US). Jiménez: Sta Eulalia plains, 1885, E. Wilkinson 205 (US). 

Valle de Zaragoza: 58 km N of Parral on Mex 24 towards Chihuahua, 14 Sep 1989, grassland, 1500 m, P.M. Peterson & Annable 8101 (US).

66. Bouteloua uniflora Vasey, Bot. Gaz. 16: 26. 1891.

FIGURE 55

Perennial; caespitose, without rhizomes or stolons. Culms 

20–60 cm tall, stiffly erect, glabrous. Sheaths mostly glabrous, a 

few long hairs present near the ligules; ligules 0.2–0.5 mm long, 

of hairs; blades 6–16 cm long, 1–2 mm wide, involute when dry, 

glabrous, bases usually with papillose-based hairs on the margins. Panicles 5–10(14) cm long, with 15–70 branches; branches 

FIGURE 53. Bouteloua simplex. A. Habit. B. Spikelet. C. Lower 

lemma. D. Lower palea. Drawn by Linda Ann Vorobik and Cindy 

Roché; copyright Utah State University.
7 8 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

FIGURE 54. Bouteloua trifida. A. Habit. B. Spikelet. C. Lower 

lemma. D. Upper floret. Drawn by Linda Ann Vorobik and Cindy 

Roché; copyright Utah State University.

FIGURE 55.Bouteloua uniflora. A. Habit. B. Inflorescence branches. 

Drawn by Linda Ann Vorobik and Cindy Roché; copyright Utah 

State University.
NUMBER 107 • 7 9

5–9 mm long, deciduous, scabrous, with 1 spikelet (lower 

branches occasionally with 2 spikelets), axes extending 3–4 mm 

beyond the terminal spikelets, apex entire; disarticulation at the 

base of the branches. Spikelets appressed, with 1 bisexual and 

0 or 1 rudimentary florets; glumes acute to slightly cleft and 

minutely apiculate, midveins usually scabrous; lower glumes 

2.5–4 mm long; upper glumes 6.2–8 mm long, mostly smooth, 

midveins usually scabrous; lowest lemmas 6–7.5 mm long, acute 

or minutely cleft, glabrous, unawned, sometimes mucronate; 

lowest paleas unawned, glabrous; anthers 2.5–3 mm long, bright 

yellow; second florets absent or reduced to 1 or 3 short awns, 

glabrous. Caryopsis about 3 mm long. 2n = 20.

Distribution and Habitat. Bouteloua uniflora

grows primarily in fertile, rocky, limestone soils of Texas and 

adjacent Coahuila, Mexico at 300–1,000 m. Plants in the region 

belong to Bouteloua uniflora var. coahuilensis Gould & Kapadia, which differs from Bouteloua uniflora var. uniflora, in having smaller (20–40 cm long, not 40–60 cm) and scapose rather 

than leafy culms, shorter leaf blades (6–12 cm versus 12–16 cm), 

and 15–40 rather than 50–70 panicle branches. 

Specimens Examined. MEXICO. Chihuahua. 

Aldama: km 100 carr. [hwy] Chihuahua–Ojinaga, 25 Nov 

1994, matorral de gobernadora [governor’s scrub], 1590 m, 

Y. Herrera & M.E. Siqueiros 1344 (CIIDIR). Guachochi: along 

río Corareachi, 30 Aug 2003, 1840–1900 m, P.M. Peterson & 

P. Catalán 17599 (CIIDIR, US). San Francisco del Oro: 21 km 

W of Parral and approx. 3.2 km N on dirt road to Torrencillo, 

26 Sep 1988, grassland, 2000 m, P.M. Peterson & Annable 

5964 (ENCB, US).

67. Bouteloua warnockii Gould & Kapadia, Southw. Naturalist 

7(3-4): 176–181. 1962.

Perennial; caespitose, forming clumps 4–10 cm in diameter, 

lacking stolons and rarely having short rhizomes.Culms20–35(50) 

cm tall, erect. Leaves mostly basal, bluish-green, more or less glaucous; sheaths mostly glabrous, hairs present distally; ligules 1–1.5 

mm long, a fringe of hairs; blades 5–15(25) cm long, 1–1.5(2.5) 

mm wide, glaucous, erect or curving, involute when dry; mostly 

glabrous, ligular area with long and short hairs, bases usually with 

papillose-based hairs on the margins. Panicles 5–10(20) cm long, 

with 9–15(25) lax branches, branches 4–5.5 mm long, deciduous, scabrous, with 2–6 spikelets, axes terminating well beyond 

the terminal spikelets, apex entire, disarticulation at the base of 

the branches. Spikelets 5–6.5 mm long, with 1 bisexual and 1 

sterile floret, appressed, all alike, green, laterally compressed; 

glumes unequal, shorter and thinner than the spikelet, membranous, 1-keeled, 1-veined, lateral veins absent, apex acuminate, 

lower glume 3–5 mm long, upper glumes 4–6 mm long, glabrous, 

sometimes scabrous; lemma of bisexual florets 5–6.5 mm long, 

glabrous, coriaceous, keeled, 3-veined, acute, 3-awned, awns less 

than 1 mm long, central awns 0.5–1 mm long, not flanked by 2 

membranous lobes; anthers 2.2–3.7 mm long, dark purple; rudimentary florets sterile, usually without paleas; lemmas reduced to 

a glabrous awn column, sometimes moderately well-developed 

and 3-awned, awns usually not exserted, central awns 2.5–4 mm 

long. Caryopsis 3.2–3.6 mm long, ovoid. 2n = 21, 22, 23, 24, 25, 

28, 38, 40.

This species frequently grows and may hybridize with 

B. curtipendula var. caespitosa.

Distribution and Habitat. Bouteloua warnockii grows on limestone ledges and dry slopes below limestone 

outcrops. Its range extends from the southwestern United States 

to the states of Coahuila and Chihuahua in Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Manuel Benavides: Rancho Los Pinos, Sierra Rica, 21 Nov 2013, 

29.17006°N, 104.04964°W, matorral desértico con [desert scrub 

with] Yucca carnerosana, Mortonia semprevirens, Bouteloua 

curtipendula, Ephedra trifurca, Flourencia cernua, and Acacia 

constricta, 1500–1800 m, A. Juárez 102 (CIIDIR, RELC).

68. Bouteloua williamsii Swallen, Ceiba 4(5): 285. 1955.

Perennial; caespitose, not rhizomatous. Culms 35–90(115) 

cm tall, slender, erect. Leaves basal; sheaths glabrous to hirsute; ligules 0.2–0.5 mm long, a delicate row of hairs; blades 

10–25(35) cm long, 1.5–3 mm wide, flat, harsh leaves to the 

tact, abundantly haired, hairs 2–5 mm. Inflorescence 8–20 cm 

long, solitary, terminal. Spikes 5–11, 2–5(7) cm long, erect or 

spreading, deciduous when mature, bearing (9)12–20 spikelets, 

rachis flat, scabrous, with a tuft of hairs at the base of the spikelet. Spikelets 5–9 mm long, congested, persistent on each spike; 

glumes unequal, wide, acute or acuminate, with purple spots, 

lower glumes 3–4.5 mm long, slender, almost translucid, upper 

glumes 4.2–6 mm long; lemma of bisexual florets 4–6(7.5) mm 

long, firm, lateral veins excurrent into 2 awns of 2–3 mm long, 

central vein into a longer awn, with a truft of hairs at the base; 

palea apex 2-toothed, slightly longer than lemma, pubescent between the veins; anthers 2–3 mm long, yellow; rudimentary florets 1(2), staminate, lemma of the rudimentary florets 3–4 mm 

long, glabrous, with a tuft of silky hairs at the base, with 3 awns 

of 4–6 mm long, strongly flattened at the base, rachilla prolonged, the second rudimentary floret small when present. Caryopsis 3–4 mm long, straw-colored, ovoid to narrowly elliptic. 

2n = 20. 

This species is easily confused with B. radicosa, which differs in its lack of rhizomes, leaves that are harsh to touch, and 

longer spikes with a larger number of spikelets.

Distribution and Habitat. Bouteloua williamsii grows in dry soils of the oak forests, grasslands, and subtropical scrub. It is found from Mexico to Honduras.

Specimens Examined. MEXICO. Chihuahua. 

Ignacio Zaraza: 20.3 km NE of Ignacio Zaragoza on Mex 23, 

28 Sep 1989, 2400 m, P.M. Peterson & R.M. King 8149 (US).

Bromus L.

Perennial, annual, or biennial; usually caespitose, occasionally rhizomatous. Culms 5–150 cm tall, 1 to several per plant. 

Sheaths closed to near the top, glabrous to pubescent; auricles 

present to usually absent; ligules to 7 mm long, membranous, 

usually erose or lacerate; blades generally flat, rarely involute, 
8 0 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

glabrous or pubescent. Inflorescences panicles, sometimes racemose, open to dense, erect to nodding. Spikelets 1.3–4 cm long, 

terete to laterally compressed; disarticulation above the glumes 

and beneath the florets. Glumes unequal, shorter than the adjacent lemmas, glabrous or pubescent, usually acute, rarely mucronate; lower glumes 1- to 7(9)-veined; upper glumes 3- to 

9(11)-veined; lemmas rounded to keeled, glabrous or pubescent, 

5- to 13-veined, apex entire, emarginate, or toothed, usually 

terminally or subterminally awned, sometimes unawned; paleas 

usually shorter than lemmas, ciliate on the keels, adnate to the 

caryopsis; anthers 2–3. Caryopses somewhat ellipsoid, dorsally 

flattened (section Bromus) to terete and laterally compressed 

(section Ceratochloa). x = 7.

Bromus grows in temperate and cool regions, and is estimated to include 165 species (Saarela et al., 2014; Soreng et al., 

2017b). 

KEY TO SPECIES OF BROMUS

1. Spikelets strongly laterally compressed; lemmas strongly keeled; upper glumes 5 or more veined.

2. Lemmas unawned or with awns up to 3 mm long; upper glumes 9(11)-veined; lemma veins usually raised . . . . . . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. catharticus

2. Lemmas awned, the awns 4–15 mm long; upper glumes 5- to 9-veined, lemma veins not raised . . . . . . . . B. carinatus

1. Spikelets not strongly laterally compressed; lemmas rounded on the mid-rib; upper glumes 1- to 3-veined.

3. Lemma apex conspicuously bidentate, the teeth hyaline, awnlike to acuminate; largest lemmas generally less than 2 mm 

wide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. tectorum

3. Lemma apex entire or inconspicuously bidentate, the teeth usualy not hyaline; largest lemma generally greater than 2 mm 

wide.

4. Plants annual; lower glumes 3(5)-veined; upper glumes 5- to 9-veined . . . . . . . . . . . . . . . . . . . . . . . . . B. japonicus

4. Plants perennial; lower glumes 1(3)-veined; upper glumes 3(5)-veined.

5. Most lower glumes 1-veined.

6. Sheath auricles usually present; ligules 0.2–1.6 mm long; leaf blades 2–4 mm wide; lemmas 7–10 mm long; 

awns 1–3 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. anomalus

6. Sheath auricles absent; ligules 1.5–4 mm long; leaf blades (3)4–10(13) mm wide; lemmas (9)10–13.5(15) mm 

long; awns 3.1–6.5 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. richardsonii

5. Most lower glumes 3-veined.

7. Sheath auricles absent; spikelets 2–3 cm long; lemma pubescent over the back or sometimes on the margins only, 

3- to 5-veined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. frondosus

7. Sheath auricles present at least on the lower leaves; spikelets 1.5–3 cm long; lemma pubescent all over the back 

and margins, 7-veined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. anomalus

69. Bromus anomalus Rupr. ex E. Fourn., Mexic. Pl. 2: 126. 

1886.

FIGURE 56

Perennial; not rhizomatous. Culms up to 110 cm tall, 

2–4 mm thick, erect or ascending, bases often weakly to strongly 

decumbent, glabrous, scabrous or pubescent. Sheaths glabrous, 

pubescent, or pilose, hairs to 1.5 mm long, midrib distinctly narrowing below the collar; auricles usually present on the lower 

leaves, sometimes absent; ligules to 0.2–1.6 mm long, glabrous, 

erose-lacerate, ciliate; blades up to 35 cm long, 2–4 mm wide, 

flat, glabrous or weakly to moderate pubescent or pilose in both 

sides, hairs up to 1 mm. Panicles 10–18 cm long, open, nodding; branches ascending or spreading, scabrous, 1–5 spikelets 

per branch. Spikelets 1.5–2.8 cm long, 4- to 12-flowered, elliptic 

to lanceolate, terete to moderately laterally compressed; glumes 

usually pubescent, hairs up to 0.4 mm long, occasionally glabrous 

to puberulent, margins hyaline, green, purplish-green to purple 

along and between the veins; lower glumes 5–7.5(8.5) mm long, 

triangular or narrowly lanceolate, 1- or 3-veined; upper glumes 

6–10.5 mm long, obovate-lanceolate, 3-veined, apex obtuse, 

acute or mucronate, mucros up to 0.6 mm; lemmas 7–10 mm 

long, elliptic to lanceolate, rounded over the back, 5- to 7-veined, 

backs and margins pubescent, apex acute, obtuse or truncate, 

entire; awns 1.2–3 mm long, straight, arising less than 0.5 mm 

below the lemma apex, straight; paleas shorter and narrower 

than the lemmas, backs glabrous or pubescent, keels ciliate, cilia 

to 0.2 mm; anthers 1.5–3.2 mm long. Caryopsis 5–9 mm long, 

light brown. 2n = 14.

This species is used by the Tarahumara (who refer to themselves as the Raramuri) people in the Sierra Madre Occidental 

(at Guachochi) to inoculate tesquino (sacred corn beer) and start 

the fermentation process by first chewing Bromus anomalus and 

then expectorating into a vat of corn mash. Author PMP was accompanied by G. A. Palma Aguirre and J. A. Bustillos Ramirez 

(two Raramuri) to a site at the edge of the Barranca Rio Verde 

(Peterson et al. 15372) to obtain a sample of this species.

Distribution and Habitat. Bromus anomalus is a common native species that occurs in the mountains in 

pine–oak forests, on slopes, at forest margins, along creeks, and 

in ravines at 1,800–2,500 m. It extends from western Texas to 

Mexico, Guatemala, and Costa Rica. 
NUMBER 107 • 8 1

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: Sierra La Campana, 10 km Pte. carr. [hwy] Panamericana, 19 Sep 73, pastizal con encino [pasture with oak], 

1700 m, Valdés-Reyna VR-336 (RELC). Guachochi: 20.3 mi S 

of Creel on road towards Rocheachic, 5 Oct 2000, pine forest, 2510 m, P.M. Peterson & J. Cayouette 15367 (US); 9 mi S 

of Guachochi at edge of Barranca Rio Verde, 1 km along trail 

descending into canyon, 6 Oct 2000, pine forest, 2470 m, P.M. 

Peterson & J. Cayouette 15372 (US); Cascada cusarare al W 

de Cusarare, 16 Sep 1983, bosque de pino–encino [pine–oak 

forest] Cupresus, 2190 m, Tenorio & R. Torres 4396 (MEXU). 

Guadalupey Calvo: about 3 mi S of La Rocha, Sierra Mohinora, on bluffs along stream (tributary of Río del Soldado), 18 

Oct 1959, 7000 ft, Correll & Gentry 23233 (ENCB). Guerrero: 

on road between Tomochic and Bassaseachic, 20 mi E of jct 

w/ road S to San Juanito, 1.8 mi W of Aqua Caliente, 5 Oct 

1986, 2000 m, Spellenberg, Soreng, R. Corral & T. Lebgue 

8875 (NMC); entre [between] La Junta & Temochi, 13 Aug 

1976, bosque de pino, 2380 m, S. González & J.M. Peña 612

(RELC). Ignacio Madera: Ciénega Ojo de la Vibora, ejido El 

Largo, 14 Aug 1990, bosque de pino, 2300 m, A. Benítez 1905

(CIIDIR); Laguna de Babícora, 4 km al N del Ejido La Raíz, 10 

Sep 1994, 2300 m, G. Quintana & E. Estrada 3680 (NMC); 

1.8 km al N de Parapetes, 27 Oct 77, bosque de pino–encino, 

2200 m, J.M. Peña JMP-788 (RELC); 10 km al SE de Madera, 

5 Oct 74, bosque de pino–encino, 2000 m, Valdés-Reyna VR668 (RELC); Cienega ojo de la víbora, ejido el Largo, 14 Oct 

1990, bosque de pino–encino con presencia de [with presence 

of] Pinus durangensis & Quercus sideroxyla, 2300 m, O. Bravo 

1905 (MEXU); Proximidad a la col. Chuichupa, 01 Sep 1990, 

pastizal & bosquete [grove] de Juniperus deppeana, 2240 m, 

A. Benitez 2180 (MEXU). Ocampo: Along drainage of Rio 

Candasneno at Cascada de Basaseachic, ca. 1 mi S of village of 

Basaseachic, 14 Oct 1984, 2000 m, Spellenberg & M. Spellenberg 7930 (NMC); Parque Nacional “Cascada de Basaseachic,” 

in the barranca [canyon] to W of falls, 4 Oct 1986, 1600 m, 

Spellenberg, Soreng, R. Corral & T. Lebgue 8825 (NMC); Area 

of cascada de Basaseachic at the confluence of rio Basaseachic 

and rio Durazno, 2 mi S of villaje of Basaseachic, 17–20 Oct 

1986, Pinus–Cupressus forest, 2000–2100 m, G. Nesom & 

L. Vorobik 5705 (MEXU); Cascada de Basaseachic, 10 Oct 

1981, bosque caducifolio [deciduous forest], 2500 m, Fierros 

& Alvarez 1679 (MEXU).Temosachi: Nabogame, 6 Nov 1988, 

1800 m, Laferr. 2273 (NMC); 1043 (MEXU).

FIGURE 56. Bromus anomalus. A. Habit. B. Auricle along margin at junction between 

sheath and blade. C. Leaf midrib distinctly narrowing below the collar, dorsal view. D. Spikelet. E. Glumes. F. Lemma. Drawn by Cindy Roché; copyright Utah State University.
8 2 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

70. Bromus carinatus Hook. & Arn., Bot. Beechey Voy. 403. 

1840.

Plants short-lived perennial; not rhizomatous. Culms 50–

150 cm tall, usually less than 3 mm thick, erect, glabrous to 

pubescent below inflorescences. Sheaths mostly glabrous or pubescent to soft pilose, hairs up to 2 mm long, throats glabrous or 

pubescent; auricles absent; ligules (1)2–3(4) mm long, glabrous 

or pubescent, lacerate or erose; blades 10–30 cm long, 3–6(11) 

mm wide, flat, glabrous or pubescent on 1 or both surfaces, midveins narrowing beneath the collar. Panicles 5–30 cm long, open, 

branches erect, ascending or spreading, 4–22 cm long, pedicels 

longer or shorter than spikelets, glabrous, scabrous or pubescent, 1–4(9) spikelets per branch. Spikelets 2–4 cm long, 4- to 

11-flowered, elliptic to lanceolate, strongly laterally compressed; 

glumes glabrous or pubescent, green to purple along and between the veins, margins hyaline; lower glumes 6.5–12 mm long, 

lanceolate, 3- to 7-veined, apex acute; upper glumes 9–15 mm 

long, shorter than the lowest lemma, obovate-lanceolate, 5- to 

9-veined, apex acute to acuminate; lemma 11–20 mm long, lanceolate, laterally compressed, strongly keeled distally, apex acute 

to obtuse, 7- to 9-veined, veins usually not raised or riblike, glabrous, scabrous, or pubescent, hairs sometimes restricted to margins, hairs up to 0.5 mm; awns 2–15 mm long, inserted 0–0.5 mm 

below the lemma apex, straight; paleas shorter than the lemmas, 

backs glabrous or pubescent, keels ciliate, cilia to 0.2 mm long; 

anthers 0.5–4.5 mm long. Caryopsis 9–11 mm long. 2n = 56. 

Distribution and Habitat. Bromus carinatus

is native from British Columbia to Saskatchewan and south to 

Mexico and Central America. Widespread in the pine forests of 

Mexico, in meadows, pastures, canyons, and on slopes at 1,500–

3,200 m.

The great variation of this species in Mexico and Central 

America is discussed in Saarela et al. (2014), who recognized two 

varieties as follows (Barkworth et al., 2006). 

KEY TO VARIETIES OF BROMUS CARINATUS

1. Most awns greater than 7 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. carinatus var. carinatus

1. Most awns less than 7 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. carinatus var. marginatus

Bromus carinatus var. carinatus.

Awns 7.1–10 mm long.

Distribution. This variety is not as widespread as 

var. marginatus. It is known from Costa Rica, Honduras, and 

Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: ejido San Ignacio Arareco, 19 Oct 1973, pine–oak 

forest, 7300 ft, Bye 5478 (MEXU). Guachochi: Cusarare S of 

Creel, 1 Sep 1973, Bye 4856 (MEXU); Cusarare near old church, 

4 Aug 1974, 6900 ft, Bye 6771 (MEXU). Madera: 1.5 km de 

Col. Chuhuichupa, 13 Oct 1990, bosque [forest] de Juniperus deppeana & Pinus engelmannii, 2240 m, O. Bravo 1894

(MEXU); Ejido Madera, 8 Sep 1977, suelo prof. arcilloso [clayey 

soil], 2400 m, Blanco 06/77 (MEXU). Riva Palacio: Majalca, 25 

Jun 1936, LeSueur 0154 (US); Majalca (Pilares), 12 Aug 1939, 

2080 m, L. H. Harvey 1485 (ENCB, US).

Bromus carinatus var. marginatus (Nees ex Steud.) Barkworth 

& Anderton, Madroño 53(3): 240. 2006.

Awns 2–7 mm long.

Distribution. Costa Rica, El Salvador, Guatemala, 

Honduras, and Mexico. 

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: SW Chihuahua, Aug 1885, E. Palmer s.n. (US); 

Yamuco at 1 km E of Hwy towards Basihuare and Creel, N 

of Rio Urique crossing, 26 Aug 2003, bosque de pino–encino 

[pine–oak forest], 1891 m, P.M. Peterson & P. Catalán 17543

(CIIDIR, US). Bocoyna: 24.7 mi N of San Juanito on road towards Cuauhtemoc, 5 Sep 2008, 2233 m, P.M. Peterson & J.M. 

Saarela 22033 (US); 7 mi NE of San Rafael on road towards 

Creel, at Divisidero lookout, 5 Sep 2008, 2240 m, P.M. Peterson 

& J.M. Saarela 22042 (US); Sánchez, 12 Oct 1910, Hitchcock 

7704, 7718, 7719 (US); 1.1 km N of San Juanito near large lumber mill, 24 Sep 1988, 2200 m, P.M. Peterson & Annable 5869

(ENCB, US); Moist llano [flat] SW of Creel near San Ignacio, 17 

Oct 1977, Bye & W.A. Weber 8279 (MEXU); Carichic: Rancho 

Nuevo a 50 km de San Juanito, 3 Aug 1979, bosque de encino, 

2100 m, M. Siqueiros 184 (MEXU). Casas Grandes: W of Casas 

Grandes, 5 mi S of Hernández, 18 Sep 1960, 7000 ft, Reeder, 

C. Reeder & Soderstrom 3519 (ARIZ, ENCB, US). Gómez 

Farías: Laguna de Babicora, alreded [around] San Jose Babicora, 18 Aug 1994, 2200 m, G. Quintana & E. Estrada 3089 

(NMC). Guachochi: in corn field south of Creel, 11 Aug 1971, 

8100 ft, Bye 1816 (MEXU); 12.1 mi W of San Juanito on road 

towards Baquiriachic, 5 Oct 2000, bosque de pino, 2530 m, P.M. 

Peterson & J. Cayouette 15357 (US); 2.3 mi W of San Juanito 

on road towards Baquiriachic, 5 Oct 2000, P.M. Peterson & 

J. Cayouette 15359 (US); Cusarare, south of Creel–La Bufa, 11 

Aug 1972, pastizal [pastureland], 7000 ft, Bye 2736 (MEXU). 

Guadalupe y Calvo: E slopes of Sierra Mohinora, 17 Oct 1959, 

Correll & Gentry 23203 (US); near Cumbre Mohinora, 13 Sep 

2006, 3300 m, P.M. Peterson 20036, F. Sánchez Alvarado & 

E.P. Gómez Ruíz (CIIDIR, US); W slopes of Sierra Mohinora, 

3008 m, 13 Sep 2006, P.M. Peterson, F. Sánchez Alvarado & 

E.P. Gómez Ruíz 20054 (CAN, US). Madera: Rio Aros, 23 

Aug 1937, LeSueur 0212 (US); Rancho La Ciénega, ejido El 

Largo, 31 Aug 1990, bosque de pino, 2500 m, O. Bravo 1399

(CIIDIR, MEXU); Proximidad a la Col. Chuichupa, 1 Sep 1990, 

pastizal & bosquete [grove] de Juniperus, 2240 m, A. Benítez 

2180 (CIIDIR); Camino Nicolas Bravo–Las Varas, 18 Aug 1994, 

2150 m, G. Quintana & E. Estrada 2998 (NMC); Laguna de 

Babicora, alrededores de [around] Nicolás Bravo, 18 Aug 1994, 
NUMBER 107 • 8 3

2200 m, Quintana, Lebgue & Estrada 3119 (NMC). Ocampo: 

Parque Nacional “Cascada de Basaseachic,” at overlook ca. 1 km 

airline S of Cascada, 3 Oct 1986, 2100 m, Spellenberg, Soreng, 

R. Corral & T. Lebgue 8702 (NMC). Práxedis G. Guerrero (San 

Ignacio): a 2 km al S del poblado del mismo nombre [village of 

the same name], Rancho Escuela de la Univ. Autónoma de Cd. 

Juárez, 18 Mar 1995, 1090 m, R. Corral, P. Olivas & E. Pérez 

RCD6030 (UACJ). Temosachi: Yepáchic, 3 Sep 1971, grows in 

profusion in abandoned fields near Yepáchic, 2100 m, C.W. Pennington 4 (MEXU).

71. Bromus catharticus* Vahl, Symb. Bot. 2: 22. 1791.

FIGURE 57

Annual, biennial, or short-lived perennial; not rhizomatous. 

Culms 20–120 cm tall, 2–4 mm thick, erect or decumbent, glabrous below inflorescences. Sheaths pubescent or pilose, hairs 

up to 1.2 mm; auricles absent; ligules 2–5(6) mm long, glabrous or pubescent, lacerate; blades 4–30 cm long, 2–10 mm 

wide, flat, sometimes conduplicate, glabrous to pubescent on 

1 or both surfaces. Panicles 8–30 cm long, usually open, nodding, branches erect to ascending, scabrous, up to 5 spikelets per 

branch. Spikelets 1.5–3(3.5) cm long, elliptic to lanceolate, 4- to 

11-flowered, strongly laterally compressed; glumes glabrous, scabrous, or pubescent, green to purplish-green along and between 

the veins, margins hyaline, midveins glabrous to scabrous distally, 

apex acute to obtuse; lower glumes 6–12 mm long, lanceolate, 

3- to 7-veined; upper glumes 8–14 mm long, ovate-lanceolate, 

9(11)-veined, shorter than the lowest lemma; lemmas 10–20 mm 

long, obovate-lanceolate, strongly keeled, apex acute to obtuse, 

7- to 11-veined, veins usually raised and riblike, green, greenishyellow or purplish-green along and between the veins, glabrous 

or scabrous, margins hyaline; awns 0.5–3.5(4) mm long, inserted 

up to 0.5 mm below lemma apex, straight; paleas shorter than 

the lemmas, backs glabrous, strongly keeled; anthers 0.5–1.3 mm 

long; caryopsis 8–10 mm long, light brown. 2n = 42.

Distribution and Habitat. Bromus catharticus

is native to South America. It has been widely introduced in the 

southern United States and Mexico. It usually grows on disturbed 

habitats at 2,200–2,600 m.

Specimens Examined. MEXICO. Chihuahua. 

Casas Grandes: camino [road] al Willis rancho Mesa de la Avena, 

29 May 1981, bosque esclero-aciculifolio [narrow-leaved sclerophyllous forest], 2570 m, R. Fierros 1270 (MEXU).

72. Bromus frondosus (Shear) Wooton & Standl., New Mexico 

Agric. Exp. Sta. Bull. 81: 144. 1912.

FIGURE 58

Perennial; not rhizomatous. Culms 54–84 cm tall, 2–4 mm 

thick, erect to spreading; nodes 3–5, glabrous below the inflorescences, rarely pubescent. Sheaths sparsely to densely pilose, hairs 

up to 1.2 mm; auricles absent; ligules 0.5–2 mm long, glabrous; 

blades 10–29 cm long, 4–6 mm wide, flat, often glaucous, usually 

FIGURE 57. Bromus catharticus. A. Habit. B. Culm and inflorescence. C. spikelet. D. Lemma. Drawn by Cindy Roché; copyright 

Utah State University.
8 4 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

glabrous, sometimes pubescent, hairs up to 1 mm. Panicles 

9–13 cm long, 3–6 cm wide, open, nodding, branches ascending to spreading, 0.5–5 cm long, shorter or longer than spikelets, scabrous, 1–4 spikelets per branch. Spikelets 1.6–3 cm long, 

7- to 9 flowered, elliptic to lanceolate, terete to moderately laterally compressed; glumes green along and between the veins, 

glabrous, scabrous or minutely pubescent, hairs when present sometimes restricted to the hyaline margins; lower glumes 

6–8.5 mm long, 0.6–1 mm wide, lanceolate, 3-veined, apex acute; 

upper glumes 8–10 mm long, 0.9–1.3 mm wide, oblong-ovate, 

3-veined, apex acute or mucronate, mucros up to 1 mm; lemmas 

9–12 mm long, 1.5–2.5 mm wide, elliptic to lanceolate, rounded 

over the backs, apex truncate, 5- to 7-veined, green along and 

between the veins, backs glabrous or sparsely to densely pubescent, margins pubescent on the lower 1⁄3 to 1⁄2, hairs up to 1 mm 

long; awns 3.5–6 mm long, straight, arising 0–0.5 mm below 

lemma apex, straight; paleas shorter than the lemmas, 9–10 mm 

long, backs glabrous or pubescent: anthers 1.5–3.5 mm long. 

Caryopsis 6–8 mm long. 2n = 14.

Distribution and Habitat. Bromus frondosus

is native and grows in open woods and on rocky slopes associated with pine forests at 1,300–2,750 m. Its range extends from 

Colorado, Arizona, and New Mexico into northern Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: Rancho el Peñasco km 150 carr [hwy] Chihuahua–

Cd. Juárez, 9 Aug 1979, pastizal mediano arbosufrutescente, 

1720 m, M. Siqueiros 336 (MEXU); 23 mi ENE of Villa Ahumada in NW canyon of Sierra la Alcaparra NE of Rancho El 

Palmar, 12 Sep 1973, bosque de encino [oak forest], 1500 m, J. 

Henrickson 12864 (MEXU); SW slope of Sierra de la Ranchería 

(on Rancho Candelaria) from the top down to a marble quarry 

at base, 29 Oct 1972, matorral inerme [unarmed small-leaved 

scrub], 1500–2180 m, T.L. Wendt, F. Chiang & M.C. Johnston 9949 (MEXU). Balleza: Creel, km 90 a Chihuahua, La 

Mesa de Yeguachi, 27°47.155′N, 107°38.611′W [27.78583°N, 

107.643611°W], 2248 m, 13 Sep 2003, R. Bye, M. Mendoza, 

G. Morales, J. Rodríguez & M. Hilerio 32541 (US); 34 mi W 

of Balleza towards Guachochi, 2500, P.M. Peterson, M.B. 

Knowles, C.H. Dietrich, S.M. Braxton 13539 (US); 19.6 km W 

of Balleza and 74.2 km E of Guachochi, 18 Sep 1991, 2120 m, 

P.M. Peterson, Annable & Valdés-Reyna 10753 (CIIDIR, US). 

Bocoyna: Bocoyna, La Junta, 13 Sep 2003, R. Bye, M. Mendoza, 

G. Morales, J. Rodríguez & M. Hilerio 32463 (US); 20 km S of 

San Juanito on road to Creel and 3 km S of Bocoyna, 2350 m, 

P.M. Peterson, Annable & Y. Herrera 8002 (US); 24.7 mi N of 

San Juanito on road towards Cuauhtemoc, 5 Sep 2008, 2233 m, 

P.M. Peterson & J.M. Saarela 22028 (US); Sánchez, 12 Oct 1910, 

Hitchcock 7665 (US). Camargo: Sierra de los Organos, 8 Sep 

1937, LeSueur 0211 (US). Guachochi: Guachochi, Norogachi, 

planicie [plain], 16 Sep 2003, R. Bye, M. Mendoza, G. Morales, 

J. Rodríguez & M. Hilerio 32771 (US); 12.1 mi W of San Juanito on road towards Baquiriachic, 5 Oct 2000, bosque de pino 

[pine forest], 2530 m, P.M. Peterson & J. Cayouette 15358 (US); 

20.3 mi S of Creel on road towards Rocheachic, 6 Oct 2000, 

FIGURE 58. Bromus frondosus. A. Culm and inflorescence. B. Leaf 

blade. C. Spikelet. D. Glumes. E. Lemma. Drawn by Cindy Roché; 

copyright Utah State University.
NUMBER 107

• 8 5

bosque de pino, 2510 m, P.M. Peterson & J. Cayouette 15368

(US). Guerrero: 8 mi N of Santo Tomas, 28.81°N, 107.5667°W, 

8 Oct 1953, 2010 m, Reeder & C. Reeder 2625 (US). Madera: 

near Col. Garcia in the Sierra Madre, 14 Sep 1899, 2300 m, 

C.H.T. Townsend & C.M. Barber 327 (NMC, US). Ocampo: 

16.7 mi W of Baquiriachic on hwy 16 towards Maycoba, 4 Oct 

2000, bosque de pino, 2000 m, P.M. Peterson & J. Cayouette 

15353 (US). Riva Palacio: Majalca, 18–20 Aug 1935, LeSueur 

Mex-030 (US); Majalca, NW Chihuahua, 29 Sep 1934, 2200 m, 

Pennell 19299 (US); Col. Cumbres de Majalca, 33.8 km W of 

Mex 45, N of Chihuahua City, 7 Sep 1989, pine forest, 2190 m, 

P.M. Peterson, Annable & Y. Herrera 7969 (ENCB, US). Zara-

goza: 20.3 km NE of Ignacio Zaragoza on Mex 23, 28 Sep 1989, 

pine woods, 2400 m, P.M. Peterson & R.M. King 8154 (ENCB).

73. Bromus japonicus* Thunb. , Syst. Veg. (ed. 14) 119. 1784.

FIGURE 59

Annual. Culms (22)30–70 cm tall, erect or ascending. 

Sheaths usually densely pilose; upper sheaths sometimes pubes-

cent or glabrous; ligules 1–2.2 mm long, pilose, obtuse, lacer-

ate; blades 10–20 cm long, 2–4 mm wide, usually pilose on both 

surfaces. Panicles 10–22 cm long, 4–13 cm wide, open, nodding; 

branches usually longer than the spikelets, spreading to ascend-

ing, slender, flexuous, somewhat drooping, sometimes sinuous, 

often with more than 1 spikelet. Spikelets 20–40 mm long, lanceo-

late, terete to moderately laterally compressed; florets 6–12, bases 

concealed at maturity; rachilla internodes concealed at maturity; 

glumes smooth or scabrous; lower glumes 4.5–7 mm long, 3- to 

5(7)-veined; upper glumes 5–8 mm long, 7- to 9-veined; lemmas 

7–9 mm long, 1.2–2.2 mm wide, lanceolate, coriaceous, smooth 

proximally, scabrous on the distal 1⁄2, obscurely (7)9-veined, 

rounded over the midvein, margins hyaline, 0.3–0.6 mm wide, 

obtusely angled above the middle, not inrolled at maturity, apex 

acute, bifid, teeth shorter than 1 mm; awns 8–13 mm long, 

strongly divergent at maturity, sometimes straight, twisted, flat-

tened at the base, arising 1.5 mm or more below the lemma apex; 

anthers 1–1.5 mm long. Caryopsis equaling or shorter than the 

paleas, thin, weakly inrolled or flat. 2n = 14.

Distribution and Habitat. Bromus japonicus

grows in fields, waste places, and roadways. It is native to central 

and southeastern Europe and Asia and is distributed throughout 

much of the United States and southern Canada with one record 

from the Yukon Territory.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: Rancho Experimental La Campana, Chihuahua, 

14 May 1977, 1540 m, S. González 838 (ENCB); Rancho 

FIGURE 59. Bromus japonicus. A. Habitat. B. Ligule. C. Culm and 

inflorescence. D. Spikelet. E. Glumes. F. Lemma. Drawn by Cindy 

Roché; copyright Utah State University.
8 6 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Experimental La Campana–Chihuahua, 28.63°N, 106.08°W, 

1540 m, 5 Aug 1977, S. González s.n. (ANSM); Rancho Experimental La Campana, 82 kms al norte de la Cd. de Chihuahua, 

1500 m, 26 August 1978, s.c. (MEXU).

74. Bromus richardsonii Link, Hort. Berol. 2: 281. 1833. Bromus mucroglumis Wagnon.

FIGURE 60

Perennial; not rhizomatous. Culms 50–110(145) cm tall, 

erect to spreading; nodes (3)4–5(6), usually glabrous, sometimes 

pubescent; internodes usually glabrous. Basal sheaths often retrorsely pilose; culm sheaths glabrous, often tufted-pilose near 

the auricle position, midrib of the culm leaves not abruptly narrowed just below the collar; auricles absent; ligules 0.4–2 mm 

long, glabrous, rounded, erose, ciliolate; blades 10–35 cm long, 

3–12 mm wide, flat, glabrous. Panicles 10–20(25) cm long, open, 

nodding; branches ascending to spreading or drooping, filiform. 

Spikelets 15–25(40) mm long, elliptic to lanceolate, terete to 

moderately laterally compressed, with (4)6–10(15) florets; 

glumes usually glabrous, sometimes pubescent; lower glumes 

7.5–12.5 mm long, 1(3)-veined; upper glumes 8.9–11.3 mm 

long, 3-veined, often mucronate; lemmas 9–14(16) mm long, elliptic, rounded over the midvein, margins more or less densely 

pilose on the lower 1⁄2 or 3⁄4, lower lemmas in a spikelet glabrous 

across the back, uppermost lemmas with appressed hairs on the 

back, apex obtuse, entire; awns (2)3–5 mm long, straight, arising 

less than 1.5 mm below the lemma apex; anthers 1.6–2.7 mm 

long. 2n = 28.

Distribution and Habitat. Bromus richardsonii grows in meadows and open woods in the upper montane and 

subalpine zones at about 2,000–4,000 m in the southern Rocky 

Mountains and at lower elevations northward. Its range extends 

from southern Alaska to southern California and northern Baja 

California, Mexico. Bromus ciliatus L., sometimes assigned as 

occurring in Mexico (Soderstrom and Beaman 1968), is distributed across southern Canada and the United States, except the 

south-central and southeastern United States (Pavlick and Anderton 2007); it is not known from Mexico (Saarela et al., 2014).

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 15 mi E of El Vergel on road to Parral, 21 Oct 1959, 

Correll & Gentry 23255 (US); 15.2 mi E of Ocote on hwy 24 

towards El Vergel, 26.1392°N, 106.66°W, 2580 m, 14 Sep 

2006, P.M. Peterson, F. Sánchez-Alvarado, & E.P. Gómez-Ruiz 

20064 (US). Batopilas: Urique, a 8.8 kms al N de Cuiteco, por 

la barranca rumbo [through the canyon heading] a San Rafael, 

27°26′10.9′′N, 108°00′04.1′′W [27.43639°N, 108.00111°W], 

1740 m, 22 Sep 2002, P. Tenorio, G. Morales & J. Rodríguez 

22111 (US). Bocoyna: Bocoyna, Colecta 3, Rancho, 10 Sep 

2003, Bye, M. Mendoza, G. Morales, J. Rodríguez & M. Hilerio 

3206 (US); entronque carr. [junction hwy] Creel, entrada [entry] 

a Bocoyna, Ldera S Rancho Cima, Rancho Lucía, 27°41.428ʹN, 

107°24.699ʹW [27.69056°N, 107.41167°W], 7538 ft, 20 Sep 

2003, Bye, M. Mendoza, G. Morales, J. Rodríguez & M. Hilerio 

3206 (US); Sánchez, 12 Oct 1910, Hitchcock 7708, 7713 (US); 

34.4 mi NW of San Juanito on road towards Baquiriachic, 4 Oct 

2000, bosque de pino [pine forest], 2800 m, P.M. Peterson & 

J. Cayouette 15356 (US). Casas Grandes: Strawberry Creek, NE 

of Col. Pacheco, 22–24 Sep 1934, Pennell 19171 (US); W of 

Casas Grandes, 3 mi E of Cuesta Blanca, 4 Sep 1958, Reeder 

& C. Reeder (US). Chihuahua: 38 km W of Hwy 45 on road 

towards Benito Juárez, 2230 m, P.M. Peterson & Annable 12576 

(US). Gomez Farías: hills S of Laguna de Bavicora, 18 airline 

km SSW of Gomez Farias, 28 Aug 1975, oak woodland, 2250 

m, N.H. Holmgren & T.K. Lowrey 8028 (MEXU). Guachochi: 

poblado [village] de Magurichi, 2a colecta comida [collect food], 

24 Oct 2003, R. Bye, M. Mendoza, G. Morales, J. Rodríguez 

& M. Hilerio 33069 (US); 5.5 mi E of Cieneguita de Barranca 

on road towards Creel, 5 Sep 2003, bosque de pino, 2160 m, 

P.M. Peterson & P. Catalán 17698 (US); 5.8 mi N of Creel on 

road (Hwy 25) towards San Juanito, 2480 m, P.M. Peterson & 

J. Cayouette 15363 (US); Approx. 22.5 mi NE of Cieneguita de 

Barranca on road to Creel, 5 Sep 2003, bosque de pino, 2160 m, 

P.M. Peterson & P. Catalán 17697 (US); 48.6 mi S of Creel on 

road towards Rocheachic, 5 Oct 2000, bosque de pino, 2630 m, 

P.M. Peterson & J. Cayouette 15371 (US); Arroyo Guachimuchi, 

ca. 15 km of Norogachi, 18 Oct 2006, pino–encino [oak], 2146 

m, Bye et al. 34824 (MEXU); 5 km antes del entronque [before 

the junction] a la Bufa carr. Guachochic–Creel, 24 Sep 1981, 

2500 m, M.E. Siqueiros 1614 (MEXU). Guadalupe y Calvo: N 

side of cerro Mohinora ca 13 mi SW of Guadalupe y Calvo, 20 

Aug 1988, open pine–fir Woods with scattered spruce, 2950 m, 

G. Neson & A. McDonald 6474 (MEXU); near Cumbre Mohinora, Sierra Mohinora, 25.95°N, 107.05°W, 3250–3300 m, 13 

Sep 2006, P.M. Peterson 20047, F. Sánchez-Alvarado, & E.P. 

Gómez-Ruiz (US). Guazapares: eastern drainage of Barranca de 

Chinipas, NW of San Rafael, 11 Nov 1973, 850 m, Bye 5860 

(MEXU). Madera: Arroyo de la Quinta, ejido “El Largo”, 30 

Aug 1990, bosque de pino, 2340 m, A. Benítez 2087 (CIIDIRMEXU); 2100 m, 13 Oct1990, A. Benítez 2837 (MEXU). 

Namiquipa: Aprox. 39 km, carr. Chihuahua–Namiquipa, 24 sep 

1997, bosque de encino, 2300 m, M.A. Vergara 176 (MEXU). 

Ocampo: 16.7 mi W of Baquiriachic on hwy 16 towards Maycoba, 4 Oct 2000, bosque de pino, 2000 m, P.M. Peterson & 

J. Cayouette 15354, 15355 (US); near Mirador de Cascada Basaseachic, 28.1647°N, 108.2°W, 2022 m, 7 Sep 2008, P.M. Peterson & J.M. Saarela 22084 (US).

75. Bromus tectorum* L., Sp. Pl. 1: 77. 1753.

FIGURE 61

Plants annual. Culms 5–80 cm tall, solitary or loosely 

tufted, erect or ascending, nodes, as well as below infloresences, 

glabrous or minutely pubescent. Sheaths glabrous or variously 

pubescent, hairs stiff and up to 0.5 mm or soft and wavy up to 1 

mm long; ligules (1)2–3 mm long, erose-lacerate; blades 1.3–1.4 

cm long, 1–5 mm wide, flat, sparsely to densely pubescent adaxially, puberulent abaxially. Panicles 4–22 cm long, 1-13.5 cm 
NUMBER 107 • 8 7

FIGURE 60. Bromus richardsonii. A. Habit. B. Spikelet. C. Glumes. D. Lower lemma. 

E. Upper lemma. Drawn by Cindy Roché; copyright Utah State University.

FIGURE 61. Bromus tectorum. A. Ligule. B. Culm and inflorescence. C. Spikelet. 

D. Lemma. Drawn by Cindy Roché; copyright 

Utah State University.
8 8 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

wide, condensed and erect when young, becoming lax and nodding, sometimes reduced to a few spikelets, branches spreading to drooping, 0.4-4 cm long, usually longer than spikelets, 

1-sided, often sinuous, scabrous to densely pubescent, 1–14 

spikelets per branch. Spikelets 1.5–2(2.5) cm long (2.5–3.5 cm 

including awns), 3- to 6(8)-flowered, linear-elliptic to cuneate, 

moderately laterally compressed, rachilla sometimes visible at 

maturity; glumes green to purplish-green, glabrous or minutely 

pubescent in a line inside the hyaline margins, the apex bifid, 

the cleft 0.1–0.5 mm deep; lower glumes 4–9 mm long, linearlanceolate, 1(3)-veined, occasionally minutely awned, awn to 

1.1 mm long, upper glumes 7–13.5 mm long, elliptic-lanceolate, 

3(5)-veined, lanceolate, awned; lemma 9–13.5 mm long, lanceolate, rounded over the backs, 7-veined, apex bifid, the teeth 

1–3 mm long, awn 8–18 mm long, arising 1–2.5 mm below the 

lemma apex, straight; palea 7–8.7 mm long, back glabrous and 

keels ciliate; anthers 0.5–0.9 mm long. Caryopsis 7–8 mm long. 

2n = 14. 

Distribution and Habitat. Bromus tectorum 

was introduced to Mexico; it grows in arroyos and meadows in 

conifer forests. It is common in northern Baja California, and 

a few other collections are from cultivated gardens in Chihuahua, Coahuila, and Sonora; apparently it has not spread from 

there.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: Maleza en jardín de observación [weed in oberservation garden] en el Rancho Experimental La Campana, 12 Apr 

1975, Valdés-Reyna VR877 (RELC).

Calamagrostis Adans.

Plants rough, perennial; caespitose or rhizomatoses. Culms 

simple, slender; ligule a membrane; blades linear, firm, flat or 

involute. Inflorescence a terminal panicle, spread or contracted. 

Spikelets lateraly compressed, 1 floret or rarely 2 florets, disarticulating above the glumes; glumes longer than the florets, equal 

or subequal, acute or acuminate, 1- to 3-veined; lemma generally 

5-veined, membranous, the apex truncate to 2-toothed or shortly 

4-awned, awn emerging from the back, the awn straight or geniculate, often twisted, insert near the base; callus obtuse, rarely 

recurved or elongated, generally pilose, the pubescence can be 

very short to long and copious; palea slender, shorter than the 

lemma; rachilla prolongate behind the palea as a naked bristle 

or pilose; stamens 1–3. Caryopsis with solid endosperms, often 

liquid or soft. x = 7.

Calamagrostis has aproximatelly 150 species of temperate 

and cold regions of the world.

76. Calamagrostis pringlei Scribn. ex Beal, Grass. N. Amer. 2: 

345. 1896.

Perennial; rhizomatous. Culms 50–70(80) cm tall, solitary 

or mat-forming, erect, glabrous, rhizomes crawling. Sheaths glabrous to sparsely pilous or scabrous when young; ligules 1–4 mm 

long, membranous, irregularly toothed; blades 10–15 cm long, 

1–4 mm wide, flat, involute when dry, pilose in both surfaces. 

Panicles 6–18 cm long, narrow, sometimes nodding; branches 

ascending, naked near base or with spiklets at the base, green 

with pinkish spots, axis glabrous or scaberulous, capillary; 

glumes 4.5–5 mm long, narrow subequal, acuminate, 1-veined, 

scabrous; lemma 4.5–5 mm long, soft and scaberulous, almost 

acuminate, awn 4–6 mm long, slender, geniculate, frequently 

twisted on the base, scabrous distally, exserted; callus with hairs 

0.8–1 mm long; rachilla 1.5–2 mm long, pubescent, the hairs 

1–2 mm long. 

Distribution and Habitat. Calamagrostis 

pringlei grows in oak forests and rocky cliffs with Pinus, Pseudotsuga menziesii (Mirb.) Franco, Cupressus, Arctostaphylos 

pungens Kunth, and Brickellia; it occurs in Aguascalientes, Chihuahua, Coahuila, Durango, Hidalgo, Michoacán, Nuevo León, 

and Zacatecas.

Specimens Examined. MEXICO. Chihuahua. 

Guadalupe y Calvo: Rio Verde crossing, 21 mi SW of El Vergel, 

14 Sep 2006, 2330–2360 m, P.M. Peterson, Sánchez Alvarado & 

Gómez Ruíz 20072 (US). Guerrero: Sierra Madre, 1 Oct 1887, 

C.G. Pringle 1422, 1704 (US) Isotype; On road between Tomochic and Bassaseachic, 20 mi E of jct w/ road S to San Juanito, 

1.8 mi W of Aqua Caliente, 5 Oct 1986, 2000 m, Spellenberg, 

Soreng, R. Corral & T. Lebgue 8878 (NMC). 

Cenchrus L.

Annual or perennial. Culms 5–200 cm tall, erect or decumbent, usually geniculate; nodes and internodes usually glabrous. 

Sheaths open, usually glabrous; ligules membranous, ciliate, cilia 

as long as or longer than the basal membrane; blades flat or 

folded, margins cartilaginous, scaberulous. Inflorescences terminal, spikelike panicles of highly reduced branches termed involucres (“burs”); involucres consisting of 1–2 series of many, stiff, 

partially fused, usually retrorsely scaberulous to strigose, sharp 

bristles surrounding, sometimes almost concealing, 1–4 spikelets; outer (lower) bristles, if present, in 1 or more whorls, terete or flattened; inner (upper) bristles usually strongly flattened, 

fused at least at the base and forming a disk, frequently to more 

than 1⁄2 their length and forming a cupule; disarticulation at the 

base of the involucres. Spikelets sessile, with 2 florets; lower florets usually sterile; upper florets bisexual. Lower glumes ovate, 

scarious, glabrous, 1-veined, acute to acuminate; upper glumes 

and lower lemmas ovate, 3- to 9-veined; lower paleas equaling 

the lemmas, tawny or purplish; upper lemmas and paleas subequal, indurate, ovate, obscurely veined, acuminate. Caryopsis 

obtrulloid. x = 17. 

Cenchrus, as now circumscribed (synonym = Pennisetum

Rich.), includes about 120 primarily tropical species, some of 

which are readily (and painfully) recognized by their spiny involucres (Soreng et al., 2017b). Many species in Mexico are considered to be undesirable weeds.
NUMBER 107 • 8 9

KEY TO SPECIES OF CENCHRUS

1. Involucres of spines or stiff bristles united at the base or halfway to the apex, usually retrorse roughened, the early ones 

antrorse scabrous.

2. Spines or bristles united only below the inferior 1⁄5 (almost at the base), forming a soft involucre, ciliate or feathery, not 

spinose, with a small disk and forming a low, deep cupule; perennial.

3. Bristles retrorsely scabrous, cylindric, all similar but the internal longer and the external gradually smaller . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. myosuroides

3. Bristles antrorsely bearded.

4. Bristles soft and densely pilose (feathery), the innermost up to 1.5 times longer than the rest; spikelets 2.5–4.8 mm 

long; inflorescences 1–2.5 cm wide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. ciliaris

4. Bristles somewhat indurate (especially the innermost ones), sparsely pilose but never feathery, the innermost ones 

2 or more times longer than the rest; spikelets 5–6(9) mm long; inflorescences 1–1.5 cm wide . . . . C. multiflorus

2. Spines or bristles united more or less halfway, forming a hardened involucre; annual and/or biannual.

5. Involucre of united spines, flattened and wider basally, in several concentric whorls, without additional bristles . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. spinifex

5. Involucre with a row of basal bristles, slender, numerous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. echinatus

1. Involucres of free bristles (or somewhat united at the base), often feathery.

6. Plants stoloniferous; culms prostrate 3–45 cm long; panicles axillary, partially or wholly hidden in the leaf sheaths at 

maturity, the rachises flattened in cross section, with 1–6 involucres; spikelets 10–22 mm long, bristles mostly shorter 

than the spikelet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. clandestinus

6. Plants not stoloniferous; culms erect, 30–300 cm tall; panicles terminal or terminal and axillary, fully exserted at maturity, the rachises terete, with 10 to many involucres; spikelets 2.5–12 mm long, the majority of the bristles as long as or 

longer than the spikelets. 

7. Inflorescences 15–30 mm wide; bristles ciliate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. polystachios

7. Inflorescences 3–15 mm wide; bristles ciliate, glabrous or scabrous.

8. Annual plants; caryopsis obovoid, exposed between gaping lemma and palea; blades 50–100 cm long, cordate at 

the base . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. americanus

8. Perennial plants; caryopsis elliptsoid, permanently hidden by the lemma and palea; blades 20–60 cm long, never 

cordate at the base.

9. Bristles mostly shorter than spikelets; spikelets 6–7 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. durus

9. Bristles mostly longer than spikelets; spikelets 4.5–6.5 mm long . . . . . . . . . . . . . . . . . . . . . . C. michoacanus

77. Cenchrus americanus* (L.) Morrone, Ann. Bot. (Oxford), 

n.s. 106: 127.

Pennisetum glaucum (L.) R. Br.

FIGURE 62

Annual. Culms 150–300 cm tall, erect, robust, branching; 

nodes bearded. Sheaths glabrous or pubescent; ligules 2–5 mm 

long, a fringe of hairs; blades 50–100 cm long, 8–70 mm wide, 

cordate on the base, flat. Inflorescence a spiciform panicle, terminal, 4–200 cm long, 8–60 mm wide, fully exserted from the 

sheaths, erect; rachises terete, densely pubescent. Involucres 33–

160 per cm; involucre axes 1–28 mm long, persistent, with 1–9 

spikelets; outer bristles 44–131, 0.5–6 mm; inner bristles 6–19, 

4–6 mm long, plumose; primary bristles 5.5–6.3 long, ciliate, 

sometimes noticeably longer than the other bristles. Spikelets 

3–6 mm long; pedicels 0.6–1.8 mm long; lower glumes absent 

or to 1.5 mm long, veinless; upper glumes 0.5–2.5 mm long, 

3- to 5-veined; lower florets staminate or sterile; lower lemmas 

1.5–6 mm long, glabrous, 3- to 7-veined, margins ciliate; lower 

paleas vestigial or fully developed, margins ciliate; anthers 2.2–

2.5 mm long, penicillate; upper florets coriaceous, shiny; upper 

lemmas 4.3–7 mm long, 5- to 7(9)-veined, margins ciliate; upper 

paleas 3.4–3.9 mm long, pubescent, at least near the base, margins ciliate; anthers 2–2.2 mm long, penicillate. Caryopsis 2–5.5 

mm long, 1.6–3.2 mm wide, obovoid, exposed between gaping 

lemma and palea at maturity. 2n = 14.

Distribution and Habitat. Cenchrus americanus, a native of Asia, is cultivated in the United States for grain, 

forage, and birdseed; reported wild from Chihuahua, Mexico 

but not seen.

78. Cenchrus ciliaris* L., Mant. Pl. 302. 1771. Pennisetum ciliare (L.) Link, Hort. Berol. 1: 213 1827.

FIGURE 63

Perennial; emerging from a hard and nodose crown or short 

rhizomes. Culms 25–100 cm long, erect, branched, glabrous. 

Sheaths compressed, glabrous or pilose near the throat, margins 

hyaline; ligule 0.5–2.5 mm long, pilose; blades 3–24 cm long, 

2–8 mm wide, flat, scabrous to pilose, narrowing toward the 

apex. Inflorescence 2–12 cm long, 1–2.5 cm wide, rachis flexible and scabrous, internodes 0.8–2 mm; involucres 9–15 mm 
9 0 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

FIGURE 62. Cenchrus americanus. A. Inflorescence and 

leaf blade. B. Spikelet involucre with caryopsis. C. Close-up 

of primary bristle. Drawn by Linda Ann Vorobik; copyright 

Utah State University.

FIGURE 63. Cenchrus ciliaris. A. Culm, inflorescence, and leaf blade. B. Spikelet involucre. C. 

Spikelet. D. Outer bristle (left) and inner bristle 

(right). Drawn by Linda Ann Vorobik; copyright 

Utah State University.
NUMBER 107 • 9 1

long, 3–4 mm wide, elongated, pubescent, pedicels small, pilose; 

straight spines or some curved, with long hairs, pubescent on the 

internal margins, united only basally or a little higher, antrorsely 

scabrous, the internal feathery; lower verticil of similar spines, 

similar to bristles, shorter than the internal spines. Spikelets 2–4 

per involucre. Lower glumes 1–2.5 mm long, 1-veined, slender, 

membranous; upper glumes 1–3 mm long, 1- to 3-veined; inferior 

floret staminate; inferior lemma 2–4.5 mm long, 5- to 6-veined, 

inferior palea 2–4 mm long, partially covered by the lemma; superior florets bisexual, 2.2–5 mm long, 1–1.5 mm wide; anthers 

2.4–2.6 mm long. Caryopsis 1.2–1.9 mm long, 0.4–1 mm wide. 

2n = 45

Distribution and Habitat. Cenchrus ciliaris 

is a weed native to Africa, western Asia, and India and grows 

along road margins and cultivated areas in desert scrub and disturbed tropical forests. It ranges from Canada, the United States, 

Mexico, Central and South America to the Caribbean Islands.

Specimens Examined. MEXICO. Chihuahua. 

Aldama: km 60 carr. [hwy] Chihuahua–Ojinaga, 25 Aug 1978, 

matorral de gobernadora [governor’s scrub], 1270 m, MolinarRodríguez & Baray 28 (CIIDIR). Chihuahua: La Campana, 

24 Sep 76, Jardines de observación [observation gardens], 

1500 m, S. González 765, 762, 777 (RELC). Hidalgo del Parral: 

approx. 20 mi N from Parral, 21 Jul 2006, grazed introduced, 

1750 m, K.R. Adams & N. Matínez 054-2006 (CIIDIR). Jiménez: along hwy 49 ca. 167 km N of Gómez Palacio, 25 Sep 2004, 

1279 m, R.M. King & R.M. Garvey 13470 (CIIDIR). Meoqui: 

In town of Meoqui, along hwy 45, SE of city of Chihuahua, 25 

Sep 2004, 1140 m, R.M. King & R.M. Garvey 13465 (CIIDIR).

79. Cenchrus clandestinus* (Hochst. ex Chiov.) Morrone, Ann. 

Bot. (Oxford), n.s. 106: 127. 2010. Pennisetum clandestinum Hochst. ex Chiov., Annuario Reale Ist. Bot. Roma 

8(1): 41, pl. 5, f. 2. 1903. 

FIGURE 64

Perennial; rhizomatous and stoloniferous, mat-forming. 

Culms 3–45 cm tall, prostrate, highly rooting from lower 

nodes; nodes glabrous. Sheaths glabrous or pubescent; ligules 

1.3–2.2 mm long; blades 1–15 cm long, 1–6 mm wide, flat or 

folded, glabrous or pubescent. Panicles 2–2.7 cm long, axillary, 

concealed in the sheaths; rachises flat, glabrous or scabrous. Involucres 1–6; axes to 0.5 mm long, with 1–2 spikelets; outer 

and inner bristles alike, 6–15, 0.5–10.9 mm; primary bristles 

FIGURE 64. Cenchrus clandestinus. A. Habit. B. Portion of culm with spikelets near 

apex. C. Spikelet. Drawn by Linda Ann Vorobik; copyright Utah State University.
9 2 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

10–14 mm long, usually not noticeably longer than the other 

bristles. Spikelets 10–22 mm long, sessile or pedicellate, pedicels 

to 0.2 mm; lower glumes usually absent, sometimes to 0.5 mm 

long, veinless; upper glumes 0–1.3(3.5) mm long, veinless; lower 

florets sterile; lower lemmas 10–22 mm long, 9- to 13-veined; 

lower paleas usually absent; upper lemmas 10–22 mm long, 8- to 

12-veined; upper paleas 2- to 7-veined; anthers 4.7–7 mm long, 

long-exserted from the florets at anthesis. 2n = 36.

Distribution and Habitat. Cenchrus clandestinus is native to Africa. It now grows in many parts of the 

world, often as a forage or lawn grass.

Specimens Examined. MEXICO. Chihuahua. In 

all the towns and municipalities of the state it is cultivated in 

gardens of houses and buildings, but there are few herbarium 

specimens.

80. Cenchrus durus (Beal) Morrone, Ann. Bot. (Oxford), n.s. 

106: 128. Pennisetum durum Beal, Grass. N. Amer. 2: 163. 

1896. 

Perennial. Culms 100–200 cm tall, erect, robust, rigid, glabrous, glaucous, solitary or grouped, from a hard, knotty base, 

branched on superior nodes, sligtly compressed. Sheaths glabrous or scabrous, pubescent on margins toward the apex, margin scarious, collar pubescent; ligules 1.5–2 mm long, densely 

ciliate; blades 20–60 cm long, 5–17 mm wide, ascending to 

divaricate, rigid, scaberulous or glabrous, largely apiculate, 

narrow on the base. Inflorescence a spike 3–10(12) cm long, 

8–10 mm wide, terminal, rachis slender, narrow, scabrous, involucres sessile, ascending, bristles scarce, glabrous, unequal, 

shorter than spikelets, internal bristle longer, sometimes twice 

as long as spikelet. Spikelets 6–7 mm long, 1.5 mm wide, acuminate, glabrous, solitary, sessile; glumes unequal, obtuse to 

subacute, ciliolate, lowerglumes 2–2.3 mm long, 1- to 3-veined, 

upper glumes 3–3.5 mm long, 3- to 5-veined; lemma sterile 

5.8–7 mm long, 5-veined, concave on the back, acute; palea reduced; lemma fertile 6–7 mm long, acuminate, scabriusculous 

especially on the apex; stigmas plumose, black. Caryopsis subhardened, acuminate.

Distribution and Habitat. Cenchrus durus is 

an endemic Mexican species from Chihuahua and Oaxaca.

Specimens Examined. MEXICO. Chihuahua. 

Guachochi: entering Barranca El Cobre, 28.3 km S of Cusarare 

on road to Guachochi, 25 Sep 1988, 1900 m, P.M. Peterson & 

Annable 5904 (US); 39.2 km S of Creel on road to Batopilas at 

the Barranca El Cobre, 10 Sep 1989, 1930 m, P.M. Peterson, 

Annable & Y. Herrera 8020 (US). Ocampo: Cascada de Basaseachic, 4 oct 1982, bosque de pino–encino [pine–oak forest], 2000 

m, Tenorio & Romero 1941 (CIIDIR); Parque Nacional “Cascada de Basaseachi”, in the barranca [canyon] at the base of the 

falls, 11 Nov 1989, 1700 m, Spellenberg, R. Corral, T. Lebgue 

& M. Mahrt 10074 (ARIZ, CIIDIR, NMC); Parque Nacional 

Cascada Basaseachic, por la vereda que va de la parte alta de la 

cascada [by path from high part of waterfall] a “La Ventana”, 22 

Sep 1990, bosque de pino–encino, 1980 m, R. Corral RCD3887

(UACJ); Area of Cascada de Basaseachic at the confluence of Rio 

Basaseachic and Rio Durazno, Ca. 2 mi S of Village of Basaseachic, 17 Oct 1986, 1800 m, G.L. Nesom & L.A. Vorobik s.n.

(ARIZ).

81. Cenchrus echinatus* L., Sp. Pl. 2: 1050. 1753.

FIGURE 65

Annual. Culms 20–100 cm tall, ascending from a geniculate base. Sheaths from shorter than to equaling the internodes, 

compressed; ligules 0.7–1.7 mm long; blades 4–18(35) cm long, 

2–10(14.2) mm wide, adaxial surfaces sparsely pilose, hairs 

papillose-based. Panicles 2.5–12 cm long; rachis internodes 

2–4 mm long; involucres 5–10 mm long, 3.5–6(6.3) mm wide, 

imbricate; outer bristles 10–20, terete, the majority no more than 

1⁄2 as long as the inner bristles; inner bristles 2–5 mm long, 0.6–

1.5 mm wide, flattened, not grooved, mostly erect, fused for at 

least 1⁄2 their length into a globose cupule, sometimes interlocking 

at maturity, shortly pubescent, often purple at maturity. Spikelets 2–3(4) per involucre (fascicle), 4.8–7 mm; lower glumes 1.3–

3.4 mm long; upper glumes 3.8–5.7 mm long, 3- to 7-veined; 

lower lemmas 4.5–6.5 mm long; upper florets 4.7–7 mm long; 

anthers 0.8–2.4 mm long. Caryopsis ovoid, 1.2–3.2 mm long, 

1.3–2.2 mm wide. 2n = (34), 68.

Distribution and Habitat. Cenchrus echinatus grows in disturbed areas throughout the coastal plain and 

piedmont of the southern United States, Mexico, Central and 

South America, and as an unwelcome introduction elsewhere. 

Widely distributed; however there are few specimens in herbaria.

Specimens Examined. MEXICO. Chihuahua. Chihuahua: SW of Chihuahua, Aug–Nov 1885, E. Palmer 22 (US).

82. Cenchrus michoacanus H. F. Gut & Morrone, Bol. Soc. Argent. Bot. 47(1–2): 268. 2012.

Pennisetum crinitum (Kunth) Spreng.

Perennial; caespitose. Culms 150–250 cm tall, 6–10 mm 

thick, erect, branched, glabrous, internodes solid. Leaves glabrous; sheaths, some carinate, short; ligules 0.5–1.3 mm long, 

a pilose membrane, blades 20–40 cm long, 8–18 mm wide, flat, 

thick, sligtly wider toward the base, never cordate. Inflorescence 

12–18 cm long, 10–15 mm wide, solitary, terminal, spikate, 

straw color or dark green, rachis striate, scabrous, straight or 

curved, involucres with 1 spikelet, sessile, bristles almost 30, 

mostly longer than spikelets, 5–8 mm long, scabrous, internal 

bristles 12–20 mm. Spikelets 5–6 mm long, acuminate, lower 

glumes 1.5–2.5 mm long, 1-veined, subacute to acute, upper 

glumes 0.5–0.7 mm shorter than the spikelet, 5-veined, acute or 

acuminate; inferior floret sterile, inferior lemma as long as the 

spikelet, 5-veined; inferior palea missing; superior lemmas 4.5–

5.4 mm long, chartaceous toward the base, apically membranaceous, glabrous; anthers 1.9–2 mm long, glabrous. Caryopsis 

0.5–1.5 mm long, elliptic.

Distribution and Habitat. Cenchrus michoacanus grows in abandoned fields and grasslands with thorny 
NUMBER 107 • 9 3

FIGURE 65. Cenchrus echinatus. A. Habit. B. Inflorescence. C. Involucre (fascicle). D. Lower glume. E. Upper glume. F. Floret. Drawn by Linda 

Ann Vorobik and Annaliese Miller; copyright Utah State University.
9 4 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

scrubs. It is a Mexican species from Chiapas, Guanajuato, 

México, and Michoacán.

Specimens Examined. MEXICO. Chihuahua. 

Delicias: approx. 3 mi S of Delicias on Mex 45, 30 Mar 1971, 

4200 ft, W.E. Harmon S-375 (ENCB). Julimes: Potrero Mts, 12 

Oct 1886, C.G. Pringle 817 (US), Isotype.

83. Cenchrus multiflorus J. Presl, Reliq. Haenk. 1(4–5): 318. 

1830.

Perennial; caespitose, base with scaly buds. Culms 50–

160 cm tall, erect, simple or scarcely branched, glabrous or pilose. Sheaths sparsely carinate, glabrous to papillose-pilose; ligule 

1.3–1.8 mm; blades 20–45 cm long, 5–10(20) mm wide, scabrous 

to sometimes spread papillose-pilose adaxially. Inflorescence 

5–10(18) cm long, 10–15 mm wide, involucres 7–12 mm long, 

2.5–3.5 mm wide, external bristles free, cylindrical, antrorse scabrous, the internal ones only united at the base, cylindrical, spread 

to moderate pilose. Spikelets 5–6(9) mm long, 2–5 per involucre 

(fascicle); lower glumes 2.2–2.9 mm long, 1-veined; upper glumes 

3–5.2 mm long, 3- to 5-veined; inferior florets staminate, lemma 

of the inferior floret as long as the spikelet, 5- to 7-veined, paleas 

equal to lemmas or a little shorter; upper florets 5.2–6.6 mm long, 

1–1.5 mm wide; anthers 1.9–3 mm long. 2n = 34.

Distribution and Habitat. Cenchrus multiflorus grows in deciduous tropical forests at 1,250–1,750 m; it is a 

Mexican species from Chiapas, Chihuahua, Durango, Guerrero, 

Jalisco, Oaxaca, and Zacatecas.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: Vicinity of Areponapuchic, slopes of Barranca de 

Urique, Aug 1954, I. Knobloch 1363 (US). Bocoyna: entre 

[between] Barranca del Cobre & Bacahipare, 17 Aug 1976, 

1160–1640 m, S. González 738 (ENCB, RELC). Chihuahua: La 

Campana, 24 Sep 76, Jardín de observación [observation garden], 1500 m, S. González 779 (RELC). Uruachi: Guazaremos, 

Río Mayo, 5 Aug 1935, Gentry 1568 (US).

84. Cenchrus myosuroides Kunth, Nov. Gen. Sp. (quarto ed.) 1: 

115–116, t. 35. 1815.

FIGURE 66

Perennial. Culms 5–200 cm long, stout, glaucous. Sheaths 

from shorter than to equaling the internodes; ligules 1.5–2(3.4) 

mm long; blades 12–40 cm long, 4–13 mm wide, glabrous or 

sparsely pilose adaxially. Panicles 4–23 cm; involucres 3.8–8 mm 

long, 1.2–2.6 mm wide, composed of several whorls of bristles, 

not bur-like; bristles 3–5.8 mm long, 0.2–0.6 mm wide, fused 

only at the base, not forming a cupule, terete, increasing in size 

inward, inner bristles pubescent on the lower 1⁄2–2⁄3. Spikelets 3.8–

4.8(5.6) mm long, 1(2–3) per involucre (fascicle); lower glumes 

1.5–3 mm long; upper glumes 3–5 mm long, 3- to 5-veined; lower 

lemmas 3–5.5 mm long; upper lemmas 3.8–5.4 mm long; anthers 

0.8–2.2 mm long. Caryopsis 1.5–2.6 mm long, 1–1.5 mm wide, 

ovoid. 2n = (54), 70.

Distribution and Habitat. Cenchrus myosuroides grows mostly along roadsides and in other waste places. Its 

native range extends through the Caribbean and Central America to northern South America.

Specimens Examined. MEXICO. Chihuahua. 

Camargo: 20 km S of Cd. Camargo, 2 Aug 1939, L. H. Harvey 

1388 (US); 10 mi N of Ciudad Camargo, 4 Oct 1953, 1280 m, 

Reeder & C. Reeder 2613 (ENCB). Chihuahua: Chihuahua, 8 

Sep 1885, E. Wilkinson s.n. (US); 5 mi SW of Chihuahua on 

road to Cuauhtémoc, 6 Oct 1959, 1463 m, Soderstrom 897

(US); near Chihuahua, 25 May 1885, C.G. Pringle 429 (US); 

Rancho experimental La Campana, 82 km al N de la cd. de Chihuahua, 26 Aug 1978, jardines de observación [observation gardens], 1550 m, C.A. Fernández s.n. (ENCB). General Trías: km 

40 carr. [hwy] Chihuahua–Cuahutémoc, 12 Aug 1976, matorral 

[scrub], 1500 m, S. González & J.M. Peña 538 (RELC). Guachochi: 8.9 km NE of La Bufa on road to Creel, 12 Sep 1989, 

1780 m, P.M. Peterson, Annable & Y. Herrera 8068 (ENCB, 

US). Jiménez: 60 km N of Escalon, 27 Jul 1939, 1280 m, L. H. 

Harvey 1302 (ENCB). Meoqui: Meoqui, 8 Aug 1936, LeSueur 

0140 (US); Saucillo: along Isla de Perla road about 4 mi E of Cd. 

Delicias, 11 Jul 1950, 1250 m, Reeder, C. Reeder & Goodding 

1265 (ENCB).

FIGURE 66. Cenchrus myosuroides. A. Involucre (fascicle). 

B. Lower glume and lower lemma. C. Upper glume. D. Floret. 

Drawn by Linda Ann Vorobik and Annaliese Miller; copyright Utah 

State University.
NUMBER 107 • 9 5

85. Cenchrus polystachios* (L.) Morrone, Ann. Bot. (Oxford), 

n.s. 106: 129. 2010. Pennisetum polystachion (L.) Schult., 

Mant. 2: 146. 1824.

FIGURE 67

Annual or perennial; caespitose from a hard, knotty base. 

Culms 30–200 cm tall, erect, branching; nodes glabrous. Sheaths 

glabrous, margins ciliate; ligules 1.5–2.7 mm long; blades 

15–55 cm long, 4–18 mm wide, flat, glabrous or pubescent. 

Panicles 10–25 cm long, 15–30 mm wide, terminal, fully exserted from the sheaths, erect to drooping, white, yellow, light 

brown, or pink to deep purple; rachises terete, scabrous. Involucres 33–45 per cm long, disarticulating at maturity; involucres axes 0.2–0.5 mm long, with 1 spikelet; outer bristles 13–30, 

1.3–5 mm long, scabrous; inner bristles 6–14, 4.3–11.5 mm 

long, long-ciliate; primary bristles 14–25 mm long, long-ciliate, 

noticeably longer than the other bristles. Spikelets 3–4.5 mm 

long, sessile; lower glumes absent or to 2 mm long, veinless; 

upper glumes 3–4.5 mm long, glabrous, 5- to 7-veined, 3-lobed; 

lower florets sterile or staminate; lower lemmas 3–3.9 mm long, 

5- to 7-veined, apex lobed; lower paleas 2.9–3.7 mm; anthers absent or 1.7–2 mm long; upper florets disarticulating at maturity; 

upper lemmas 1.7–3 mm long, coriaceous, shiny, 5-veined, apex 

ciliate; anthers 1.3–2.1 mm long. Caryopsis about 1.7 mm long, 

concealed by the lemma and palea at maturity. 2n = 18, 36, 45, 

48, 52, 53, 54, 56, 78.

Distribution and Habitat. Cenchrus polystachios is a polymorphic, weedy African species that has become 

established in the tropics and subtropics; it is considered a noxious weed in North America. Wipff (2003) followed Brunken 

(1979a; 1979b) in recognizing two subspecies in the Flora of 

North America, and we concur. Ours is perennial, usually sparingly branched, and has involucres yellow, light brown, or purplish. We make a new combination for this taxon below.

Cenchrus polystachios subsp. setosum (Sw.) P. M. Peterson & 

Y. Herrera, comb. nov. Basionym: Cenchrus setosus Sw., 

Prodr. 26. 1788 ≡ Pennisetum polystachion subsp. setosus

(Sw.) Brunken, Bot. J. Linn. Soc. 79: 63. 1979. Holotype: 

WEST INDIES (JAMAICA). O.P. Swartz s.n. (S S06-637 

[image!]).

Specimens Examined. MEXICO. Chihuahua.

Delicias: approx. 3 mi S of Delicias on Mex 45, 30 Mar 1971, 

along railroad adjacent to and creosote flats, 4200 ft, W.E. Harmon & Dunn 5375 (ENCB); P. Gallian & B.J. Cox 394 (ENCB); 

B.J. Cox 2879 (ENCB).

86. Cenchrus spinifex Cav., Icon. 5 : 38, t. 461. 1799.

Cenchrus incertus M. A. Curtis.

FIGURE 68

Annual or biannual; caespitose. Culms 10–80 cm tall, 

ascending or erect, branched, forming big mats, scabrous. 

FIGURE 67. Cenchrus polystachios. A. Habit. B. Spikelet involucre. 

C. Spikelet showing lower glume on left. D. Spikelet showing upper 

glume. E. Upper lemma. Drawn by Linda Ann Vorobik; copyright 

Utah State University.
9 6 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Sheaths carinate, glabrous to pubescent along the margins; 

ligule 1–1.5 mm long, pilose; blades 3–10 cm long, 2–6 mm 

wide, flat to sometimes subinvolute. Inflorescence 2–8.5 mm 

long, 0.8–2 cm wide, with variable numbers of fascicles, the 

axis slender flexuous, scabrous or pilose; involucres 5–10 mm 

long, 2.5–5.5 mm wide, ovoid or globose, densely pubescent, 

with 8–40 united thorns fused to 1⁄2 their length, extended or 

reflexed, wide at the base, the exterior cylindrical, the interior 

flattened, involucre body deeply notched on the external face. 

Spikelets 3.5–5.8 mm long, 2–4 per involucre (fascicle); lower 

glumes 1.5–3 mm long, 1-veined, upper glumes 2.8–5 mm 

long, 5- to 7-veined; inferior florets staminate, inferior lemma 

3–5.8 mm long, 4- to 7-veined, inferior palea 3–5.8 mm long; 

superior florets bisexual, 3.4–6 mm long; anthers 0.5–2 mm 

long. 2n = 34.

Distribution and Habitat. Cenchrus spinifex 

is a weed that grows in disturbed sites and wet areas in the subtropical and xerophilous scrub and grasslands at elevations of 

1,250–2,200 m. It ranges from United States, Mexico, Caribbean, and Central America to South America. 

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 7.4 km W of Balleza on road to Guachochi, 18 Sep 

1991, scrub lands, 1660 m, P.M. Peterson, Annable & ValdésReyna 10728 (CIIDIR, US). Camargo: 20 km S of Cd. Camargo, 2 Aug 1939, L. H. Harvey 1393 (US). Casas Grandes: 

near Casas Grandes, 30 Aug 1899, E.W. Nelson 6327 (US). 

Chihuahua: near Chihuahua, 3 Sep 1935, LeSueur Mex-07

(US); Hitchcock 7788 (US); 5 mi SW of Chihuahua on road 

to Cuauhtémoc, 6 Oct 1959, Soderstrom 908 (US); 6 mi N of 

Chihuahua, 8 Oct 1959, 1494 m, Soderstrom 925 (US); La 

Campana Experimental Station & Rancho El Arco Iris, 81–84 

km along Pan American Hwy to Chihuahua City, Oct 1977, 

J.K. Meents & W.H. Moir 90 (NMC); Presa Chihuahua, 7 Aug 

1975, vegetación riparia [riparian vegetation], 1550 m, J.M. 

Peña JMP-75 (RELC). Delicias: 7 mi S of Delicias along Hwy 

45, 24 Sep 1972, 1350 m, J. Henrickson 8002 (NMC). Gran 

Morelos: 10 mi W of General Trias off hwy 16, 19 Aug 1975, 

5850 ft, Ellis, Dunn, & Wallace 936 (ENCB). Hidalgo del 

Parral: 2 mi E of Parral on road to Cd. Juarez, 3 Oct 1959, 

Soderstrom 861 (US). Janos: Chihuahua–Sonora Border, Rancho Carretas, 26 Aug 1937, 1450 m, L. H. Harvey 1605 (US). 

Juárez: aprox. 7 km al N del poblado [village] de Samalayuca, 

a los lados de la carr. [to sides of hwy], 30 Jul 1994, 1200 m, 

R. Corral, E. Pérez, A. Domínguez & F. Félix RCD5316

(UACJ); km 32 Juárez–Chih., 13 Oct 1997, matorral de gobernadora [governor’s scrub], I. Enríquez, S. Ordoñez & J. Leyva 

IEA4 (UACJ). Meoqui: Lazaro Cardenas, 5 Aug 1974, C. Rodríguez, O. Agundis, S. Acosta 1191 (US). Riva Palacio: Col. 

Cumbres de Majalca, 33.8 km W of Mex 45, N of Chihuahua 

City, 7 Sep 1989, pine forest, 2190 m, P.M. Peterson, Annable 

& Y. Herrera 7956 (US); San Francisco de Conchos: carr. de 

Aldama a la presa sobre [to dam on] el Río Conchos, 25 Aug 

1966, 1300 m, M.F. Robert s.n. (ENCB). Saucillo: along Isla de 

Perla, about 4 mi E of Ciudad Delicias, 11 Jul 1950, 1250 m, 

Reeder, C. Reeder & Goodding 1257, 1263 (ENCB).

Chaetium Nees

Perennial; with flatted leaves and panicles narrow and 

dense. Spikelets with a fertile floret and another rudimentary, 

represented by a sterile lemma, pedicelled, dorsally compressed, 

the bearded base of the lower glumes attached to rachilla, forming a long callus, slender, at the point of disarticulation above the 

very oblique base of pedicel. Glumes narrow or wide, subequal, 

prolonged into long awns; lemma of the sterile floret shortly 

FIGURE 68. Cenchrus spinifex. A. Habit. B. Involucre (fascicle). 

C. Lower glume. D. Upper glume. E. Floret. Drawn by Linda Ann 

Vorobik and Annaliese Miller; copyright Utah State University.
NUMBER 107 • 9 7

awned or only mucronate; lemma of the fertile floret somewhat 

hardened, acuminate, mucronate or awned, the margins slender, 

flatened, not enclosing the paleas at the base.

Chaetium is a genus with three species, one distributed in 

Cuba, one from South America, and ours found in Mexico and 

Central America.

87. Chaetium bromoides (J. Presl) Benth. ex Hemsl., Biol. Cent.-

Amer., Bot. 3: 503. 1885. Berchtoldia bromoides J. Presl, 

Reliq. Haenk. 1: 324, t. 43. 1830.

Perennial; with strong stolons at the base. Culms 35–100 cm 

tall, erect or ascending, simple or branched; internodes compressed, glabrous, nodes bearded. Sheaths keeled, glabrous, but 

densely silky-pubescent on margins; ligule 1–2 mm long, a row 

of cilia; blades 10–30 cm long, 3–7 mm wide, papillose-pilose, 

flat to folded, narrowed toward the apex. Panicle 10–23 cm long, 

1–2 cm wide, erect, the axis and rachis scabrous, racemes erect, 

appressed. Spikelets 6–8 mm long excluding the awns, fusiform, 

greenish or purpurescent, with pedicels 2–3 mm long, antrorsely 

hispid with hairs 2–3.5 mm long; glumes 6–8 mm long, wide, 

5- to 7-veined, scabrous, with purple spots, the awns 10–35 mm 

long, straight or slightly flexuous; lemma of the inferior florets 

6–8 mm long, 3-veined; lemma of the superior floret 6–8 mm 

long, smooth, the awns 1.5–2 mm long; callus 1.5–2.5 mm long; 

anthers 1.2–1.5 mm long. 2n = 26. 

Distribution and Habitat. Chaetium bromoides grows in pine–oak forests in open or disturbed areas; it 

ranges from Mexico to Central America.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: Chihuahua, 1886, E. Palmer s.n. (US).

Chloris Sw.

Annual or perennial; rhizomatous, stoloniferous, or caespitose. Culms internodes pith-filled. Sheaths strongly keeled, 

glabrous, scabrous, or pubescent; ligules membranous, erose to 

lacerate, ciliate or absent; blades often with long, coarse hairs 

near the base of the adaxial surface and margins. Inflorescence 

terminal, panicles with (1)5–30 spikelike branches, these usually 

borne digitately, in 2 to several whorls, often with a few isolated 

branches below the primary whorl(s), all branches usually exceeding the upper leaves; branches with spikelets in 2 rows on 1 side 

of the branch axes. Spikelets solitary, sessile to pedicellate, laterally compressed, with 2–3(5) florets, usually only the lowest floret 

bisexual, rarely the lower 2 florets bisexual, remaining floret(s) 

sterile or staminate; florets laterally compressed or terete, cylindrical to obovoid, awned or unawned, sterile and staminate florets 

progressively reduced distally; disarticulation usually beneath the 

lowest floret in the spikelets, all florets falling as a unit. Glumes 

unequal, exceeded by the florets, lanceolate, acute to acuminate, 

unawned, occasionally awned, awns to 0.3 mm; calluses bearded; 

lemmas of bisexual florets 3-veined, marginal veins pubescent, 

midveins usually glabrous, sometimes scabrous, usually excurrent 

into awn, sometimes merely mucronate, lemma apex truncate or 

obtuse, entire or bilobed, lobes when present can be awn-tipped; 

paleas shorter than lemmas, 2-veined, veins scabrous; anthers 3; 

lodicules 2. Caryopsis ovoid, elliptic, or obovoid. x = (9)10.

As interpreted here, Chloris is a tropical to subtropical 

genus of about 55 species and is most abundant in the Southern 

Hemisphere (Peterson et al., 2015). Two species treated here are 

native and one is introduced.

KEY TO SPECIES OF CHLORIS

1. Fertile and rudimentary lemmas awnless or with a short mucro, less than 2 mm long, apiculate . . . . . . . . . C. submutica

1. Fertile and rudimentary lemmas prominently awned, the awn more than 3 mm long.

2. Fertile lemma conspicuously grooved on the sides along the midvein and margins, with hairs about 1.5–2.4 mm long; 

annual; staminate or reduced florets 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. virgata

2. Fertile lemma not grooved on the sides, the hairs less than 1 mm long; perennial; staminate or reduced florets usually 2 

or more . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. gayana

88. Chloris gayana* Kunth, Révis. Gramin. 2: 293, t. 58. 1830.

FIGURE 69

Perennial; usually stoloniferous. Culms to 300 cm tall, erect. 

Sheaths glabrous or scabrous, often ciliate apically; ligules ciliate; blades to 30 cm long, 15 mm wide, scabrous. Panicles digitate, with 9–30 evidently distinct branches; branches 8–20 cm 

long, usually somewhat divaricate, spikelet-bearing to the base, 

averaging 10 spikelets per centimeter. Spikelets strongly imbricate, tawny, with 1 bisexual and (1)2–4 usually staminate, 

sometimes sterile, florets; lower glumes 1.4–2.8 mm long; 

upper glumes 2.2–3.5 mm long; lowest lemmas 2.5–4.2 mm 

long, 0.7–1 mm wide, ovate to obovate or elliptic, somewhat 

gibbous, sides not grooved, pubescence variable, sides usually 

glabrous, sometimes scabrous or appressed-pubescent, margins 

usually glabrous or appressed-pubescent on the lower portions, 

sometimes throughout, sometimes with strongly divergent hairs 

distally, the hairs less than 1 mm long, oftern divergent, apex 

inconspicuously bilobed, awned, awns 1.5–6.5 mm long; second florets 2.2–3.2 mm long, 0.3–1 mm wide, staminate or 

sterile, similar to the first floret but more cylindrical, not widened distally, inflated, if at all, only near the apex, inconspicuously bilobed, awned, the awns 0.8–3.2 mm long; distal florets 

progressively smaller, longer than the subtending rachilla segment, awn-tipped or unawned. Caryopsis 1–1.5 mm long, about 

0.5 mm wide. 2n = 20, 30, 40.
9 8 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Distribution and Habitat. Chloris gayana

grows in warm-temperate to tropical regions throughout the 

world, including Mexico. It is cultivated as a meadow grass in 

irrigated regions of the southwestern United States.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: La Campana, Potrero El Plan; 3 km Ote. [W] carr. 

[hwy] Panamericana, 13 Sep 1973, Jardín de Observación [observation garden], 1500 m, Valdés-Reyna VR-237 (MEXU, RELC).

89. Chloris submutica Kunth, Nov. Gen. Sp. (quarto ed.) 1: 167, 

t. 50. 1815.

FIGURE 70

Perennial; usually caespitose, occasionally shortly stoloniferous. Culms 30–75 cm tall, erect. Sheaths glabrous; ligules 

about 0.5 mm long, short ciliate; blades to 20 cm long, to 5 mm 

wide, sometimes with long basal hairs, otherwise scabrous. Panicles with 5–17 distinct branches in 1–3 closely spaced whorls; 

branches to 7 cm long, usually erect when young, spreading to 

reflexed at maturity, averaging 12 spikelets per centimeter. Spikelets with 1 bisexual and 1 staminate floret; lower glumes 1.5–

3.2 mm long; upper glumes 2.5–3.4 mm long; lowest lemmas 

2.8–3.7 mm long, 0.6–1.1 mm wide, broadly linear to elliptic, 

mostly glabrous but the margins appressed-pubescent, apex obtuse, not conspicuously bilobed, sometimes mucronate; second 

florets 1.4–2.2 mm long, 0.3–0.9 mm wide, usually at least twice 

as long as wide, not lobed, unawned, occasionally mucronate. 

Caryopsis 1.7–2.3 mm long, 0.5–0.6 mm wide, ellipsoid. 2n = 

ca. 65, 80.

Distribution and Habitat. Chloris submutica

occurs in the southwestern United States, Mexico, Guatemala, 

and Colombia to Venezuela. In Mexico it is generally found between 1,000 and 2,100 m.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: La Ranchería, 14 km al E de Cabórachi, 14 Aug 1982, 

bosque de pino–encino [pine–oak forest], 2100 m, R. Hernández 

et al. 8925 (MEXU). Batopilas: Yamuco, 1 mi E of hwy N of 

Rio Urique crossing towards Basihuare and Creel, 6 Sep 2008, 

P.M. Peterson & J.M. Saarela 22057 (US). Casas Grandes: Rancho Palanganas (La Leona), 11 Sep 1995, pastizal [pastureland], 

2200 m, Ing. González 114 (MEXU). Chihuahua: Valley near 

Chihuahua, 20 Aug 1885, C.G. Pringle 424 (US); La Campana, 4 km E carr. [hwy] Panamericana, 6 Sep 1973, 1500 m, 

Valdés-Reyna VR-115 (ENCB, RELC); Valley near Chihuahua, 

6 Oct 1886, C.G. Pringle 993 (MEXU); Rancho Tepehuanes, acceso [access] de Chihuahua hacia [toward] Namiquipa, desviar 

[diver] en Campo 73 a la derecha tercac [to right dirt road] 6 km, 

11 Oct 2000, pastizal, G. Gómez 312 (MEXU). Cuauhtémoc: 

21 km W of Cuauhtemoc, on Hwy 16, 23 Aug 1990, 2000 m, 

P.M. Peterson & Annable 9590 (US); along hwy 16 W of Chihuahua, 43.6 mi W of General Trias, edge of oak scrub and some 

pine just outside Casa-Colorada, 3 Aug 1977, 7900 ft, Dunn, 

Bennett, Torke & Wieder 22591 (ENCB); 11 mi W of Cuahtemoc, 4 Sep 1967, 7000 ft, Reeder & C. Reeder 4845 (ARIZ, 

FIGURE 69. Chloris gayana. A. Habit. B. Glumes. C. Florets. 

Drawn by Linda Ann Vorobik and Annaliese Miller; copyright Utah 

State University.
NUMBER 107 • 9 9

ENCB, US); 9–7 km al N de entronques carrs. 26 & 18, 10 Aug 

1975, comunidad riparia [riparian community], 2100 m, J.M. 

Peña JMP-141 (RELC). Cusihuiriáchi: Río Papigochic, 40 km 

al Pte. de Chihuahua, carr. Cuahutémoc–Ocampo, 8Aug 75, 

pastizal, 2100 m, J.M. Peña JNP-85 (RELC); Carichic, Laguna 

Mexicanos, 29 Aug 1977, pastizal, 2030 m, Blanco & Gómez 

01/77 (MEXU). Gómez Farías: 3 km al W del pueblo [town] 

de Gómez Farías, 8 Oct 1995, orilla [shore] de carr., 2100 m, 

R. Corral, P. Olivas & J.O. Torres RCD6530 (UACJ). Guachochi: Carr. Guachochi–Creel km 20, 24 Sep 1981, bosque 

esclero-aciculifolio [narrow-leaved sclerophyllous forest], R. Fierros 1612 (MEXU); Cusarare, 17 Sep 1973, bosque de pino, 

6900 ft, Bye 5164 (MEXU). Gran Morelos: km 32.5 (a partir 

del entronque de la carr. [from junction of hwy] Panamericana) 

carr. Chihuahua–Namiquipa, 24 Sep 1997, bosque de encino, 

2340 m, M.A. Vergara 185 (MEXU). Guerrero: 38.6 km SW of 

La Junta and approx. 70.8 km N of Creel at p. Arroyo Ancho 

crossing, 21 km marker, 24 Sep 1988, pine woods, 2200 m, P.M. 

Peterson & Annable 5841 (ENCB, US); railroad NW of San 

Isidro, Sierra Madre Occidental, 18 Sep 1934, 1990–2010 m, 

Pennell 18986 (MEXU, US); Carr. La Junta–San Juanito, 17 km, 

22 Sep 1997, 2290 m, B. Tah V. 3 (MEXU); Temochi, 2 km alrededor del poblado [around the village], 24 Sep 1997, bosque de 

pino, 2100 m, M.A. Vergaara 141 (MEXU). Ignacio Zaragoza: 

20.3 km NE of Ignacio Zaragoza on Mex 23, 28 Sep 1989, 

2400 m, P.M. Peterson & R.M. King 8166 (US). Madera: Paraje Agua Caliente, predio particular [private property] El Chorrito, 17 Oct 1990, bosque de encino, 2350 m, O. Bravo 1947

(CIIDIR); 10 km al N de Madera, 5 Oct 74, bosque de pino–

encino, 2100 m, Valdés-Reyna VR-687 (RELC). Moris: Mesa del 

Agua, 4.8 km S of Campanero (on Mesa de Campanero), 29 Sep 

2003, 1990 m, T.R. Van Devender, A.L. Reina, M.A. Dimmitt 

& M.W. Eubanks 2003-1101 (NMC). Ocampo: Parque Nacional “Cascada de Basaseachic,” at overlook ca. 1 km airline S of 

Cascada, 3 Oct 1986, 2100 m, Spellenberg, Soreng, R. Corral & 

T. Lebgue 8672(NMC); Parque Nacional “Cascada de Basaseachic,” ca. 130 air km W of Cuauhtemoc, 12 Sep 1987, 1980 

m, Spellenberg & D. Jewell 9289 (MEXU, NMC). Riva Palacio: 

Majalca (Pilares), 12 Aug 1939, L. H. Harvey 1483 (US); Col. 

Cumbres de Majalca, 33.8 km W of Mex 45, N of Chihuahua 

City, 7 Sep 1989, pine forest, 2190 m, P.M. Peterson, Annable & 

Y. Herrera 7967 (US). Temosachi: Nabogame, 29 Jul 1987, 1800 

m, Laferr. 585 (MEXU).

90. Chloris virgata Sw., Fl. Ind. Occid. 1: 203. 1797.

Chloris elegans Kunth.

FIGURE 71

Annual; usually tufted, occasionally stoloniferous. Culms 

10–100+ cm tall. Sheaths usually glabrous; ligules to 4 mm long, 

erose or ciliate; blades to 30 cm long and 15 mm wide, basal 

hairs to 4 mm long, otherwise usually glabrous, occasionally 

pilose. Panicles digitate, with 4–20 distinct branches; branches 

5–10 cm long, erect to ascending, averaging 10 spikelets per centimeter. Spikelets strongly imbricate, with 1 bisexual and 1(2) 

sterile floret(s); lower glumes 1.5–2.5 mm long; upper glumes 

2.5–4.3 mm long; lowest lemmas 2.5–4.2 mm long, keels usually prominently gibbous, glabrous, or conspicuously pilose, 

sides not grooved, margins glabrous, scabrous or pilose basally 

with conspicuously longer hairs distally, the hairs 1.5–2.4 mm 

long, lemma apex not conspicuously bilobed, awned, the awns 

2.5–15 mm long; second florets 1.4–2.9 mm long, 0.4–0.8 mm 

wide, somewhat widened distally, not inflated, bilobed, lobes 

less than 1⁄5 as long as the lemmas, awned from the sinuses, the 

awns 3–9.5 mm long; third florets greatly reduced, unawned 

and shorter than the subtending rachilla segment or absent but 

the rachilla segment present. Caryopsis 1.5–2 mm long, about 

0.5 mm wide, elliptic. 2n = 20, 26, 30, 40.

Distribution and Habitat. Chloris virgata is a 

widespread species that grows in many habitats, from tropical to 

temperate areas with hot summers, including much of the United 

States, and is a common weed in alfalfa fields of the southwestern United States.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 32 km SW de Villa Ahumada, cerca [near] del rancho Santo Domingo rumbo [course] a Casas Grandes, 22 Oct 

54, Hern.-Xol. & C. Tapia N-93 (US); km 1891 carr. [hwy] 

Juárez, sur [S] de Gallegos, 1 Dec 1954, Hern.-Xol. & C. Tapia 

FIGURE 70. Chloris submutica. A. Habit. B. Glumes. C. Florets. 

D. Upper floret. Drawn by Linda Ann Vorobik and Annaliese 

Miller; copyright Utah State University.
100 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

N-1154 (US); Cañón de Santa Clara, 90 km al N de Chihuahua, 19 Oct 1974, 1700 m, Rzedowski 32369 (ENCB); 44 km 

al N del poblado [village] Villa Ahumada por la carr. Panamericana (Méx 45), 7 Oct 1995, 1200 m, R. Corral, P. Olivas & 

J.O. Torres RCD6443 (UACJ); 10 km al S de Moctezuma, 30 

Jul 1994, 1200 m, R. Corral, E. Pérez, A. Domínguez & F. Félix 

RCD5369 (UACJ). Aldama: San Diego de Alcalá por la carr. Chihuahua–Delicas, matorral–pastizal [scrub–pastureland], 20 Aug 

1996, 1200 m, E. Estrada & C. Yen 5713(NMC); Baños de San 

Diego, 1.8 km E of San Diego de Alcalá, ca. 16 km of jet of local 

road with Hwy 45, 14 Oct 1986, area of hot springs, 1200 m, 

G. Neson & L. Voborobic 5515 (MEXU); 30.5 mi NE of Aldama 

along Hwy 16, 15 Sep 1972, pastizal, 4300 ft, J. Henrickson 

7600 (MEXU); 60 km Chih–Ojinaga, 25 Aug 1978, matorral, 

1270 m, Molinar, rodríguez, Baray 45 (MEXU). Allende: 20 mi 

N from Parral to Jiménez on hwy 45, 21 Jul 2006, grassland, 

1750 m, K.R. Adams & N. Martínez 057-2006 (CIIDIR). Ascensión: Cerro de Borregas, about 8 km E of Guzmán, 22 Aug 1972, 

matorral, 1250 m, F. Chiang, T. Wendt &M.C. Johnston 8790

(MEXU). Balleza: 10 mi SW of El Ojito, 12 Sep 2006, 1902 m, 

P.M. Peterson 20020, F. Sánchez Alvarado & E.P. Gómez Ruíz

(CIIDIR, US). Batopilas: SW Chihuahua, Aug 1885, E. Palmer 

118 (US); Yamuco at 1 km E of Hwy towards Basihuare and 

Creel, N of Rio Urique crossing, 26 Aug 2003, bosque de pino–

encino [pine–oak forest], 1891 m, P.M. Peterson & P. Catalán 

17537 (US). Bocoyna: Sánchez, 12 Oct 1910, Hitchcock 7688

(US); Buenaventura: 19 km El Carmen–El Sueco, 25 Oct 1954, 

pastizal, Hern.-Xol. & C. Tapia N-252 (US). Camargo: 20 km S 

of Cd. Camargo, 2 Aug 1939, L. H. Harvey 1392 (US); Rancho 

Mesteñas, 20 km S de La Perla, 20 Oct 1996, 1450 m, C. Yen 

& E. Estrada 6728 (NMC). Casas Grandes: between Casas 

Grandes and Sabinal, 4–5 Sep 1899, E.W. Nelson 6354 (US); 

Valle de las Cuevas al S del Ejido Ignacio Zaragoza, 25 Sep 1982, 

1760 m, Tenorio & Romero 1710 (ENCB, MEXU); Rancho Tapiecitas, Casas Grandes a Col. Juárez, 18 Abr [Apr] 2000, pastizal, G. Gómez 21 (MEXU). Chihuahua: near Chihuahua, 20 

Sep 1885, C.G. Pringle 474 (US); Mts near Chihuahua, 10 Oct 

1935, LeSueur Mex-063, Mex-067 (US); 6 mi N of Chihuahua, 

8 Oct 1959, Soderstrom 920 (US); Cd. Guerrero–Sto. Tomas, 29 

Oct 1954, Hernández-X & C. Tapia N-364 (US); 5 mi SW of 

Chihuahua, 14 Sep 1960, Reeder, C. Reeder &Soderstrom 3461

(ARIZ, ENCB, US); Rancho La Presa, 21 Oct 1954, 1100 m, 

Hern.-Xol. & C.Tapia N-70 (ENCB, US); La Campana, Potrero 

El Plan, 4 km Ote.[W] Carr. PanAmer., 6 Sep 73, lotes producción de semilla [seed-production lots], 1500 m, Valdés-Reyna 

VR-101 (RELC). Potrero El Bajío, 11 km Ote. carr. PanAmer., 

18 Sep 73, pastizal halófito [halophyte grassland], 1480 m,

Valdés-Reyna VR-322 (RELC); Presa Chihuahua, 7 Aug 1975, 

FIGURE 71. Chloris virgata. A. Habit. B. Glumes. C. Florets. Drawn by Linda Ann 

Vorobik and Annaliese Miller; copyright Utah State University.
NUMBER 107 • 101

vegetación riparia [riparian vegetation], 1550 m, J.M. Peña JMP74 (RELC); km 1773 carr. Juárez, 15 Sep 55, pastizal, 1500 m, 

Hern.-Xol. & V. Mathus N-1839 (RELC); Chihuahua, 15 Jul 

1976, pastizal, 1500 m, Blanco, Ochoa 45 (MEXU). Cusihuiriáchi: Subida al Cerro [climb hill] de la Bufa, al sur de Cusihuiriáchi, 10 Aug 1997, bosque de encino–tascate [juniper], 2060 m, 

A. Espejo et al. 5750 (MEXU). Gran Morelos: 47 mi W of Cd. 

Chihuahua on hwy 16, 7 Oct 1972, 6000 ft, L. H. Harvey 9292

(ENCB); km 21 carr. Chih.–Namiquipa (via corta [short]), 24 Sep 

1997, bosque de encino, 1830 m, M.A. Vergara 194 (MEXU). 

Ignacio Zaragoza: Along hwy, 17.9 mi N of Ignacio Zaragoza, 

8 Abril 1977, 7000 ft, Dunn, Bennett, Torke & Wieder 22669

(ENCB). Janos: Chihuahua–Sonora Border, Rancho Carretas, 27 

Aug 1937, 1450 m, L. H. Harvey 1629 (ENCB, US). Jiménez: Sta 

Eulalia plains, 15 Aug 1885, E. Wilkinson 54 (US); Banks of Río 

Florido, Cd. Jiménez, 28 Jul 1939, L. H. Harvey 1318 (US); along 

hwy 49 ca. 167 km N of Gómez Palacio, 25 Sep 2004, matorral 

xerófilo [xerophilous scrub], 1279 m, R.M. King & R.M. Garvey 

13469 (CIIDIR); Reserva de la Biosfera de Mapimí, 1 km de Las 

Palomas, 6 Jul 1997, matorral xerófilo, 1055 m, A. García 2636

(CIIDIR); At Papalote Las Juntas (Presón de Anteojos) 2 km NW 

of Hacienda El Berrendo, on Las Pampas ranch, 25 Aug 1972, 

mezquital, 1450 m, F. Chiang, T. Wendt & M.C. Johnston 8856

(MEXU); El Hugo, Torreoncitos, 13 Aug 2010, matorral de 

Prosopis sp., 1355 m, D. Ramírez & M.L. Juárez 3377, 3398

(CIIDIR). Juárez: Parque “El Chamizal”, 7 Sep 1995, maleza de 

prados & canales de riego [grass meadow and irrigation canals], 

1120 m, R. Corral RCD6284 (UACJ); 23 km al S del poblado 

de Samalayuca, por la carr. Panamericana, 9 Sep 1995, 1250 m, 

R. Corral & P. Olivas RCD6345 (UACJ); 23 km al S del poblado 

de Samalayuca, por la carr. Panamericana, 9 Sep 1995, 1250 m, 

R. Corral & P. Olivas RCD6347 (UACJ). Nuevo Casas Grandes: 

3 km al SE del Rancho Santa María, 7 Oct 1979, M.A. López s.n.

(ENCB). Madera: Paraje Sirupa, ejido Cebollitas, 16 Oct 1990, 

bosque de encino, 1200 m, A. Benítez 2908 (CIIDIR, MEXU). 

Riva Palacio: Col. Cumbres de Majalca, 33.8 km W of Mex 45, 

N of Chihuahua City, 7 Sep 1989, pine forest, 2190 m, P.M. Peterson, Annable & Y. Herrera 7963 (US); San Francisco De Conchos: carr. de Aldama a la presa sobre el río [dam on the river] 

Conchos, 25 Aug 1966, M.F. Robert s.n. (ENCB). Valle de Zaragoza: 58 km N of Parral on Mex 24 towards Chihuahua, 14 Sep 

1989, grassland, 1500 m, P.M. Peterson & Annable 8096 (US).

Cortaderia Stapf

Perennial; often dioecious or monoecious; caespitose. Culms 

erect, densely clumped. Leaves primarily basal; sheaths open, 

often overlapping, glabrous or hairy; auricles absent; ligules of 

hairs; blades flat to folded, arching, edges usually sharply serrate. Inflorescences terminal, plumose panicles, subtended by a 

long, ciliate bract; branches stiff to flexible. Spikelets somewhat 

laterally compressed, usually unisexual, sometimes bisexual, 

with 2–9 unisexual florets; disarticulation above the glumes and 

below the florets. Glumes unequal, nearly as long as the spikelets, 

hyaline, 1-veined; calluses pilose; lemmas 3- to 5(7)-veined, longacuminate, bifid and awned or entire and mucronate; lemmas of 

pistillate and bisexual florets usually long-sericeous; lemmas of 

staminate florets less hairy or glabrous; lodicules 2, cuneate and 

irregularly lobed, ciliate; paleas about 1⁄2 as long as the lemmas, 

2-veined; anthers of bisexual florets 3, 1.5–6 mm long, those of 

the pistillate florets smaller or absent. Caryopsis 1.5–3 mm long. 

x = 9.

Cortaderia, a genus of 21 species, is native to South America and New Zealand, with the majority of species being South 

American (Soreng et al., 2017b).

91. Cortaderia selloana* (Schult. & Schult. f.) Asch. & Graebn., 

Syn. Mitteleur. Fl. 2(1): 325. 1900. Arundo selloana Schult. 

& Schult. f., Mant. 3 (Add. 1): 605. 1827.

FIGURE 72

Plants usually dioecious, sometimes monoecious. Culms 

2–4 m tall, usually 2–4 times as long as the panicles. Leaves primarily basal; sheaths mostly glabrous, with a dense tuft of hairs 

at the collars; ligules 1–2 mm long; blades to 2 m long, 3–8 cm 

wide, mostly flat, cauline, ascending, arching, bluish-green, abaxial surfaces glabrous basally. Panicles 30–130 cm long, only 

slightly, if at all, elevated above the foliage, whitish or pinkish 

when young. Spikelets 15–17 mm long; calluses to 1 mm long, 

with hairs to 2 mm; lemmas long-attenuate to an awn, awns 

2.5–5 mm long; paleas to 4 mm long; stigmas exserted. Caryopsis and florets not separating easily from the rachilla. 2n = 72.

FIGURE 72. Cortaderia selloana. A. Spikelet. B. Florets. Drawn 

by Linda Ann Vorobik and Cindy Roché; copyright Utah State 

University.
102 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Distribution and Habitat. Cortaderia selloana is native to central South America. It is cultivated as an ornamental in the warmer parts of North America.

Specimens Examined. MEXICO. Chihuahua. 

There are no herbarium specimens of this species, but it is included here because it often found growing as an ornamental in 

many cities of Chihuahua.

Cottea Kunth

Perennial; caespitose, softly pilose throughout. Culms 

25–70 cm tall, ascending or erect from hard knotty bases. Sheaths 

pilose, rounded on the backs; blades flat, linear; microhairs of 

blades each with an elongated basal cell and an inflated terminal cell. Inflorescences terminal, open, rather narrow panicles; 

disarticulation above the glumes and between the florets. Spikelets with 6–10 florets, distal florets reduced. Glumes subequal, 

about as long as the lowest lemmas, pilose, 7- to 13-veined, 

midveins sometimes prolonged as short awns, apex acuminate 

or 3-toothed; lemmas rounded on the backs, with 9–13 prominent veins, some of these excurrent into antrorsely barbed awns 

of various lengths, others into awned teeth, awns and teeth not 

forming a pappus-like crown; paleas slightly longer than the lemmas, 2-veined, 2-keeled, keels hairy; anthers 3. Cleistogamous 

spikelets, usually consisting of a single floret, produced in the 

lower sheaths. x = 10.

Cottea is a monotypic American genus.

92. Cottea pappophoroides Kunth, Révis. Gramin. 1: 84. 1829.

Culms 25–70 cm tall. Blades 5–15 cm long, 4–7 mm wide. 

Panicles 8–15 cm long, 2–6 cm wide, green or purplish; branches 

loosely ascending. Spikelets 5–10 mm (including the awns); 

glumes 4–5 mm long; lemmas 3–4 mm long, conspicuously longpilose basally, awns and teeth more or less alternating. Caryopsis 

about 1.5 mm long, plump, elliptical; embryos about 1⁄2 as long 

as the caryopsis. 2n = 20.

Distribution and Habitat. Cottea pappophoroides grows on open hillsides from Arizona and Texas south to 

central Mexico and from Ecuador to Argentina.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: SW Chihuahua, Aug 1885, E. Palmer 162, 207 (US). 

Camargo: 20 km S of Cd. Camargo, 2 Aug 1939, 1220 m, L. H. 

Harvey 1395 (ENCB, US). Chihuahua: Rocky hills near Chihuahua, 12 Sep 1885, C.G. Pringle 420 (ENCB, US); C.G. Pringle 534 (US). Cuauhtémoc: 23 mi NW of Zavalza, 3 Oct 1966, 

4800 ft, Reeder & C. Reeder 4587 (ARIZ, ENCB, MEXU, US). 

Jiménez: Dunas de arena [sand dunes] La Soledad, Reserva de 

la Biosfera Mapimí Chihuahua, 21 Sep 1998, matorral xerófilo 

[xerophilous scrub], 1140 m, A. García 3085, 3691 (CIIDIR); 

33 mi SE of Jiménez, 27 Sep 1963, Reeder & C. Reeder 3848

(ARIZ, US). Matamoros: 24 mi NW of Chihuahua–Durango 

State line, 3 Sep 1967, 4600 ft, Reeder & C. Reeder 4837 (ARIZ, 

ENCB, MEXU). Meoqui: 1 km al N del Rancho El Pilar, 26 Oct 

1974, Valdés-Reyna VR-816 (ENCB); 14 km N of Delicias on 

rd from Chihuahua to Delicias, 29 Jun 1974, S.D. Koch 74152

(US); 1 km al S del rancho El Pilar, 26 Oct 74, matorral, 1150 m, 

Valdés-Reyna VR-816 (RELC). Ojinaga: Near S end of La Perla–

Ojinaga road 6 km N of where it joins the Camargo–Jiménez 

Hwy and due E of Camargo, 29 Sep 1972, matorral, 1400 m, 

F. Chiang, T. Wendt & M.C. Johnston 9581 (MEXU). Saucillo:

Mancomún El Pajarito Dominguero, 18 km de las Varas, 10 Oct 

1996, matorral, 1280 m, Fierros 106 (MEXU); Rancho El Salvador, 10 Oct 1995, matorral, 1300 m, Fierros 117 (MEXU).

Cynodon Rich.

Perennial; sometimes stoloniferous, sometimes also rhizomatous, often forming dense turf. Sheaths open; auricles absent; ligules of hairs or membranous; blades flat, conduplicate, 

convolute, or involute, sometimes disarticulating. Inflorescence 

terminal, digitate or subdigitate panicles of spikelike branches; 

branches (1)2–20, 1-sided, with 2 rows of solitary, subsessile, appressed, imbricate spikelets. Spikelets laterally compressed, with 

1(3) florets, only the lowest floret functional; rachilla extension 

usually present, sometimes terminating in a reduced floret; disarticulation above the glumes. Glumes usually shorter than the 

lemmas, membranous, keeled, usually muticous; lower glumes 

1-veined; upper glumes 1- to 3-veined, occasionally shortly 

awned; lemmas membranous to cartilaginous, 3-veined, keeled, 

keels with hairs, occasionally winged, apex mucronate or muticous; paleas about as long as the lemmas, 2-keeled; anthers 3; 

style branches 2, plumose; lodicules 2. x = 9.

Cynodon is a genus of nine species, all of which are native 

to tropical regions of the Eastern Hemisphere. Several species are 

used as lawn and forage grasses in tropical and warm-temperate 

regions. The most widespread species, C. dactylon, is also the 

only one encountered in Chihuahua.

93. Cynodon dactylon* (L.) Pers., Syn. Pl. 1: 85. 1805. Panicum 

dactylon L., Sp. Pl. 58. 1753.

FIGURE 73

Plants stoloniferous, usually also rhizomatous. Culms 

5–40(50) cm tall, not becoming woody. Sheaths glabrous or 

with scattered hairs; collars usually with long hairs, particularly at the margins; ligules about 0.5 mm long, of hairs; blades 

1–6(16) cm long, (1)2–4(5) mm wide, flat at maturity, conduplicate or convolute in bud, glabrous or the adaxial surfaces pilose. 

Panicles with (2)4–6(9) branches; branches 2–6 cm long, in a 

single whorl, axes triquetrous. Spikelets 2–3.2 mm long; lower 

glumes 1.5–2 mm long; upper glumes 1.4–2.3 mm long; lemmas 

1.9–3.1 mm long, keels not winged, pubescent, margins usually 

less densely pubescent; anthers dehiscent at maturity; paleas glabrous. 2n = 18, 36.

Distribution and Habitat. Cynodon dactylon 

is from temperate regions of the Old World, introduced in America and widely distributed in Canada, United States, Mexico, 

Central and South America, and the Caribbean Islands.
NUMBER 107 • 103

Specimens Examined. MEXICO. Chihuahua. Aldama: km 91 carr. [hwy] Chihuahua–Ojinaga, 29 Aug 1978, matorral [scrub], 1395 m, Molinar, Baray, Rodríguez 68 (MEXU). 

Ascensión: alrededores del cruce del río [around river crossing] 

Casas Grandes con la carr. Juárez–Ascensión, 11 Jun 2005, 1180 

m, R. Corral, M. Vargas & H. Gutiérrez RCD7156 (UACJ). Camargo: 5 km W of Cd. Camargo, 5 Aug 1939, 1220 m, L. H. 

Harvey 1410 (ENCB). Chihuahua: Rancho Experimental La 

Campana, 16 Oct 1980, pastizal [pastureland], 1640 m, A. Melgoza 621 (CIIDIR); La Campana, 24 Sep 76, Jardín de observación [observation garden], 1500 m, S. González 778 (RELC). 

Delicias: 14 km al N of Delicias on road from Chihuahua to 

Delicias, 29 Jun 1974, weedy vegetation in irrigated area, S.D. 

Koch 74152 (US). approx. 3 mi S of Delicias on Mex 45; 30 

Mar 1971, 4200 ft, W.E. Harmon & Dunn 5381 (ENCB). Jiménez: along hwy 49, ca 167 km N of Gómez Palacio, 25 Sep 

2004, 1279 m, R.M. King & R.M. Garvey 13467 (CIIDIR); El 

Hugo, Torreoncitos, 13 Aug 2010, terrenos de cultivo [farmland], 1355 m, D. Ramírez & M.L. Juárez 3389 (CIIDIR). 

Juárez: Parque “El Chamizal”, 7 Sep 1995, maleza de prados & 

canales de riego [grass meadows and irrigation canals], 1120 m, 

R. Corral RCD6296 (UACJ); km 40 carr. No. 2, a los lados 

[sides] del canal de riego, 8 Sep 1994, 1100 m, R. Corral, Bye, 

A. Domínguez, K. Chico & P. Yañez RCD5432 (UACJ); Ciudad 

Juárez a lo largo [along] de la “Asequia Madre” desde la intersección de las calles [from the intersection of streets] Mejía 

& Santos Degollado, hasta el túnel bajo [below the tunnel] el 

Viaducto Díaz Ordaz, 3 Jun 1995, 1140 m, R. Corral & L.M. 

Barraza RCD6112 (UACJ); Ciudad Juárez a lo largo de la “Asequia Madre” al N del fracc. Rincones de San Marcos, 13 Oct 

1995, 1140 m, R. Corral, P. Olivas & L.M. Barraza RCD6544

(UACJ); en campos [fields] de la Univ. Autónoma de Cd. Juárez, 

edificio [building] ICB, 15 Abr [Apr] 2005, R. Corral, M. Vargas & D. Alvarado RCD7103 (UACJ). Ocampo: Ca 1 km W 

of W boundary of Parque Nacional “Cascada de Basaseachic,” 

10.6 km from the Cahuisori–Ocampo road on the road to Candamena, at Cruz Verde, 23 Sep 1994, 1920 m, Spellenberg, Corral & Estrada 12114 (NMC). Riva Palacio: Nuevo Majalca, 

approx. 14.5 km W of hwy 45, N of Chihuahua, 22 Sep 1988, 

grassland, 1700 m, P.M. Peterson & Annable 5772 (US).

Dactylis L.

Perennial; caespitose, sometimes with short rhizomes. 

Culms to 2.1+ m, bases laterally compressed; internodes hollow; nodes glabrous. Leaves mostly basal, glabrous; sheaths

closed for at least 1⁄2 their length; auricles absent; ligules membranous; blades flat to folded. Inflorescences panicles; primary 

branches 1-sided, naked proximally, with dense clusters of subsessile spikelets distally, at least some branches longer than 1 

cm. Spikelets oval to elliptic in outline, laterally compressed, 

with 2–6 florets; rachillas glabrous, not prolonged beyond 

the distal floret; disarticulation above the glumes and beneath 

the florets. Glumes shorter than the florets, lanceolate, 1- to 

FIGURE 73. Cynodon dactylon. A. Habit. B. Spikelet. Drawn by 

Linda Ann Vorobik and Annaliese Miller; copyright Utah State 

University.
104 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

3-veined, ciliate-keeled, awn-tipped; calluses short, blunt; lemmas 5-veined, scabrous to ciliate-keeled, tapering to a short 

awn; paleas 2-keeled, tightly clasped by the lemmas, unawned, 

apex notched; lodicules 2, glabrous, toothed; anthers 3; ovaries

glabrous. Caryopsis shorter than the lemmas, concealed at maturity, oblong to ellipsoid, falling free or adhering to the lemma 

and/or palea; hila round. x = 7.

Dactylis is interpreted here as a variable monotypic genus, 

although five species are recognized by Russian taxonomists. 

Numerous infraspecific taxa have been recognized in Eurasia 

where Dactylis is native, but it does not seem feasible to identify 

subspecies and varieties in North America.

94. Dactylis glomerata* L., Sp. Pl. 71 (1753).

FIGURE 74

Culms to 2.1 m tall, erect. Leaves dark green; sheaths longer 

than the internodes, glabrous, usually keeled; ligules 3–11 mm 

long, truncate to acuminate; blades (2)4–8(10) mm wide, elongate, lax, with a conspicuous midrib and white, scaberulous to 

scabrous margins. Panicles 4–20 cm long, typically pyramidal, 

lower branches spreading, upper branches appressed. Spikelets

5–8 mm long, subsessile; glumes 3–5 mm long; lemmas 4–8 mm 

long, scaberulous; paleas slightly shorter than the lemmas; anthers 2–3.5 mm long. 2n = 14, 21, 27–31, 42.

Distribution and Habitat. Dactylis glomerata grows in pastures, meadows, fence rows, roadsides, and 

similar habitats throughout North America. Native to Eurasia 

and Africa, it has been introduced throughout most of the cooltemperate regions of the world as a forage grass.

Specimens Examined. MEXICO. Chihuahua. 

Juárez: Universidad Autónoma de Ciudad Juárez, Campus ICB, 

15 Abr [Apr] 2005, 1118 m, R. Corral, M. Vargas & D. Alvarado RCD7084 (UACJ); Chihuahua: La Campana, 24 Sep 76, 

Jardín de observación [observation garden], 1500 m, S. González 

772 (RELC).

Dactyloctenium Willd.

Annual or perennial; tufted, stoloniferous, or rhizomatous. 

Culms erect or decumbent, often rooting at the lower nodes, not 

branching above the base. Sheaths not overlapping, open, keeled; 

auricles absent; ligules membranous, membranous and ciliate, or 

of hairs; blades flat or involute. Inflorescences terminal, panicles 

of 2–11, digitately arranged spicate branches; branches extending beyond the spikelets, terminating in a point, the spikelets imbricate in 2 rows on the lower sides. Spikelets with 3–7 bisexual 

florets, additional sterile florets distally; disarticulation usually 

above the glumes, the florets falling as a unit. Glumes unequal, 

shorter than the adjacent lemmas, 1-veined, keeled; lower glumes 

acute, mucronate; upper glumes subapically awned, awns curved; 

calluses glabrous; lemmas membranous, glabrous, 3-veined (lateral veins sometimes indistinct), strongly keeled, apex entire, mucronate, or awned; paleas glabrous; anthers 3, yellow; ovaries 

glabrous; styles fused. Fruit utricles; seeds falling free of the hyaline pericarp, transversely rugose or granular. x = 10. 

Dactyloctenium is primarily an African and Australian 

genus of 13 species (Soreng et al., 2017b).

95. Dactyloctenium aegyptium* (L.) Willd., Enum. Pl. 2: 1029. 

1809. Cynosurus aegyptius L., Sp. Pl. 72. 1753.

FIGURE 75

Plants tufted annuals or short-lived, shortly stoloniferous 

perennials. Culms 10–35(100) cm tall, usually geniculately ascending and rooting at the lower nodes. Sheaths keeled, with 

papillose-based hairs distally; ligules 0.5–1.5 mm long, membranous, ciliate; blades 5–22 cm long, 2–8(12) mm wide, with 

papillose-based hairs. Panicles with (1)2–6(8) digitately arranged spicate branches; branches 1.5–6 cm long, only the first 

few spikelets in contact with the spikelets of adjacent branches; 

branch axes extending beyond the spikelets for 1–6 mm. Spikelets 3–4.5 mm long, about 3 mm wide; glumes 1.5–2 mm long; 

lower glumes ovate, acute; upper glumes oblong elliptic, obtuse, 

awned, awns 1–2.5 mm long; lemmas 2.5–3.5 mm long, ovate, 

midveins extended into curved mucros 0.5–1 mm long; paleas 

about as long as the lemmas; anthers 0.5–0.8 mm long, pale yellow. Seeds cuboid, about 1 mm long and wide, transversely rugose, light tan to reddish-brown. 2n = 20, 36, 40, 45, 48.

Distribution and Habitat. Dactyloctenium 

aegyptium is a widely distributed weed of disturbed sites in 

Chihuahua.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: SW Chihuahua, Aug 1885, E. Palmer 73 (US). Ojinaga: 31 km a Chihuahua, 28 Aug 1978, área agrícola [agricultural area], 1235 m, Molinar, Rodríguez, Baray 49 (MEXU).

Dasyochloa Willd. ex Rydb.

Perennial; stoloniferous, sometimes mat-forming. Culms 

initially erect, eventually bending and rooting at the base of 

the inflorescence. Leaves not basally aggregated on the primary 

culms; sheaths with a tuft of hairs to 2 mm long at the throat; 

ligules of hairs; blades involute. Inflorescence terminal, short, 

dense panicles of spikelike branches in a tight capitate cluster, each subtended by leafy bracts and exceeded by the upper 

leaves; branches with 2–4 subsessile to shortly pedicellate 

spikelets. Spikelets laterally compressed, with 4–10 florets; disarticulation above the glumes. Glumes subequal to the adjacent 

lemmas, glabrous, 1-veined, rounded or weakly keeled, shortly 

awned to mucronate; florets bisexual; lemmas rounded or 

weakly keeled, densely pilose on the lower 1⁄2 and on the margins, thinly membranous, 3-veined, 2-lobed, lobes about 1⁄2 as 

long as the lemmas and obtuse, midveins excurrent into awns 

as long as or longer than the lobes, lateral veins not excurrent; 

paleas about as long as the lemmas; anthers 3. Caryopsis oval 

in cross section, translucent; embryos more than 1⁄2 as long as 

the caryopsis. x = 8.
NUMBER 107 • 105

FIGURE 74. Dactylis glomerata. A. Habit. B. Ligule. C. Inflorescence. D. Inflorescence branch. 

E. Spikelet. F. Floret. Drawn by Linda Ann Vorobik and Karen Klitz; copyright Utah State University.
106 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Dasyochloa is a monotypic genus that is endemic to North 

America. It has been included in each of the following genera: 

Munroa, Triodia, Tridens, and Erioneuron.

96. Dasyochloa pulchella (Kunth) Willd. ex Rydb., Agric. Exp. 

Sta. Agric. Colorado Bull. 100: 18, 37. 1906. Triodia pulchella Kunth, Nov. Gen. Sp. (quarto ed.) 1: 155–156, t. 47. 

1815.Tridens pulchellus (Kunth) Hitchc., Fl. Calif. 1: 141. 

1912. Erioneuron pulchellum (Kunth) Tateoka, Amer. J. 

Bot. 48(7): 572. 1961. Munroa pulchella (Kunth) L. D. Amarilla, Darwiniana, n. s. 1(2): 245. 2013. 

FIGURE 76

Culms (1)4–15 cm long, scabrous or puberulent; peduncles 

(internode below the panicles) 3–7(11) cm. Sheaths striate, margins scarious; ligules 3–5 mm long; blades (1)2–6 cm long, abaxial surfaces scabrous, adaxial surfaces scaberulous. Panicles 

1–2.5 cm long, 1–1.5 cm wide, densely white-pubescent, light 

green or purple-tinged. Spikelets (5)6–9(10) mm long, with 

(4)6–10 florets; lower glumes 6–8.5 mm long; upper glumes 

6.5–9 mm long, as long as or longer than the florets; lemmas 

FIGURE 75. Dactyloctenium aegyptium. 

A. Habit. B. Spikelet. C. Floret. D. Caryopsis. Drawn by Linda Ann Vorobik and Karen 

Klitz; copyright Utah State University.

FIGURE 76. Dasyochloa pulchella. A. Habit. B. Spikelet. C. Floret. 

Drawn by Linda Ann Vorobik and Cindy Roché; copyright Utah 

State University.
NUMBER 107 • 107

3–5.5 mm long, lobes (1)3–3.2 mm long, midveins excurrent 

into straight awns (1.5)2.5–4 mm long; paleas 2–3.5 mm long, 

keels long pilose proximally, ciliate distally; anthers 0.2–0.5 mm 

long. Caryopsis 1–1.5 mm long, translucent. 2n = 16.

Distribution and Habitat. Dasyochloa pulchella grows in rocky soils of arid regions. Its range extends from 

the western United States southward to central Mexico. It is the 

most common grass in the Larrea–Flourensia scrub of the Chihuahuan Desert, Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Aldama: NE of Aldama along Chihuahua hwy 16, 15 Sep 

1972, J. Henrickson 7501, 7628 (US). Juárez: 41.2 mi S of 

US–Mexican border on Mex 45, 29 Mar 1971, matorral xerófilo [xerophilous scrub], 1300 m, Harmon, Cox & Dunn 5309

(ENCB); 43.7 mi NE of Aldama along Hwy 16 (km 96.5) in low 

clay roadside ditch, 15 Sep 1972, 1500 m, J. Henrickson 7928

(ARIZ). Ascensión: a los lados de la carr. [sides of hwy] Juárez–

Janos, en los alrededores de la [around] Falla del Camello, área 

de transición de la plataforma del desierto & la depresión [old 

transition between desert platform and depression] del paleo, 

l Aug “Cabeza de Vaca”, 11 Oct 2005, 1180 m, R. Corral, 

M. Vargas & H. Gutiérrez RCD7175 (UACJ). Camargo: 20 km 

S of Cd. Camargo, 2 Aug 1939, 1220 m, L. H. Harvey 1399

(US). Chihuahua: Chihuahua, 3–4 Sep 1935, LeSueur Mex-011

(US); near Chihuahua, 22 May 1885, C.G. Pringle 496 (US); 

13 mi SW of Chihuahua on road to Cuauhtémoc, 6 Oct 1959, 

1585 m, Soderstrom 911 (US); Carr. Chih.–Delicias km 18 entronque [junction] a Mapula, 29 Sep 1995, pastizal [pastureland], 1520 m, Quiñones 98 (MEXU). Coyame: 17 mi ENE de 

Coyame along Hwy 16 at base of limestone hill near Sierra del 

Cuchillo Parado, 16 Sep 1972, matorral, 3400 ft, J. Henrickson 7689 (MEXU). Cuauhtémoc: 16 mi NW of Zavalza, 3 Oct 

1966, Reeder & C. Reeder 4585 (US). Jiménez: Sta Eulalia, 21 

Jul 1885, E. Wilkinson 46 (US); W slope of Sierra de Sta Eulalia, 

18 Aug 1939, L. H. Harvey 1529 (US); 50 km N of Jimenez, 

1 Aug 1939, L. H. Harvey 1364 (US); along hwy 49 ca. 167 km 

N of Gómez Palacio, 25 Sep 2004, 1279 m, R.M. King & R.M. 

Garvey 13468 (CIIDIR). Juárez: 41.2 mi S of US–Mexican border on Mex 45, 29 mar 1971, 4325 ft, W.E. Harmon & Dunn 

5309 (ENCB); 14.5 mi S of Samlayuca along Hwy 45, ca 46 

mi S of Cd Juárez, 20 Aug 1971, 1300 m, J. Henrickson 5793

(NMC); km 32 Juárez, 13 Oct 1997, matorral de gobernadora 

[governor’s scrub], I. Enríquez, S. Ordoñez & J. Leyva IEA2 

(UACJ). Matamoros: 19.3 km S of Villa Matamoros on hwy 

45 to Durango, 27 Sep 1988, grassland, 1800 m, P.M. Peterson 

& Annable 5978 (ENCB, US). Meoqui: Cerca de [near] Felipe 

Ángeles, 31 Jul 1976, matorral de Larrea–Fouquieria–Cassia, 

1330 m, S. González & J.M. Peña 391 (ENCB). Nuevo Casas 

Grandes: 27.4 km S of Nuevo Casa Grandes on Mex 2, 28 Sep 

1989, oak woods, 1585 m, P.M. Peterson & R.M. King 8145

(ENCB, MEXU). Valle de Zaragoza: 58 km N of Parral on Mex 

24 towards Chihuahua, 14 Sep 1989, grassland, 1500 m, P.M. 

Peterson & Annable 8094 (ENCB).

Deschampsia P. Beauv.

Plants usually perennial, some annual; caespitose or tufted. 

Culms 5–140 cm tall, hollow, erect. Leaves mainly basal, often 

forming a dense tuft; sheaths open; ligules membranous, decurrent, rounded to acuminate; blades often all or almost all tightly 

rolled or folded and some flat, sometimes most flat. Inflorescences 

terminal panicles, open or contracted, disarticulation above the 

glumes, beneath the florets. Spikelets 3–9 mm long, with 2(3) florets in all or almost all spikelets, florets usually bisexual, sometimes viviparous; rachillas hairy, usually prolonged more than 

0.5 mm beyond the base of the distal floret, sometimes terminating in a highly reduced floret. Glumes subequal to unequal, 

usually exceeding the adjacent florets, often exceeding all florets, 

1- or 3-veined, acute to acuminate; calluses antrorsely strigose; 

lemmas obscurely (3)5- to 7-veined, rounded over the back, apex 

truncate-erose to 2- to 4-toothed, awned, awns usually attached 

on the lower 1⁄2 of the lemmas, occasionally subapical, straight 

to strongly geniculate, slightly to strongly twisted proximally, 

straight distally; paleas shorter than the lemmas, 2-keeled, keels 

often scabrous; lodicules 2, lanceolate to ovate-lanceolate, usually entire; anthers 3; ovaries glabrous; styles 2. Caryopsis oblong; embryos about 1⁄4 the length of the caryopsis. x = 7. 

Deschampsia includes 20–40 species. It is best represented 

in the Americas and Eurasia and grows in cool, damp habitats 

throughout the world. Two species are native to Chihuahua.

KEY TO SPECIES OF DESCHAMPSIA

1. Plants annual; leaves not forming a basal tuft; awns 4–9 mm long, strongly geniculate . . . . . . . . . . . . . D. danthonioides

1. Plants perennial; leaves sometimes forming a basal tuft; awns 1.5–5.5(6) mm long, straight to slightly geniculate . . . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. elongata

97. Deschampsia danthonioides (Trin.) Munro, Pl. Hartw. 342. 

1857.

FIGURE 77

Annual. Culms 10–40(70) cm tall, erect. Leaves not forming a basal tuft; ligules (0.5)2–3(4.7) mm long, acute to acuminate, entire; blades 0.3–1.5 mm wide, involute or flat. Panicles 

5–15(25) cm long, 2–8 cm wide, contracted to open, erect; 

branches with the spikelets confined to the distal portion. Spikelets 4–9 mm long, bisexual, narrowly V-shaped, usually pale 

green; glumes exceeding the distal florets, glabrous to scaberulous, 3-veined; lower glumes 4–9 mm long; upper glumes 3.5–

8.5 mm long; callus hairs 0.4–1.6 mm long; lemmas 1.5–3 mm 

long, smooth, shiny, glabrous, pale green or purplish, apex blunt, 
108 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

erose to 4-toothed, ciliate, the awns 4–9 mm long, attached from 

near the base to about the middle of the lemmas, strongly geniculate, geniculate above the lemma apex, distal segment 1.5–5 mm 

long; anthers 0.3–0.5 mm long. 2n = 26.

Distribution and Habitat. Deschampsia danthonioides grows in temperate and cool-temperate regions, usually in open, wet to dry habitats and often in disturbed ground. 

Its primary range extends from southern British Columbia to 

Washington and Idaho, south to Baja California, Mexico. The 

species has recently been collected in Chihuahua. It also occurs, 

as a disjunct, in Chile and Argentina. 

Specimens Examined. MEXICO. Chihuahua. 

Gómez Farías: Laguna de Babicora, 18 Aug 1994, 2150 m, 

T. Lebgue & E. Estrada 3324 (NMC). 

98. Deschampsia elongata (Hook.) Munro, Pl. Hartw. 342. 1857.

FIGURE 78

Plants perennial; densely caespitose. Culms (10)30–120 cm 

tall. Leaves sometimes forming a basal tuft; sheaths glabrous; 

ligules 2.5–8(9) mm long, acute to acuminate; blades 7–30 cm 

long, 0.2–2 mm wide, usually involute. Panicles 5–30(35) cm 

long, 0.5–1.5(2) cm wide, erect or nodding; branches erect 

to ascending. Spikelets 3–6.7 mm long, bisexual, narrowly 

V-shaped, appressed to the branches; glumes equaling or exceeding the florets, narrowly lanceolate, usually pale green, 

sometimes purple-tipped, 3-veined, acuminate; lower glumes 

(3)3.2–5.5(6.7) mm long; upper glumes (3)3.1–5.4(6) mm 

long; callus hairs 0.3–1.15 mm long; lemmas 1.7–4.3 mm long, 

smooth, shiny, glabrous, apex weakly toothed or erose, awns 

1.5–5.5(6) mm long, straight to slightly geniculate, attached 

from slightly below to slightly above the middle of the lemma, 

exceeding the florets by 1–2.5 mm; anthers 0.3–0.5(0.7) mm 

long. 2n = 26.

Distribution and Habitat. Deschampsia elongata grows in moist to wet habitats from near sea level to alpine 

elevations from Alaska and the Yukon south to northern Mexico 

and east to Montana, Wyoming, and Arizona. It also grows as a 

disjunct in Chile. 

Specimens Examined. MEXICO. Chihuahua. 

Ocampo: Parque Nacional “Cascada de Basaseachic,” 25 Abr 

[Apr] 1986, 1700 m, Spellenberg, R. Soreng, R. Corral & 

T. Lebgue 8474 (NMC).

Dichanthelium (Hitchc. & Chase) Gould

Perennial; caespitose, sometimes rhizomatous, sometimes 

with hard, cormlike bases, often with basal winter rosettes of 

leaves having shortly ovate to lanceolate blades, these often 

sharply distinct from the blades of the cauline leaves. Culms herbaceous, hollow, usually erect or ascending, rarely sprawling, in 

the spring often spreading; branches rebranching 1–4 times. Cauline leaves 3–14, usually distinctly longer and narrower than the 

rosette blades; ligules of hairs, membranous, ciliate, sometimes 

FIGURE 77. Deschampsia danthonioides. A. Habit. B. Spikelet. 

C. Floret. Drawn by Cindy Roché; copyright Utah State University.
NUMBER 107 • 109

absent; pseudoligules of 1–5 mm hairs often present at the bases 

of the blades immediately behind the true ligules; blades usually 

distinctly longer and narrower than those of the basal rosette. Inflorescence panicles, terminal on the culms and branches; sterile 

branches and bristles absent; disarticulation below the glumes. 

Spikelets 0.8–5.2 mm long, not subtended by bristles, dorsally 

compressed, surfaces unequally convex, apex unawned. Glumes 

apex not or only slightly gaping at maturity; lower glumes 1⁄5–3⁄4

as long as the spikelets, 1- to 5-veined, truncate, acute, or acuminate; upper glumes slightly shorter than the spikelets or exceeding the upper florets by up to 1 mm long, 5- to 11-veined, not 

saccate, apex rounded to attenuate. Lower florets sterile or staminate; lower lemmas similar to the upper glumes; lower paleas 

sometimes present, thin, shorter than the lower lemmas; upper 

florets bisexual, sessile, plump, usually apiculate to mucronate, 

sometimes minutely so, or subacute to (rarely) acute; upper lemmas striate, chartaceous-indurate, shiny, usually glabrous, margins involute; upper paleas striate; anthers 3. Caryopsis smooth; 

pericarp thin. x = 9.

Dichanthelium is a genus of approximately 62 species, 2 of 

which are present in Chihuahua. It is often included in Panicum 

sensu lato, the two taxa being similar in gross morphology.

KEY TO SPECIES OF DICHANTHELIUM

1. Spikelets 2.7–4.2 mm long; blades basally narrow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. oligosanthes

1. Spikelets 1.4–1.8 mm long; blades basally chordate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. sphaerocarpon

99. Dichanthelium oligosanthes (Schult.) Gould, Brittonia 

26(1): 60. 1974. Panicum oligosanthes Schult., Mant. 2: 

256. 1824.

Plants caespitose, with caudices. Basal rosettes welldifferentiated; blades 2–6 cm long, few, ovate to lanceolate. 

Culms 20–75 cm tall, geniculate basally, stiffly erect distally; 

nodes glabrous or sparsely pubescent; internodes often purplish, 

glabrous, puberulent, or papillose-hirsute; fall phase branching 

from the midculm nodes, branches initially ascending to erect, 

sometimes developing simultaneously with and overtopping the 

primary panicles, later rebranching to form short, bushy clumps 

of blades and small, included secondary panicles. Cauline leaves 

5–7; sheaths not overlapping, glabrous, puberulent, or ascending papillose-hispid, margins ciliate, collars loose, puberulent; 

ligules 1–3 mm long, of hairs; blades 5–12 cm long, 4–15 mm 

wide, flat or partly involute, glabrous or pubescent abaxially, 

with 7–9 major veins only slightly more prominent than the 

minor veins, bases ciliate, rounded to truncate, margins cartilaginous. Primary panicles 5–9 cm long, 3–6 cm wide, partly 

enclosed to long-exserted, with 6–60 spikelets; branches stiff 

or wiry, puberulent or scaberulous. Spikelets 2.7–4.2 mm long, 

1.7–2.4 mm wide, ellipsoid to broadly obovoid, turgid, glabrous 

or sparsely pubescent; lower glumes 1–1.6 mm long, acute, similar in texture and vein prominence to the upper glumes; upper 

glumes strongly veined, often orange to purplish at the base; 

lower florets sterile; upper florets with minutely umbonate apex. 

2n = 18.

Distribution and Habitat. Dichanthelium 

oligosanthes grows throughout the southern United States and 

extends into northern Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Bocoyna: Divisadero Overlook of Cascada de Basaseachic, on 

trail below overlook, 23 Jun 1987, 2100 m, T.R. Van Devender, 

R.K. Van Devender, P.S. Martin 87–151 (NMC). Ocampo: 

Parque Nacional “Cascada de Basaseachic,” in the barranca 

[canyon] at the base of the falls, 11 Nov 1989, 1700 m, Spellenberg, R. Corral, T. Lebgue & M. Mahrt 10073 (CIIDIR, NMC); 

100. Dichanthelium sphaerocarpon (Elliott) Gould, Brittonia 

26(1): 60. 1974. Panicum sphaerocarpon Elliott, Sketch 

Bot. S. Carolina 1(2): 125. 1816.

Plants caespitose. Basal rosettes well-differentiated; blades 

2–6 cm long, about 1 cm wide, ovate, the uppermost leaves 

often resembling the lower cauline blades. Culms 15–50 cm tall, 

few together, decumbent or ascending, light green, glabrous, 

slightly fleshy or thickened; fall phase branching mostly near 

the bases, with sparse branching; nodes appressed-pubescent 

or glabrous. Cauline leaves 3–4(6); sheaths sometimes overlapping near the bases, glabrous, margins ciliate; ligules almost 

obsolete, or of 0.2–0.8 mm hairs from a tiny membranous 

base; blades 1.5–10 cm long, 5–14 mm wide, thick, light green, 

faintly veined, bases cordate, with papillose-based cilia, margins white, cartilaginous. Primary panicles 4–14 cm long, more 

than 1⁄2 as wide as long, usually long-exserted. Spikelets 1.4–1.8 

mm long, broadly obovoid-spherical, usually puberulent, sometimes glabrous; lower glumes 0.4–0.8 mm long, acute to obtuse; upper florets 1.1–1.5 mm long, broadly ellipsoid, blunt. 

2n = 18.

Distribution and Habitat. Dichanthelium 

sphaerocarpon grows in dry, open woods and roadsides. Its range 

extends from eastern North America to Ecuador and Venezuela.

Specimens Examined. MEXICO. Chihuahua. 

Ocampo: Cascadas de Basaseachic, 6 Jul 1936, LeSueur Mex0105 (US); Parque Nacional “Cascada de Basaseachic,” 0.5 km 

up the Rio Durazno from the camp area near the parking lot 

at the head of the falls, 1 Aug 1988, 2000 m, Spellenberg, 

R. Corral, J Brunt & L. Huenneke 9644 (NMC); Parque Nacional “Cascada de Basaseachic,” in the barranca [canyon] at the 

base of the falls, 11 Nov 1989, 1700 m, Spellenberg, R. Corral, 

T. Lebgue & M. Mahrt 10072 (NMC).

Dichanthium Willem.

Annual or perennial; caespitose, sometimes with extensive creeping stolons. Leaves usually not aromatic; ligules 
110 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

membranous, sometimes ciliate. Inflorescence terminal, sometimes also axillary but the axillary inflorescences not numerous; 

peduncles with 1 to many rames in digitate or subdigitate clusters; rames sometimes naked basally, axes terete to slightly flattened, without a translucent, longitudinal groove, bearing 1 to 

many sessile-pedicellate spikelet pairs and a terminal triplet of 

1 sessile and 2 pedicellate spikelets, basal pair(s) homomorphic 

and homogamous, staminate or sterile, unawned, persistent, distal spikelet pairs homomorphic but heterogamous, sessile spikelets bisexual and awned, pedicellate spikelets staminate or sterile 

and unawned; disarticulation in the rames, beneath the bisexual 

sessile spikelets. Sessile spikelets often imbricate, dorsally compressed, with blunt calluses; lower glumes chartaceous to cartilaginous, broadly convex to slightly concave, sometimes pitted; 

lower florets reduced, sterile; upper florets sterile or staminate 

and unawned in the homogamous pairs, bisexual and awned in 

the heterogamous pairs; awn usually glabrous; anthers (2)3. Pedicels free of the rame axes, terete to somewhat flattened, slender, 

not grooved. Pedicellate spikelets sterile or staminate. x = 10. 

Dichanthium, a genus of 20 species, grows in habitats ranging from subdeserts to marshlands in tropical Asia and Australia. 

Introduced in America.

101. Dichanthium annulatum* (Forssk.) Stapf, Fl. Trop. Afr. 

9: 178. 1917. Andropogon annulatus Forssk., Fl. AegyptArab. 173. 1775.

Perennial; stoloniferous. Culms to 100 cm tall, decumbent, 

erect portions generally to 60 cm long, often branched above 

the bases, glabrous beneath the inflorescences; nodes glabrous or 

short-pubescent. Sheaths glabrous; ligules 1–1.8 mm long, truncate; blades 3–30 cm long, 2–7 mm wide, scabrous, sparsely pilose, hairs sometimes papillose-based. Rames 2–9, 2.5–7 cm long, 

subdigitate, erect to ascending, bases without spikelets, glabrous, 

internodes ciliate on the margins. Sessile spikelets 2.5–5 mm long, 

1–1.5 mm wide; lower glumes elliptic or oblong, sparsely pubescent below, apex obtuse, irregularly 2- to 3-toothed, 5- to 9-veined; 

upper glumes 3-veined; awns 1.3–2.2 cm long, twice-geniculate. 

Pedicellate spikelets 2.5–5 mm long, usually staminate. 2n = 20, 40.

Distribution and Habitat. Dichanthium annulatum is native to southeastern Asia and is a highly esteemed 

forage grass, especially in India. It is now established at scattered 

locations in northern Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000) and Herrera Arrieta and 

Cortés Ortiz (2010).

Digitaria Haller

Annual, perennial, or of indefinite duration. Culms erect or 

decumbent, branching basally or at aerial culm nodes, when annual or of indefinite duration usually decumbent and rooting at 

the lower nodes. Sheaths open; ligules membranous, sometimes 

ciliate; blades usually flat. Inflorescences terminal, sometimes 

also axillary, usually panicles of 1-sided spikelike branches 

(sometimes only 1 branch) attached digitately or racemosely 

to a rachis, sometimes simple panicles of solitary, pedicellate 

spikelets; spikelike branches, if present, sometimes with secondary branches, primary branch axes triquetrous, bearing spikelets 

abaxially, in 2 rows, usually in unequally pedicellate groups of 

2–5, occasionally borne singly. Spikelets lanceoloid to ellipsoid, 

dorsally compressed, apex obtuse to acuminate, unawned, with 

2 florets; disarticulation beneath the glumes. Lower glumes absent or to 1⁄4 as long as the spikelets; upper glumes usually from 

1⁄6 as long as to equaling the spikelets, occasionally absent, 0- to 

5-veined, usually pubescent; lower florets sterile; lower lemmas 

membranous, usually as long as the upper lemmas, usually pubescent, (3)5- to 7(13)-veined; lower paleas absent or reduced; 

upper lemmas mostly stiffly chartaceous to cartilaginous, obscurely veined, with hyaline margins that embrace the upper 

paleas; upper paleas similar to the upper lemmas in texture and 

size; lodicules 3, cuneate; anthers 3. Caryopsis plano-convex; 

embryos 1⁄5–1⁄2 as long as the caryopsis; hila punctiform to ellipsoid. x = 9. 

Digitaria has approximately 200 species and grows primarily in tropical and warm-temperate regions, often in disturbed, 

open sites.

KEY TO SPECIES OF DIGITARIA

1. Inflorescence a diffuse panicle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. cognata

1. Inflorescence with 2 or several spiciform branches.

2. Spikelets densely silky-pilose, pubescence white or coppery brown; inflorescence a dense racemose panicle. 

3. Lower lemmas pubescent between most, sometimes all, of the veins and on the margin, the hairs 3–6 mm long, golden 

brown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. insularis

3. Lower lemmas glabrous between the veins, pubescent on the margins, sometimes also on the lateral veins, the hairs 

1.5–5 mm long, silvery-white to purple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. californica

2. Spikelets glabrous or with a row of hairs between the veins, but never silky-pilose; inflorescence digitate or subdigitate 

on the culm axis.

4. Lemma of the bisexual floret light or dark brown to black when mature; blades and sheaths glabrous, pubescent or 

papillose-pilose. 

5. Spikelets sparsely to densely pubescent with clavate to capitate hairs; rachis triquetrous, not wing-margined; pedicels glabrous or sparsely pubescent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. filiformis
NUMBER 107 • 111

5. Spikelets densely pubescent over the veins, hairs not clavate to capitate; rachis shortly winged; pedicels with a ring 

of stiff hairs just below the spikelets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. ternata

4. Lemma of the bisexual floret light gray or straw-colored when mature; blades essentially glabrous and sparsely 

papillose-hirsute especially near the collar, in contrast with the always papillose-pilose sheaths.

6. Sterile lemmas of the inferior spikelets with 5 equidistant veins; sterile lemmas of the pedicellate spikelets strongly 

ciliate, the hairs divergent at maturity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. bicornis

6. Sterile lemma of the inferior spikelets with notably wider spaces at the interveins nearer to the midvein than lateral 

ones; sterile lemmas of the pedicellate spikelets glabrous without any hairs.

7. Marginal veins of the inferior lemma scabrous; inflorescence branches verticillately inserted, branch rachis 

winged . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. sanguinalis

7. Marginal veins of the inferior lemma glabrous or nearly glabrous; inflorescence branches racemosely inserted, 

branch rachis not winged . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. ciliaris

102. Digitaria bicornis (Lam.) Roem. & Schult., Syst. Veg. 2: 

470. 1817.

FIGURE 79

Plants of indefinite duration; sometimes stoloniferous. 

Culms with erect portion 10–85 cm tall, long-decumbent, 

rooting and branching at the lower nodes. Sheaths with 

papillose-based hairs or the upper sheaths glabrous; ligules 

1–4 mm long; blades 3–14 cm long, 2–9 mm wide, mostly 

glabrous but the adaxial surfaces with papillose-based hairs 

basally. Panicles with (2)3–6 spikelike primary branches, these 

digitate or a few solitary branches below; lowest nodes glabrous or with hairs less than 0.4 mm; primary branches 6.5–

21 cm long, 0.6–1.3 mm wide, axes winged, wings at least 1⁄2

as wide as the midribs, lower and middle portions with spikelets in unequally pedicellate pairs, pedicels not adnate to the 

branches; secondary branches absent; shorter pedicels about 

0.2 mm; longer pedicels to 2 mm. Spikelets 2.6–3.7 mm long, 

spikelet pairs dimorphic in their pubescence and venation pattern of the lower lemmas. Lower glumes absent or to 0.9 mm 

long, deltoid or bifid; upper glumes 1.7–2.8 mm long, 1⁄2–3⁄4 as 

long as the spikelets, 3-veined; lower lemmas 7-veined, veins 

smooth; lower lemmas of shortly pedicellate spikelets with 3 

equally spaced, glabrous or shortly pubescent central veins, 

lemma margins and the region between the 2 lateral veins 

with appressed or spreading 0.5–1 mm hairs; lower lemmas 

of long-pedicellate spikelets with unequally spaced veins, 

midvein well-separated from the 3 lateral veins, lateral veins 

crowded together near the margins, lemma margins and the 

region between the 2 inner lateral veins hairy with appressed 

or strongly divergent hairs 1–2 mm long, sometimes also with 

longer, glassy yellow hairs; upper lemmas of all spikelets usually yellow or gray, sometimes light brown at maturity; anthers 

0.5–0.6 mm long. 2n = 54, 72.

Distribution and Habitat. Digitaria bicornis

is a common species on the sandy coastal plain of the southeastern United States. Its range extends through Mexico to Costa 

Rica and northern South America and to the West Indies.

Specimens Examined. MEXICO. Chihuahua. 

Ocampo: ca 1 km W of W boundary of Parque Nacional “Cascada de Basaseachic,” 13 km from the Cahuisori–Ocampo road 

on the road to Candamena, 2.25 km below Cruz, 23 Sep 1994, 

1570 m, Spellenberg, Corral & Estrada 12147 (NMC).

103. Digitaria californica (Benth.) Henrard, Blumea 1(1): 99. 

1934. Panicum californicum Benth., Bot. Voy. Sulphur 55. 

1840.

FIGURE 80

Perennial; caespitose, neither rhizomatous nor stoloniferous. Culms 40–100 cm tall, erect, sometimes geniculate, not 

rooting, at the lower nodes. Basal sheaths villous; upper sheaths 

glabrous, densely villous or densely tomentose, or sparsely to 

densely hairy, with papillose-based hairs; ligules (1)1.5–6 mm 

long, entire or lacerate, not ciliate; blades 2–12(18) cm long, 

2–5(7) mm wide, glabrous or the adaxial surfaces sparsely to 

densely villous or tomentose. Panicles with 4–10 spikelike primary branches on 5–10 cm rachises, rarely with secondary 

branches; primary branches 3–6 cm long, appressed to ascending, axes not wing-margined; internodes (mid branch) 2–5.5 mm 

long, with spikelets in unequally pedicellate pairs; secondary 

branches rarely present; pedicels not adnate to the branch axes; 

shorter pedicels 0.1–0.3 mm; longer pedicels 1–2 mm; terminal 

pedicels of branches 1.7–6(7) mm long. Spikelets homomorphic, 

(3.7)4–7.5 mm long (including pubescence), 3–5.4 mm long (excluding pubescence), 0.9–1 mm wide; lower glumes 0.4–0.6 mm 

long; upper glumes 2.5–5.1 mm long (excluding pubescence), 

narrower than the upper florets, 3-veined, densely villous, hairs 

1.5–5 mm long, silvery-white to purple, widely divergent at maturity; lower lemmas 2.7–5 mm long (excluding pubescence), 

pubescence exceeding the upper florets by 2.2–4 mm, glabrous 

between the veins, pubescent on the margins, sometimes also on 

the lateral veins, 7-veined, veins unequally spaced, only the 3 or 

5 central veins visible, the hairs 1.5–5 mm long, silvery-white 

to purple, widely divergent at maturity, intercostal regions glabrous, apex attenuate (acuminate); upper lemmas 2.5–3.4 mm 

long, ovate-lanceolate, brown to dark brown, acuminate. Caryopsis 1.3–2 mm long. 2n = 36, 54, 70, 72.

Distribution and Habitat. Digitaria californica grows on plains and open ground from Arizona, southern 

Colorado, and Oklahoma through Mexico and Central America 

to South America.
112 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

FIGURE 78. Deschampsis elongata. A. Habit. 

B. Spikelet. C. Florets. Drawn by Cindy Roché; 

copyright Utah State University.

FIGURE 79. Digitaria bicornis. A. Habit. B. Culm 

and inflorescence. C. Inflorescence branch. Drawn 

by Linda Ann Vorobik and Hana Pazdírková; 

copyright Utah State University.
NUMBER 107 • 113

Specimens Examined. MEXICO. Chihuahua. 

Aldama: Santo Domingo, 50 km SW of Coyame of Mex 16 between Presidio, Texas and Chihuahua, 22 Sep 1988, 1400 m, 

P.M. Peterson & Annable 5754 (US). Allende: 20 mi N from 

Parral to Jiménez on hwy 45, 21 Jul 2006, grassland, 1750 m, 

K.R. Adams & N. Martínez 061-2006 (CIIDIR). Ahumada: 

Cañón de Santa Clara, 90 km al N de Chihuahua, 19 Oct 1974, 

1700 m, Rzedowski 32371 (ENCB); aprox. 25 km al N del poblado [village] Flores Magón, 7 Oct 1995, 1140 m, R. Corral, 

P. Olivas & J.O. Torres RCD6456 (UACJ). Batopilas: SW of 

Chihuahua, Aug 1885, E. Palmer 207 (US). Buenaventura: 6 mi 

E of Buenaventura, 2 Sep 1978, 1768 m, Reeder & C. Reeder 

3198 (ENCB, US). Camargo: 20 km S of Cd. Camargo, 2 Aug 

1939, L. H. Harvey 1390 (US). Casas Grandes: El Alamito, Col. 

Cuauhtémoc, 12 Aug 1999, P. Olivas, R. Rivas, I. Enríquez & 

A. Márquez POS 837 (UACJ). Chihuahua: near Chihuahua, 23 

Aug 1885, C.G. Pringle 494 (US); 10 Oct 1935, LeSueur Mex077 (US); 14 Oct 1910, Hitchcock 7791 (US); 5–10 Jun 1908, 

E. Palmer 343 (US); La Campana; 1 km Pte. carr. [hwy] Panamericana, 16 Sep 76, pastizal mediano abierto [mostly open 

grassland], 1500 m, Valdés-Reyna VR-311 (RELC). Hidalgo del 

Parral: 4 mi S of Parral, 1950 m, Soderstrom 835-A (US). Janos: 

Chihuahua–Sonora Border, Rancho Carretas, 27 Aug 1937, 1460 

m, L. H. Harvey 1619 (ENCB, US); Rancho El Carrizo, 30 Sep 

1982, 1600 m, pastizal mediano abierto, P. Rojas s.n. (CIIDIR). 

Jiménez: 50 km N of Jiménez, 1 Aug 1939, 1270 m, L.H. Harvey 

1374 (US). Juárez: km 32 Juárez–Chih., 13 Oct 1997, matorral 

de gobernadora [governor’s scrub], I. Enríquez, S. Ordoñez & 

J. Leyva IEA6 (UACJ). Manuel Benavides: E Chihuahua, Coalhuila Boundary, 1 mi E of Pozo de Villa, along rd from Ojinaga 

to Castillon, via La Mula, Trincheras, 12 Aug 1941, I.M. Johnston 8173 (US). Meoqui: Cerca [near] de Felipe Angeles, 31 Aug 

1976, matorral, 1280 m, S. González 386 (RELC).

104. Digitaria ciliaris (Retz.) Koeler, Descr. Gram. 27. 1802. 

Panicum ciliare Retz., Observ. Bot. 4: 16. 1786.

FIGURE 81

Annual or of indefinite duration. Culms 10–100 cm tall, 

erect portion 30–60 cm long, long-decumbent, rooting and 

branching at the decumbent nodes, sparingly branched or unbranched from the upper nodes; nodes 2–5, glabrous. Sheaths 

with papillose-based hairs; ligules 2–3.5 mm long, erose; blades 

1.5–14.4(18.9) cm long, 3–9 mm wide, flat, glabrous, a few scattered papillose-based hairs at the base of the adaxial surfaces 

(occasionally over the whole adaxial surface), usually also scabrous on both surfaces. Panicles with 2–10 spikelike primary 

FIGURE 80. Digitaria californica. A. Habit. B. Leaf blades. C. Spikelet showing lower 

glume and lower lemma. D. Spikelet showing upper glume. Drawn by Linda Ann Vorobik 

and Hana Pazdírková; copyright Utah State University.
114 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

branches, these digitate or in 1–3 whorls on rachises to 2 cm; 

lowest panicle nodes with hairs more than 0.4 mm; primary 

branches 3–24 cm long, 0.6–1.2(2) mm wide, glabrous or with 

less than 1 mm hairs, axes wing-margined, wings at least 1⁄2 as 

wide as the midribs, lower and middle portions of the branches 

with spikelets in unequally pedicellate pairs; secondary branches 

absent; shorter pedicels 0.5–1 mm; longer pedicels 1.5–4 mm. 

Spikelets (2.7)2.8–4.1 mm long, homomorphic; lower glumes 

0.2–0.8 mm long, acute; upper glumes (1.2)1.5–2.7 mm long, 

about 2⁄3 to almost as long as the spikelet, 3-veined, margins and 

apex pilose; lower lemmas 2.7–4.1 mm long, 7-veined, veins unequally spaced, outer 3 veins crowded together near each margin, 

well-separated from the midvein, usually smooth, occasionally 

the lateral veins scaberulous on the distal 1⁄3, margins and regions 

between the 2 inner lateral veins hairy, hairs 0.5–1 mm long 

(rarely glabrous), sometimes also with glassy yellow hairs between the 2 inner lateral veins, these more common on the upper 

spikelets; upper lemmas 2.5–4 mm long, glabrous, yellow, tan, 

or gray when immature, becoming brown, often purple-tinged 

(occasionally completely purple) at maturity; anthers 0.6–1 mm 

long. 2n = 54.

Distribution and Habitat. Digitaria ciliaris is 

a weedy species, found in open, disturbed areas in most warmtemperate to tropical regions, primarily in the eastern United 

States and Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: SW Chihuahua, Aug 1885, E. Palmer 110F (US); 

Yamuco, 1 mi E of hwy N of Rio Urique crossing, towards Basihuare and Creel, 6 Sep 2008, slopes with pines and oaks, 1890 

m, P.M. Peterson & J.M. Saarela 22073 (US). Bocoyna: Barrancas del Cobre, camino [road] a alto río Urique, por Estación Divisadero, 16 Aug 1976, bosque bajo de leguminosas [low legume 

forest], 1975 m, S. González & J.M. Peña 707 (RELC). Camargo: Cd. Camargo, 1 Aug 1939, L. H. Harvey 1381 (US); Rio 

Conchos, d. Camargo, 5 Aug 1939, 1220 m, L. H. Harvey 1415 

(US). San Francisco de Conchos: about 1 mi E of Boquilla Reservoir, 6 Oct 1966, 4200 ft, Reeder & C. Reeder 4604 (ARIZ, 

ENCB). Madera: Mesa del Yerbanís, ejido El Largo, 12 Oct 

1990, bosque de Quercus, 1900 m, O. Bravo 1824 (CIIDIR). 

Riva Palacio: Col. Cumbres de Majalca, 33.8 km W of Mex 45, 

N of Chihuahua City, 7 Sep 1989, pine forest, 2190 m, P.M. 

Peterson, Annable & Y. Herrera 7948 (ENCB, US).

105. Digitaria cognata (Schult.) Pilg., Nat. Pflanzenfam. (ed. 2) 

14e: 50. 1940. Panicum cognatum Schult., Mant. 2: 235. 

1824. Leptoloma cognata (Schult.) Chase, Proc. Biol. Soc. 

Washington 19(34): 192. 1906. 

Perennial; caespitose, without rhizomes. Culms 30–56 cm 

tall, erect; nodes glabrous. Leaves mainly cauline; sheaths 

glabrous or sparsely to densely pubescent, sometimes with 

papillose-based hairs; ligules 0.2–1.5 mm long, entire to lacerate; blades 2.4–12.6 cm long, 2–5.4 mm wide, glabrous or 

pubescent. Panicles simple, 12.8–27.5 cm long, 16.5–44.5 cm 

wide, open; branches divergent; lower primary branches 

10.5–24 cm long, often with 1 to several sterile branches near 

the base; pedicels divergent, spikelets solitary. Spikelets 2.2–

3.1 mm long, 0.7–1.1 mm wide, obovate or broadly elliptic; 

lower glumes 0.1–0.8 mm long; upper glumes 1.8–2.8 mm 

long, 3(5)-veined, glabrous or pubescent between the veins, 

hairs appearing as a narrow stripe; lower lemmas similar to 

the upper glumes in length, texture, and pubescence, 7-veined, 

FIGURE 81. Digitaria ciliaris. A. Habit. B. Spikelet showing upper 

glume and upper lemma. C. Spikelet showing lower glume and 

lower lemma. Drawn by Linda Ann Vorobik and Hana Pazdírková; 

copyright Utah State University.
NUMBER 107 • 115

veins unequally spaced, lateral veins closer together than the 3 

central veins; upper lemmas 1.9–2.9 mm long, glabrous, dark 

brown, narrowly acute; anthers 0.5–0.7 mm long, yellow or 

purple. Caryopsis 1.3–1.6 mm long. 2n = 36.

Distribution and Habitat. Digitaria cognata grows in dry, sandy soils in the eastern portion of Canada 

through the United States and to southern Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: near Chihuahua, 23 Aug 1885, C.G. Pringle 489 

(US); La Campana Experimental Station and Rancho El Arco 

Iris, about 81–84 km along the Pan American hwy to Chihuahua 

City. cattle pastures, June 1977, J.K. Meents & W.H. Moir 146

(ENCB); La Campana; Potrero la Sierra, 1 km W Carr. [hwy] 

Panamericana, 31 Aug 1973, pastizal mediano abierto [mostly 

open grassland], 1500 m, Valdés-Reyna VR-51 (RELC). Juárez: 

ca 23 (air) mi S of Cd. Juarez, Sierra Presidio 2.3 mi up road 

towards Microondas [microwave] Presidio, 11 Sep 1973, 1450 

m, J. Henrickson 12795 (NMC); La Campana Experimental Station and Rancho El Arco Iris, 81–84 km along Pan American 

Hwy to Chihuahua City, Oct 1977, J.K. Meents & W.H. Moir 

76 (NMC).

106. Digitaria filiformis (L.) Koeler, Descr. Gram. 26. 1802. 

Panicum filiforme L., Sp. Pl. 57. 1753.

Annual, or short-lived perennial; caespitose, not rhizomatous. Culms (10)25–150 cm tall, erect or decumbent, branching, sometimes rooting at the lower nodes; nodes 3–6. Sheaths 

keeled, basal sheaths usually with papillose-based hairs, rarely 

glabrous; ligules 0.3–1.5 mm long; blades 2–18 cm long, 1–6 mm 

wide, flat or involute, glabrous, scabrous, or pilose. Panicles with 

2–7 spikelike primary branches, these digitate or subdigitate, the 

rachises to 1 cm in length; longest primary branches 3–25 cm 

long, 0.2–0.4 mm wide, axes triquetrous, not wing-margined, 

with spikelets in groups of 2–5 on the lower and middle portions; pedicels glabrous or sparsely pilose. Spikelets 1.3–2.8 mm 

long; lower glumes to 0.1 mm long or absent; upper glumes 

1–2 mm long, from 3⁄4 to almost as long as the spikelets, almost 

glabrous or sparsely to densely pubescent with clavate to capitate hairs (use 20× magnification), glume apex rounded; lower 

lemmas equaling the spikelets, glabrous or glandular-pubescent, 

5- to 7-veined, veins unequally spaced, outer 3 veins on each side 

closer to each other than the midvein is to the inner lateral veins; 

upper lemmas 1.3–2 mm long, apiculate, dark brown at maturity; anthers 0.3–0.6 mm long. 2n = 36, 54.

Distribution and Habitat. Digitaria filiformis

grows throughout the warmer parts of the eastern United States 

extending into Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Guachochi: 37.4 km S of Creel on road to Batopilas, 10 Sep 

1989, pine forest, 2045 m, P.M. Peterson, Annable & Y. Herrera 

8012 (ENCB, US); 5.5 mi S of Cienegulta de Barranca on road 

towards Sorichique, 5 Sep 2003, bosque de pino–encino [pine–

oak forest], 2125 m, P.M. Peterson & P. Catalán 17703 (US). 

Guerrero: near Guerrero, 9 Oct 1887, C.G. Pringle 1405 (US).

107. Digitaria insularis (L.) Fedde, Just’s Bot. Jahresber. 31(1): 

778. 1904. Andropogon insularis L., Syst. Nat. (ed. 10) 2: 

1304. 1759. 

Perennial; caespitose, short rhizomatous, with knotty bases. 

Culms 80–130 cm tall, erect, with densely villous cataphylls, 

branching from the lower and middle nodes. Sheaths usually 

sparsely to densely papillose-hirsute, occasionally glabrous; ligules 

4–6 mm long, usually lacerate, not ciliate; blades 20–50 cm long, 

10–17 mm wide, lax, smooth or scaberulous abaxially, scaberulous to scabrous adaxially. Panicles 20–35 cm long, 2–10 cm wide, 

with numerous spikelike primary branches; primary branches 

10–15 cm long, appressed to ascending at maturity, axes not 

wing-margined or with wings less than 1⁄2 as wide as the midribs; 

internodes 3–4.5(6) mm (mid branch), with spikelets in unequally 

pedicellate pairs; secondary branches rarely present; pedicels not 

adnate to the branches; shorter pedicels 0.7–2 mm; longer pedicels 

2.5–5 mm; terminal pedicels 2–5 mm. Spikelets 5.5–8.2 mm long 

(including pubescence), 4.2–5.9 mm long (excluding pubescence), 

0.5–0.7 mm wide, narrowly ovate, long apiculate; lower glumes 

0.6–0.8 mm long; upper glumes 3.5–4.5 mm long, 3- to 5-veined, 

pubescent on the margins; lower lemmas 4.1–5.7 mm long (exceeded 1.5–5 mm by pubescence), narrowly ovate, 7-veined, 

pubescent between most, sometimes all, of the veins and on the 

margin, the veins usually obscured by a dense covering of golden 

brown hairs, hairs 3–6 mm long, spreading at maturity, intercostal 

regions on either side of the midvein glabrous or pubescent with 

shorter, fine, white hairs, sometimes intermixed with the golden 

brown hairs; upper lemmas 3.2–4.5 mm long, narrowly ovate, 

brown when immature, dark brown at maturity, acuminate; anthers 1–1.2 mm long. 2n = 36.

Distribution and Habitat. Digitaria insularis

grows in low, open ground in the southern United States and extends to the West Indies, Mexico, and through Central America 

to Argentina.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 7.4 km W of Balleza on road to Guachochi, 18 Sep 

1991, Acacia scrub, 1660 m, P.M. Peterson, Annable & ValdésReyna 10738 (CIIDIR, US). Batopilas: SW Chihuahua, Aug 

1885, E. Palmer 207 (US). Chihuahua: near Chihuahua, Aug 

1885, C.G. Pringle 378 (US). Guachochi: 7.4 km SW of La Bufa 

and 15 km NE of Batopilas, 920 m, thorn scrub vegetation, 20 

Sep 1991, P.M. Peterson, Annable & Valdés-Reyna 10849 (US).

108. Digitaria sanguinalis* (L.) Scop., Fl. Carniol. (ed. 2) 1: 52. 

1771. Panicum sanguinale L., Sp. Pl. 1: 57. 1753.

FIGURE 82

Annual. Culms 20–70(112) tall, often decumbent and rooting at the lower nodes. Sheaths keeled, usually sparsely pubescent 

with papillose-based hairs; ligules 0.5–2.6 mm; blades 2–11(14) 

cm long, 3–8(12) mm wide, usually with papillose-based hairs 

on both surfaces, sometimes glabrous. Panicles with 4–13 spikelike primary branches, these subdigitate or on rachises to 6 cm; 

primary branches 3–30 cm long, 0.7–1.5 mm wide, flattened 
116 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

and winged, wings more than 1⁄2 as wide as the midribs, lower 

and middle portion of the branches with spikelets in unequally 

pedicellate pairs, pedicels not adnate to the branches; secondary 

branches rarely present. Spikelets 1.7–3.4 mm long, 0.7–1.1 mm 

wide, homomorphic; lower glumes 0.2–0.4 mm long, veinless; upper glumes 0.9–2 mm long, 1⁄3–1⁄2 as long as the spikelets, 3-veined, pubescent on the margins; lower lemmas usually 

exceeded or equaled by the upper florets, sometimes exceeding 

them but by no more than 0.2 mm long, glabrous, 7-veined, lateral (or all) veins scabrous throughout or smooth on the lower 

1⁄3(1⁄2) and scabrous distally, 3 middle veins usually widely spaced, 

remaining veins on each side close together and near the margins; upper lemmas 1.7–3 mm long, yellow or gray, frequently 

purple-tinged when immature, often becoming brown at maturity; anthers 0.5–0.9 mm long. 2n = 36, 28, 34, 54.

Distribution and Habitat. Digitaria sanguinalis is a weedy Eurasian species that is now found in waste 

ground in fields, gardens, and lawns throughout much of the 

world, including Chihuahua.

Specimens Examined. MEXICO. Chihuahua. 

Bocoyna: Sánchez, 12 Oct 1910, Hitchcock 7695 (US); Barrancas del Cobre camino [road] a Alto Río Urique, 18 Aug 

1976, bosque bajo de leguminosas [low legume forest], 1900 

m, S. González & J.M. Peña 720 (RELC). Chihuahua: La Campana, 1 km Pte. carr. [hwy] Panamericana, 18 Sep 73, pastizal 

[pastureland], 1570 m, Valdés-Reyna VR-296 (RELC). La 

Campana; 4 km Ote. [W] carr. Panamericana, 6 Sep 73, lotes 

producción de semilla [seed-production lots], 1500 m, ValdésReyna VR-102 (RELC). Cusihuiriáchi: Laguna Grande, 10 Aug 

1975, vegetación riparia [riparian vegetation], 1950 m, J.M. 

Peña JMP-133 (RELC). Guachochi: Barranca de Basihuare, 28 

Aug 2003, bosque de encino [oak forest], 1700 m, P.M. Peterson 

& P. Catalán 17587 (CIIDIR, US). Janos: Chihuahua–Sonora 

Border, Rancho Carretas, 26 Aug 1937, 1450 m, L. H. Harvey 

1595 (US). Madera: Chuichupa, 31 Aug 1936, LeSueur 0186

(US); Paraje Sirupa, ejido Cebollitas, 16 Oct 1990, bosque de 

encino, 1200 m, A. Benítez 2898 (CIIDIR); La Tinaja, ejido El 

Largo, 29 Aug 1990, bosque de encino–pino [oak–pine forest], 

1840 m, O. Bravo 1335 (CIIDIR); Arroyo de la Quinta, ejido 

“El Largo”, 30 Aug 1990, bosque de pino, 2340 m, A. Benítez 

2103 (CIIDIR). Matamoros: 9 mi S of Villa Matamoros, 7 Sep 

1967, Reeder & C. Reeder 4881 (ARIZ, US). Moris: Mesa del 

Agua, 4.8 km S of Campanero (on Mesa de Campanero), 29 Sep 

2003, 1990 m, T.R. Van Devender, A.L. Reina, M.A. Dimmitt & 

M.W. Eubanks 2003-1096 (NMC). Ocampo: Parque Nacional 

FIGURE 82. Digitaria sanguinalis. A. Habit. B. Spikelet showing lower 

glume and lower lemma. C. Spikelet showing upper glume and upper 

lemma. Drawn by Linda Ann Vorobik and Hana Pazdírková; copyright 

Utah State University.
NUMBER 107 • 117

“Cascada de Basaseachic,” along the road as it enters camp area 

at trail head to top of falls, 1 Aug 1988, 2000 m, Spellenberg, 

R. Corral,J Brunt & L. Huenneke 9649 (NMC). Riva Palacio: 

Majalca (Pilares), 12 Aug 1939, L. H. Harvey 1484 (US).

109. Digitaria ternata (Hochst. ex A. Rich.) Stapf, Fl. Cap. 7: 

376–377. 1898. 

Annual; geniculate at the base. Culms very variable in size, 

up to (20)50−125 cm tall. Sheaths glabrous with hyaline margins; 

ligule membranous truncate; blades 5–20(50) cm long, 4–6 mm 

wide, flat, apiculate, glabrous, with some cilia adaxially. Panicles 

4–10(15) cm long, with 2–10 racemes erect, the rachis shortly 

winged, pedicels with a ring of stiff hairs just below the spikelets; 

spikelets 2–2.5 mm long, oblong-elliptic, in pairs and those from 

the central part, the racemes in triads, 1 sessile and 2 pedicelate, 

tomentose; lower glumes missing, upper glumes 0.9–1.8 mm long, 

elliptic-lanceolate, 3-veined, pubescent between veins. Lemmas of 

the sterile floret 1.8–2.5 mm long, 5-veined, densely pubescent especially in the lateral veins; paleas reduced to a scale; lemma of the 

fertile floret 1.8–2.5 mm long, elliptic, dark brown.

Distribution and Habitat. Digitaria ternata

grows in open land, grasslands, and road edges; it is known from 

Mexico to South America.

Specimens Examined. MEXICO. Chihuahua.

Moris: Mesa del Agua, 4.8 km S of Campanero (on Mesa de 

Campanero), 29 Sep 2003, 1990 m, T.R. Van Devender, A.L. 

Reina, M.A. Dimmitt & M.W. Eubanks 2003–1098 (NMC).

Dinebra Jaq.

Plants annual. Culms 13–120 cm tall, not woody. Ligules membranous, truncate, lacerate, sometimes ciliate; blades 

linear, flat. Inflorescence terminal, panicles of 1–70, 1-sided, 

spikelike branches, irregularly disposed on elongate rachises, 

clearly exceeding the upper leaves; branches with 2 rows of 

1 or more closely imbricate, sessile spikelets, proximal spikelets sometimes replaced by short, tardily deciduous, secondary 

branches; disarticulation at the base of the branches or at the 

base of the secondary branches and (eventually) beneath the 

florets. Spikelets laterally compressed, cuneate, with 1–3 florets. Glumes subequal, much longer than the florets, usually exceeding the distal florets, coriaceous or membranous, strongly 

keeled, acuminate-aristate; lemmas thinly membranous, weakly 

keeled, 3-veined, pilose over the veins, apex acute to 2-lobed, 

central veins excurrent, forming mucros. Caryopses ellipticoblong, trigonous. x = 10.

Dinebra, a genus of 23 species, is native from Africa to 

Madagascar and India and in the Americas (Peterson et al., 

2012, 2015, 2016). Four species have been reported from 

Chihuahua.

KEY TO SPECIES OF DINEBRA

1. Sheaths sparsely to densely hairy, the hairs papillose-based . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. panicea

1. Sheaths lacking hairs or with hairs that are not papillose-based.

2. Panicles with 25–150 branches.

3. Lemmas 2.4–3 mm long; anthers 0.6–0.8 mm long; spikelets 4–5 mm long . . . . . . . . . . . . . . . . . . . . D. panicoides

3. Lemmas 1.2–2.4 mm long; anthers 0.2–0.6 mm long; spikelets 2.5–4.5 mm long . . . . . . . . . . . . . . . . . . . D. scabra

2. Panicles with 2–25 branches.

4. Panicles 2–17 cm long, with 5–23 branches; anthers 0.4–0.5 mm long; caryopses 0.4–0.5 mm wide . . . . . . D. viscida

4. Panicles 20–35 cm long, with 20–90 branches; anthers 0.6–0.8 mm long; caryopses about 0.7 mm wide . . . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. panicoides

110. Dinebra panicea (Retz.) P. M. Peterson & N. Snow, Ann. 

Bot. 109: 1317–1329. 2012. Poa panicea Retz., Observ. 

Bot. 3: 11. 1783. Leptochloa panicea (Retz.) Ohwi, (Retz.) 

Ohwi, Bot. Mag. (Tokyo) 55(655): 311. 1941. 

Annual. Culms (5)13–150 cm tall, usually erect, compressed, branching; internodes hollow. Sheaths sparsely or 

densely hairy, particularly distally, hairs papillose-based; ligules 

0.6–3.2 mm long, membranous, truncate, erose; blades 6–25 cm 

long, 2–21 mm wide, glabrous or sparsely pilose on both surfaces. Panicles 8–30 cm long, with 3–100 racemose branches; 

branches 1–19 cm long, ascending to reflexed. Spikelets 2–4 mm 

long, distant to imbricate, green, magenta, or maroon, with 

2–5(6) florets; glumes sometimes exceeding the florets, linear 

to narrowly elliptic, acute, attenuate, or aristate; lower glumes 

1.6–4 mm long, linear to lanceolate; upper glumes 1.6–3.6 mm 

long, lanceolate; lemmas 0.9–1.7 mm long, glabrous or somewhat sericeous, acute to obtuse; paleas glabrous or sericeous; 

anthers 3, 0.2–0.3 mm long. Caryopsis 0.8–1.2 mm long, 0.5–

0.6 mm wide, nearly round in cross section, with or without a 

ventral groove, apex acute to broadly obtuse.

Distribution and Habitat. Dinebra panicea is 

a cosmopolitan species, Two varieties are present in Chihuahua.

KEY TO VARIETIES OF DINEBRA PANICEA

1. Glumes linear to narrowly lanceolate, exceeding the florets; lemmas 0.9–1.2 mm long; caryopsis without a ventral groove, 

often somewhat coarsely rugose, the apex broadly obtuse . . . . . . . . . . . . . . . . . . . . . . . . . . D. panicea subsp. mucronata
118 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

1. Glumes lanceolate to narrowly elliptic, not or only slightly exceeding the florets; lemmas 1.3–1.7 mm long; caryopsis usually 

with a narrow, shallow ventral groove, smooth, the apex broadly obtuse to acute . . . . . . . . . D. panicea subsp. brachiata

D. panicea subsp. brachiata (Steud.) P. M. Peterson & N. Snow, 

Ann. Bot. 109: 1317–1329. 2012.

FIGURE 83

Distribution and Habitat. United States, Mexico, Central America, South America, and Caribbean Islands.

Specimens Examined. MEXICO. Chihuahua.

Batopilas: SW Chihuahua, Aug 1885, E. Palmer 117 (US); “La 

cueva larga” [long cave] a 4 km al NE de Batopilas, 16 Sep 1983, 

selva baja caducifolia [low deciduous forest], 650 m, Tenorio & 

R. Torres 4439 (MEXU); 12.3 km N of Batopilas near the Río 

Batopilas, 12 Sep 1989, oak forest, 800 m, P.M. Peterson, Annable & Y. Herrera 8058 (ENCB, US); Batopilas, 25 Sep 1981, 

selva baja caducifolia, 530 m, M.E. Siquieros 1659 (MEXU). 

Bocoyna: entre [between] Barrancas del Cobre & Bacahipare, 

bosque bajo de leguminosas [low legume forest], 17 Aug 1976, 

1000 m, S. González & J.M. Peña 731 (ENCB). Janos: Chihuahua–Sonora Border, Rancho Carretas, 26 Aug 1939, 1460 m, 

L. H. Harvey 1507 (US). Juarez: Paso del Norte, 28 Aug 1886, 

C.G. Pringle 1161 (US). Ocampo: Ca 1 km W of W boundary 

of Parque Nacional “Cascada de Basaseachic,” 18 km from the 

Cahuisori–Ocampo road on the road to Candamena, 7.5 km 

below Cruz, 24 Sep 1994, 1260 m, Spellenberg, Corral & Estrada 12183 (NMC). Saucillo: along Isla de Perla road about 

4 mi E of Cd. Delicias, in cultivated and irrigated valley, 11 Jul 

1950, Reeder, C. Reeder & Goodding 1259 (ENCB).

D. panicea subsp. mucronata (Michx.) P. M. Peterson & 

N. Snow, Ann. Bot. 109: 1317–1329. 2012.

Distribution and Habitat. United States, Mexico, Central America, South America, and Caribbean Islands.

Specimens Examined. MEXICO. Chihuahua.

Batopilas: Bajada de Batopilas, 25 Sep 1981, selva baja [low 

jungle], 780 m, R. Fierros 1656 (MEXU); Batopilas, 25 Sep 

1981, selva baja, 530 m, M.E. Siqueiros 1659 (MEXU); along 

Arroyo Samachique, on N side of Barranca de Batopilas, west 

of La Bufa, 5 Aug 1973, tree forest, clump grass, 3000 ft, Bye 

4563 (MEXU). Camargo: Km 2 carr. [hwy] Camargo–Chih. 

29 Sep 1995, orilla del camino [wayside], 1240 m, González 

93 (MEXU). Chihuahua: SW Chihuahua, Aug–Nov. 1885, 

E. Palmer 117 (MEXU).

111. Dinebra panicoides (J. Presl) P. M. Peterson & N. Snow, 

Ann. Bot. 109: 1317–1329. 2012. Megastachya panicoides

J. Presl, Reliq. Haenk. 1(4–5): 283. 1830. Leptochloa panicoides (J. Presl) Hitchc.

Annual. Culms (7)45–110 cm tall, often geniculate below, 

usually ascending to erect above, rarely branching at the base, 

often branching distally; internodes hollow. Sheaths glabrous, 

margins occasionally sparsely ciliate on the basal 1⁄2; ligules 

2.2–3.8 mm long, membranous, truncate, somewhat erose; 

blades 4–20 cm long, 4–8 mm wide, both surfaces smooth or 

scaberulous. Panicles 20–35 cm long, with 20–30(90) racemose branches; branches 2.5–7 cm long, ascending, mostly 

stiff. Spikelets 4–5 mm long, usually somewhat imbricate, with 

4–6(7) florets; lower glumes 0.9–1.9 mm long, usually lanceolate, sometimes falcate, acute; upper glumes 1.8–2.3 mm long, 

ovate, acute to obtuse; lemmas 2.4–3 mm long, narrowly elliptic 

to ovate, membranous, midveins and lateral veins sericeous basally, lateral veins prominent, excurrent, apex acute to broadly 

acute, unawned, sometimes mucronate; paleas glabrous; anthers 

3, 0.6–0.8 mm long. Caryopsis 1.1–1.4 mm long, 0.7 mm wide, 

elliptic, depressed obovate in cross section. 2n = 20.

Distribution and Habitat. Dinebra panicoides is native from the central Mississippi and Ohio River drainages south through Mesoamerica to Brazil.

Specimens Examined. MEXICO. Chihuahua. 

Guachochi: Barranca de Basihuare, 28 Aug 2003, bosque de 

encino [oak forest], 1700 m, P.M. Peterson & P. Catalán 17588 

(CIIDIR, US).

112. Dinebra scabra (Nees) P. M. Peterson & N. Snow, Ann. Bot. 

109: 1317–1329. 2012. Leptochloa scabra Nees, Agrostogr. 

Bras. 2: 435. 1829.

Annual. Culms (12)20–125 cm tall, mostly erect, often 

strongly compressed, branching; internodes hollow. Sheaths 

glabrous, smooth to scabrous; ligules 1.5–2 mm long, membranous, truncate, erose; blades 25–35(50) cm long, 8–16 mm 

wide, scabrous on both surfaces. Panicles 8–35 cm long, with 

50–150 racemose branches; branches (2)5–12 cm long, lax, 

sometimes arcuate, lower branches often remaining enclosed in 

the upper leaf sheaths. Spikelets 3–4.5 mm long, usually tightly 

imbricate, green but straw-colored when dry, with 2–6 florets; 

glumes sometimes mucronate; lower glumes 0.8–1.6 mm long, 

narrowly triangular to lanceolate; upper glumes 1.1–2.1 mm 

long, ovate; rachilla internodes not visible between the florets; 

lemmas 2.1–2.4 mm long, lanceolate to narrowly ovate, membranous, sparsely sericeous along the lateral veins, apex acute, 

unawned; anthers 0.2–0.4 mm long. Caryopsis 0.8–1.3 mm 

long, 0.3–0.5 mm wide, elliptic to obovate, depressed obovate in 

cross section. 2n = 60.

Distribution and Habitat. Dinebra scabra is 

a neotropical species that extends into South America and is uncommon in Mexico and the United States. It is often confused 

with D. panicoides, but it has more flexuous to arcuate panicle 

branches, shorter spikelets, and less prominent lemma veins. It 

may also be confused with Diplachne fusca subsp. uninervia, 

from which it differs in its acute lemmas.

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000).
NUMBER 107 • 119

FIGURE 83. Dinebra panicea subsp. brachiata. A. Habit. B. Inflorescence C. Sheath showing 

papillose-based hairs. D. Spikelet. E. Floret. Drawn by Linda Ann Vorobik and Karen Klitz; copyright Utah State University.
120 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

113. Dinebra viscida (Scribn.) P. M. Peterson & N. Snow, Ann. 

Bot. 109: 1317–1329. 2012. Diplachne viscida Scribn., 

Bull. Torrey Bot. Club 10(1): 30. 1883. Leptochloa viscida

(Scribn.) Beal, Grass. N. Amer. 2: 434. 1896.

Annual. Culms (3)10–60 cm tall, prostrate or erect, round 

or somewhat compressed, often highly branched; internodes 

hollow. Sheaths glabrous (rarely sparsely pilose near the base), 

sometimes with a sticky exudate; ligules 1.2–2.5 mm long, truncate, erose to lacerate; blades 1–15 cm long, 1.2–5.5 mm wide, 

glabrous abaxially and adaxially. Panicles 2–17 cm long, with 

5–23 racemose branches; branches 1–2.5(3.5) cm long, stiff, 

often included in the upper leaf sheaths. Spikelets 4.5–7.5 mm 

long, more or less imbricate, magenta or green, with 2–6 florets; glumes triangular, acute; lower glumes 1.6–2 mm long, 

acute; upper glumes 2–2.9 mm; lemmas 2.4–3.5 mm long, ovate, 

membranous, sericeous along the lower veins, lateral veins pronounced, apex acute, obtuse, or truncate, awned, the awns 0.5–

1.5 mm long; paleas minutely scabrous along the veins; anthers 

3, 0.4–0.5 mm long. Caryopsis 1.2–1.6 mm long, 0.4–0.5 mm 

wide, narrowly elliptic to obovate, transversely elliptic in cross 

section. 2n = 40.

Distribution and Habitat. Dinebra viscida is 

a Sonoran Desert species that occurs from southern California 

to southwestern New Mexico and south into adjacent Mexico. It 

differs from Diplachne fusca subsp. fascicularis, which grows in 

the same region, in its consistently short-awned lemmas, smaller 

panicles, often prostrate and much-branched growth habit, and 

often reddish florets.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 3 mi W of El Sueco, 16 Sep 1960, Reeder, C. Reeder 

& Soderstrom 3494 (ARIZ, US). Chihuahua: near Chihuahua, 

17 Sep 1885, C.G. Pringle 814 (US); Chihuahua, 14 Oct 1910, 

Hitchcock 7781 (US). Hidalgo del Parral: 8 mi S of Parral, 2 Oct 

1959, Soderstrom 851 (US). Matamoros: 9 mi S of Villa Matamoros, in water of a depression, 7 Sep 1967, 5600 ft, Reeder 

& C. Reeder 4882 (ARIZ, ENCB, US). Moris: Rancho El Berrendo, junto al preson del [next to] Moris, 17 Oct 1980, pastizal 

[pastureland], I.D. Enriquez 752 (MEXU).

Diplanchne Haller

Annual. Culms 15–120 cm tall, erect or geniculately ascending. Ligule an eciliate or ciliolate membrane. Inflorescence composed of racemes along a central axis, spreading or 

deflexed, linear, oblong or cuneate, unilateral, bearing 2–20 

fertile spikelets on each; rachis persistent or deciduous from 

axis, wingless or narrowly winged, flattened or angular. Spikelet appressed, solitary; fertile spikelets sessile, lanceolate or cuneate, laterally compressed, comprising 1–4 fertile florets, with 

diminished florets at the apex, disarticulating below each fertile 

floret when mature; rachilla internodes definite. Glumes 1.5–3 

length of adjacent fertile lemma, subequal, exceeding apex 

of florets, persistent, firmer than fertile lemma, lanceolate or 

elliptic, 1-keeled, (1)2- to 3-veined, apex acute, attenuate or 

caudate, membranous or coriaceous; fertile lemma ovate, membranous, keeled, wingless, 3-veined, midvein pubescent, surface 

unwrinkled, without grooves, margins pubescent, apex entire 

or dentate, bifid, emarginate, obtuse or acute, muticous or mucronate; palea 0.8–0.9 length of lemma, 2-veined, keels eciliate 

or pubescent. Cryopsis with adherent pericarp, ellipsoid, isodiametric, trigonous.

Diplachne is a genus with two species from Africa, Asia, or 

Australasia (Peterson et al., 2012, 2015, 2016; Snow et al., in 

press). A single species occurs in Chihuahua.

114. Diplachne fusca (L.) P. Beauv. ex Roem. & Schult., Syst. 

Veg. 2: 615. 1817. Leptochloa fusca (L.) Kunth, Révis. 

Gramin. 1: 91. 1829.

FIGURE 84

Annual or weak perennials. Culms 5–170 cm tall, prostrate to erect; compressed, often branching; internodes hollow. 

Sheaths glabrous or scabrous; ligules 2–8 mm long, membranous, attenuate, becoming lacerate at maturity; blades 3–50 cm 

long, 2–7 mm wide, glabrous or scabrous, those of the flag leaves 

sometimes exceeding the panicles. Panicles (1.5)10–105 cm long, 

0.5–22 cm wide, with 3–35 racemose branches, bases of the panicles sometimes remaining enclosed in the upper leaf sheaths at 

maturity; branches 1.5–20(22) cm long, ascending to reflexed. 

Spikelets 5–12(14) mm long, with 6–20 florets; lower glumes 

1–3(4.9) mm long; upper glumes 1.8–5.5 mm long; lemmas 

2–6 mm long, sometimes with a dark spot near the base, apex 

acute to truncate, sometimes emarginate to bifid, unawned, mucronate, or awned; paleas somewhat sericeous along the veins; 

anthers 0.2–2.7 mm long, 1–3. Caryopsis 0.8–2.4 mm long, elliptic to ovate or obovate. 2n = 20.

Distribution and Habitat. Diplachne 

fusca grows in warm areas throughout the world. There are 

two subspecies in the region, subsp. uninervia and subsp. 

fascicularis.

KEY TO SUBPECIES OF DIPLACHNE FUSCA

1. Uppermost leaf blades exceeding the panicles; panicles usually partially enclosed in the uppermost leaf sheaths; mature 

lemmas often whitish with a dark spot in the basal 1⁄2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. fusca subsp. fascicularis

1. Uppermost leaf blades exceeded by the panicles; panicles usually completely exserted; mature lemmas usually greenish or 

plumbeous, lacking a dark spot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. fusca subsp. uninervia
NUMBER 107 • 121

FIGURE 84. Diplachne fusca subsp. fusca. A. Habit. B. Inflorescence. C. Ligule. D. Spikelet. E. Lemma. 

F. Floret. G. Palea with lodicules, stamens, and ovary. Drawn by Alice R. Tangerini for Smithsonian 

Institution, Department of Botany.
122 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Diplachne fusca subsp. fascicularis (Lam.) P. M. Peterson & 

N. Snow, Ann. Bot. 109: 1317–1329. 2012. Festuca fascicularis L., Amer. Tabl. Encycl. 1: 189. 1791.

Distribution and Habitat. Diplachne fusca 

ssp. fascicularis is the most common subspecies from aquatic 

environments; it grows in cultivated and irrigated places; distributed throughout America.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: aprox. 25 km al N del poblado [village] Flores 

Magón, 7 Oct 1995, 1140 m, R. Corral, P. Olivas & J.O. Torres RCD6464 (UACJ). Camargo: Río Conchos, Cd. Camargo, 

5 Aug 1939, 1220 m, L. H. Harvey 1403 (US). Chihuahua: 

near Chihuahua, 17 Sep 1885, C.G. Pringle 813 (US). Cuauhtémoc: 11 mi W of Cuauhtémoc, 4 Sep 1967, 7000 ft, Reeder & 

C. Reeder 4844 (ARIZ, ENCB, US). Gómez Farías: Laguna de 

Babicora,18 Aug 1994, 2150 m, T. Lebgue & E. Estrada 3298

(NMC). Jiménez: bank of the Río Florido, 28 Jul 1939, 1340 m, 

L. H. Harvey 1320 (ENCB, US); At Papalote Las Juntas, (Preson 

de Anteojos) 2 km NW de Hacienda El Berrendo, on Las Pampas 

ranch, 25 Aug 1972, mezquital, 1450 m, F. Chiang, T. Wendt & 

M.C. Johnston 8870 (MEXU). Madera: Río Aros, 23 Aug 1937, 

LeSueur 0202 (US). Matamoros: 9 mi S of Villa Matamoros, 

7 Sep 1967, Reeder & C. Reeder 4883 (ARIZ, US). Nuevo Casas 

Grandes: km 33 Nuevo Casas Grandes–Buenaventura 23 Oct 

1954, Hern.-Xol. & C. Tapia N-130 (US).

Diplachne fusca subsp. uninervia (J. Presl) P. M. Peterson & 

N. Snow, Ann. Bot. 109: 1317–1329. 2012. Megastachya 

uninervia J. Presl, Reliq. Haenk. 1(4–5): 283. 1830.

Distribution and Habitat. This subspecies 

is native from the southern United States to Argentina and has 

been found in Chihuahua growing in an irrigation canal..

Specimens Examined. MEXICO. Chihuahua: 

Cerca del Río, 15 May 1885, C.G. Pringle 438 (MEXU). Juárez: 

Parque “El Chamizal”, 7 Sep 1995, maleza de prados & canales 

de riego [grass meadow and irrigation canals], 1120 m, R. Corral RCD6279 (UACJ).

Disakisperma Steud.

Annual or perennial; caespitose. Culms usually ascending to 

erect, often geniculate at the lower nodes, occasionally prostrate 

and rooting at the lower nodes, often branching at the aerial 

nodes; nodes usually glabrous; internodes usually hollow. Leaves 

usually primarily cauline, occasionally in basal rosettes; sheaths 

open; ligules obtuse to attenuate, usually membranous, sometimes ciliate; blades flat, involute when dry, usually ascending to 

erect, apex attenuate. Primary inflorescences terminal, panicles of 

2–150 nondisarticulating, spikelike branches, usually exceeding 

the leaves; branches digitate, subdigitate, or racemose on the rachises, 1-sided, usually spikelet-bearing throughout their length, 

spikelets in 2 rows, axes terminating in a functional spikelet, 

lower branches occasionally with secondary branching; secondary panicles sometimes present, axillary to and concealed by the 

lower sheaths, their florets not disarticulating; disarticulation in 

the primary panicles beneath the florets. Spikelets rounded to 

slightly keeled on the back, distant to tightly imbricate, not conspicuously pubescent, with (2)3–12(20) bisexual florets; rachillas 

rarely prolonged. Glumes usually unequal, sometimes subequal, 

exceeded by the florets, membranous, rounded to weakly keeled, 

1-veined, veins scabrous, apex unawned (rarely mucronate); florets usually bisexual; calluses distinct or poorly developed, glabrous or pubescent; lemmas membranous, usually pubescent at 

least over the lower portion of the veins, 3(5)-veined, apex entire 

or minutely bilobed, unawned, mucronate, or awned; paleas usually subequal to the lemmas, membranous or hyaline. Caryopsis 

obovate to elliptic, falling free of the lemmas and paleas. x = 10.

Disakisperma was recently segregated from Leptochloa and 

is a genus of four species, with only one in Chihuahua (Peterson 

et al., 2012; Snow et al., 2013).

115. Disakisperma dubium (Kunth) P. M. Peterson & N. Snow, 

Ann. Bot. 109: 1317–1329. 2012. Chloris dubia Kunth, 

Nov. Gen. Sp. (quarto ed.) 1: 169. 1815. Leptochloa dubia

(Kunth) Nees, Syll. Pl. Nov. 1: 4. 1824.

FIGURE 85

Perennial. Culms (10)30–110 cm tall, round or basally 

compressed, tillering from the basal nodes, not branching from 

the aerial nodes, mostly glabrous, sometimes pilose basally; internodes solid. Sheaths sometimes with a pilose collar; ligules 

1–2 mm long, truncate, erose; blades (2)8–35 cm long, 2–8 mm 

wide, glabrous, strigose, or pilose. Panicles 8–20 cm long, with 

2–15 subdigitate or racemose branches; secondary panicles often 

hidden in the lowest leaf sheaths; branches 2–19 cm long, ascending to spreading at maturity. Spikelets 4–12 mm long, light 

brown to dark olive-green, with 4–13 florets, often widely divergent at anthesis; glumes narrowly triangular to ovate, acute; 

lower glumes 2.3–4.8 mm long; upper glumes 3.3–6 mm long; 

lemmas 3.5–5 mm long, membranous, ovate to obovate, lateral 

veins glabrous or sericeous, hairs often restricted to the basal 

portion, sometimes also sericeous on the midvein and between 

the veins, apex obtuse to truncate, usually emarginate, unawned, 

sometimes mucronate; paleas ciliate on the margins; anthers 3, 

0.3–1.6 mm long. Caryopsis 1.5–2.3 mm long, 0.9–1 mm wide, 

strongly dorsally compressed. 2n = 40, 60, 80.

Distribution and Habitat. Disakisperma 

dubia ranges from the southwestern United States and Florida 

throughout Mexico to Argentina, often in well-drained, sandy 

or rocky soils. It provides fair to good forage but is seldom 

abundant.

Specimens Examined. MEXICO. Chihuahua. Ahumada: Cañón de Santa Clara, 90 km al N de Chihuahua, pastizal con encinos [pastureland with oak], 19 Oct 

1974, 1700 m, Rzedowski 32376 (ENCB); Rancho el Peñasco 

km 150, carr [hwy] Chih–Cd. Juárez, 9 Aug 1979, pastizal, 

Siqueiros 334 (MEXU). Aldama: 50 km SW of Coyame of 

Mex 16 between Presidio, Texas and Chihuahua, 22 Sep 1988, 
NUMBER 107 • 123

FIGURE 85. Disakisperma dubium. A. Habit. B. Inflorescence. C. Ligule. D. Spikelet. E. Floret. F. Lower 

glume. G. Upper glume. H. Lemma. I. Palea, ventral view. J. Palea, dorsal view. K. Lodicules. L. Floret, ventral view. M. Palea with lodicules, pistil, and stamens. N. Caryopsis, ventral view. O. Caryopsis, dorsal view. 

P. Caryopsis, cross section. Drawn by Alice R. Tangerini for Smithsonian Institution, Department of Botany.
124 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

1400 m, P.M. Peterson & Annable 5761 (ENCB, US); km 53 

Chihuahua–Ojinaga, 24 Aug 1978, matorrral [scrub], 1325 m, 

M. Gutiérrez, B. Rodríguez 29 (MEXU). Allende: carr. 45 Parral–Torreón, 20 km al N del poblado Río Florido, zacatal & 

manchones de juniperus [grassland and spots of juniper], 15 Sep 

1970, 1850 m, L.M. Villarreal de Puga 4106 (ENCB). Balleza: 

7.4 km W of Balleza on road to Guachochi, 18 Sep 1991, 

huizachal, 1660 m, P.M. Peterson, Annable & Valdés-Reyna 

10727 (CIIDIR); carr. Parral–Balleza, 27 Sep 1981, bosque de 

encino [oak forest], 2100 m, M.E. Siqueiros 1570 (MEXU); 

10 mi SW of El Ojito, 12 Sep 2006, 1902 m, P.M. Peterson 

20026, F. Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, US). 

Camargo: km 2 carr. Camargo–Chih., 29 Sep 1995, orilla de 

camino [wayside], 1240 m, Ing. González 92(MEXU); 10 mi 

N of Ciudad Camargo, 4 Oct 1953, 1280 m, cultivated area, 

1280 m, Reeder & C. Reeder 2612 (MEXU).Casas Grandes:

Rancho Palanganas (Mesa el Cuervo), 12 sept 1996, pastizal, 

2200 m, Fierros 124 (MEXU). Chihuahua: W of Chihuahua, 

10 Oct 1935, LeSueur Mex-079 (US); 6.1 mi W of Hwy 45 

on dirt road towards Santa Clara, 18 Oct 1992, bosque de 

encino, 1640 m, P.M. Peterson & Annable 12581 (US); hills 

& plains near Chihuahua, Aug 1885, C.G. Pringle 537 (US), 

422 (US) Isotype; Valley near Chihuahua, 27 Sep 1886, C.G. 

Pringle 1027 (MEXU); Chihuahua, 14 Oct 1910, Hitchcock 

7776 (US). Gran Morelos: km 21 carr. Chihuahua–Namiquipa 

(via corta [short]), 25 Nov 1997, bosque de encino, 1830 m, 

M.A. Vergara 193 (MEXU). Hidalgo del Parral: 10 km al S de 

Parral, ruderal, 29 Sep 1983, 1800 m, Blanco-Aguirre 2108 

(ENCB). Janos: Chihuahua–Sonora Border, Rancho Carretas, 

27Aug 1939, 1460 m, L. H. Harvey 1620 (ENCB, US). Ignacio 

Zaragoza: 20.3 km NE of Ignacio Zaragoza on Mex 23, 28 Sep 

1989, 2400 m, P.M. Peterson & R.M. King 8160 (US). Jiménez: 

8 mi N of Jiménez on Mex. 45, 30 Aug 1971, 4400 ft, L. H. 

Harvey 8893 (ENCB). Práxedis G. Guerrero: aprox. 3 km al 

NW del Porvenir, por la carr. Juárez–Porvenir, a los lados de 

cultivo de algodón [near cultivated cotton], 8 Sep 1994, 1090 m, 

R. Corral, Bye, A. Domínguez, K. Chico & P. Yañez RCD5404

(UACJ). Riva Palacio: Nuevo Majalca, approx. 14.5 km W of 

hwy 45, N of Chihuahua, 22 Sep 1988, grassland, 1700 m, P.M. 

Peterson & Annable 5769 (ENCB, US). Saucillo: Mancomún El 

Pajarito Dominguero 18 km de las Varas, 10 Oct 1995, matorral, 1280 m, Fierros 99 (MEXU). Valle de Zaragoza: 58 km N 

of Parral on Mex 24 towards Chihuahua, 14 Sep 1989, grassland, 1500 m, P.M. Peterson & Annable 8095 (ENCB, US); 87.7 

km N of Parral on Mex 24 towards Chihuahua, 14 Sep 1989, 

grassland, 1620 m, P.M. Peterson & Annable 8105 (ENCB, US). 

P.M. Peterson, Annable & Valdés-Reyna 10727 (US).

Distichlis Raf. 

Perennial; usually unisexual, occasionally bisexual; strongly 

rhizomatous and/or stoloniferous. Culms usually erect, glabrous. 

Leaves conspicuously distichous; lower leaves reduced to scalelike sheaths; upper sheaths strongly overlapping; ligules shorter 

than 1 mm long, membranous, serrate; upper blades stiff, glabrous, ascending to spreading, usually equaling or exceeding the 

pistillate panicles. Inflorescences terminal, contracted panicles or 

racemes, sometimes exceeding the upper leaves. Spikelets laterally compressed, with 2–20 florets; disarticulation of the pistillate spikelets above the glumes and below the florets, staminate 

spikelets not disarticulating. Glumes 3- to 7-veined; lemmas coriaceous, staminate lemmas thinner than the pistillate lemmas, 

9- to 11-veined, unawned; paleas 2-keeled, keels narrowly to 

broadly winged, serrate to toothed, sometimes with excurrent 

veins; anthers 3. Caryopsis glabrous, free from the palea at maturity, brown. x = 10. 

Distichlis, a genus of 11 species, grows in saline soils of 

the coasts and interior deserts of the Western Hemisphere and 

Australia (Peterson et al., 2016). All the species grow in South 

America, four grow in North America with two in Chihuahua.

KEY TO SPECIES OF DISTICHLIS

1. Inflorescences with multiple spikelets; leaf blades 1–8(20) cm long, stiff or lax . . . . . . . . . . . . . . . . . . . . . . . . . . D. spicata

1. Inflorescences composed of a single spikelet; leaf blades 0.5–1.5 cm long, stiff . . . . . . . . . . . . . . . . . . . . . . . . . D. littoralis

116. Distichlis littoralis (Engelm.) H. L. Bell & Columbus, Syst. 

Bot. 33(3): 536–551. 2008. Monanthochloë littoralis Engelm., Trans. Acad. Sci. St. Louis 1: 437, pl. 13–14. 1859.

Plants with long, wiry stolons. Culms 8–15 cm tall, clustered, 

erect, with numerous short, leafy, lateral branches. Leaves clustered on distant to closely spaced, short, lateral shoots; sheaths 

4–6 mm long, rounded, smooth, shiny, glabrous or puberulent 

at the base; ligules thickly membranous ciliate rims; blades 0.5–

1.5 cm long, 1–2(3) mm wide, stiff, subulate, uniformly manyveined. Inflorescences terminal, composed of a single glabrous 

spikelet, this enclosed, and almost concealed, by the uppermost 

leaf sheaths. Pistillate spikelets subterete, with 3–5 florets, distal 

florets rudimentary; disarticulation tardy, below the lowest floret; glumes absent; lemmas coriaceous, glabrous, 9-veined, acute; 

paleas coriaceous, keels prominently winged, wings overlapping 

and enclosing the caryopses. Staminate spikelets similar to the 

pistillate spikelets, but smaller and the glumes and lemmas thinner. 2n = 40.

Distribution and Habitat. Distichlis littoralis grows in moist, sandy, saline soils along the coast of southern California and the southeastern United States, northeastern 

Mexico, and the Caribbean Islands. It was previously placed in 

Monanthochloë, but Bell and Columbus (2008) demonstrated 

that Monanthochloë is nested within Distichlis.
NUMBER 107 • 125

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000) and Herrera Arrieta and 

Cortés Ortiz (2010).

117. Distichlis spicata (L.) Greene, Bull. Calif. Acad. Sci. 2: 415. 

1887. Uniola spicata L., Sp. Pl. 71. 1753.

FIGURE 86

Plants rhizomatous and sometimes stoloniferous. Culms 

10–60 cm long, usually erect, sometimes decumbent or prostrate. 

Blades of upper leaves 1–8(20) cm long, rigid and divaricate to 

lax and ascending, usually equaling or exceeding the pistillate 

panicles, varying with respect to the staminate panicles. Pistillate panicles 1–7 cm long, often congested, with 2–20 spikelets. 

Pistillate spikelets 5–20 mm long, 4–7 mm wide, with 5–20 florets; lower glumes 2–3 mm long; upper glumes 3–4 mm long; 

lemmas 3.5–6 mm long; paleas with serrate keels. Caryopsis 2–5 

mm long, tapered or truncate. Staminate panicles and spikelets 

similar to the pistillate panicles and spikelets, but the lemmas 

somewhat thinner in texture and the paleas not bowed-out; anthers 3–4 mm long. 2n = 40.

Distribution and Habitat. Distichlis spicata

grows in saline soils of the Western Hemisphere and Australia 

and has three varieties; only Distichlis spicata var. mexicana

Beetle is found in Chihuahua.

Specimens Examined. MEXICO. Chihuahua. Ascensión: ca 65 (air) mi SW of Cd. Juarez, 6.8 (rd) mi N of Guzman, in saline flats of, 14 Sep 1974, 1162 m J. Henrickson 14104

(MEXU, NMC), 14110 (US). Camargo: Cerca [near] de laguna 

de Jaco, 3 Aug 1976, orilla de laguna [shore of lagoon], 1220 m, 

S. González & J.M. Peña 509 (RELC). Chihuahua: Balneario de 

San Diego, 11 Aug 1976, comunidad halófita [halophyte community], 1170 m, J.M. Peña JNP-153 (RELC). Delicias: 14 km al 

N of Delicias on road from Chihuahua to Delicias, 29 Jun 1974, 

weedy vegetation in irrigated area, S.D. Koch 74154 (MEXU). 

Galeana: km 145 de Galeana, 8 Aug 1979, pastizal [pastureland], 

1370 m, M. Siqueiros 296 (MEXU). Gómez Farías: Laguna de 

Babicora, 18 Aug 1994, 2150 m, T. Lebgue & E. Estrada 3489

(NMC); Laguna Babicora, 9 Sep 1994, 2150 m, G. Quintana & 

E. Estrada 3507 (NMC). Janos: near Mexican boundary line, 16 

Jun 1892, E.A. Mearns 266 (US). Juárez: Rio Grande bottom, 

12 Jun 1912, E. Stearus 335 (US); Ciudad Juárez, a lo largo de 

[along] la “Asequia Madre” entre [between] la Av. Américas & 

Paseo Triunfo de la República, 29 Sep 1995, 1140 m, R. Corral, 

P. Olivas & L.M. Barraza RCD6399 (UACJ). Madera: Laguna de 

Babicora, alrededores de [around] Nicolas Bravo, 18 Aug 1994, 

2200 m, Quintana, Lebgue & Estrada 3572 (NMC). Meoqui: ca 

1 mi S of Meoqui, 18 Aug 1959, D. Marsh 1905 (US); 14 km N 

of Delicias on rd from Chihuahua to Delicias, 29 Jun 1974, S.D. 

Koch 74153 (US). Práxedis G. Guerrero: aprox. 3 km al NW del 

Porvenir, por la carr. [hwy] Juárez–Porvenir, a los lados de cultivo 

de algodón [near cultivated cotton], 8 Sep 1994, 1090 m, R. Corral, Bye, A. Domínguez, K. Chico & P. Yañez RCD5411 (UACJ).

FIGURE 86. Distichlis spicata. A. Staminate habit. B. Pistillate inflorescence. C. Pistillate floret. D. Staminate spikelet. E. Staminate floret. Drawn by Linda Ann Vorobik and Hana Pazdírková; copyright 

Utah State University.
126 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Echinochloa P. Beauv.

Annual or perennial; with or without rhizomes. Culms 10–

460 cm tall, prostrate, decumbent or erect, distal portions sometimes floating, sometimes rooting at the lower nodes; nodes usually 

glabrous; internodes hollow or solid. Sheaths open, compressed; 

auricles absent; ligules usually absent but, if present, of hairs; 

blades linear to linear-lanceolate, usually more than 10 times longer than wide, flat, with a prominent midrib. Inflorescences terminal, panicles of simple or compound spikelike branches attached 

to elongate rachises, axes not terminating in a bristle, spikelets 

subsessile, densely packed on the angular branches; disarticulation below the glumes (cultivated taxa not or tardily disarticulating). Spikelets plano-convex, with 2(3) florets; lower florets sterile 

or staminate; upper florets bisexual, dorsally compressed; glumes 

membranous; lower glumes usually 1⁄4–2⁄5 as long as the spikelets 

(varying to more than 1⁄2 as long), unawned to minutely awntipped; upper glumes unawned or shortly awned; lower lemmas 

similar to the upper glumes in length and texture, unawned or 

awned, awns to 60 mm; lower paleas vestigial to well-developed; 

upper lemmas coriaceous, dorsally rounded, mostly smooth, apex 

short or elongate, firm or membranous, unawned; upper paleas 

free from the lemmas at the apex; lodicules absent or minute; anthers 3. Caryopsis ellipsoid, broadly ovoid or spheroid; embryos 

usually 0.7–0.9 times as long as the caryopsis. x = 9. 

Echinochloa is a tropical to warm-temperate genus of 40–50 

species that are usually associated with wet or damp places. 

Seven species are present in Chihuahua.

KEY TO SPECIES OF ECHINOCHLOA

1. Ligules of stiff hairs present on the lower leaves; perennial.

2. Awns 40–50 mm long, lower floret sterile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. holciformis

2. Awns 5–20 mm long; lower floret staminate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. polystachya

1. Ligules usually absent from all leaves, the ligule region sometimes pubescent; plants usually annual, sometimes short-lived 

perennials.

3. Panicle branches 0.7–2(4) cm long, without secondary branches; spikelets 2–3 mm long, unawned . . . . . . . . E. colona

3. Panicle branches 1–14 cm long, usually rebranched, the secondary branches often short and inconspicuous; spikelets 

2.5–5 mm long, awned or unawned.

4. Upper lemmas broadly ovate to elliptical, if elliptical, then each with a line of minute (use 25× magnification) hairs 

across the base of the early withering tips

5. Upper lemmas with rounded or broadly acute coriaceous apex that passes abruptly into a membranous tip, a line 

of minute hairs present at the base of the tip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. crus-galli

5. Upper lemmas with acute or acuminate coriaceous apex that extend into the membranous tip, without hairs at the 

base of the tip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. muricata

4. Upper lemmas narrowly ovate to elliptical, never with a line of minute hairs across the base of the early withering, 

membranous tips.

6. Spikelets 2.5–3.4 mm long; lower lemmas unawned or with awns 3–10(15) mm long, curved . . . . E. crus-pavonis

6. Spikelets 3–5 mm long; lower lemmas usually with awns 8–25 mm long, typically straight.

7. Blades 10–35(60) mm wide; sheaths usually hirsute and the margins ciliate with prominent papillose-based 

hairs, sometimes the sheaths only papillose; lower lemmas awned, the awns 8–25(60) mm long . . . . . E. walteri

7. Blades 5–10 mm wide; sheaths glabrous or with papillose-based hairs; lower lemmas unawned or awned, the 

awns 8–16(50) mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. oplismenoides

118. Echinochloa colona* (L.) Link, Hort. Berol. 2: 209. 1833. 

Panicum colonum L., Syst. Nat. (ed. 10) 2: 870. 1759.

FIGURE 87

Annual; erect or decumbent, caespitose or spreading, rooting from the lower cauline nodes. Culms 10–70 cm tall; lower 

nodes glabrous or hispid, hairs appressed; upper nodes glabrous. Sheaths glabrous; ligules absent, ligule region frequently 

brown-purple; blades 8–22 cm long, 3–6(10) mm wide, mostly 

glabrous, sometimes hispid, hairs papillose-based on or near 

the margins. Panicles 2–12 cm long, erect, rachises glabrous or 

sparsely hispid; primary branches 5–10, 0.7–2(4) cm long, erect 

to ascending, spikelike, somewhat distant, without secondary 

branches, axes glabrous or sparsely hispid, hairs 1.5–2.5 mm 

long, papillose-based. Spikelets 2–3 mm long, disarticulating 

at maturity, pubescent to hispid, hairs usually not papillosebased, tips acute to cuspidate; lower glumes about 1⁄2 as long as 

the spikelets; upper glumes about as long as the spikelets; lower 

florets usually sterile, occasionally staminate; lower lemmas unawned, similar to the upper glumes; lower paleas subequal to 

the lemmas; upper lemmas 2.6–2.9 mm long, not or sparsely exceeding the upper glumes, elliptic, coriaceous portion rounded 

distally, passing abruptly into a sharply differentiated, membranous, soon-withering tip; anthers 0.7–0.8 mm long. Caryopsis 

1.2–1.6 mm long, whitish; embryos 63%–83% as long as the 

caryopsis. 2n = 54.

Distribution and Habitat. Echinochloa 

colona is widespread in tropical and subtropical regions. It is 
NUMBER 107 • 127

adventive and weedy in North America, growing in low-lying, 

damp to wet, disturbed areas.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 44 km al N del poblado [village] Villa Ahumada 

por la carr. [hwy] Panamericana (Méx 45), 7 Oct 1995, 1200 

m, R. Corral, P. Olivas & J.O. Torres RCD6437 (UACJ). Aldama: km 38, Cd. Chihuahua–Hormigas, N of V. Aldama, 31 

Oct 1954, matorral xerófilo [xerophilous scrub], 1100 m, Hern.-

Xol. & C. Tapia N-518 (US). Bocoyna: Sánchez, 12 Oct 1910, 

Hitchcock 7600 (US). Chihuahua: Chihuahua, 14 Oct 1910, 

Hitchcock 7780 (US); 50 mi W of Chihuahua, 15 Oct 1935, 

LeSueur Mex-042, Mex-081 (US); 12 mi N of Chihuahua on 

rd to Cd. Juárez, 8 Oct 1959, 1800 m, Soderstrom 934 (US). 

Cuauhtémoc: About 10 mi SE of Bachimba along hwy 7, 11 Jul 

1950, Reeder, C. Reeder & Goodding 1248 (ENCB). Gran Morelos: km 20, Cd. Cuauhtémoc de Cd. Chihuahua, 27 Oct 1954, 

1500 m, Hern.-Xol. & C. Tapia N-278 (US). Guachochi: Small 

spring below Napuchis, 2 Sep 2003, vegetación acuática [aquatic 

vegetation], P.M. Peterson & P. Catalán 17661 (US). Jiménez: 

Sta Eulalia Mts, E. Wilkinson 42 (US); Bank of the Río Florido, 

Cd. Jiménez, 28 Jul 1939, 1340 m, L. H. Harvey 1330 (ENCB, 

US); Reserva de la Biosfera de Mapimí, Laguna Palomas, 31 

Oct 1998, matorral xerófilo, 1055 m, A. García 3171 (CIIDIR). 

Juárez: Parque “El Chamizal”, 7 Sep 1995, maleza de prados & 

canales de riego [grass meadow and irrigation canals], 1120 m, 

R. Corral RCD6295 (UACJ); Práxedis G. Guerrero: aprox. 3 km 

al NW del Porvenir, por la carr. Juárez–Porvenir, a los lados de 

cultivo de algodón [near cultivated cotton], 8 Sep 1994, 1090 m, 

R. Corral, Bye, A. Domínguez, K. Chico & P. Yañez RCD5401

(UACJ); Rancho Escuela, 18 Oct 1997, I. Enriquez, S. Ordoñez, 

L. Sushii, S. Carrasco, A. Perales & N. Loya IEA11 (UACJ). 

Meoqui: Lázaro Cárdenas, 7 Aug 1974, suelo arcilloso, arvense 

en el algodón [clay soil, growing in cotton], 1250 m, C. Rodríguez, O. Agundis, S. Acosta 1221 (ENCB); Entre [between] 

Julimes & Felipe Ángeles, 30 Jul 1976, cañada [glen] con Prosopis baccharis, 1295 m, S. González & J.M. Peña 373 (ENCB, 

RELC). Ojinaga: 1 km al Pte. del rancho Escobilla, 30 Oct 76, 

matorral, Valdés-Reyna VR-833 (RELC). Riva Palacio: Col. 

Cumbres de Majalca, 33.8 km W of Mex 45, N of Chihuahua 

City, 7 Sep 1989, pine forest, 2190 m, P.M. Peterson, Annable 

& Y. Herrera 7955 (US); Nuevo Majalca, approx. 14.5 km W of 

hwy 45, N of Chihuahua, 22 Sep 1988, grassland, 1700 m, P.M. 

Peterson & Annable 5771 (ENCB, US).

119. Echinochloa crus-galli* (L.) P. Beauv., Ess. Agrostogr. 1: 

53, 161, 169, t. 11, f. 2. 1812. Panicum crus-galli L., Sp. 

Pl. 1: 56. 1753.

FIGURE 88

Annual. Culms 30–200 cm tall, spreading, decumbent or 

stiffly erect; nodes usually glabrous or the lower nodes puberulent. Sheaths glabrous; ligules absent, ligule region sometimes 

pubescent; blades to 65 cm long, 5–30 mm wide, usually glabrous, occasionally sparsely hirsute. Panicles 5–25 cm long, with 

FIGURE 87. Echinochloa colona. A. Habit. B. Spikelet showing 

lower glume and lower lemma. C. Spikelet showing upper glume. 

D. Upper lemma. Drawn by Linda Ann Vorobik and Hana Pazdírková; copyright Utah State University.
128 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

few to many papillose-based hairs at or below the nodes of the 

primary axes, hairs sometimes longer than the spikelets; primary 

branches 1.5–10 cm long, erect to spreading, longer branches 

with short, inconspicuous secondary branches, axes scabrous, 

sometimes also sparsely hispid, hairs to 5 mm long, papillosebased. Spikelets 2.5–4 mm long, 1.1–2.3 mm wide, disarticulating at maturity; upper glumes about as long as the spikelets; 

lower florets sterile; lower lemmas unawned to awned, sometimes varying within a branch, the awns to 50 mm long; lower 

paleas subequal to the lemmas; upper lemmas broadly ovate to 

elliptical, coriaceous portion rounded distally, passing abruptly 

into an early withering, acuminate, membranous tip that is further demarcated from the coriaceous portion by a line of minute 

hairs (use 25× magnification); anthers 0.5–1 mm long. Caryopsis 

1.3–2.2 mm long, 1–1.8 mm wide, ovoid or oblong, brownish; 

embryos 59%–86% as long as the caryopsis. 2n = 54.

Distribution and Habitat. Echinochloa crusgalli is an Eurasian species that is now widely established in 

North America, where it grows in moist, disturbed sites, including rice fields.

KEY TO VARIETIES OF ECHINOCHLOA CRUS-GALLI

1. Racemes 10–20(25) mm long, simple or branched, open; spikelets hirsute and papillose, sometimes purple-motted . . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. crus-galli var. crus-galli

1. Racemes 8–10(14) mm long, simple, plicate; spikelets sparsely papillose, generally green throughout . . . . . . . . . . . . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. crus-galli var. zelayensis

Echinochloa crus-galli (L.) P. Beauv. var. crus-galli.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: aprox. 25 km al N del poblado [village] Flores Magón, 

7 Oct 1995, 1140 m, R. Corral, P. Olivas & J.O. Torres RCD6465

(UACJ). Aldama: San Diego de Alcalá por la carr. [hwy] Chihuahua–Delicas, matorral-pastizal [scrub–pastureland], 20 Aug 1996, 

1200 m, E. Estrada & C. Yen 5709 (ENCB). Ascensión: Col. Guadalupe Victoria, 11 Aug 1981, zona agrícola [agricultural zone], 

1220 m, M.E. Siqueiros 1827 (ENCB). Casas Grandes: Valle de 

las Cuevas al S del Ejido Ignacio Zaragoza, bosque de pino [pine 

forest], 25 Sep 1982, 1760 m, Tenorio & Romero 1711 (ENCB). 

Chihuahua: 50 mi W of Chihuahua, 15 Oct 1935, LeSueur Mex043 (US); Río Bonito, 25 Aug 1936, LeSueur Mex-095 (US); La 

Campana; 4 km al Ote. [W] carr. Panamericana, 6 Sep 73, maleza 

en lote de producción de semilla [weed in seed-production lot], 

1500 m, Valdés-Reyna VR-113 (RELC). Orilla [shore] de Río 

Chuviacar, 7 Aug 73, lugar pantanoso [marshy place] con Typha, 

1450 m, J.M. Peña JMP-69 (RELC). Gómez Farías: Laguna de 

Babicora,18 Aug 1994, 2150 m, T. Lebgue & E. Estrada 3308, 

3310-A (NMC). Guerrero: Entre [between] La Junta & Temochi, 

12 Aug 76, Pastizal, 2135 m, S. González & J.M. Peña 576A

(RELC). Juárez: Parque “El Chamizal”, 7 Sep 1995, maleza de 

prados & canales de riego [grass meadow and irrigation canals], 

1120 m, R. Corral RCD6288 (UACJ); km 40 carr. No. 2, a los 

lados [sides] del canal de riego, 8 Sep 1994, 1100 m, R. Corral, 

Bye, A. Domínguez, K. Chico & P. Yañez RCD5441-A (UACJ); 

Ciudad Juárez a lo largo de [along] la “Asequia Madre” al N del 

fracc. Rincones de San Marcos, 13 Oct 1995, 1140 m, R. Corral, 

P. Olivas & L.M. Barraza RCD6539 (UACJ). Madera: Chuichupa, Aug 1936, LeSueur 085 (US); Arroyo de la Quinta, ejido “El 

Largo”, 13 Oct 1990, bosque de pino, 2340 m, A. Benítez 1867

(CIIDIR). Meoqui: Lázaro Cárdenas, 7 Aug 1974, arvense en el 

algodón [growing in cotton], 1250 m, C. Rodríguez, O. Agundis 

& S. Acosta 1218 (US). Ocampo: Parque Nacional “Cascada de 

Basaseachic,” ca. 130 air km W of Cuauhtemoc, 12 Sep 1987, 

1600 m, Spellenberg & D. Jewell 9296 (NMC). Riva Palacio: 

Parque cumbres de Majalca, 13 sep 1997, pino–encino–pastizal 

[pine–oak–pastureland], 2120 m, C. Yen & E. Estrada 8530

(ENCB). Temosachi: Nabogame, 7 Sep 1987, 1800 m, Laferr. 

1026 (NMC).

Echinochloa crus-galli var. zelayensis (Kunth) Hitchc., Man. 

Grass. U.S. 841. 1935. Oplismenus zelayensis Kunth, Nov. 

Gen. Sp. (quarto ed.) 1: 108. 1815.

Specimens Examined. MEXICO. Chihuahua.

Casas Grandes: near Casas Grandes, 26 Sep 1899, C.H.T. 

Townsend & C.M. Barber 353 (US). Chihuahua: 50 mi W of 

Chihuahua, 15 Oct 1935, LeSueur Mex-043 (US); km 15 V. 

Guerrero–Sto. Tomás, 29 Oct 1954, Hern.-Xol. & C. Tapia N379 (US). Madera: Río Aros, 23 Aug 1937, LeSueur 0178 (US). 

Nuevo Casas Grandes: E of Nuevo Casas Grandes 23 Oct 1954, 

Hern.-Xol. & C. Tapia N-12 (US). Riva Palacio: Majalca (Pilares), 12 Aug 1939, 2075 m, L. H. Harvey 1490 (US).

120. Echinochloa crus-pavonis (Kunth) Schult., Mant. 2: 269. 

1824. Oplismenus crus-pavonis Kunth, Nov. Gen. Sp. 

(quarto ed.) 1: 108. 1815.

FIGURE 89

Annual or short-lived perennial. Culms 30–150 cm tall; 

nodes glabrous. Sheaths glabrous, often purplish; ligules absent; blades 12–60 cm long, 10–25 mm wide, glabrous. Panicles 10–30 cm long, erect or drooping, nodes sparsely hispid, 

hairs papillose-based, internodes glabrous; primary branches to 

14 cm long, nodes sometimes sparsely hispid, hairs papillosebased, internodes usually glabrous; secondary branches to 3 cm. 

Spikelets 2.5–3.4 mm long, 1.2–1.4 mm wide, disarticulating at 

maturity; upper glumes subequal to the spikelets; lower florets 

sterile; lower lemmas unawned or awned, awns 3–10(15) mm 

long, curved; lower paleas absent, vestigial, or well-developed; 

upper lemmas narrowly elliptic, not or sparsely exceeding the 

upper glumes, acute or obtuse, with a well-differentiated, early 
NUMBER 107 • 129

withering tip, glabrous or pubescent at the base of the tip, hairs 

not forming a line across the base; anthers 0.5–0.7 mm long. 

Caryopsis 1.2–1.5 mm long, 1–1.3 mm wide; embryos 50%–

70% as long as the caryopsis. 2n = 36.

Distribution and Habitat. Echinochloa cruspavonis is a native species found in scattered locations from 

British Columbia to Arizona, east to Florida, and south into 

Mexico to South America. It favors marshes and wet places at 

lower elevations, often being found in the water. It has about 

four varieties, Echinochloa crus-pavonis var. crus-pavonis is in 

our study area.

Specimens Examined. MEXICO. Chihuahua. 

Casas Grandes: between Casas Grandes and Sabinal, 4–5 Sep 

1899, E.W. Nelson 6355-A (US).

120. Echinochloa holciformis (Kunth) Chase, Proc. Biol. Soc. 

Wash. 24: 155. 1911. Oplismenus holciformis Kunth, Nov. 

Gen. Sp. (quarto ed.) 1: 107. 1815.

Perennial; caespitose. Culms 100–150(200) cm tall, decumbent at the base, rooted at the inferior nodes, glabrous. Sheaths 

glabrous; ligules 1.5–3.5 mm long, a dense row of rigid hairs; 

blades 30–45 cm long, 8–15 mm wide, scabrous on the margins. 

Panicles 15–40 cm long, dense, lightly pendulous, racimes numerous, 6–8 cm long, rachis scabrous and sparsely hispid, spikelets in 4 rows or irregularly grouped, changing to purple or black 

at maturity, the awns stay green or sometimes purple motted. 

Spikelets 6.5–9 mm long, densely hispid, with short-plicate hairs; 

lower glumes 2.6–3.9 mm long, 3-veined, mucronate, upper 

glumes 6.5–7 mm long, 5-veined mucronate. Lemma of inferior 

floret sterile, 5-veined, the awn 30–55 mm long; palea missing; 

superior floret bisexual, lemma of the bisexual floret 5.5–6 mm 

long, acute, mucronate or awned, awn 1.5–3 mm long; anthers 

0.7–1.1 mm long.

Distribution and Habitat. Echinochloa holciformis is an aquatic or subaquatic species known from Mexico 

and Central America.

Specimens Examined. MEXICO. Chihuahua. Madera: Col. García, 2 Sep 1990, pastizal [pastureland], 

2240 m, A. Benítez 2192 (CIIDIR).

121. Echinochloa muricata (P. Beauv.) Fernald, Rhodora 

17(198): 106. 1915.

FIGURE 90

Annual. Culms 80–160 cm tall, erect or spreading, sometimes rooting at the lowest nodes, often developing short axillary 

FIGURE 88. Echinochloa crus-galli. A. Habit. B. Ligule. C. Spikelet 

showing lower glume and lower lemma. D. Spikelet showing upper 

glume. E. Upper lemma. F. Apex of upper lemma. Drawn by Linda 

Ann Vorobik and Hana Pazdírková; copyright Utah State University.
130 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

FIGURE 89. Echinochloa crus-pavonis. A. Habit. B. Culm and inflorescence. C. Spikelet. D. Upper floret, dorsal view. E. Apex of upper floret. 

F. Upper floret, ventral view showing palea. Drawn by Linda Ann Vorobik and Hana Pazdírková; copyright Utah State University.
NUMBER 107 • 131

flowering shoots at most upper nodes when mature; lower nodes 

glabrous or puberulent; upper nodes glabrous. Sheaths glabrous; 

ligules absent; blades 1–27 cm long, 0.8–30 mm wide. Panicles 

of primary culms 7–35 cm long, rachises and branches glabrous 

or hispid, hairs to 3 mm long, papillose-based; primary branches 

2–8 cm long, usually spreading and rather distant, often with 

secondary branches. Spikelets 2.5–5 mm long, disarticulating at 

maturity, usually purple or streaked with purple, usually hispid, 

hairs papillose-based; upper glumes about as long as the spikelets; lower florets sterile; lower lemmas unawned or awned, awns 

to 16 mm; lower paleas well-developed; upper lemmas broadly 

obovoid or orbicular, narrowing to an acute or acuminate coriaceous portion that extends into the membranous tip, boundary 

between the coriaceous and membranous portions not marked 

by minute hairs; anthers 0.4–1.1 mm long. Caryopsis 1.2–

2.5 mm long, broadly obovoid or spheroid, yellowish; embryos 

1.4–2 mm long, 80%–91% as long as the caryopsis. 2n = 36.

Distribution and Habitat. Echinochloa muricata is native to North America, growing from southern Canada 

to northern Mexico in moist, often disturbed sites (but not rice 

fields). It resembles E. crus-galli in gross morphology and ecology but differs consistently by not having a line of minute hairs 

separating the tip of the lemma from the coriaceous base. There 

are two varieties; only Echinochloa muricata var. microstachya

Wiegand is in Chihuahua.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: SW Chihuahua, Aug 1885, E. Palmer 18 (US). Chihuahua: near Chihuahua, 20 Jul 1936, LeSueur 0135 (US). Madera: 

Río Aros, 23 Aug 1937, LeSueur 0179, 0180, 0181, 0182 (US); 

between Col. García and Pratt’s Rancho below Pacheco, 22–24 

Aug 1899, E.W. Nelson 6244 (US).

122. Echinochloa oplismenoides (E. Fourn.) Hitchc., Contr. U.S. 

Natl. Herb. 22(3): 136, f. 27. 1920. Berchtoldia oplismenoides E. Fourn., Mexic. Pl. 2: 41. 1886.

FIGURE 91

Annual. Culms to 100 cm tall, erect, succulent, glabrous, 

branching from the lower nodes. Sheaths glabrous or hirsute with 

papillose-based hairs; ligules absent or the ligule region pubescent; blades 10–35 cm long, 5–10 mm wide. Panicles 15–30 cm 

long, narrow; primary branches appressed to ascending, with 

papillose-based hairs at the base of the spikelets. Spikelets 4–5 mm 

long, disarticulating at maturity; glumes with hairs over the veins, 

glabrous, scabrous, or hirsute between the veins; upper glumes 

about equal to the spikelets, muticous or awned, awns to 1 mm; 

lower florets sterile; lower lemmas unawned or awned, the awns 

8–16(50) mm long; lower paleas absent or hyaline and subequal 

to the lemmas; upper lemmas 4–4.5 mm long, 1.7–1.9 mm wide, 

elliptic; anthers 0.5–0.7 mm long, purple. Caryopsis 2.7–2.9 mm 

long, 1.7–1.8 mm wide, elliptic in outline, mucronate; embryos 

about 75% as long as the caryopsis; hila obovate.

Distribution and Habitat. Echinochloa oplismenoides was previously known from northwestern Mexico to 

Guatemala; it is now found in southern Arizona (Fishbein, 1995). 

FIGURE 90. Echinochloa muricata. A. Culm and inflorescence. 

B. Spikelet showing lower glume and lower lemma. C. Spikelet 

showing upper glume. D. Upper lemma. E. Apex of upper lemma. 

Drawn by Linda Ann Vorobik and Hana Pazdírková; copyright 

Utah State University.
132 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Specimens Examined. MEXICO. Chihuahua. 

Carichi: Sánchez, 12 Oct 1910, H.S. Hitchcock 7696 (US). Cuauhtémoc: 11 mi W of Cuauhtémoc, 4 Sep 1967, oak forest, 7000 

ft, Reeder & C. Reeder 4846 (ENCB). Guerrero: Miñaca, 13 Oct 

1910, Hitchcock 7758 (US); Sierra Madre, porphyry ledges near 

Guerrero, 18 Oct 1887, C.G. Pringle 1404 (US). Madera:10 km 

al N de Madera, 6 Oct 74, bosque de pino–encino [pine–oak 

forest], 2100 m, Valdés-Reyna VR-676 (RELC). Riva Palacio: 

Majalca, 24 Jun 1936, LeSueur 0117 (US); Majalca, Canon Encantado, 24 Jul 1936, LeSueur Mex-096 (US). 

123. Echinochloa polystachya (Kunth) Hitchc., Contr. U.S. 

Natl. Herb. 22(3): 135, f. 26. 1920.

Perennial; not rhizomatous. Culms 1–2 m tall, to 1 cm 

thick, erect or decumbent and rooting at the lower nodes, upper 

portion sometimes floating distally; nodes glabrous or antrorsely 

villous. Sheaths mostly glabrous, minutely puberulent, or hispid, 

hairs papillose-based, throat hispid; ligules 1–5 mm long, present on the lower leaves, of stiff hairs; blades 15–70 cm long, 

5–13 mm wide, glabrous. Panicles 13–45 cm long, erect, rachis 

nodes hispid, hairs 3–6.5 mm long, papillose-based, internodes 

scabrous; primary branches 4–10 cm long, subverticillate, ascending, nodes hispid, hairs 2.5–4 mm long, papillose-based, 

internodes scabrous; secondary branches short, spikelets subsessile, in clusters. Spikelets 4–7 mm long, hispid, hairs appressed, 

disarticulating at maturity; lower glumes at least 1⁄2 as long as 

the spikelets; lower florets staminate; lower lemmas apiculate or 

awned, awns to 18 mm; lower paleas subequal to the lower lemmas, often purple; anthers of lower florets 1.5–3.6 mm long, orange; upper lemmas 2.5–5 mm long, elliptic or narrowly ovate, 

apex obtuse, with a membranous, soon-withering tip; anthers of 

upper florets shorter than those of the lower florets. Caryopsis to 

3 mm long. 2n = 54.

Distribution and Habitat. Echinochloa polystachya grows in coastal marshes, often in standing water, from 

Texas to Louisiana and south through Mexico and the Caribbean 

Islands to Argentina. Echinochloa polystachya var. polystachya

is found in Mexico; it has glabrous culms and sheaths; Echinochloa polystachya var. spectabilis (Nees ex Trin.) Mart. Crov., 

has swollen, pubescent cauline nodes and pubescent sheaths.

Specimens Examined. MEXICO. Chihuahua. 

Manuel Benavides: entre [between] Manuel Benavides & Pocitos, 2 Aug 1976, pastizal [pastureland], 1342 m, S. González & 

J.M. Peña 452 (RELC).

124. Echinochloa walteri (Pursh) A. Heller, Cat. N. Amer. Pl. 

ed. 2, p. 21. 1900. Panicum walteri Pursh, Fl. Amer. Sept. 

1: 66–67. 1814.

FIGURE 92

Annual. Culms (30)50–200+ cm tall, to 2.5 cm thick; nodes 

pilose or villous, upper nodes usually with sparser and shorter 

pubescence, occasionally glabrous. Lower sheaths usually hispid, 

hairs papillose-based, sometimes just papillose; upper sheaths 

FIGURE 91. Echinochloa oplismenoides. 

A. Culm and inflorescence. B. Spikelet showing 

lower glume and lower lemma. C. Floret showing 

upper lemma. Drawn by Linda Ann Vorobik and 

Hana Pazdírková; copyright Utah State University.
NUMBER 107 • 133

hirsute or glabrous; ligules absent; blades to 55 cm long, 10–

35(60) mm wide, scabrous. Panicles 8.5–35 cm long, erect to 

slightly drooping, nodes hispid, hairs 3.5–5 mm long, papillosebased, sometimes sparsely so, internodes usually glabrous, sometimes hispid, hairs papillose-based; primary branches 1–10 cm 

long, loosely erect, not concealed by the spikelets, nodes usually 

hispid, hairs papillose-based, sometimes glabrous, internodes 

scabrous, sometimes also sparsely hispid, hairs papillose-based; 

secondary branches present on the longer primary branches. 

Spikelets 3–5 mm long, disarticulating at maturity, scabrous to 

variously muricate and hairy, hairs usually not papillose-based, 

margins sometimes with a few papillose-based hairs; lower 

glumes usually more than 1⁄2 as long as the spikelets, abruptly 

narrowing to a fine, 0.5 mm point; lower florets sterile; lower 

lemmas usually awned, the awns 8–25(60) mm long; lower paleas subequal to the lower lemmas; upper lemmas 3–5 mm long, 

about 1.5 mm wide, not or sparsely exceeding the upper glumes, 

narrowly ovate to elliptical, coriaceous portion subacute, tips 

acuminate, membranous, without a line of hairs at the base of 

the tip; anthers 0.6–1(1.2) mm long. Caryopsis 1.2–1.8 mm 

long, brownish. 2n = 36.

Distribution and Habitat. Echinochloa walteri grows in wet places, often in shallow water and brackish 

marshes. It is a native species, found in both disturbed and undisturbed sites, although not in rice fields. Occasional specimens 

of E. walteri with glabrous lower sheaths and short awns can be 

distinguished from E. crus-pavonis by having less dense panicles.

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000) and Herrera Arrieta and 

Cortés Ortiz (2010).

Eleusine Gaertn.

Annual or perennial; caespitose. Culms 10–150 cm tall, 

herbaceous, glabrous, branching both at and above the base. 

Sheaths open; ligules membranous, ciliate. Inflorescences terminal, panicles of (1)2–20 nondisarticulating, spikelike branches, 

exceeding the upper leaves; branches 1–17 cm long, all or most 

in a digitate cluster, sometimes 1(2) branch(es) attached immediately below the terminal whorl, axes flattened, terminating in 

a functional spikelet. Spikelets 3.5–11 mm long, laterally compressed, with 2–15 bisexual florets; disarticulation above the 

glumes and between the florets. Glumes unequal, shorter than 

the lower lemmas; lower glumes 1- to 3-veined; upper glumes 

3- to 5(7)-veined; lemmas 3-veined, glabrous, keeled, apex entire, neither mucronate nor awned; paleas sometimes with 

winged keels; anthers 3, 0.5–1 mm long; ovaries glabrous. Fruit 

modified caryopsis, pericarp thin, separating from the seed at an 

early stage in its development; seeds usually obtusely trigonous, 

the surfaces ornamented. x = 8, 9, 10. 

Eight of the nine species of Eleusine are native to Africa, 

where they grow in mesic to xeric habitats. One species is native 

in South America; three species are introduced to Mexico, and 

two of these are present in Chihuahua.

FIGURE 92. Echinochloa walteri. A. Culm and inflorescence. 

B. Spikelets showing lower glume and lower lemma on left; upper 

glume on right. Drawn by Linda Ann Vorobik and Hana Pazdírková; copyright Utah State University.
134 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

KEY TO SPECIES OF ELEUSINE

1. Spikes 1–3 cm long, 6–10(12) mm wide; rachis prominently winged and toothed; upper glume keel winged . . . . . . . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. multiflora

1. Spikes 4–15 cm long, 2–4 mm wide; rachis wingless or winged with an entire (not toothed) wing, upper glume keel not 

winged . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. indica

125. Eleusine indica* (L.) Gaertn., Fruct. Sem. Pl. 1: 8. 1788. 

Cynosurus indicus L., Sp. Pl. 1: 72–73. 1753.

FIGURE 93

Annual. Culms 30–90 cm tall, erect or ascending, somewhat compressed; lower internodes 1.5–2 mm thick. Sheaths 

conspicuously keeled, margins often with long, papillose-based 

hairs, particularly near the throat; ligules 0.2–1 mm long, truncate, erose; blades 15–40 cm long, 3–7 mm wide, with prominent, white midveins, margins and/or adaxial surfaces often with 

basal papillose-based hairs. Panicles with 4–10(17) branches, 

often with 1 branch attached as much as 3 cm below the terminal cluster; branches (3.5)7–16 cm long, 3–5.5 mm wide, 

linear. Spikelets 4–7 mm long, 2–3 mm wide, with 5–7 florets, 

obliquely attached to the branch axes; lower glumes 1.1–2.3 mm 

long, 1-veined; upper glumes 2–2.9 mm long; lemmas 2.4–4 mm 

long; paleas with narrowly winged keels. Seeds ovoid, rugulose 

and obliquely striate, usually not exposed at maturity. 2n = 18.

Distribution and Habitat. Eleusine indica is a 

common weed in warmer regions of the world. It usually grows 

in disturbed areas and lawns and has been found in most states 

of contiguous Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: SW Chihuahua, Aug 1885, E. Palmer 40 (US). Bocoyna: Entre barrancas [between canyons] del Cobre & Bacahipare, 17 Aug 1976, bosque bajo de leguminosas [low legume 

forest], 1050 m, S. González & J.M. Peña 732 (ENCB). Ocampo: Parque Nacional “Cascada de Basaseachic,” en el area 

de los divisaderos [in area of divisions], 23 Sep 1990, 2100 m, 

R. Corral RCD-3929 (NMC). Temosachi: Nabogame, 10 Sep 

1987, 1800 m, Laferr. 1061 (MEXU).

126. Eleusine multiflora* Hochst. ex A. Rich., Tent. Fl. Abyss. 

2: 412. 1851.

Annual. Culms 20–30 cm tall, forming dense mats, slender, 

striate, glabrous or pilose. Sheaths flattened, collar sparsely pubescent with white hairs; ligules 0.8–1 mm long, truncate; blades 

10–20 cm long, 3–6 mm wide, sparsely hairy. Inflorescence 2–4 

short spikes, alternate, 1–4 cm long, over a winged and toothed 

rachis. Spikelets 4.5–5 mm long, ovate, with 5–10 florets; glumes 

3–4 mm long, laterally compressed, carinate, upper glumes with 

FIGURE 93. Eleusine indica. A. Habit. B. Spikelet. C. Floret. D. Caryopsis. Drawn by 

Linda Ann Vorobik and Karen Klitz; copyright Utah State University.
NUMBER 107 • 135

a winged keel; lemma 4.5–5 mm long, wide, laterally compressed, 

apiculate, with a scabrous keel and membranous margins. Caryopsis 1–1.2 mm long, laterally compressed, deeply sulcate, surface scaberulous and densely glandular. 

Distribution and Habitat. Eleusine multiflora is a common weed in the warmer regions of the world, 

native of Africa. It usually grows in disturbed areas and lawns 

and has been found in most states of the contiguous United 

States to Mexico in Aguascalientes, Chiapis, Chihuahua, Coahuila, Distrito Federal, Durango, Guanajuato, Hidalgo, Jalisco, 

México, Michoacán, Oaxaca, Puebla, Querétaro, San Luis Potosí, Sinaloa, Tlaxcala, and Zacatecas.

Specimens Examined. MEXICO. Chihuahua.

Bocoyna: Ejido San Ignacio Arareco, E of Creel, 19 Oct 1973, 

pine–oak forest, 7300 ft, Bye 5477 (MEXU). Guachochi: weeds 

in the plaza at Creel, 14 Oct 1977, Bye & W.A. Weber 8134

(MEXU). Ignacio Zaragoza: 20.3 km NE of Ignacio Zaragoza 

on Mex 23, 28 Sep 1989, 2400 m, P.M. Peterson & R.M. King 

8165 (US). Madera: Laguna de Babicora alrededores de [around] 

Nicolas Bravo,15 Sep 1994, 2150 m, T. Lebgue, G. Quintana 

& E. Estrada 3744 (NMC). Ocampo: Cascada de Basaseachic, 

Río Basaseachic, 5 Sep 2001, 2000 m, T.R. Vandevender & A.L. 

Reina 2001-864 (MEXU-1205781, NMC). Temosachi: Nabogme, 10 Sep 1987, 1800 m, Laferr. 1056 (MEXU).

Elionurus Humb.& Bonpl. ex Willd.

Perennial, occasionally annual; caespitose, sometimes 

with short rhizomes. Culms 10–150 cm long, erect, sometimes 

branching above the base. Leaves sometimes aromatic; sheaths 

without glandular pits; ligules shortly membranous and densely 

ciliate or of hairs; blades involute, flat, or folded. Inflorescences 

terminal, sometimes also axillary, composed of solitary, flexuous rames; rame internodes columnar to clavate, apex strongly 

oblique, not hollowed or rimmed; disarticulation in the rames, 

below the sessile spikelets. Spikelets in sessile-pedicellate pairs. 

Sessile spikelets dorsally compressed; calluses blunt, sometimes 

resembling a short pedicel; lower glumes enclosing the upper 

glumes, subcoriaceous, 2-keeled, keels prominently ciliate, intercarinal surface smooth, apex cuspidate to bilobed, rarely 

entire; lower florets reduced, sterile; upper florets bisexual, 

unawned; pedicels stout, appressed but not fused to the rame 

axes, pubescent or ciliate on the angles. Pedicellate spikelets 

3–8 mm long, about equal to the sessile spikelets, staminate, 

muticous to awn-tipped. x = 5. 

Elionurus has 15 species. Most species of Elionurus

are native to tropical Africa and America; one species is 

Australian. There are two species found in Mexico and in 

Chihuahua.

KEY TO SPECIES OF ELIONURUS

1. Rhizomes present; culms with nodes and internodes glabrous; racemes sparsely pubescent; lower glumes glabrous . . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. tripsacoides

1. Rhizomes absent; culms hirsute to long-pilose beneath the nodes; racemes conspicuously lanose; lower glumes pilose . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. barbiculmis

127. Elionurus barbiculmis Hack., Monogr. Phan. 6: 339. 1889.

Plants caespitose. Culms 40–60 cm tall, erect, usually unbranched, densely antrorsely hirsute to long-pilose beneath the 

nodes. Sheaths mostly glabrous, often ciliate on the margins, 

particularly at the throat; ligules with 1–2 mm long hairs; blades 

15–30 cm long, 1–2(4) mm wide, usually involute, abaxial surfaces with scattered long hairs adjacent to the margins, adaxial 

surfaces usually densely pilose. Rames 5–10 cm long, internodes 

densely villous. Sessile spikelets 4.5–8 mm; calluses about 0.5 

mm long, hirsute; lower glumes densely hirsute, acuminate, bifid, 

teeth 1.5–2.5 mm long; pedicels densely pilose dorsally. Pedicellate spikelets with densely pilose lower glumes. 2n = 20.

Distribution and Habitat. Elionurus barbiculmis grows on mesas, rocky slopes, hills, and in canyons, 

usually above 1,200 m. Its range extends from southern Arizona 

and southwestern Texas into northern Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Bachiniva: 55 air km NW Cuauhtemoc 6 km S junction to Bachiniva on road to Cuauhtemoc, 30 Oct 1989, 2300 m, Spellenberg, A. Whittemore, W. Boecklen, M. Mahrt & D. Ward10050

(NMC). Batopilas: Yamuco at 1 km E of Hwy towards Basihuare and Creel, N of Rio Urique crossing, 26 Aug 2003, bosque 

de pino–encino [pine–oak forest], 1891 m, P.M. Peterson & 

P. Catalán 17544 (US). Bocoyna: 24.7 mi N of San Juanito on 

road towards Cuauhtemoc, 5 Sep 2008, 2233 m, P.M. Peterson 

& J.M. Saarela 22032 (US). Casas Grandes: At first mt range 

SE Nuevo Casas Grandes, ca 12 mi SE of town on Hwy to Buenaventura, 30 Aug 1986, 2100 m, Spellenberg & R. Corral 

8580 (NMC). Chihuahua: Rancho Experimental La Campana, 

23 Oct 1982, pastizal [pastureland], 1640 m, A. Melgoza 631

(CIIDIR); km 37–38 carr. [hwy] Chihuahua–Cuauhtémoc, 16 

Sep 1997, 1690 m, E. Estrada & C. Yen 8574 (NMC); La Campana; Potrero La Sierra, 3 km Pte. carr. Panamericana, 7 Sep 73, 

pastizal con encinos, 1600 m, Valdés-Reyna VR-140 (RELC). 

Cuauhtémoc: km 37–38 carr. Chihuahua–Cuauhtémoc, 16 Sep 

1997, 1690 m, C. Yen & E. Estrada 8574 (ENCB). Guachochi: 39.2 km S of Creel on road to Batopilas at the Barranca El 

Cobre, 10 Sep 1989, 1930 m, P.M. Peterson, Annable & Y. Herrera 8025 (US); 1–2 km south of Río Osichi and Río Basihuare 

jct, 1 Sep 2003, bosque de encino–pino, 1600 m, P.M. Peterson 

& P. Catalán 17646 (CIIDIR); W of Munérachi, 7 Sep 2003, 

matorral xerófilo [xerophilous scrub], 1200 m, P.M. Peterson & 

P. Catalán 17717 (US). Guerrero: Miñaca, 13 Oct 1910, Hitchcock 7745 (US); Entre [between] La Junta & Temochi, 12 Aug 
136 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

1976, pastizal, 2135 m, M. González & J.M. Peña 576 (RELC). 

Matamoros: 19.3 km S of Villa Matamoros on Mex 45 to Durango, 3 Oct 1989, 1910 m, P.M. Peterson & R.M. King 8257 

(US). San Francisco del Oro: 21 km W of Parral and approx. 3.2 

km N on dirt road to Torrencillo, 26 Sep 1988, grassland, 2000 

m, P.M. Peterson & Annable 5958 (ENCB, US).

128. Elionurus tripsacoides Humb. & Bonpl. ex Willd., Sp. Pl. 

4(2): 941. 1806.

Plants caespitose; with short, knotty, rhizomatous bases. Culms 

60–120 cm long, glabrous throughout. Sheaths glabrous or pilose 

on the margins; ligules 0.5–1 mm long, membranous, short ciliate; 

blades 16–30 cm long, 2–4 mm wide, adaxial surfaces with hairs 

to 5 mm basally, glabrous distally, margins ciliate near the bases. 

Rames 6–15 cm long; internodes pilose. Sessile spikelets 6–8 mm 

long; calluses about 1 mm long, antrorsely hirsute; lower glumes 

usually mostly glabrous, rarely sparsely pilose dorsally, keels ciliate 

distally, apex acuminate, bidentate, teeth about 0.5 mm long; pedicels hirsute on the margins, usually glabrous elsewhere. Pedicellate 

spikelets similar to the sessile spikelets. 2n = 20.

Distribution and Habitat. Elionurus tripsacoides grows in moist pine woods and low prairies from 

southern Texas and the Gulf coast to Georgia, and south through 

Mexico and Central America to Argentina.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 16.1 km W of Balleza and 77.9 km E of Guachochi, 18 

Sep 1991, bosque de encino [oak forest], 1990 m, P.M. Peterson, Annable & Valdés-Reyna 10747 (CIIDIR, US). Batopilas: 

SW Chihuahua, Aug 1885, E. Palmer 22 (US). Camargo: E Chihuahua, just E of Organos, Vicinity of Organos, slopes of the 

igneous Sierra de los Organos, 6 Oct 1941, R. Stewart & I.M. 

Johnston 2058 (US). Chihuahua: near Chihuahua, 5 Aug 1885, 

C.G. Pringle 423 (US); La Campana, Potrero La Sierra, 3 km al 

W de la carr. [hwy] Panamericana, 7 Sep 1973, 1600 m, ValdésReyna VR-140 (ENCB). Guachochi: along Río Corareachi, 30 

Aug 2003, slopes with Quercus, 1840–1900 m, P.M. Peterson 

& P. Catalán 17604 (CIIDIR, US). Guerrero: Entrada [entry] a 

la Junta & Temochi, 12 Aug 1976, 2135 m, S. González & J.M. 

Peña 571 (ENCB). Ocampo : NE of Villa Ocampo near quad. 

41, 21 Aug 1948, Gentry 8652 (US).

Elymus L.

Perennial; sometimes caespitose, with or without rhizomes, 

sometimes stoloniferous. Culms usually erect to ascending, sometimes strongly decumbent to prostrate, usually glabrous. Leaves 

usually evenly distributed, sometimes somewhat basally concentrated; sheaths open for most of their length; auricles often 

present; ligules membranous, truncate or rounded, sometimes 

acute, entire or erose, often ciliolate; blades abaxial surfaces usually smooth or scabrous, sometimes with hairs, adaxial surfaces 

scabrous or with hairs, particularly over the veins, usually with 

unequal, not strongly ribbed, widely spaced veins, sometimes 

with equal, strongly ribbed, closely spaced veins. Inflorescences 

spikes, usually exserted, with 1–3(5) spikelets per node; rachises 

with scaberulous, scabrous, or ciliate edges. Spikelets usually appressed to ascending, sometimes strongly divergent or spreading, with 1–11 florets, the distal florets often reduced, the lowest 

florets usually functional, sterile and glume-like in some species; 

disarticulation usually above the glumes and beneath each floret, 

sometimes also below the glumes or in the rachises; glumes usually 2, absent or highly reduced in some species, usually equal 

to subequal, sometimes unequal, usually linear-lanceolate to linear, setaceous, or subulate, sometimes oblanceolate to obovate, 

(0)1- to 7-veined, sometimes keeled over 1 vein, not necessarily 

the central vein, the keel vein sometimes extended into an awn; 

lemmas linear-lanceolate, obscurely 5(7)-veined, apex acute, 

often awned, sometimes bidentate, sometimes with bristles, awns 

terminal or from the sinus, straight or arcuately divergent, not 

geniculate; paleas from shorter than to slightly longer than the 

lemmas, keels scabrous or ciliate, at least in part. Caryopsis with 

hairy apex. x = 7. 

Elymus is a widespread, north-temperate genus of about 

241 species (Soreng et al., 2017b). It now includes Sitanion Raf., 

but other taxa previously included in Elymus have been moved 

to Leymus and Thinopyrum (Barkworth, 2007).

KEY TO SPECIES OF ELYMUS

1. Inflorescence a spike with 2–3 spikelets per node; rachis disarticulating when mature; glumes with excurrent awns, 11–

135 mm long, linear to setaceous; lemma awn (10)15–120 mm long; anthers 0.9–3.5 mm long.

2. Pairs of glumes essentially equal in length, 11–40 mm long, linear-lanceolate to subsetaceous; lemma awn (10)15–40 mm 

long, moderately to strongly outcurving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. canadensis

2. Pairs of glumes mostly unequal in length, 20–135 mm long, linear to setaceous, sometimes highly reduced (as filiform 

bristles) to absent; lemma awn 15–120 mm long, flexuous to curved near the base . . . . . . . . . . . . . . . . . . E. elymoides

1. Inflorescence a spike with 1 spikelet per node; rachis continuous, rarely disarticulating when mature; glumes wide or narrow, not elongate and setaceous, lacking excurrent awns; lemma awn absent or up to 40 mm long; anthers 3–7 mm long.

3. Lemma of the bisexual floret awnless or the awn 2–4(10) mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. repens

3. Lemma of the bisexual floret awned, the awns 1–40 mm long.

4. Lemma awn straight to flexuous; leaf blades 10–40 mm wide; sometimes weakly rhizomatous or caespitose . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. trachycaulus

4. Lemma awn markedly divergent, recurved; leaf blades 2.5–7 mm wide; plants caespitose, not rhizomatous . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. arizonicus
NUMBER 107 • 137

129. Elymus arizonicus (Scribn. & J. G. Sm.) Gould, Madroño 9(4): 

125. 1947. Agropyron arizonicum Scribn. & J. G. Sm., Bull. 

Div. Agrostol. U.S.D.A. 4: 27–28. 1897. Elytrigia arizonica 

(Scribn. & J. G. Sm.) D. R. Dewey, Brittonia 35(1): 31. 1983.

Plants caespitose, not rhizomatous. Culms 45–100 cm tall, 

erect or decumbent at the base; nodes glabrous or almost so. Leaves 

evenly distributed over the lower 1⁄2 of the culms; sheaths glabrous; 

auricles usually present, to 1 mm long; ligules to 1 mm long on the 

basal leaves, 1–3 mm on the flag leaves; blades 2.5–7 mm wide, 

lax, abaxial surfaces smooth and glabrous, adaxial surfaces scabrous, with scattered 0.5–1 mm hairs, veins close together. Spikes 

12–25 cm long, 2.5–6 cm wide including the awns, 10–15 mm 

wide excluding the awns, flexuous, usually nodding or pendent 

at maturity, with 1 spikelet per node; internodes 11–17 mm long, 

0.4–1 mm wide, glabrous, mostly smooth, scabrous on the edges. 

Spikelets 14–26 mm long, 6–8 mm wide, appressed to divergent, 

1.5–2 times as long as the internodes, with 4–6 florets; rachillas glabrous; disarticulation above the glumes and beneath each 

floret; glumes narrowly lanceolate, margins about 0.2 mm wide, 

3(5)-veined, the bases flat, evidently veined, margins hyaline, widest at about midlength, acute or acuminate, unawned or awned, 

awns to 4 mm long, straight; lower glumes 5–9 mm long, upper 

glumes 8–10 mm long; lemmas 8–15 mm long, scabrous, rounded 

on the back, awns 10–25 mm long, arcuately diverging; paleas as 

long as or longer than the lemmas, tapering, apex truncate, about 

0.3 mm wide; anthers 3–5 mm long. 2n = 28.

Distribution and Habitat. Elymus arizonicus

grows in moist, rocky soil in mountain canyons of the southwestern United States and northern Mexico 

Specimens Examined. MEXICO. Chihuahua. 

Carichi: Sánchez, 12 Oct 1910, Hitchcock 7711 (US). Casas 

Grandes: 3 mi S of Cuesta Blanca, W of Casas Grandes, 18 Sep 

1960, Reeder, C. Reeder & Soderstrom 3536 (ARIZ); 3537

(MEXU, US); Cool ledges, Sierra Madre, 8 Oct 1887, 9000 ft, 

C.G. Pringle 1439 (US, MEXU). Chihuahua: Canyon de St. 

Diego, 17 Sep 1891, C.V. Hartman 805 (US); Santa Clara Canyon, 18 Aug 1936, LeSueur 0173 (MEXU). Galeana: Río Galeana, 12 Aug 1982, Vegetación Riparia [riparian vegetation], 

1460 m, Ing. Enríquez 1862 (MEXU). Gómez Farías: Laguna 

de Babicora, Cerro Canoas, 3 Sep 1994, 2400 m, T. Lebgue, 

G. Quintana & E. Estrada 2931 (NMC). Guadalupe y Calvo: 

about 3 mi S of La Rocha, Sierra Mohinora, on bluffs along 

stream (tributary of Río del Soldado), 18 Oct 1959, 7000 ft, 

Correll & Gentry 23232 (ENCB); near Cumbre Mohinora, 13 

Sep 2006, 3300 m, P.M. Peterson 20041, F. Sánchez Alvarado & 

E.P. Gómez Ruíz (CIIDIR, US). Madera: Ciénega Ojo de la Vibora, ejido El Largo, 14 Oct 1990, bosque de pino [pine forest], 

2300 m, O. Bravo 1904 (CIIDIR); A. Benítez 2865 (CIIDIR, 

MEXU); Sierra Madre near Col. García, 19 Sep 1899, bosque de 

encino [oak forest], 2300 m, C.H.T. Townsend & C.M. Barben 

337 (US); Chuichupa, Aug 1936, LeSueur 0115 (US); Puerto del 

Tenedor, ejido El Largo, 21 Aug 1990, bosque de pino, 2450 m, 

O. Bravo 1208 (CIIDIR); Laguna de Babícora, 4 km al N del 

Ejido La Raíz, 10 Sep 1994, G. Quintana & E. Estrada 3657

(NMC). Ocampo: Parque Nacional “Cascada de Basaseachic,” 

at base falls, 26 Abr [Apr] 1985, 1600 m, Spellenberg, R. Soreng 

& R. Corral 8013 (MEXU, NMC); Parque Nacional “Cascada 

de Basaseachic,” in canyon along Río Candamena leading to 

falls, 4 Oct 1986, 2000 m, Spellenberg, Soreng, R. Corral & 

T. Lebgue 8781 (NMC).

130. Elymus canadensis L., Sp. Pl. 1: 83–84. 1753.

Plants loosely caespitose, rarely with rhizomes of 1–2 mm 

thick, often glaucous. Culms (40)60–150(180) cm tall, erect or decumbent; nodes 4–10, mostly concealed by the sheaths, glabrous. 

Sheaths smooth or scaberulous, glabrous or hirsute, often reddish 

brown; auricles 1.5–4 mm long, brown or purplish black; ligules 

to 1(2) mm long, truncate, ciliolate; blades (3)4–15(20) mm wide, 

usually firm, often ascending and somewhat involute, usually dull 

green, drying to grayish. Spikes 6–30 cm long, 3–7 cm wide, usually nodding, sometimes pendent or almost erect, usually with 

2(3) spikelets per node, occasionally to 5 at some nodes, rarely 

with 1 at some nodes but never throughout; internodes (2)3–

5(7) mm long, or 5–10 mm long toward the base, 0.2–0.35 mm 

thick at the thinnest sections, glabrous or with a few hairs below 

the spikelets. Spikelets 12–20 mm long excluding the awns, more 

or less divergent, with (2)3–5(7) florets, lowest florets functional; 

disarticulation usually above the glumes and beneath each floret, 

rarely also below the glumes; glumes usually equal, occasionally 

subequal, 11–40 mm long including the awns, the basal 0–1 mm 

subterete and slightly indurate, glume bodies 6–13 mm long, 

0.5–1.6 mm wide, linear-lanceolate to subsetaceous, entire, widening or parallel-sided above the base, 3- to 5-veined, glabrous to 

scabrous-ciliate, rarely villous on the veins, margins firm, awns 

(5)10–25(27) mm long, straight to outcurving; lemmas 8–15 mm 

long, glabrous, scabrous, hispid, or uniformly villous with the 

hairs generally appressed, awns (10)15–40 mm long, moderately 

to strongly outcurving, often contorted at the spike bases; paleas 

7–13 mm long, acute, usually bidentate; anthers 2–3.5 mm long. 

2n = 28, rarely 42.

Distribution and Habitat. Elymus canadensis

grows on dry to moist or damp, often sandy or gravelly soil on 

prairies, dunes, stream banks, ditches, roadsides, and disturbed 

ground or, especially to the south, in thickets and open woods 

near streams. It is widespread in most of temperate North America, extending from the southwestern Northwest Territories to 

northern Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Camargo: 5 km W of Cd. Camargo, 5 Aug 1939, 1220 m, L. H. 

Harvey 1406 (ENCB). Chihuahua: Valley near Chihuahua, 20 

Sep 1885, C.G. Pringle 505 (MEXU, US); 14 Oct 1910, Hitchcock 7771 (US).

131. Elymus elymoides (Raf.) Swezey, Doane Coll. Nat. Hist. 

Stud. 1: 155. 1891. Sitanion elymoides Raf., J. Phys. Chim. 

Hist. Nat. Arts 89: 103. 1819.

FIGURE 94

Plants caespitose, often glaucous, not rhizomatous. Culms 

8–65(77) cm tall, erect or geniculate to slightly decumbent, 
138 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

sometimes puberulent; nodes 4–6, mostly concealed, usually glabrous, sometimes pubescent. Leaves evenly distributed; sheaths 

glabrous, scabrous, puberulent, or densely white-villous; auricles usually present, to about 1 mm long, often purplish; ligules 

shorter than 1 mm long, truncate, entire or lacerate; blades (1)2–

4(6) mm wide, spreading or ascending, often involute, sometimes 

folded, abaxial surfaces glabrous to puberulent, adaxial surfaces 

scabrous, puberulent, hirsute, or white-villous. Spikes 3–20 cm 

long, 5–15 cm wide, erect to subflexuous, with 2–3 spikelets 

per node, rarely with 1 at some nodes; internodes 3–10(15) mm 

long, 0.1–0.4 mm thick at the thinnest sections, usually glabrous, 

sometimes puberulent beneath the spikelets. Spikelets 10–20 mm 

long, divergent, sometimes glaucous, at least 1 spikelet at a node 

with 2–4(5) florets, 1–4(5) florets fertile, sometimes all florets 

FIGURE 94. Elymus elymoides subsp. brevifolius. A. Habit. B. Two spikelets. C. Spikelet. D. Lower floret. 

E. Lower floret, magnified. Drawn by Cindy Roché and Annaliese Miller; copyright Utah State University.
NUMBER 107 • 139

sterile in the lateral spikelets; disarticulation initially at the rachis nodes, subsequently beneath each floret; glumes subequal, 

20–135 mm including the often undifferentiated awns, the bases 

indurate and glabrous, glume bodies 5–10 mm long, 1–3 mm 

wide, linear to subulate and setaceous, sometimes highly reduced 

(as filiform bristles) to absent, 1- to 3-veined, margins firm, awns 

15–125 mm long, scabrous, sometimes split into 2–3 unequal 

divisions, flexuous to outcurving from near the base at maturity; 

fertile lemmas 6–12 mm long, glabrous, scabrous, or appressedpubescent, 2 lateral veins excurrent into bristles to 10 mm long, 

awns 15–120 mm long, about 0.4 mm wide at the base, often 

reddish or purplish, scabrous, flexuous to curved near the base; 

paleas 6–11 mm long, veins often excurrent into bristles to 

2(5) mm long, apex acute to truncate; anthers 0.9–2.2 mm long. 

Anthesis from late May to July. 2n = 28.

Distribution and Habitat. Elymus elymoides

grows in dry, often rocky, open woods, thickets, grasslands, and 

disturbed areas. It is widespread in western North America, from 

British Columbia to northern Mexico. It comprises four subspecies; only Elymus elymoides subsp. brevifolius (J. G. Sm.) Barkworth is in Mexico (Chihuahua).

Specimens Examined. MEXICO. Chihuahua. Bocoyna: weeds in the plaza at Creel, 14 Oct 1977, maleza [meadow], 

2200 m, Bye & W.A. Weber 8138 (MEXU). Carichi: Carichi, 23 

Sep 1982, pastizal [pastureland], 2200 m, Blanco 1897 (MEXU). 

Casas Grandes: Just S of hernández, W of Casas Grandes, 18 Sep 

1960, Reeder, C. Reeder & Soderstrom 3529 (ARIZ); W of Casas 

Grandes just south of Hernandéz, 18 Sep 1960, region pine–oak, 

6800 m, Reeder, C. Reeder & Soderstrom 3534 (MEXU). Chihuahua: Chihuahua, Aug.–Sept 1936, LeSueur 088 (MEXU); Sierra de la Parra across Rio Grande from Sierra Vieja, 13 Jun 1973, 

bosque juniperus–pino [juniper–pine forest], 1450–2158 m, M.C. 

Johnston, T.L Wendt & F. Chiang 11307 (MEXU). Janos: Rancho 

Santa Anita, 12 Jun 1979, pastizal halófito [halophyte grassland], 

1600 m, Blanco 91 (MEXU). Madera: Laguna de Babicora, alrededores [surroundings] de Nicolas Bravo, 18 Aug 1994, 2200 

m, Quintana, Lebgue & Estrada 3130 (NMC);12 km adelante 

[ahead] del Paraje Ojo de la Víbora, ejido El LAug, 26 Jun 1990, 

bosque de pino–encino [oak], 2000 m, A. Benítes 1437 (MEXU); 

Paraje El 8, junto [next to] al arroyo del ocho, ejido El LAug, 

2 May 1992, bosquete [grove] de Populus tremuloides, 2400 m, 

E. Guízar 2641 (MEXU). Ocampo: Parque Nacional de la Cascada de Basaseachic, 26 Abr [Apr] 1985, Spellenberg et al 8057

(MEXU). Temosachi: Nabogame, 23 May 1987, riverbank, 1800 

m, Laferr. 497 (MEXU).

132. Elymus repens* (L.) Gould, Madroño 9(4): 127. 1947. Triticum repens L., Sp. Pl. 1: 86. 1753.

Plants strongly rhizomatous, sometimes glaucous. Culms 

50–100 cm tall. Leaves sometimes basally concentrated; sheaths 

pilose or glabrous proximally; auricles 0.3–1 mm; ligules 0.25–

1.5 mm; blades 6–10 mm wide, usually flat, glabrous abaxially 

or sparsely pilose, adaxial surfaces usually sparsely pilose over 

the veins, sometimes glabrous, veins smooth, widely spaced, 

primary veins prominent, separated by the secondary veins. 

Spikes 5–15 cm long, 0.5–1.5 cm wide, erect, usually with 1 

spikelet per node, occasionally with 2 at a few nodes; internodes 

4–6(9.5) mm long, 0.5–1.2 mm wide, smooth or scabrous, glabrous, evenly puberulent, or sparsely pilose, hairs to 0.3 mm. 

Spikelets 10–27 mm long, appressed to ascending, with 4–7 florets; disarticulation tardy, usually below the glumes, the spikelets 

falling intact; glumes oblong, glabrous, keeled distally, keels inconspicuous and smooth proximally, scabrous and conspicuous 

distally, lateral veins inconspicuous, hyaline margins present in 

the distal 1⁄2, apex acute, unawned or awned, awns to 3 mm; 

lower glumes 8.8–11.4 mm long, 3- to 6-veined; upper glumes 

7–12 mm long, 5- to 7-veined; lemmas 8–12 mm long, glabrous, 

mostly smooth, sometimes scaberulous distally, unawned or with 

a 0.2–4(10) mm awn, awns straight; paleas 7–9.5 mm long, keels 

ciliate from 1⁄2 to almost the entire length, apex emarginate, truncate, or rounded; anthers 4–7 mm long. 2n = 22, 42.

Distribution and Habitat. Elymus repens

grows well in disturbed sites, spreading rapidly via elongate rhizomes as well as by seed. It is native to Eurasia and established 

through much of the North America, extending from Alaska to 

Greenland and south to California, Texas, and northern Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: Sierra Madre, 18 Oct 1887, C.G. Pringle 1176 

(MEXU). Bocoyna: Along old road W of Sisoguichic: pine–oak 

forest region, 12 Aug 1971, Bye 1842 (MEXU). Casas Grandes: 

5 mi S of Hernández, W of Casas Grandes, 18 Sep 1960, Reeder, 

C. Reeder & Soderstrom 3517 (ARIZ); 3525 (MEXU, US). 

Cuauhtémoc: 12 mi W of Cuauhtémoc, 5 Sep 1967, Reeder & 

C. Reeder 4884 (ARIZ); 21 km W of Cuauhtemoc, on Hwy 16, 23 

Aug 1990, 2000 m, P.M. Peterson & Annable 9601 (US). Gómez 

Farías: Laguna de Babicora, 18 Aug 1994, 2150 m, T. Lebgue & 

E. Estrada 3306 (NMC). Guachochic: Near Cusarare S of Arroyo 

Cusarare vado, 11 Aug 1972, pine–oak–juniper forest, 6900 ft, 

Bye 2734 (MEXU). Ocampo: Parque Nacional Cascada Basaseachi, ca. 100 m upstream from the top of the falls along río Basaseachi, 1 Aug 1988, grassland, 2000 m, Spellenberg, R. Corral, 

J. Brunt & L. Huenneke 9607 (CIIDIR, MEXU); Near Mirador 

of Cascada Basaseachic, 2022 m, slopes with Pinus, 7 Sep 2008, 

P.M. Peterson & J.M. Saarela 22093 (US).

133. Elymus trachycaulus (Link) Gould ex Shinners, Rhodora 

56(663): 28. 1954.

FIGURE 95

Plants caespitose, sometimes weakly rhizomatous. Culms 

30–150 cm tall, ascending to erect; nodes usually glabrous. 

Leaves basally concentrated; sheaths usually glabrous, sometimes markedly retrorsely hirsute or villous; auricles absent or 

to 1 mm; ligules 0.2–0.8 mm long, truncate; blades 2–5(8) mm 

wide, flat to involute, usually straight and ascending, abaxial 

surfaces usually smooth and glabrous, sometimes hairy, adaxial 

surfaces usually glabrous, sometimes conspicuously hairy. Spikes 

4–25 cm long, 0.4–1 cm wide, erect, with 1 spikelet at all or most 
140 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

nodes; internodes (4)7–9(12) mm long, edges scabrous, both surfaces smooth and glabrous. Spikelets 9–17(20) mm long, usually 

at least twice as long as the internodes, 3–6 mm wide, appressed, 

with 3–9 florets, lowest florets functional; rachillas glabrous or 

hairy, hairs to 0.3 mm; disarticulation above the glumes, beneath 

each floret; glumes subequal, 5–17 mm long, from 3⁄4 as long as 

to longer than the adjacent lemmas, 1.8–2.3 mm wide, lanceolate to narrowly ovate, widest about midlength, usually green, 

purple at higher latitudes and elevations, flat or asymmetrically 

keeled for their full length, 3- to 7-veined, the keel vein usually 

scabrous, the others smooth or scabrous, only 1 vein excurrent 

to the apex, adaxial surfaces glabrous, margins hyaline or scarious, usually more or less equal, 0.2–0.5 mm wide, widest at or 

slightly beyond midlength, apex acute to awned, awns to 11 mm 

long; lemmas 6–13 mm long, glabrous, usually smooth proximally, often scaberulous distally over the veins, apex acute, usually awned, awns to 40 mm long, usually straight, sometimes 

weakly curved if shorter than 10 mm; paleas subequal to the 

lemmas, keels straight or slightly outwardly curved below the 

apex, tapering to the apex, apex truncate, 0.15–0.3 mm wide, 

keel veins often excurrent beyond the intercostal region, sometimes forming teeth; anthers (0.8)1.2–2.5(3) mm long. 2n = 28.

FIGURE 95. Elymus trachycaulus. A. Habit. B. Ligule. C. Inflorescence. D. Spikelet. 

E. Lemma. F. Palea. Drawn by Cindy Roché and Annaliese Miller; copyright Utah 

State University.
NUMBER 107 • 141

Distribution and Habitat. Elymus trachycaulus grows from sea level to 3,300 m, usually in open or moderately open areas and sometimes in forests. Its range extends 

from the boreal forests of North America east through Canada 

to Greenland and south into Mexico. It has two varieties in 

Mexico; only Elymus trachycaulus var. trachycaulus is found 

in Chihuahua.

Specimens Examined. MEXICO. Chihuahua. 

Guachochi: Approx. 22.5 mi NE of Cieneguita de Barranca on 

road towards Creel, 5 Sep 2003, bosque de pino [pine forest], 

2160 m, P.M. Peterson & P. Catalán 17690 (US). Madera: Sierra 

Madre near Col. Garcia, 14 Sep 1899, bosque de encino [oak 

forest], 2300 m, C.H.T. Townsend & C.M. Barben 328 (US); 

Chuichupa, 22 Aug 1937, LeSueur 0201 (US). Ocampo: Parque 

Nacional “Cascada de Basaseachic,” 100 m upstream from the 

top of the falls along the Rio Basaseachi, 1 Aug 1988, 2000 m, 

Spellenberg, R. Corral, J Brunt & L. Huenneke 9607 (NMC). 

Riva Palacio: Majalca, 26 Jul 1936, LeSueur 0139 (MEXU); 

13 Aug 1939, L. H. Harvey 1489 (US).

Enneapogon Desv. ex P. Beauv.

Perennial or annual; caespitose, more or less hairy throughout. Culms 3–100 cm tall; nodes hairy; internodes hollow. 

Sheaths open; ligules of hairs; microhairs of blades each with an 

elongated basal cell and an inflated terminal cell. Inflorescences 

terminal, spikelike to somewhat open panicles, bases often included within the uppermost leaf sheath; disarticulation above 

the glumes but not between the florets, florets falling as a unit. 

Spikelets with 3–6 florets, frequently only the lowest floret bisexual, distal florets progressively reduced. Glumes subequal, as 

long as or slightly shorter than the florets (including the awns), 

more or less pubescent; lower glumes 5- to 7-veined; lemmas 

firm, rounded on the backs, villous below the middle, strongly 

9-veined, veins excurrent into equal, plumose awns 3–5 times 

as long as the lemma bodies and forming a pappuslike crown; 

paleas longer than the lemmas, entire, thinly membranous, 

2-veined, 2-keeled, keels hairy; anthers 0.2–1.5 mm long, 3; 

styles 2, free to the base, white. x = 10. Enneapogon includes 

about 24 species. It is found in tropical and warm regions of the 

world, especially in Africa and Australia.

134. Enneapogon desvauxii P. Beauv., Ess. Agrostogr. 82, 161. 

t. 16, f. 11. 1812.

FIGURE 96

Perennial. Culms 20–45 cm tall, about 1 mm thick, ascending to erect from a hard knotty base, often branching; nodes 

pubescent. Sheaths usually shorter than the internodes, more 

or less pubescent; ligules about 0.5 mm long; blades mostly 

2–12 cm long, 1–2 mm wide, more or less hairy, soon involute. 

Panicles 2–10 cm long, spikelike, grayish-green or lead-colored. 

Spikelets mostly 5–7 mm long, usually only the lowest floret bisexual; glumes subequal, 3–5 mm long, thin, puberulent; upper 

FIGURE 96. Enneapogon desvauxii. A. Habit. B. Spikelet. C. Floret. D. Cleistogamous spikelet. Drawn by Linda Ann Vorobik and 

Karen Klitz; copyright Utah State University.
142 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

glumes often 3- to 4-veined; lowest lemmas 1.5–2 mm long, firm, 

rounded on the back; awns 3–4 mm long; anthers 0.3–0.5 mm 

long. Caryopsis 1–1.2 mm long, oval, plump; embryos subequal 

to the caryopsis. Cleistogamous spikelets commonly present in 

the lower sheaths, their lemmas larger than those of the florets 

in the aerial panicles, unawned or with awns that are much reduced. 2n = 20.

Distribution and Habitat. Enneapogon desvauxii grows in open areas of the southwestern United States 

and in much of Mexico. It also grows in Peru, Bolivia, Argentina, 

and most of Africa, extending eastward through Saudi Arabia 

and India to China.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 12 km al N de Flores Magón, 7 Oct 1995, 1180 m, 

R. Corral, P. Olivas & J.O. Torres RCD6485 (UACJ); 5 km al 

N de Flores Magón, 30 Jul 1994, 1200 m, R. Corral, E. Pérez, 

A. Domínguez & F. Félix RCD5377 (UACJ); 10 km al norte de 

Estación Sueco, 10 Oct 74, matorral [scrub], 1400 m, ValdésReyna VR-643 (RELC). Aldama: 10.9 (rd) mi NE of Aldama 

along Chihuahua Hwy 16, 14 Sep 1972, matorral, 4200 ft, 

J. Henrickson 7502 (MEXU); km 50 carr. [hwy] Chihuahua–

Ojinaga, 24 Aug 1978, matorral, 1250 m, Rodríguez, Molinar 

& Baray 278 (MEXU); 24, Aug 1978, matorral, 1250 m, Rodríguez, Molinar & Baray 20 (MEXU). Aquiles Serdan: Aquiles 

Serdán km 2 camino [road] a San Diego de Alcalá, 29 Sep 1995, 

matorral, 1260 m, Ing. González 99 (MEXU). Camargo: 6 mi 

W of Piloncillo, rd from Jimenez to Camargo, 24 Sep 1938, I.M. 

Johnston 7876 (US). 17 mi SSE of Camargo, 6 Sep 1967, 4200 ft, 

Reeder & C. Reeder 4869 (ARIZ, ENCB); km 2 carr. Camargo–

Chihuahua, 29 Sep 1995, orilla de camino [wayside], 1240 m, 

Ing. González 86 (MEXU). Casas Grandes: Arroyo Los Nogales, 

20 km al S de Col. Juárez, 23 Sep 1982, 1450 m, pastizal en 

barranca [pastureland in canyon], Tenorio 1602 & Romero

(ENCB, MEXU). Chihuahua: Chihuahua, 14 Oct 1910, Hitchcock 7801 (US); near Chihuahua, 4 Sep 1885, C.G. Pringle 483

(MEXU, US); 20 Aug 1935, LeSueur Mex-045 (US); 5 mi SW of 

Chihuahua on rd to Cuauhtémoc, 6 Oct 1959, Soderstrom 903 

(MEXU, US), 922 (MEXU, US); 12 mi N of Chihuahua, 16 Sep 

1960, grassland, 1500 m, Reeder, C. Reeder & Soderstrom 3483

(ENCB, US); 17 km al Oeste [W] de Chihuahua, carr. Chihuahua–Cuauhtemoc, 11 Aug 1996, 1500 m, E. Estrada & C. Yen 

5219 (NMC); La Campana, Potrero El Plan, 22 Sep 74, pastizal 

mediano abierto [mostly open grassland], 1500 m, Valdés-Reyna 

VR-625 (RELC); carr. Chih–Delicias km 18 entronque [junction] a Mapula, 29 Sep 1995, pastizal, 1520 m, Quiñones 105, 

111 (MEXU). Delicias: 7 mi S of Delicias along Hwy 45, 24 Sep 

1972, matorral, 4000 ft, J. Henrickson 7993 (MEXU). Hidalgo 

del Parral: 2 mi E of Parral, 3 Oct 1959, Soderstrom 860 (US); 

NE edge of Parral, 30 Sep 1959, D.S. Correl 22670 (ENCB). 

Jiménez: Reserva de la Biosfera de Mapimí, dunas de arena 

[sand dunes] La Soledad, 9 Jul 1997, matorral xerófilo [xerophilous scrub], 1140 m, A. García 2702 (CIIDIR); 20 Sep 1999, 

A. García 3689 (CIIDIR); 8 mi NW of Jiménez on Mex. 45, 30 

Ag 1971?, 4400 ft, L. H. Harvey 8890 (ENCB); Bank of Rio 

Florido, Cd. Jiménez, 28 Jul 1939, 1340 m, L. H. Harvey 1329

(ENCB); 33 mi SE of Jiménez, 27 Sep 1963, Reeder & C. Reeder 

3618 (ARIZ); 9 km NW of Las Pampas ranch, on the road to 

Camargo, at the main ranch gate, 24 Aug 1972, matorral, 1450 

m, F. Chiang, T. Wendt & M.C. Johnston 8818 (MEXU). Juárez: 

parte alta [high part] de la Sierra de Samalayuca, aprox. 50 km 

al S de Cd. Juárez, 9 Sep 1995, 1300 m, R. Corral & P. Olivas 

RCD6365 (UACJ); Sierra de Samalayuca, 13 Oct 1997, pastizal, 

I. Enríquez, S. Ordoñez & J. Leyva IEA16 (UACJ). Manuel 

Benavides: E Chihuahua, vicinity of Pirámide, 11 Aug 1941, 

I.M. Johnston 8116 (US). Meoqui: Entre [between] Julimes & 

Felipe Ángeles, 31 Jul 76, matorral, 1330 m, S. Gonzáles & J.M. 

Peña 394 (RELC). Nuevo Casas Grandes: 27.4 km S of Nuevo 

Casa Grandes on MEX 2, 28 Sep 1989, oak woods, 1585 m, 

P.M. Peterson & R.M. King 8146 (ENCB). Ojinaga: 43 km W of 

Ojinaga on Hwy to Chihuahua city, about 2 km N of the deeply 

incised canyon of Río Conchos, 20 Oct 1972, matorral, 950 m, 

T.L. Wendt, F. Chiang & M.C. Johnston 9734 (MEXU); Mina 

Las Marías on Mesa de Aguila, 5 Oct 1972, matorral, 900 m, 

F. Chiang, T. Wendt & M.C. Johnston 9685 (MEXU). Saucillo: 

Rancho El Salvador, 10 Oct 1995, matorral, 1300 m, Fierros 

113 (MEXU). Valle de Zaragoza: 58 km N of Parral on Mex 

24 towards Chihuahua, 14 Sep 1989, grassland, 1500 m, P.M. 

Peterson & Annable 8098 (ENCB, US).

Eragrostis Wolf

Annual or perennial; usually synoecious, sometimes dioecious; caespitose, stoloniferous, or rhizomatous. Flowering culms 

not woody, erect, decumbent, or geniculate, sometimes rooting 

at the lower nodes, simple (without innovations or sprouts at 

the lower nodes) or branched (with innovations or sprouts at 

the lower nodes); internodes solid or hollow. Sheaths open, 

often with tufts of hairs at the apex; ligules usually membranous 

and ciliolate or ciliate, cilia sometimes longer than the membranous base, occasionally of hairs or membranous and nonciliate; blades flat, folded, or involute. Inflorescences terminal, 

sometimes also axillary, simple panicles, open to contracted or 

spikelike, terminal panicles usually exceeding the upper leaves; 

pulvini in the axils of the primary branches glabrous or hairy; 

branches not spikelike, not disarticulating, laterally compressed, 

with 2–45 florets; disarticulation below the fertile florets, sometimes also below the glumes. Glumes usually shorter than the adjacent lemmas, (1)3(5)-veined, not lobed, apex obtuse to acute, 

awnless; calluses glabrous or sparsely pubescent; lemmas usually 

glabrous, obtuse to acute, 3(5)-veined, usually keeled, awnless 

or mucronate; paleas shorter than the lemmas, longitudinally 

bowed-out by the caryopsis, 2-keeled, keels usually ciliate; anthers 2 or 3; ovaries glabrous. Cleistogamous spikelets occasionally present, sometimes on the axillary or on terminal panicles. 

Caryopsis variously shaped. x = 10. 

Eragrostis, a genus of approximately 444 species, occurs in 

tropical and subtropical regions throughout the world (Soreng et 

al., 2017b). There are 18 species of Eragrostis in Chihuahua and, 

of these, 10 are native (Peterson, 2003a; Peterson and Valdés 

Reyna, 2005) .
NUMBER 107 • 143

KEY TO SPECIES OF ERAGROSTIS

1. Annual, caespitose or mat-forming, without innovations at the basal nodes.

2. Palea keels prominently ciliate, the cilia 0.2–0.8 mm long.

3. Spikelets 1.8–3.2 mm long, 1–2 mm wide, with 6–11 florets; lemmas 0.8–1.3 mm long without glands on the keels; 

anthers 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. ciliaris

3. Spikelets 6–20 mm long, 2–4 mm wide, with 10–40 florets; lemmas 2–2.8 mm long with 1–3 crateriform glands on 

the keels; anthers 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. cilianensis

2. Palea keels smooth or scabrous, the cilia less than 0.2 mm long.

4. Caryopsis with a shallow or deep ventral groove, ovoid to straight angular-prismatic, the surface striate . . . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. mexicana

4. Caryopsis without a ventral groove, usually globose, pyriform, ovoid to prism-shaped, or ellipsoid, the surface smooth 

to faintly striate.

5. Plants without glandular pits or bands.

6. Lower glumes 0.5–1.5 mm long, at least 1⁄2 as long as the lowest lemmas; spikelets 1.2–2.5 mm wide; panicle 

branches solitary or paired at the lowest 2 nodes; lemmas with moderately conspicuous lateral veins . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. pectinacea

6. Lower glumes 0.3–0.6(0.8) mm long, usually less than 1⁄2 as long as the lowest lemmas; spikelets 0.6–1.4 mm 

wide; panicle branches usually whorled at the lowest 2 nodes; lemmas within conspicuous lateral veins . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. pilosa

5. Plants with glandular pits or bands somewhere, the location(s) various, including any or all of the following: below 

the cauline nodes, on the sheaths, blades, rachises, panicle branches, or pedicels, or on the keels of the lemmas.

7. Spikelets 0.6–1.4 mm wide; pedicels 1–10 mm long, lax, appressed or divergent . . . . . . . . . . . . . . . . E. pilosa

7. Spikelets 1.1–4 mm wide; pedicels 0.2–4 mm long, stiff, straight, usually divergent.

8. Lemmas 1–1.4 mm long; spikelets with 2–3(5) florets; pedicels with a glandular ring or band; lower glumes 

0.5–0.8 mm long; sheaths with papillose-hirsute hairs on the collar . . . . . . . . . . . . . . . . . . . . . E. pringlei

8. Lemmas 1.4–2.8 mm long; spikelets with 7–40 florets; pedicels without a glandular ring or band; lower 

glumes 0.9–2 mm long; sheaths without papillose-hirsute hairs on the collar

9. Lemmas 2–2.8 mm long, with 1–3 crateriform glands along the keels; spikelets 6–20 mm long, 2–4 mm 

wide, with 10–40 florets; disarticulation below the florets, the rachillas persistent; anthers yellow . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. cilianensis

9. Lemmas 1.4–1.8 mm long, without crateriform glands along the keels; spikelets 4–7(11) mm long, 1.1–

2.2 mm wide, with 7–12(20) florets; disarticulation below the lemmas, both the paleas and rachillas usually persistent; anthers reddish-brown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. barrelieri

1. Perennial, sometimes rhizomatous, forming innovations at the basal nodes.

10. Paleas with a broad lower portion forming a wing or tooth on each side, these often projecting beyond the lemmas.

 11. Spikelets 5.5–16 mm long, 2.7–9 mm wide; lemmas 3–5 mm long, the keels without crateriform glands; pedicels 

with a narrow band or abscission line just below the apex; anthers 1.4–2.8 mm long . . . . . . . . . . . . . E. superba

 11. Spikelets 2–5 mm long, 2–3.5 mm wide; lemmas 1.8–2.3 mm long, the keels with a few crateriform glands; pedicels 

without a narrow band or abscission line just below the apex; anthers 0.5–0.9 mm long . . . . . . E. echinochloidea

10. Paleas without a broad lower portion forming a wing or tooth, the bases never projecting beyond the lemmas.

 12. Plants with short, knotty rhizomes less than 4 mm thick, often stout but never elongated . . . . . . . . E. spectabilis

 12. Plants not rhizomatous

 13. Caryopsis with shallowly to deeply grooved adaxial surfaces, straight angular-prismatic to ellipsoid, ovoid, or 

obovoid in overall shape. 

 14. Caryopsis strongly dorsally compressed, translucent, mostly light brown, bases sometimes greenish.

 15. Lemmas 1.8–3 mm long; panicles 16–35(40) cm long, (4)8–24 cm wide; blades 12–50(65) cm long; 

caryopsis 1–1.7 mm long; ligules 0.6–1.3 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. curvula

 15. Lemmas 1.5–1.7 long; panicles 7–18 cm long, 2–8 cm wide; blades 2–12 cm long; caryopsis 0.6–0.8 mm 

long; ligules 0.3–0.5 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. lehmanniana

 14. Caryopsis laterally compressed, terete, or slightly dorsally compressed, usually opaque and reddish–brown.

 16. Lemmas 1.2–1.6 mm long; culms (20)30–50(60) cm tall; sheaths usually glabrous . . . . . . . . . E. lugens

 16. Lemmas 1.6–3 mm long; culms (30)40–170 cm tall; sheaths usually hairy.

 17. Lemmas 1.6–2.2 mm long; anthers 0.5–0.8 mm long, purplish . . . . . . . . . . . . . . . . . E. intermedia

 17. Lemmas 2–3 mm long; anthers 0.6–1.7 mm long, purplish to yellowish.
144 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

 18. Caryopsis 0.8–1.6 mm long; lemmas 2.4–3 mm long . . . . . . . . . . . . . . . . . . . . . . . . . E. erosa

 18. Caryopsis 0.6–0.8 mm long; lemmas 2–2.6 mm long . . . . . . . . . . . . . . . . . . . . . . . . E. palmeri

 13. Caryopsis not grooved on the adaxial surfaces, ellipsoid, ovoid, obovoid, globose, to pyriform, prism-shaped, 

and straight angular-prismatic in overall shape.

 19. Anthers 2; primary branches stiff; panicles 1–15 cm wide, narrowly oblong to ovate and open; pedicels 

0–1(3) mm long, always shorter than the spikelets; spikelets 2.4–5 mm wide . . . . . . . . . . . E. secundiflora

 19. Anthers 3.

 20. Primary panicle branches not rebranched; proximal spikelets on each branch sessile or subsessile, the 

pedicels shorter than 0.4 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. sessilispica

 20. Primary panicle branches with secondary branches; proximal spikelets on each branch pedicellate, the 

pedicels longer than 0.4 mm.

 21. Spikelets 2–5.5 mm long; lemmas 1.2–1.6 mm long; culms (20)30–50(60) cm tall . . . . . . E. lugens

 21. Spikelets 4–12 (14) mm long; lemmas 1.5–3 mm long; culms (20) 40–150 cm tall.

 22. Lemmas 1.8–3 mm long; panicles 16–35(40) cm long, (4)8–24 cm wide; blades 12–50(65) cm 

long; caryopsis 1–1.7 mm long; ligules 0.6–1.3 mm long . . . . . . . . . . . . . . . . . . . . . E. curvula

 22. Lemmas 1.5–1.7 long; panicles 7–18 cm long, 2–8 cm wide; blades 2–12 cm long; caryopsis 

0.6–0.8 mm long; ligules 0.3–0.5 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . E. lehmanniana

135. Eragrostis barrelieri* Daveau, J. Bot. (Morot) 8: 289. 1894.

FIGURE 97

Caespitose annual; without innovations. Culms (5)10–60 cm 

tall, erect to decumbent and prostrate, much-branched near the 

base, somewhat glaucous, with a ring of glandular tissue below 

the nodes, rings often shiny or yellowish. Sheaths 1⁄2–7⁄8 the length 

of the internodes, hairy at the apex, hairs to 4 mm long; ligules 

0.2–0.5 mm long, ciliate; blades 1.5–10 cm long, 1–3(5) mm 

wide, flat, abaxial surfaces glabrous, adaxial surfaces glabrous, 

sometimes scaberulous, occasionally with white hairs to 3 mm 

long, margins without crateriform glands. Panicles 4–20 cm long, 

2.2–8(10) cm wide, ovate, open to contracted, rachises with shiny 

or yellowish glandular spots or rings below the nodes; primary 

branches 0.5–6 cm long, diverging 20°–100° from the rachises; 

pulvini glabrous; pedicels 1–4 mm long, stout, stiff, divergent, 

without glandular bands. Spikelets 4–7(11) mm long, 1.1–

2.2 mm wide, narrowly ovate, reddish-purple to greenish, occasionally grayish, with 7–12(20) florets; disarticulation acropetal, 

paleas persistent; glumes broadly ovate, membranous, 1-veined; 

lower glumes 0.9–1.4 mm long; upper glumes 1.2–1.6 mm long; 

lemmas 1.4–1.8 mm long, broadly ovate, membranous, lateral 

veins evident, apex acute to obtuse; paleas 1.3–1.7 mm long, hyaline, keels scabrous, scabrousities to 0.1 mm long, apex obtuse 

to acute; stamens 3; anthers 0.1–0.2 mm long, reddish-brown. 

Caryopsis 0.4–0.7 mm long, ellipsoid, not grooved, smooth to 

faintly striate, light brown. 2n = 40, 60.

Comments: The ring of glandular tissue is most conspicuous below the upper cauline nodes.

Distribution and Habitat. Eragrostis barrelieri is an introduced European species that is now naturalized in 

North America. It grows on gravelly roadsides, in gardens, and 

in other disturbed, sandy sites, especially near railroad yards, at 

10–1,800 m.

Specimens Examined. MEXICO. Chihuahua. 

Aldama: Rancho la Urraca, acceso [access] de Camargo hacia 

[toward] Ojinaga, desviar hacia [divert toward] Hércules por 

terracería [dirt road], aprox. 60 km tomar a la izquierda [take 

left] 30 km, 19 Oct 2000, Matorral [scrub], G. Gómez 520, 551 

(MEXU). Jiménez: Costado del Río Florido, Torreoncitos, 4 Aug 

2010, 1330 m, D. Noya & M.L. Juárez 3402 (CIIDIR); 50 km al 

FIGURE 97. Eragrostis barrelieri. A. Inflorescence. B. Palea and 

lemma above. Drawn by Linda Ann Vorobik and Cindy Roché; 

copyright Utah State University.
NUMBER 107 • 145

S de Jiménez, 15 Aug 2010, 1442 m, D. Ramírez & M.L. Juárez 

3416 (CIIDIR). Juárez: 14 km S of Cd. Juárez, adj. to the rd to Cd 

of Chihuahua, 3 Oct 1978, S.D. Koch & I. Sánchez 78114 (US).

136. Eragrostis cilianensis* (All.) Vignolo ex Janch., Mitt. 

Naturwiss. Vereins Univ. Wien, n.s., 5: 110. 1907.

FIGURE 98

Caespitose annual; without innovations. Culms 15–

45(65) cm tall, erect or decumbent and prostrate, sometimes 

with crateriform glands below the nodes. Sheaths overlapping 

below, 2⁄3 the length of the internodes above, glabrous, occasionally glandular, apex hairy, hairs to 5 mm long; ligules 0.4–0.8 mm 

long, ciliate; blades (1)5–20 cm long, (1)3–5(10) mm wide, flat 

to loosely involute, abaxial surfaces glabrous, sometimes glandular near margins, adaxial surfaces scaberulous, occasionally 

also hairy. Panicles (3)5–16(20) cm long, 2–8.5 cm wide, oblong to ovate, condensed to open; primary branches 0.4–5 cm 

long, appressed or diverging 20°–80° from the rachises; pulvini 

glabrous or hairy; pedicels 0.2–3 mm long, stout, straight, stiff, 

usually divergent, occasionally appressed. Spikelets 6–20 mm 

long, 2–4 mm wide, ovate-lanceolate, plumbeous, greenish, with 

10–40 florets; disarticulation below the florets, each floret falling 

as a unit, rachillas persistent; glumes broadly ovate to lanceolate, membranous, usually glandular; lower glumes 1.2–2 mm 

long, usually 1-veined; upper glumes 1.2–2.6 mm long, often 

3-veined; lemmas 2–2.8 mm long, broadly ovate, membranous, 

keels with 1–3 crateriform glands, apex obtuse to acute; paleas 

1.2–2.1 mm long, hyaline, keels scabrous, sometimes also ciliate, 

cilia to 0.3 mm long, apex obtuse to acute; stamens 3; anthers 

0.2–0.5 mm long, yellow. Caryopsis 0.5–0.7 mm long, globose 

to broadly ellipsoid, smooth to faintly striate, not grooved, 

reddish-brown or translucent. 2n = 20.

Distribution and Habitat. Eragrostis cilianensis is an introduced European species that grows in disturbed 

sites such as pastures and roadsides through most of the North 

America up to 2,300 m.

Specimens Examined. MEXICO. Chihuahua. 

Aldama: Santo Domingo, 50 km SW of Coyame of Mex 16 between Presidio, Texas and Chihuahua, 22 Sep 1988, 1400 m, 

P.M. Peterson & Annable 5755 (US); Rancho El Morrion, acceso 

[access] de Aldama hacia [toward] Ojinaga, desviar [divert] en el 

km 55 a la derecha [to right] 5 km por terracería [dirt road], 24 

Oct 2000, matorral [scrub], G. Gómez 629 (MEXU). Allende: 

20 mi N from Parral to Jiménez on hwy 45, 21 Jul 2006, grassland, 1750 m, K.R. Adams & N. Martínez 056–2006 (CIIDIR). 

Ascensión: Rancho La Viuda Ascensión, 7 Sept 1981, matorral, 

Serrano & Alvarez 1531 (MEXU); Cerro de Borregas, about 

8 km E of Guzmán, 22 Aug 1972, matorral, 1250 m, F. Chiang, 

T. Wendt & M.C. Johnston 8790H (MEXU). Buenaventura: 

9 km al S de Buenaventura, 5 Sept 1978, pastizal [pastureland], 

1574 m, Melgoza 351 (MEXU). Camargo: 20 km S of Cd. Camargo, 1 Aug 1939, 1220 m, L. H. Harvey 1377 (US); km 2 carr. 

[hwy] Camargo–Chih., 29 Sept 1995, orilla de camino [wayside], 

1240 m, Ing. González 89 (MEXU). Casas Grandes: Arroyo de 

FIGURE 98. Eragrostis cilianensis. A. Habit. B. Culm and inflorescence. C. Spikelet. D. Palea and lemma above. Drawn by Linda Ann 

Vorobik and Cindy Roché; copyright Utah State University.
146 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

los Nogales, 20 km al S de Col. Juárez, Casas Grandes, 23 Sep 

1982, pastizal en barranca [pastureland in canyon], 1450 m, 

Tenorio 1603 & Romero (ENCB, MEXU); Rancho Tapiecitas, 

acceso de Casas Grandes a Col. Hidalgo, aprox. 20 km desviar a 

la derecha por terracería 20 km, 4 Oct 2000, pastizal, G. Gómez 

124 (MEXU). Chihuahua: Chihuahua, 10 Oct 1935, LeSueur 

Mex-083 (US); 5 mi SW of Chihuahua on rd to Cuauhtémoc, 6 

Oct 1959, Soderstrom 901 (MEXU, US); Base de la Sierra de La 

Campana, 80 km al N de Chihuahua, 19 Oct 1974, pastizal con 

encinos [oaks], 1700 m, Rzedowski 32339 (ENCB); La Campana, Potrero El Plan, 4 km E carr. Panamericana, 6 Sep 73, 

lotes de producción de semilla [seed-production lots], 1500 m, 

Valdés-Reyna VR–90 (RELC); carr. Chih–Delicias km 18 entronque [junction] a Mapula, 29 sept 1995, 1520 m, Quiñones 

115 (MEXU); Ejido La Haciendita (EL TARAIS), 16 Aug 1996, 

pastizal, 2620 m, Quiñones 117 (MEXU); Presa Chihuahua, 7 

Nov 1936, LeSueur 0122 (MEXU). Guerrero: Miñaca, 13 Oct 

1910, Hitchcock 7738 (US). Janos: 10 km W of Carretas, 21 

Aug 1939, L. H. Harvey 1577 (US); Chihuahua–Sonora Border, Rancho Carretas, 26 Aug 1937, 1450 m, L. H. Harvey 

1592 (US); Mexican boundary line near White Water, 11 Sep 

1893, E.A. Mearns 2273 (US); 10 km antes [before] de Janos, 

(carr. Casas Grandes–Cd. Juárez), 23 Oct 74, Valdés-Reyna 

VR-753 (RELC). Jiménez: Bank of the Río Florido, Cd. Jiménez, 28 Jul 1939, 1340 m, L. H. Harvey 1324 (US); Sta. Eulalia Mts, 1280 m, E. Wilkinson 52 (US); 9 mi W of Jiménez, 6 

Sep 1967, in thorn scrub, 4500 ft, Reeder & C. Reeder 4872 

(ARIZ, ENCB); El Hugo, Torreoncitos, 13 Aug 2010, terrenos 

de cultivo [farmland], 1355 m, D. Ramírez & M.L. Juárez 3386

(CIIDIR). Juárez: 14 km S of Cd. Juárez, along rd to the ciudad 

of Chihuahua, 3 Oct 1978, S.D. Koch & I. Sánchez 78113 (US). 

Manuel Benavides: E Chihuahua, vicinity of Pirámide, 12 Aug 

1941, I.M. Johnston 8119 (US). Ojinaga:1 km SW of Rancho 

San Francisco on the road to Rancho San Fernándo, 30 Sept 

1972, pastizal, 1400 m, F. Chiang, T. Wendt & C. Johnston 9596

(MEXU). Riva Palacio: Majalca, 18 Aug 1935, LeSueur Mex027 (US). San Francisco del Oro: Mts by San Francisco del Oro, 

19 mi from Parral, Soderstrom 870-a (US).

137. Eragrostis ciliaris* (L.) R. Br., Narr. Exped. Zaire 478. 1818.

FIGURE 99

Caespitose annual; without innovations. Culms (3)9–75 cm 

tall, erect or geniculate in the lower portion, not rooting at the 

lower nodes, glabrous. Sheaths 1⁄2–3⁄4 as long as the internodes, 

hairy on the margins and at the apex, hairs to 4 mm long; ligules 

0.2–0.5 mm long; blades 1.8–12(15) cm long, 2–5 mm wide, usually flat, occasionally involute, glabrous or ciliate basally. Panicles 

1.7–17 cm long, 0.2–5 cm wide, cylindrical, contracted or open, 

spikelike, branches forming glomerate lobes or sometimes more 

open, often interrupted in the lower portion; primary branches 

0.4–4 cm long, appressed or diverging up to 50° from the rachises; pulvini usually glabrous, occasionally sparsely pilose; 

pedicels 0.1–1 mm long, erect, shorter than the spikelets, glabrous. Spikelets 1.8–3.2 mm long, 1–2 mm wide, elliptical-ovate 

FIGURE 99. Eragrostis ciliaris. A. Habit. B. Spikelet. C. Floret. 

Drawn by Linda Ann Vorobik and Cindy Roché; copyright Utah 

State University.
NUMBER 107 • 147

to ovate-lanceolate, yellowish-brown, sometimes with a purple 

tinge, with 6–11 florets, densely packed next to one another or 

widely separated; disarticulation basipetal, glumes persistent; 

glumes ovate to lanceolate, keels scaberulous, veins commonly 

green, apex acute; lower glumes 0.7–1.2 mm long; upper glumes 

1–1.6 mm long; lemmas 0.8–1.3 mm long, elliptical-ovate to lanceolate, membranous, keels scaberulous, lateral veins evident, 

apex obtuse to acute; paleas 0.8–1.3 mm long, membranous, 

keels prominently ciliate, cilia 0.2–0.8 mm long, apex obtuse 

to acute; anthers 2, 0.1–0.3 mm long, purplish. Caryopsis 0.4–

0.5 mm long, ovoid, reddish-brown. 2n = 20, 40.

Distribution and Habitat. Eragrostis ciliaris

is native to the paleotropics and introduced and naturalized 

in Mexico and the United States, growing along roadsides, on 

waste sites, in xerothermic vegetation, and sometimes in saline 

habitats up to 1,950 m. It may be more widespread than indicated. Eragrostis ciliaris var. ciliaris, found in Chihuahua, is 

more common than Eragrostis ciliaris var. laxa Kuntze, which is 

known only from the Yucatán.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: Chihuahua, Aug 1885, E. Palmer s.n. (US). Guachochi: 10 km W of La Bufa and 12.9 km NE of Batopilas, 770 m, 

P.M. Peterson, Annable & Valdés-Reyna 10851 (US).

138. Eragrostis curvula* (Schrad.) Nees, Fl. Afr. Austral. Ill. 

397. 1841.

FIGURE 100

Caespitose perennial; forming innovations at the basal 

nodes. Culms (45)60–150 cm tall, erect, glabrous or glandular. 

Sheaths 1⁄3–2⁄33 the length of the internodes, with scattered hairs, 

hairs to 9 mm long; ligules 0.6–1.3 mm long; blades 12–50(65) 

cm long, 1–3 mm wide, flat to involute, abaxial surfaces glabrous, sometimes scaberulous, adaxial surfaces with scattered 

hairs basally, hairs to 7 mm. Panicles 16–35(40) cm long, (4)8–

24 cm wide, ovate to oblong, open; primary branches 3–14 cm 

long, diverging 10°–80° from the rachises; pulvini glabrous or 

not, the hairs up to 3 mm long; pedicels 0.5–5 mm long, appressed, flexible. Spikelets 4–8.2(10) mm long, 1.2–2 mm wide, 

linear–lanceolate, plumbeous to yellowish, with 3–10 florets; 

disarticulation irregular to acropetal, proximal rachilla segments persistent; glumes lanceolate, hyaline; lower glumes 1.2–

2.6 mm long; upper glumes 2–3 mm long; lemmas 1.8–3 mm 

long, ovate, membranous, lateral veins conspicuous, apex acute; 

paleas 1.8–3 mm long, hyaline to membranous, apex obtuse; 

stamens 3; anthers 0.6–1.2 mm long, reddish-brown. Caryopsis 1–1.7 mm long, ellipsoid to obovoid, dorsally compressed, 

adaxial surfaces with a shallow, broad groove or ungrooved, 

smooth, mostly translucent, light brown, bases often greenish. 

2n = 40, 50.

Distribution and Habitat. Eragrostis curvula

is native to southern Africa and introduced in North America. 

It is often used for reclamation because it provides good ground 

cover but, once introduced, it easily escapes. In North America, it grows on rocky slopes, at the margins of woods, along 

roadsides, and in waste ground, usually in pine–oak woodlands, 

and in yellow pine and mixed hardwood forests at 10–2,000 m.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: Barranca de Batopilas, 28 Oct 1973, Bye 5646 

(MEXU). Chihuahua: La Campana, 24 Sep 76, Jardín de observación [observation garden], 1500 m, S. González 764, 766 (RELC).

FIGURE 100. Eragrostis curvula. A. Inflorescence. B. Spikelet. 

C. Floret. Drawn by Linda Ann Vorobik and Cindy Roché; copyright Utah State University.
148 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

139. Eragrostis echinochloidea* Stapf, Fl. Cap. 7: 627. 1900.

FIGURE 101

Caespitose perennial; with innovations. Culms 30–100 cm 

tall, erect to geniculate, with narrow, sunken glandular bands. 

Sheaths sometimes glandular, apex hairy, hairs to 5 mm long; 

ligule 0.4–1 mm long; blades 5–20 cm long, 2–6(7) mm wide, flat 

to involute, with small crateriform glands on the keels and veins, 

sparsely pilose adaxially. Panicles 4–19 cm long, 0.8–7 cm wide, 

oblong to ovate, glomerate, spikelets clustered in 1-sided groups; 

primary branches 0.5–7.5 mm long, angled, sinuous, glandular; 

pulvini hairy, hairs to 2 mm long; pedicels 0.2–2 mm long, stout, 

erect, without a narrow band of abscission line near the apex. 

Spikelets 2–5 mm long, 2–3.5 mm wide, broadly ovate, greenish, stramineous to plumbeous, with 7–14 florets, disarticulation 

basipetal, glumes persistent; glumes subequal, 1.7–2.2 mm long, 

ovate, membranous, keels with small crateriform glands, apex 

acute to acuminate; lemmas 1.8–2.3 mm long, broadly ovate to 

orbicular, chartaceous, keels with small crateriform glands, apex 

acute to obtuse; paleas 1.7–2.2 mm long, chartaceous, each side 

with a broad wing at the base, wings often projecting beyond the 

lemma bases, apex acute; anthers 3, 0.5–0.9 mm long, yellowish. 

Caryopsis 0.8–1.1 mm long, ellipsoid, reddish-brown. 2n = 30.

Distribution and Habitat. Eragrostis echinochloidea is native to southern Africa and seems to be spreading 

rapidly in Mexico. It is now established in Chihuahua and San 

Luis Potosí, Mexico, and Arizona, United States. It grows in gravelly soils, often along roadsides and sidewalks; 1,800−2,200 m. 

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: Lote baldío a un costado del periférico [on edge of 

waste lot] de la Juventud, Plaza Saucito, Cd. Chihuahua, 22 Sep 

2009, A. Melgoza s.n. (CIIDIR, UACH, US).

140. Eragrostis erosa Scribn. ex Beal, Grass. N. Amer. 2: 483. 

1896.

FIGURE 102

Caespitose perennial; with innovations, not glandular. 

Culms 70–110 cm tall, erect, glabrous below the nodes. Sheaths 

overlapping, 1⁄2 to about as long as the internodes below, hairy 

at the apex and sometimes on the upper margins, hairs to 4 mm 

long, not papillose-based; ligules 0.2–0.4 mm long; blades (8)12–

30 cm long, 1.5–3.8 mm wide, flat to involute, abaxial surfaces 

glabrous, adaxial surfaces scaberulous, glabrous or sparsely 

hairy, hairs to 4 mm long. Panicles 25–45 cm long, (5)12–30 cm 

wide, broadly ovate, open; primary branches mostly 4–20 cm 

FIGURE 101. Eragrostis echinochloidea. A. Habit. B. Culm and inflorescence. C. Spikelet. D. Floret. E. Palea. F. Gland along midrib. 

Drawn by Linda Ann Vorobik and Cindy Roché; copyright Utah 

State University.
NUMBER 107 • 149

long, diverging 20°–90° from the rachises, capillary, sinuous; pulvini glabrous or hairy; pedicels 1–18 mm long, appressed or divergent, proximal spikelets on each branch usually with pedicels 

shorter than 5 mm long. Spikelets 5–9 mm long, 1–3 mm wide, 

lanceolate, plumbeous, with 5–12 florets; disarticulation acropetal, glumes first, then the lemmas, paleas persistent; glumes lanceolate to ovate, membranous; lower glumes 1.3–2.4 mm long; 

upper glumes 1.6–2.6 mm long; lemmas 2.4–3 mm long, ovate, 

mostly membranous, hyaline near the margins and apex, lateral 

veins inconspicuous, apex acute; paleas 1.5–3 mm long, hyaline, 

narrower than the lemmas, apex obtuse to truncate; stamens 

3; anthers 0.6–1.7 mm long, purplish. Caryopsis 0.8–1.6 mm 

long, subellipsoid, terete to somewhat laterally compressed, 

with a well-developed adaxial groove, faintly striate, opaque, 

reddish-brown.

Distribution and Habitat. Eragrostis erosa is 

native to North America and grows on rocky slopes and hills, 

often in association with Pinus edulis, Juniperus monosperma, 

and Bouteloua gracilis, at 1,100–2,300 m. Its range extends 

from northern Mexico to New Mexico and western Texas.

Specimens Examined. MEXICO. Chihuahua. 

Aldama: Sierra de Santo Domingo (Sierra de Palomas on geol. 

Maps) SW of and above the minas Plomosas, 23 Oct 1972, crasifolio espinosos [thick and spiny-leaved], 1250–1700 m, T.L. 

Wedt, F. Chiang & M.C. Johnston 9864B (MEXU). Guachochi: Parque Nacional Barranca del Cobre, 1.6 km E of La Bufa, 

1950 m, P.M. Peterson & M.B. Knowles 13582 (US); 8.8 km NE 

of La Bufa and 4.8 km S of Kirare, 1730 m, P.M. Peterson, Annable & Valdés-Reyna 10823 (US). Janos: Pass between Rancho 

Carretas, Chihuahua and Bavispe, Sonora, 12 Sep 1939, L. H. 

Harvey 1749 (US). Jiménez: Sta. Eulalia Mts, C.G. Pringle 415 

(US); Sta Eulalia plains, 27 Oct 1885, E. Wilkinson 56, 341 (US). 

Juárez: Estación Microondas [microwave station] Presidio on a 

low disjunct peak the NW end of Sierra del Presidio, ca. 24 km S. 

of Cd. Juárez, 28 Oct 1972, 1500–1623 m, T.L. Wendt, F. Chiang & M.C. Johnston 9912 (MEXU). Madera: Paraje Sirupa, 

ejido Cebollitas, 16 Oct 1990, bosque de encino [oak forest], 

1200 m, O. Bravo 1919 (CIIDIR, MEXU). Ocampo: Parque Nacional “Cascada de Basaseachic,” on ridge top SE side of canyon 

of Rio Basaseachic leading to falls, 4 Oct 1986, 1800 m, Spellenberg, Soreng, R. Corral & T. Lebgue 8732 (NMC).

141. Eragrostis intermedia Hitchc., J. Wash. Acad. Sci. 23(10): 

450. 1933.

FIGURE 103

Caespitose perennial; with innovations, not glandular. Culms (30)40–90(110) cm tall, erect, glabrous below the 

nodes. Sheaths overlapping, 1⁄2 to about as long as the internodes below, sparsely pilose on the margins, apex hairy, hairs to 

8 mm long, not papillose-based; ligules 0.2–0.4 mm long; blades 

(4)10–20(30) cm long, 1–3 mm wide, flat or involute, abaxial 

surfaces glabrous, adaxial surfaces densely hairy behind the 

ligules, elsewhere usually glabrous, occasionally sparsely hairy. 

Panicles 15–40 cm long, (8.5)15–30 cm wide, ovate, open; primary branches 4–25 cm long, diverging 20°–90° from the rachises, capillary; pulvini hairy or glabrous; pedicels 2–14 mm 

long, divergent. Spikelets 3–7 mm long, 1–1.8 mm wide, narrowly lanceolate, olivaceous to purplish, with (3)5–11 florets; 

disarticulation acropetal, paleas persistent; glumes lanceolate to 

ovate, hyaline to membranous; lower glumes 1.1–1.7 mm long, 

narrower than the upper glumes; upper glumes 1.3–2 mm long, 

FIGURE 102. Eragrostis erosa. A. Inflorescence. B. Spikelet. C. Floret. Drawn by Linda Ann Vorobik and Cindy Roché; copyright Utah State University.
150 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

apex acuminate to acute; lemmas 1.6–2.2 mm long, ovate, membranous, hyaline near the margins, lateral veins inconspicuous, 

apex acute; paleas 1.4–2.1 mm long, hyaline, narrower than the 

lemmas, apex obtuse to acute; stamens 3; anthers 0.5–0.8 mm 

long, purplish. Caryopsis 0.5–1.0 mm long, straight angularprismatic, somewhat laterally compressed, with a well-developed 

adaxial groove, striate, opaque, reddish-brown. 2n = ca. 54, 60, 

72, ca. 74, 80, 100, 120.

Distribution and Habitat. Eragrostis intermedia is native to the North America and grows in clay, sandy, 

and rocky soils, often in disturbed sites up to 2,500 m. Its range 

extends from the United States through Mexico and Central 

America to South America. Eragrostis intermedia is similar to 

the more widespread E. lugens, but differs from that species in 

having wider spikelets, longer lemmas, and caryopsis with a 

prominent adaxial groove.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: Rancho Byarly, Sierra Charuco, 17–25 Apr 1948, 

1700 m, Gentry 8157 (US); Arroyo Baqueachi, at 1/2 km E of 

small villaje, 28 Aug 2003, grassland, 2004 m, P.M. Peterson & 

P. Catalán 17572 (CIIDIR, US); Barranca [canyon] between La 

Bufa and Batopilas, along arroyo to Guimivo N side Rio Batopilas, 16 Aug 1971, 2580 ft, Bye 1872 (MEXU). Balleza: 24.9 km 

SE of Balleza and 22.5 km N of hwy 24, W of Parral, 26 Sep 

1988, grassland, 1900 m, P.M. Peterson & Annable 5953 (US); 

56.4 km W of Parral on road to Balleza and 35.5 km S of Balleza 

on Mex 432, near Corral de Duarte, 18 Sep 1991, pine forest–

encino [oak], 2210 m, P.M. Peterson, Annable & Valdés-Reyna 

10715 (CIIDIR, US); 11 mi SE of Balleza on road to Parral, 

1800, P.M. Peterson, M.B. Knowles, C.H. Dietrich, S.M. Braxton 13518 (US); 16.1 km W of Balleza and 77.9 km E of Guachochi, 18 Sep 1991, bosque de encino [oak forest], 1990 m, P.M. 

Peterson, Annable & Valdés-Reyna 10745 (CIIDIR). Bocoyna:

Cañada Recogoata, 23 Sep 1997, pine forest–encino, 1900 m, 

B. Tah V. 55 (MEXU). Chinipas: Sierra Saguarivo, 1.3 mi W of 

Curahui, 9 Sep 2008, tropical deciduous forest, 1001 m, P.M. 

Peterson & J.M. Saarela 22146 (US). Chihuahua: N of Chihuahua, 24 Jul 1936, LeSueur Mex-097 (US); Base de la Sierra de 

La Campana, 80 km al N de Chihuahua, 19 Oct 1974, pastizal 

con encinos [pastureland with oaks], 1700 m, Rzedowski 32295

(ENCB); Cañón de Santa Clara, 90 km al N de Chihuahua, 19 

Oct 1974, 1700 m, Rzedowski 32360 (ENCB); El Vallecito, 

30 km al W de Chihuahua, carr. [hwy] Chihuahua–Cuauhtémoc, 14 Sep 1996, pastizal, 1720 m, E. Estrada & C. Yen 6084

(ENCB); Rancho Experimental La Campana, 16 Oct 1980, 

pastizal, 1640 m, A. Melgoza 641 (CIIDIR); La Campana Experimental Station & Rancho El Arco Iris, 81–84 km along Pan 

American Hwy to Chihuahua City, 17 Sep 1977, 1500 m, J.K. 

Meents & W.H. Moir 70, 85 (NMC); La Campana; Potrero La 

Sierra, 2 km Ote. [W] Carr. Panamericana, 14 Sep 73, Pastizal 

con encino, 1550 m, Valdés-Reyna VR–277 (RELC); mts NW 

of Chihuahua, 9 Oct 1936, LeSueur 0144 (MEXU, US); rocky 

hills near Chihuahua, 19 Oct 1885, C.G. Pringle 472 (MEXU). 

Guachochi: 20.3 km NE of La Bufa and 3.2 km S of Basigochi, 

2180 m, P.M. Peterson & Annable 10817 (US); 0.5 km al E de 

La Bufa at the bridge crossing Río Batopilas, 1000 m, 20 Sep 

1991, P.M. Peterson, Annable & Valdés-Reyna 10846 (US); Entering Barranca El Cobre, approximately 25.7 km S of Cusarare 

on road to Guachochi, 25 Sep 1988, 2000 m, P.M. Peterson 

& Annable 5898 (US); Barranca de Basihuare, 28 Aug 2003, 

bosque de encino, P.M. Peterson & P. Catalán 17592 (CIIDIR, 

US). Janos: Chihuahua–Sonora Border, Rancho Carretas, 24 Aug 

1937, 1675 m, L. H. Harvey 1603, 1626 (US). Jiménez: Costado 

del Rio Florido, Torreoncitos, 4 Aug 2010, 1330 m, D. Noya & 

M.L. Juárez 3410 (CIIDIR). Madera: Mesa del Yerbanís, ejido 

El Long, 12 Oct 1990, bosque de Quercus, 1900 m, O. Bravo 

2818 (CIIDIR); N of Chuichupa, 30 Aug 1937, LeSueur 0208

(MEXU). Matamoros: 12 mi S of Villa Matamoros, 7 Sep 1967, 

Reeder & C. Reeder 4887 (ARIZ, US). Moris: Región de El Carmen, 3 km SW de el Pilar de Moris, 20 Aug 1996, bosque de 

FIGURE 103. Eragrostis intermedia. A. Inflorescence. B. Spikelet. C. Floret. Drawn by Linda Ann Vorobik and Cindy 

Roché; copyright Utah State University.
NUMBER 107 • 151

encino, A. Búrquez 96-474 (MEXU). Ocampo: Parque Nacional “Cascada de Basaseachic,” in the barranca [canyon] to W 

of falls, 4 Oct 1986, 1800 m, Spellenberg, Soreng, R. Corral & 

T. Lebgue 8823 (NMC); Along drainage of Río Candasneno at 

Cascada Basaseachi. Ca, 1 mi S of village of Basaseachi, 14 Oct 

1984, pine forest-encino, 2000 m, R.& M. Spellenberg 7947

(MEXU). Temosachi: Nabogame, 24 Jul 1988, 1800 m, Laferr. 

1538, 1584 (MEXU). 

142. Eragrostis lehmanniana* Nees, Fl. Afr. Austral. Ill. 402. 

1841.

FIGURE 104

Caespitose perennial; forming innovations at the basal 

nodes, without glands. Culms (20)40–80 cm tall, erect, commonly geniculate, sometimes rooting at the lower nodes, glabrous, lower portions sometimes scaberulous. Sheaths 1⁄3–2⁄3 the 

length of the internodes, sometimes shortly silky pilose basally, 

hairs less than 2 mm long, apex sparsely hairy, hairs to 3 mm long; 

ligules 0.3–0.5 mm long, ciliate; blades 2–12 cm long, 1–3 mm 

wide, flat to involute, glabrous, abaxial surfaces sometimes scaberulous, adaxial surfaces scaberulous. Panicles 7–18 cm long, 

2–8 cm wide, oblong, open; primary branches 1–8 cm long, appressed or diverging to 40° from the rachises; pulvini glabrous; 

pedicels 0.5–4 mm long, diverging or appressed, flexible. Spikelets 5–12(14) mm long, 0.8–1.2 mm wide, linear-lanceolate, 

plumbeous to stramineous, with 4–12(14) florets; disarticulation 

irregular to basipetal, paleas usually persistent; glumes oblong 

to lanceolate, membranous; lower glumes 1–1.5 mm long; upper 

glumes 1.3–2 mm long; lemmas 1.5–1.7 mm long, ovate, membranous, lateral veins inconspicuous, apex acute to obtuse; paleas 1.4–1.7 mm long, obtuse; stamens 3; anthers 0.6–0.9 mm 

long, yellowish. Caryopsis 0.6–0.8 mm long, ellipsoid to obovoid, dorsally compressed, sometimes with a shallow adaxial 

groove, smooth, translucent, mostly light brown, embryo region 

dark brown with a greenish ring. 2n = 40, 60.

Distribution and Habitat. Eragrostis lehmanniana is introduced in North America and native to southern 

Africa, where it grows in sandy, savannah habitats. In North 

America, it grows in sandy flats, along roadsides, on calcareous 

slopes, and in disturbed areas at 1,500–2,300 m. It is commonly 

found in association with Larrea tridentata, Opuntia, Quercus, 

Juniperus, and Bouteloua gracilis.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 5 km al N de Flores Magón, 30 Jul 1994, 1200 m, 

R. Corral, E. Pérez, A. Domínguez & F. Félix RCD5384 (UACJ). 

Ascensión: Rancho La Viuda Ascensión, 7 Sept 1981, matorral 

[scrub], 1200 m, Serrano & Alvarez 1543 (MEXU); a los lados 

[sides] de la carr. [hwy] Juárez–Janos, en los alrededores [surroundings] de la Falla del Camello, área de transición de la plataforma del desierto & la depresión [old transition between desert 

platform and depression] del paleo, “Cabeza de Vaca”, 11 Oct 

2005, 1180 m, R. Corral, M. Vargas & H. Gutiérrez RCD7172

(UACJ). Chihuahua: Rancho Experimental La Campana, 82 km 

FIGURE 104. Eragrostis lehmanniana. A. Culm and inflorescence. 

B. Spikelet. Drawn by Linda Ann Vorobik and Cindy Roché; copyright Utah State University.
152 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

al N de la Cd. Chihuahua, 26 Aug 1978, pastizal [pastureland], 

1500 m, M.A. Bernal s/n (MEXU); carr. Chihuahua–Juárez, 

6 Aug 1988, mezquital–pastizal [mesquite–pastureland], Chávez 

11 (MEXU); Rancho Experimental La Campana, Chihuahua, 

25 Sep 76, pastizal, 1540 m, S. González 786 (ENCB, RELC). 

Cuauhtémoc: Rancho Aguja, acceso [access] de Chihuahua 

hacia [toward] Namiquipa, desviar [diver] en “campo 73” a la 

derecha terrac.[to right dirt road] 6 km, 13 Oct 2000, pastizal, 

G. Gómez 329 (MEXU). Namiquipa: Aprox. km 39 carr. Chihuahua–Namiquipa, 24 Sep 1997, bosque de encino [oak forest], 2300 m, M.A. Vergara 181 (MEXU).

143. Eragrostis lugens Nees, Fl. Bras. Enum. Pl. 2: 505–506. 1829.

FIGURE 105

Caespitose perennial; with innovations, not glandular. 

Culms (20)30–50(60) cm tall, erect, sometimes geniculate, glabrous below the nodes. Sheaths overlapping, 1⁄2–2⁄3 as long as the 

internodes above, mostly glabrous, apex hairy, hairs 2–5 mm 

long, papillose-based, this sometimes not readily seen; ligules 

0.2–0.3 mm long; blades (4)8–22 cm long, 1–3.5 mm wide, involute to flat, both surfaces glabrous, margins sometimes with 

scattered hairs, hairs to 7 mm long. Panicles 16–28 cm long, 

10–21 cm wide, ovate, open; primary branches 0.6–15 cm 

long, diverging up to 100° from the rachises, naked basally; 

pulvini hairy; pedicels 1.4–5(7) mm long, diverging, wiry, present on all spikelets. Spikelets 2–4.5(5) mm long, 0.5–1(1.3) mm 

wide, narrowly lanceolate, plumbeous to reddish-purple, with 

2–7 florets; disarticulation acropetal, paleas persistent; glumes 

broadly ovate to narrowly lanceolate, hyaline, sometimes 

reddish-purple; lower glumes 0.6–1 mm long; upper glumes 

1.1–1.4 mm long, usually broader than the lower glumes; lemmas 1.2–1.6 mm long, broadly ovate, mostly membranous but 

the distal margins hyaline, lateral veins inconspicuous, apex 

acute; paleas 1.1–1.7 mm long, membranous to hyaline, apex 

obtuse; stamens 3; anthers 0.2–0.7 mm long, reddish-purple. 

Caryopsis 0.5–0.6 mm long, obovoid to somewhat prismshaped, terete to somewhat laterally compressed, with an adaxial groove, finely striate, usually opaque, faintly reddish-brown 

to whitish. 2n = 40, 80, ca. 108.

Distribution and Habitat. Eragrostis lugens

is native to North America and grows in montane areas along 

roadsides and waste places up to 2,500 m. Its range extends from 

the southern United States to Peru and Argentina.

Specimens Examined. MEXICO. Chihuahua.

Chihuahua: km 52 carr. [hwy] Chihuahua–Cd. Juárez, 3 Aug 

1978, pastizal [pastureland], 1450 m, I.D. Enríquez, Delgadillo, 

Molinar 7, 12 (MEXU).

144. Eragrostis mexicana (Hornem.) Link, Hort. Berol. 1: 190. 

1827. 

Caespitose annual; without innovations. Culms 10–130 cm 

tall, erect, sometimes geniculate, glabrous, sometimes with a ring 

of glandular depressions below the nodes. Sheaths 1⁄2–2⁄3 as long 

as the internodes, sometimes with glandular pits, pilose near the 

apex and on the collars, hairs to 4 mm long, papillose-based; ligules 0.2–0.5 mm long, ciliate; blades 5–25 cm long, 2–7(9) mm 

wide, flat, abaxial surfaces glabrous, adaxial surfaces scaberulous, occasionally pubescent near the base. Panicles (5)10–40 cm 

long, (2)4–18 cm wide, less than 1⁄2 the height of the plant, ovate, 

FIGURE 105. Eragrostis lugens. A. Habit. B. Inflorescence. C. Spikelet. D. Floret and palea above. Drawn by Linda Ann Vorobik 

and Cindy Roché; copyright Utah State University.
NUMBER 107 • 153

rachises angled and channeled; primary branches 3–12(15) cm 

long, solitary to whorled, appressed or diverging to 80° from the 

rachises; secondary branches somewhat appressed; pulvini glabrous; pedicels 1–6(7) mm long, almost appressed to narrowly 

divergent, stiff. Spikelets (4)5–10(11) mm long, 1.5–2.4 mm 

wide, ovate to oblong, gray-green to purplish, with 5–11(15) 

florets; disarticulation acropetal; glumes 1.2–2.3 mm long, subequal, ovate to lanceolate, membranous; lemmas 1.2–2.4 mm 

long, ovate, membranous, glabrous or with a few hairs, graygreen, lateral veins evident, often greenish, apex acute; paleas 

1–2.2 mm long, hyaline, keels scabrous, apex obtuse to truncate; 

stamens 3; anthers 0.2–0.5 mm long, purplish. Caryopsis 0.5–

0.8(1) mm long, ovoid to straight angular-prismatic, laterally 

compressed, shallowly to deeply grooved on the adaxial surface, 

striate, reddish-brown, distal 2⁄3 opaque. 2n = 60.

Distribution and Habitat. Eragrostis mexicana is native to North America and grows along roadsides, near 

cultivated fields, and in disturbed open areas at 100–3,000 m. 

Two subspecies, E. mexicana subsp. virescens and E. mexicana subsp. mexicana, occur in the study area.

KEY TO SUBSPECIES OF ERAGROSTIS MEXICANA

1. Spikelets 1.2–2.4 mm wide, oblonge-ovoid; first glume 1.2–2.4 mm long . . . . . . . . . . . . . . E. mexicana subsp. mexicana

1. Spikelets up to 1.5 mm wide, linear to linear-lanceolate; lower glume 0.7–1.7 mm long . . . . E. mexicana subsp. virescens

Eragrostis mexicana subsp. mexicana.

FIGURE 106

Distribution and Habitat. Eragrostis mexicana subsp. mexicana grows from Ontario through the midwestern United States to California, South Carolina, and Texas 

and southward to Mexico, Central America, and northern South 

America to Argentina.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 44 km al N del poblado [village] Villa Ahumada por 

la carr.[hwy] Panamericana (Méx 45), 7 Oct 1995, 1200 m, R. 

Corral, P. Olivas & J.O. Torres RCD6435 (UACJ). Balleza: 11 

mi SE of Balleza on road to Parral, 1800, P.M. Peterson, M.B. 

Knowles, C.H. Dietrich & S.M. Braxton 13522 (US). Batopilas: 

SW Chihuahua, Aug 1885, E. Palmer 8, 507 (US). Bocoyna:

entre [between] Estación Divisadero & Río Urique, rumbo 

[course] a Barrancas del Cobre, 16 Aug 1976, pine forest–encino 

[oak], 1875 m, S. González & J.M. Peña 682 (RELC); San Ignacio Arareco, around house of Sebastian Gloria, 7 Oct 1973, 

pine–oak forest, Bye 5430 (MEXU). Carichi: Sánchez, 12 Oct 

1910, Hitchcock 7705 (US). Casas Grandes: Casas Grandes, 

25 Aug 1899, E.W. Nelson 6300 (US); W of Casas Grandes, 

5 mi S of Hernández, 18 Sep 1960, pine–oak region, 2100 m, 

Reeder, C. Reeder & Soderstrom 3518 (ARIZ, ENCB, US); 8 

mi NE of Cuesta Blanca, W of casas Grandes, 18 Sep 1960, 

Reeder, C. Reeder & Soderstrom 3551 (ARIZ); Rancho Palanganas (La Leona), 11 Sep 1996, pastizal [pastureland], 2200 m, 

González 113 (MEXU). Chihuahua: N of Chihuahua, 20 Oct 

1935, LeSueur Mex-047 (US); 8 mi SW of Chihuahua on road 

to Cuauhtémoc, 6 Oct 1959, Soderstrom 909 (US); km 1773 

carr a Cd. Juárez, 15 Sep 55, pastizal, 1500 m, Hern.-Xol. & V. 

Mathus N-1792 (RELC). Cuauhtémoc: 21 km W of Cuauhtemoc, on Hwy 16, 23 Aug 1990, 2000 m, P.M. Peterson & Annable 9602, 9603 (US); 12 mi W of Cuauhtémoc, 5 Sep 1967, 

pine and oak covered slopes, 7000 ft, Reeder & C. Reeder 4854

(ENCB); entre Cuahutémoc & La Junta, 12 Aug 1976, bosque 

de encino [oak forest], 2185 m, J.M. Peña N. & S. González 

565 (RELC). Guachochi: Parque Nacional Barranca del Cobre, 

0.5 km E of La Bufa at the bridge crossing the Río Batopilas, 

1000 m, P.M. Peterson, Annable & Valdés-Reyna 10840 (US); 

West of Munérachi, 7 Sep 2003, matorral espinoso [thorny 

scrub], 1200 m, P.M. Peterson & P. Catalán 17713 (US); Barranca de Basihuare, 28 Aug 2003, bosque de encino, 1700 m, 

P.M. Peterson & P. Catalán 17590 (CIIDIR, US). Gómez Farías: 

Laguna de Babicora,18 Aug 1994, 2150 m, T. Lebgue & E. 

Estrada 3348 (NMC). Guerrero: 33.5 km W La Junta on road 

to Parque Nacional Cascada de Basaseachic, 2200 m, P.M. Peterson & Annable 9606 (US); Miñaca, 13 Oct 1910, Hitchcock 

FIGURE 106. Eragrostis mexicana subsp. mexicana. A. Inflorescence. B. Spikelet. C. Two paleas below lemma. Drawn by Linda 

Ann Vorobik and Cindy Roché; copyright Utah State University.
154 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

7732 (US); entre Cuauhtémoc & La Junta, 12 Aug 1976, bosque 

de Quercus, 2185 m, S. González & J.M. Peña 565 (ENCB). 

Ignacio Zaragoza: 10 mi N of Ignacio Zaragoza, along hwy, 

pinyon and Juniper, 8 Apr 1977, 7800 ft, Dunn, Torke, Bennet 

& Wieder 22632 (ENCB). Janos: 2 km W of Carretas, 21 Aug 

1939, L. H. Harvey 1565 (US); Cañon de Carretas, Chihuahua–

Sonora Border, Rancho Carretas, 26 Aug 1937, 1460 m, L. H. 

Harvey 1590 (US). Jiménez: Banks of the Río Florido, Cd. Jiménez, 28 Jul 1939, 1340 m, L. H. Harvey 1325 (US). Madera: 

Paraje Sirupa, ejido Cebadilla de Dolores, 24 Aug 1990, bosque 

de encino, 1200 m, O. Bravo 1253 (CIIDIR, MEXU); Mesa del 

Yerbanís, ejido El Long, 12 Oct 1990, bosque de Quercus, 1900 

m, O. Bravo 1842 (CIIDIR, MEXU); Paraje Sirupa, ejido Cebollitas, 16 Oct 1990, bosque de encino, 1200 m, A. Benítez 

2903 (CIIDIR, MEXU); Laguna de Babicora, Ejido Año de 

Hidalgo,15 Sep 1994, 2300 m, T. Lebgue, G. Quintana & E. 

Estrada 3784 (NMC); Arroyo de la Quinta, ejido El Long, 30 

Aug 1990, pinyon–encino, 2340 m, A. Benítez 2104 (MEXU). 

Manuel Benavides: Entre Manuel Benavides & Pocitos, 2 Aug 

1976, pastizal, 1342 m, S. González & J.M. Peña 457 (RELC). 

Moris: Mesa del Agua, 4.8 km S of Campanero (on Mesa de 

Campanero), 29 Sep 2003, 1990 m, T.R. Van Devender, A.L. 

Reina, M.A. Dimmitt & M.W. Eubanks 2003-1097 (NMC). 

San Francisco del Oro: San Francisco del Oro, Arroyo de Grañadena, 4 Oct 1959, Soderstrom 878 (US). Temosachi: Nabogame, 10 Sep 1987, 1800 m, Laferr. 1063 (MEXU).

Eragrostis mexicana subsp. virescens (J. Presl) S. D. Koch & 

Sánchez Vega, Phytologia 58: 380. 1985.

Distribution and Habitat. Native from Canada, United States, Mexico, and South America. In Mexico it is 

found in Baja California, Baja California Sur, and Chihuahua 

(Espejo Serna et al., 2000).

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000) and Herrera Arrieta and 

Cortés Ortiz (2010). 

145. Eragrostis palmeri S. Watson, Proc. Amer. Acad. Arts 18: 

182. 1883.

FIGURE 107

Caespitose perennial; with innovations and knotty bases, 

not glandular. Culms 50–90(120) cm tall, glabrous below the 

nodes. Sheaths overlapping, 1⁄2 to about as long as the internodes below, villous and the hairs not papillose-based, or mostly 

glabrous, apex hairy, hairs to 5 mm long; ligules 0.2–0.4 mm 

long; blades (14)20–35 cm long, 1–2.4 mm wide, involute, abaxial surfaces glabrous, adaxial surfaces scaberulous, sometimes 

sparsely hairy. Panicles 12–40 cm long, 4–20 cm wide, oblong, 

open; primary branches 2–20 cm long, diverging 20°–70° from 

the rachises, capillary; pulvini glabrous or sparsely hairy; pedicels (0.4)1–4(14) mm long, appressed or diverging, only the terminal pedicels on each branch longer than 4 mm long. Spikelets 

4–6(7.3) mm long, 1–2 mm wide, linear-lanceolate, plumbeous, 

with 5–12 florets; disarticulation acropetal, paleas persistent; 

glumes lanceolate to ovate, hyaline; lower glumes 1.1–1.8 mm 

long; upper glumes 1.2–2.2 mm long, exceeded by the basal 

lemmas; lemmas 2–2.6 mm long, ovate, membranous, hyaline 

toward the apex and margins, keels weak or strong, without 

glands, lateral veins from inconspicuous to conspicuous, apex 

acute; paleas 1.7–2.4 mm long, hyaline, bases not projecting beyond the lemmas, apex truncate, often notched; stamens 3; anthers 0.6–1.3 mm long, yellowish to purplish. Caryopsis 0.6–0.8 

mm long, straight angular-prismatic to subellipsoid, laterally 

compressed, with a well-developed adaxial groove, faintly striate, opaque, reddish-brown. 2n = 40.

FIGURE 107. Eragrostis palmeri. A. Culm, sheath, and blade. B. Inflorescence. C. Spikelet. D. Two paleas below 

floret. Drawn by Linda Ann Vorobik and Cindy Roché; copyright Utah State University.
NUMBER 107 • 155

Distribution and Habitat. Eragrostis palmeri

is native to North America and grows on rocky slopes and hills 

generally in association with Pinus, Juniperus, Bouteloua gracilis, and Prosopis at 300–2,150 m. Its range extends from the 

southwestern United States to Oaxaca.

Specimens Examined. MEXICO. Chihuahua. Aldama: Rancho El Morrion, acceso [access] de Aldama hacia [toward] Ojinaga, desviar [divert] en km 55 a la derecha [to right] 

5 km por terracería [dirt road], 25 Oct 2000, matorral [scrub], 

G. Gómez 632 (MEXU). Mpio.?: Sierra de los Pinos, Dec 1937, 

LeSueur 0219 (US). 

146. Eragrostis pectinacea (Michx.) Nees, Fl. Afr. Austral. Ill. 

406. 1841. 

Caespitose annual; without innovations, without glandular pits. Culms 10–80 cm tall, erect to geniculate or decumbent 

below, glabrous. Sheaths overlapping below, 1⁄2–3⁄4 as long as the 

internodes above, hirsute at the apex, hairs to 4 mm long; ligules 0.2–0.5 mm long; blades 2–20 cm long, 1–4.5 mm wide, 

flat to involute, abaxial surfaces glabrous and smooth, adaxial surfaces scaberulous. Panicles 5–25 cm long, 3–12(15) cm 

wide, ovoid to pyramidal, usually open, sometimes contracted; 

primary branches 0.6–8.5 cm long, appressed or diverging to 80° 

from the rachises, solitary or paired at the lowest 2 nodes; pulvini glabrous or sparsely hairy; pedicels 1–7 mm long, flexible, 

appressed to widely divergent, sometimes capillary. Spikelets 

3.5–11 mm long, 1.2–2.5 mm wide, linear-oblong to narrowly 

lanceolate, plumbeous, yellowish-brown or dark reddish-purple, 

with 6–22 florets; disarticulation acropetal, paleas persistent; 

glumes subulate to ovate-lanceolate, hyaline; lower glumes 0.5–

1.5 mm long, at least 1⁄2 as long as the adjacent lemmas; upper 

glumes 1–1.7 mm long, usually broader than the lower glumes; 

lemmas 1–2.2 mm long, ovate-lanceolate, hyaline to membranous, grayish-green proximally, reddish-purple distally, lateral 

veins moderately conspicuous, apex acute; paleas 1–2 mm long, 

hyaline to membranous, keels scaberulous, apex obtuse; stamens 

3; anthers 0.2–0.4 mm long, purplish. Caryopsis 0.5–1.1 mm 

long, pyriform, slightly laterally compressed, smooth, faintly 

striate, brownish. 2n = 60.

Distribution and Habitat. Eragrostis pectinacea is native from southern Canada to Argentina. It grows in 

disturbed sites such as roadsides, railroad embankments, gardens, and cultivated fields up to 2,400 m. Two varieties occur 

in Chihuahua.

KEY TO VARIETIES OF ERAGROSTIS PECTINACEA

1. Pedicels appressed, rarely diverging to 20° from the rachises . . . . . . . . . . . . . . . . . . . . . . . . E. pectinacea var. pectinacea

1. Pedicels widely divergent, usually diverging 20°–60° from the rachises . . . . . . . . . . . . . . . . . E. pectinacea var. miserrima

Eragrostis pectinacea var. miserrima (E. Fourn.) Reeder, Phytologia 60(2): 154. 1986. 

Pedicels widely divergent, usually spreading 20°–60° from 

the branches.

Distribution and Habitat. Eragrostis pectinacea var. miserrima grows in the southern United States, from 

Texas to Florida, and south throughout Mexico to the lowland 

tropics of Brazil. 

Specimens Examined. MEXICO. Chihuahua. 

Casas Grandes: Between Casas Grandes and Sabinal, 4–5 Sep 

1899, E.W. Nelson 6353 (US). Chihuahua: N of Chihuahua, 20 

Oct 1935, LeSueur Mex-078 (MEXU, US). Guerrero: Miñaca, 

13 Oct 1910, Hitchcock 7733 (US); 2 km al S de Miñaca, 10 Aug 

1975, 2000 m, J.M. Peña JMP-117 (ENCB, RELC). Janos: San 

Pedro River, Mexican boundary line, 11 Sep 1893, E.A. Mearns 

2309 (US); Chihuahua–Sonora Border, Rancho Carretas, 26 

Aug 1939, L. H. Harvey 1591, 1604 (US). Madera: 30 mi N of 

Madera, 7 Jul 1950, Reeder, C. Reeder & Goodding 1224 (US). 

Riva Palacio: Nuevo Majalca, approx. 14.5 km W of Hwy 45, N 

of Chihuahua, 22 Sep 1988, 1700 m, P.M. Peterson & Annable 

5765 (US).

Eragrostis pectinacea (Michx.) Nees var. pectinacea.

FIGURE 108

Pedicels appressed or diverging to 20° from the branch axes.

Distribution and Habitat. Eragrostis pectinacea var. pectinacea grows throughout the range of the species, 

including most of the states within Mexico. 

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 5 km al S de Villa Ahumada, sobre la carr. [on hwy] 

Cd. Chihuahua, matorral desértico [desert scrub], 3 Oct 1978, 

S.D. Koch & I. Sánchez 78116 (ENCB, US). Bachiniva: 2 km 

de San José de Bachiniva, 9 Aug 1974, suelo arcilloso [clay 

ground], 1900 m, C. Rodríguez, O. Agundis & S. Acosta 1249 

(ENCB, CHAPA, US). Balleza: 43 mi E of Guachochi and 16 

mi W of Balleza, 2100 m, P.M. Peterson & Annable 5936

(US); 56.4 km W of Parral on road to Balleza and 35.5 km S 

of Balleza, 2210 m, P.M. Peterson, Annable & Valdés-Reyna 

10702 (US); 56.4 km W of Parral on road to Balleza and 35.5 

km S of Balleza on Mex 432, near Corral de Duarte, 18 Sep 

1991, pine forest–encino [oak], P.M. Peterson, Annable & 

Valdés-Reyna 10718 (CIIDIR, US); 10 mi SW of El Ojito, 12 

Sep 2006, 1902 m, P.M. Peterson 20027, F. Sánchez Alvarado 

& E.P. Gómez Ruíz (CIIDIR, US). Batopilas: Yamuco, 1 mi 

E of hwy N of Rio Uriquecrossing towards Basihuare and 

Creel, 5 Sep 2008, P.M. Peterson & J.M. Saarela 22049 (US); 

SW Chihuahua, Aug 1885, E. Palmer 8B, 50 (US). Bocoyna: 

Sánchez, 12 Oct 1910, Hitchcock 7689 (US); a 5 km al N 

de Creel, 16 Sep 1983, pine forest–encino, 2200 m, Tenorio 

L & R. Torres 4392 (MEXU). Camargo: Arroyo 20 km S of 

Cd. Camargo, 2 Aug 1939, 1220 m, L. H. Harvey 1394 (US); 
156 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Rancho la Urraca, acceso [access] de Camargo hacia [toward] 

Ojinaga, desviar hacia [divert toward] Hércules por terracería 

[dirt road], aprox. 60 km tomar a la izquierda [take left] 30 

km, 20 Oct 2000, Matorral, G. Gómez 550 (MEXU). Chihuahua: near Chihuahua, 24 Aug 1885, C.G. Pringle 416 (US); N 

of Chihuahua, 20 Jul 1936, LeSueur 0126 (US); 5 mi SW of 

Chihuahua on road to Cuauhtémoc, 6 Oct 1959, Soderstrom 

898 (US); 12 mi N of Chihuahua on rd to Cd. Juárez, 8 Oct 

1959, Soderstrom 933 (US); La Campana Experimental Station & Rancho El Arco Iris, 81–84 km along Pan American 

Hwy to Chihuahua City, Oct 1977, 1500 m, J.K. Meents & 

W.H. Moir 93 (NMC). Cuauhtémoc: 11 mi W of Cuauhtémoc, 

4 Sep 1967, Reeder & C. Reeder 4863 (ARIZ); 12 mi W of 

Cuauhtémoc, 5 Sep 1967, Reeder & C. Reeder 4847 (ENCB, 

US); 4879 (ARIZ); 4854 (US). Gran Morelos: 47 mi W of cd 

Chihuahua on Chih 16, 7 oct 1972, 6000 ft, L. H. Harvey & 

J.T. Witherspoon 9295 (ENCB). Guachochi: Parque Nacional 

Barranca del Cobre, 20 mi NW of Aborreachi on road towards 

Creel, 2390 m, P.M. Peterson, M.B. Knowles, C.H. Dietrich & 

S.M. Braxton 13563 (US); 12.4 km S of Cusarare on road to 

Guachochi, 2400 m, P.M. Peterson & Annable 5891 (US); Barranca de Basihuare, 28 Aug 2003, bosque de encino [oak forest], 1700 m, P.M. Peterson & P. Catalán 17584 (CIIDIR, US). 

Guerrero: 38.6 km SW of La Junta and approx... 70.8 km N of 

Creel at P. Arroyo Ancho crossing, 21 km marker, 24 Sep 1988, 

2200 m, P.M. Peterson & Annable 5844 (US). Janos: Cañon 

de Carretas, Chihuahua–Sonora Border, Rancho Carretas, 26 

Aug 1937, 1460 m, L. H. Harvey 1591 (US). Jiménez: Banks of 

Río Florido, Cd. Jiménez, 28 Jul 1939, 1340 m, L. H. Harvey 

1313, 1334 (US); 9 mi W of Jiménez, 6 Sep 1967, Reeder & 

C. Reeder 4870 (ENCB); 4873 (ARIZ, US); 14 mi SE of Jiménez, 3 Sep 1967, Reeder & C. Reeder 4840 (ARIZ-4836, US); 

Zona del Silencio, 5 Aug 1976, matorral de Prosopis–Condalia, 

1098 m, S. González & J.M. Peña 528 (ENCB, RELC). Hidalgo del Parral: 2 mi E of Parral, 3 Oct 1959, Soderstrom 858 

(US). Madera: Nueva Madera, 8 Aug 1974, cultivo de maíz 

[corn crop], 2050 m, C. Rodríguez, O. Agundis & S. Acosta 

1230 (CHAPA, ENCB, MEXU). Manuel Benavides: E Chihuahua, vicinity of Pirámide, 11 Aug 1941, I.M. Johnston 8137

(US). Meoqui: 4 km antes de [before] Rosales, 6 Aug 1974, 

suelo arcilloso, 1250 m, C. Rodríguez, O. Agundis & S. Acosta 

1212 (CHAPA, ENCB). Nuevo Casas Grandes: Rancho el Pilo 

a 6.5 km del Rancho Santa Rosa, 7 Aug 1979, M.A. López s.n.

(ENCB). Ocampo: Parque Nacional “Cascada de Basaseachic,” 

at overlook ca. 1 km airline S of Cascada, 3 Oct 1986, 2100 

m, Spellenberg, Soreng, R. Corral & T. Lebgue 8653 (NMC); 

Parque Nacional Cascada Basaseachic, canyon along Río Candamene leading to falls, 4 Oct 1986, 1800 m, Spellenberg, 

Soreng, R. Corral & T. Lebgue 8859 (NMC); Parque Nacional 

“Cascada de Basaseachic,” near hotel, 25 Oct 1992, 2050 m, 

Spellenberg 11672 (NMC). Riva Palacio: 2.7 km W of Nuevo 

Majalca, 17.2 km W of Hwy 45, 1700 m, P.M. Peterson & Annable 5775 (US); Nuevo Majalca, 14.5 km W of Hwy 45, N of 

Chihuahua, 22 Sep 1988, 1700 m, P.M. Peterson & Annable 

5764 (US); Majalca, 18–20 Aug 1935, LeSueur Mex-035 (US); 

Majalca (Pilares), 11 Aug 1939, 2075 m, L. H. Harvey 1460 

(ENCB). Saucillo: along Isla de Perla road about 4 mi E of cd. 

Delicias, 11 jul 1950, in cultivated and irrigated valley, Reeder, 

C. Reeder & Goodding 1262 (ENCB).

FIGURE 108. Eragrostis pectinacea var. pectinacea. A. Habit. 

B. Spikelet. C. Two paleas below floret. Drawn by Linda Ann Vorobik and Cindy Roché; copyright Utah State University.
NUMBER 107 • 157

147. Eragrostis pilosa* (L.) P. Beauv., Ess. Agrostogr. 71: 162, 

175. 1812. Poa pilosa L., Sp. Pl. 1: 68. 1753.

FIGURE 109

Caespitose annual; without innovations. Culms 8–45(70) 

cm tall, erect or geniculate, glabrous, occasionally with a few 

glandular depressions. Sheaths overlapping below, about 1⁄2 as 

long as the internodes, mostly glabrous, occasionally glandular, apex hirsute, hairs to 3 mm long; ligules 0.1–0.3 mm long, 

ciliate; blades 2–15(20) cm long, 1–2.5(4) mm wide, flat, abaxial surfaces glabrous, occasionally with glandular pits along 

the midrib, adaxial surfaces scaberulous. Panicles 4–20(28) cm 

long, 2–15(18) cm wide, ellipsoid to ovoid, diffuse; primary 

branches 1–10 cm long, diverging 10°–80°(110°) from the rachises, capillary, whorled on the lowest 2 nodes, rarely glandular; pulvini glabrous or hairy; pedicels 1–10 mm long, flexible, 

appressed or divergent. Spikelets (2)3.5–6(10) mm long, 0.6–

1.4 mm wide, linear-oblong to narrowly ovate, plumbeous, with 

(3)5–17 florets; disarticulation acropetal, paleas tardily deciduous, rachillas persisting longer than the paleas; glumes narrowly 

ovate to lanceolate, hyaline; lower glumes 0.3–0.6(0.8) mm 

long; upper glumes 0.7–1.2(1.4) mm long; lemmas 1.2–2 mm 

long, ovate-lanceolate, membranous to hyaline, grayish-green 

proximally, reddish-purple distally, lateral veins inconspicuous, 

apex acute; paleas 1–1.6 mm long, membranous to hyaline, 

keels scaberulous to scabrous, apex obtuse; stamens 3; anthers 

0.2–0.3 mm long, purplish. Caryopsis 0.5–1 mm long, obovoid 

to prism-shaped, adaxial surfaces flat, smooth to faintly striate, 

light brown. 2n = 40.

Specimens Examined. MEXICO. Chihuahua. 

E. Palmer 507 (MEXU); Gentry 1854 (MEXU).

148. Eragrostis pringlei Mattei, Contr. Biol. Veg. 4: 241. 1909. 

Caespitose annual. Culms 10–25 cm tall. Sheaths papillosehirsute, hairy at the collar; ligules 0.3–0.4 mm long; blades 

1.5–5 cm long, 1–4 mm wide, generally wider toward base, 

densely papillose-hirsute. Panicles 7–10 cm long, 0.5–2.5 cm 

wide, oblong-ellipsoid, pedicels 1.8–2.5 mm long, with a glandular ring in the central part. Spikelets 1.7–2.3 mm long, ovate, 

with 2–3(5) florets; glumes unequal, shorter than lemma, lower 

glumes 0.5–0.8 mm long, upper glumes 0.8–1.1 mm; lemmas 

1–1.4 mm long, inconspicuously veined, dark at maturity; palea 

0.9–1.2 mm long, persistent. Caryopsis subglobose, ca. 0.5 mm 

long, minutely striate, the surface with a crustaceous layer.

Distribution and Habitat. Eragrostis pringlei is native to North America and grows in prairies, limestone 

mesas, oak forest, and grasslands at 2,000–2,200 m, often in 

association with Prosopis. It is found in the following states of 

FIGURE 109. Eragrostis pilosa. A. Culm and inflorescence. B. Glandular band. C. Inflorescence. D. Spikelet. 

E. Palea below floret. Drawn by Linda Ann Vorobik and Cindy Roché; copyright Utah State University.
158 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Mexico: Chihuahua, Durango, Guanajuato, Jalisco, Michoacán, 

and Zacatecas.

Specimens Examined. MEXICO. Chihuahua. 

Guerrero: Between Cd. Guerrero and Creel, 3 Aug 1974, Beetle 

M-3282 (US); 11 km E Tomochic, 6 Oct 1986, 2100 m, Spellenberg, Soreng, R. Corral & T. Lebgue 8889 (MEXU, NMC). 

Madera: 2 mi N of Madera in a park-like stand of Pinus latifolis,

9 Sep 1953, 2165 m, Reeder & C. Reeder 2647 (ENCB, MEXU). 

Ocampo: Parque Nacional Cascada de Basaseachic, near hotel, 

25 Oct 1992, 2050 m, Spellenberg 11674 (MEXU, NMC).

149. Eragrostis secundiflora J. Presl, Reliq. Haenk. 1(4–5): 276. 

1830.

FIGURE 110

Caespitose perennial; with innovations, not glandular. 

Culms 30–75 cm tall, erect, glabrous below. Sheaths overlapping below, 1⁄2 as long as the internodes above, mostly glabrous, 

hairy at the apex, hairs to 4 mm long; ligules 0.2–0.3 mm long; 

blades 10–25(40) cm long, 1–5 mm wide, involute, glabrous 

abaxially, scaberulous adaxially, sometimes also sparsely pilose. Panicles (3)5–30 cm long, 1–15 cm wide, from narrowly 

oblong, glomerate, and interrupted below to ovate and open; 

primary branches 0.5–12(16) cm long, appressed or diverging 

up to 40° from the rachises, stiff; pulvini glabrous or sparsely 

hairy; pedicels 0–1(3) mm long, appressed, flattened. Spikelets 

6–16(23) cm long, 2.4–5 mm wide, ovate to linear-elliptic, flattened, stramineous, with reddish-purple margins or completely 

reddish-purple, with 10–45 florets; disarticulation basipetal, florets falling intact and before the glumes; glumes ovate-lanceolate 

to lanceolate, membranous; lower glumes 1.7–3 mm long; upper 

glumes 2.2–4 mm long, apex acuminate; lemmas 2–6 mm long, 

ovate, membranous to leathery, apex usually acuminate or attenuate, sometimes acute; paleas 1.5–3 mm long, membranous 

to leathery, narrower than the lemmas, apex obtuse, sometimes 

bifid; stamens 2; anthers 0.2–0.5 mm long, brownish. Caryopsis 0.8–1.3 mm long, ellipsoid, somewhat laterally flattened, 

smooth, reddish-brown. 2n = 40.

Distribution and Habitat. There are two 

subspecies of E. secundiflora; plants from Chihuahua belong to 

Eragrostis secundiflora subsp. secundiflora. It is native to North 

America and grows in sandy soils, dunes, grasslands, beaches, 

and roadsides up to1,000 m. The range of E. secundiflora extends into southern United States and Mexico in Campeche, Chiapas, Chihuahua, Guerrero, Jalisco, Nayarit, Oaxaca, Quintana 

Roo, Tabasco, Tamaulipas, Veracruz, and the Yucatán.

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000). 

150. Eragrostis sessilispica Buckley, Proc. Acad. Nat. Sci. Philadelphia 14: 97. 1862.

FIGURE 111

Caespitose perennial; with innovations, not glandular. 

Culms 30–90 cm tall, erect or decumbent, glabrous below the 

nodes. Sheaths overlapping below, 1⁄2 to as long as the internodes above, hairy at the apex and on the collars, sometimes 

also on the distal portion of the margins, hairs to 5 mm; ligules 

0.4–0.5 mm long; blades 5–30 cm long, 1–3 mm wide, usually 

involute, sometimes flat, abaxial surfaces glabrous or sparsely 

pilose, hairs to 5 mm long, adaxial surfaces scaberulous. Panicles 20–65 cm long, 10–35 cm wide, ovate, open; primary 

branches 2–20(24) cm long, widely spaced, diverging 20°–100° 

from the rachises, not rebranched, naked basally; pulvini hairy; 

pedicels 0–12 mm long, appressed, proximal spikelets on each 

branch sessile or subsessile, the pedicels shorter than 0.4 mm. 

Spikelets 5–13 mm long, 1.4–3 mm wide, oblong to oblanceolate, stramineous to reddish-purple, with 3–12 florets; disarticulation tardy, basipetal, in the rachilla below the florets, 

glumes persistent; glumes lanceolate, broad basally, indurate; 

lower glumes 2.5–6 mm long; upper glumes 3–6 mm long, apex 

acuminate; lemmas 3–5 mm long, narrowly ovate to lanceolate, 

indurate, apex acuminate; paleas 2.4–4.6 mm long, indurate, 

gibbous basally but the sides not projecting beyond the lemmas, 

keels ciliolate, apex obtuse; stamens 3; anthers 0.3–0.5 mm 

long, reddish-brown. Caryopsis 0.9–1.5 mm long, ovoid to 

FIGURE 110. Eragrostis secundiflora subsp. oxylepis (Torr.) S.D. 

Koch. A. Inflorescence. B. Floret. Drawn by Linda Ann Vorobik and 

Cindy Roché; copyright Utah State University.
NUMBER 107 • 159

FIGURE 111. Eragrostis sessilispica. A.Habit. B. Inflorescence branch. C. Floret. Drawn by Linda Ann Vorobik and Cindy Roché; copyright 

Utah State University.
160 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

pyriform, laterally flattened, tapering distally, smooth to faintly 

striate, brownish. 2n = 40.

Distribution and Habitat. Eragrostis sessilispica is native from the United States and grows in prairies, 

limestone mesas, thorn forest openings, and grasslands, generally in sandy soils, at 0–300 m, often in association with Prosopis and Quercus. Its range extends into Texas, New Mexico, 

Oklahoma, and Kansas to Chihuahua and Tamaulipas.

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000) and Herrera Arrieta and 

Cortés Ortiz (2010).

151. Eragrostis spectabilis (Pursh) Steud., Nomencl. Bot. (ed. 2) 

1: 564. 1840.

FIGURE 112

Caespitose perennial; with innovations and short, knotty 

rhizomes less than 4 mm thick. Culms 30–70(85) cm tall, erect 

to ascending, often sprawling, glabrous. Sheaths overlapping, 

hairy on the margins and at the apex, hairs to 7 mm long; ligules 

0.1–0.2 mm long; blades 10–32 cm long, 3–8 mm wide, flat to involute, both surfaces usually pilose, sometimes glabrous on both 

surfaces or glabrous abaxially and sparsely pilose adaxially, often 

with a line of hairs behind the ligules, hairs to 8 mm long. Panicles (15)25–45(60) cm long, 15–35 cm wide, broadly ovate to oblong, open, basal portions sometimes included in the uppermost 

sheaths; primary branches (6)12–20 cm long, diverging 20°–90° 

from the rachises, capillary, naked below; pulvini hairy, hairs to 

6 mm; pedicels 1.5–17 mm long, divergent or appressed. Spikelets 

3–7.5 mm long, 1–2 mm wide, linear-lanceolate, reddish-purple, 

sometimes olivaceous, with (4)6–12 florets; disarticulation basipetal, glumes persistent; glumes (1)1.3–2.3 mm long, subequal to 

equal, lanceolate, membranous to chartaceous; lemmas (1)1.3–

2.5 mm long, ovate to lanceolate, leathery, 3-veined, apex acute; 

paleas (1)1.2–2.4 mm long, membranous, keels sometimes shortly 

ciliate, apex obtuse to truncate; stamens 3; anthers 0.3–0.5 mm 

long, purplish. Caryopsis 0.6–0.8 mm long, ellipsoid, strongly 

flattened, adaxial surfaces with 2 prominent ridges separated by a 

groove, reddish-brown. 2n = 20, 40, 42.

Distribution and Habitat. Eragrostis spectabilis is native in North America, extending from southern Canada through the United States, Mexico, and Belize. It grows in 

fields and on the margins of woods, along roadsides, and in other 

disturbed sites, usually in sandy to clay loam soils, and is associated with hardwood forests, Prosopis–Acacia grasslands, and 

short grass prairies at 0–1,000 m. 

Specimens Examined. MEXICO. Chihuahua. 

Guachochic: camino Guachochic–Creel, 5 km antes del entronque [before junction] a la Bufa, 24 Sep 1981, bosque esclerófilo caducifolio [deciduous sclerophyllous forest], 2700 m, 

M.E. Siqueiros 1636 (MEXU). Moris: 14 km al W de Ocampo, 

brecha [gap] a Moris, 29 Sep 1985, bosque de encino [oak forest], 1720 m, Tenorio 10029 (MEXU).

152. Eragrostis superba* Peyr., Sitzungsber. Kaiserl. Akad.Wiss., 

Math.-Naturwiss. Cl. 38: 584. 1860.

FIGURE 113

Caespitose perennial; with innovations, without glands. 

Culms 45–95 cm tall, erect, glabrous. Sheaths overlapping 

below, 1⁄3–1⁄2 the length of the internodes above, hairy at the apex 

and on the margins, hairs to 6 mm long; ligules 0.5–1.2 mm 

FIGURE 112. Eragrostis spectabilis. A. Habit. B. Spikelet. 

C. Floret. Drawn by Linda Ann Vorobik and Cindy Roché; 

copyright Utah State University.
NUMBER 107 • 161

long; blades 7–30 cm long, 2.5–7 mm wide, flat to loosely involute, glabrous abaxially, scabrous adaxially, margins sharply scabrous. Panicles 10–30 cm long, 1–6 cm wide, oblong, condensed, 

interrupted below; primary branches 1–11 cm long, appressed 

or diverging to 40° from the rachises, naked basally; pulvini glabrous; pedicels 0.5–25 mm long, with a narrow band or abscission line below the apex. Spikelets 5.5–16 mm long, 2.7–9 mm 

wide, ovate, flattened, greenish to stramineous, sometimes with 

a reddish-purple tinge, with 4–22 florets; disarticulation below 

the glumes, spikelets falling intact; glumes 3–4.5 mm long, equal, 

ovate, chartaceous; lemmas 3–5 mm long, broadly lanceolate, 

chartaceous to leathery, lateral veins green, apex acute; paleas 

3–5 mm long, chartaceous to hyaline, keels broadly winged 

below, forming a wing or tooth on each side that often projects 

beyond the lemma bases, apex acuminate; stamens 3; anthers 

1.4–2.8 mm long, golden-yellow. Caryopsis 1–2 mm long, ellipsoid, adaxial surfaces flattened, reddish-brown. 2n = 40.

Distribution and Habitat. Eragrostis superba

is introduced to North America and native to Africa, where it is 

grown for hay, being fairly palatable and drought resistant. It 

is also used for erosion control and re-vegetation. It grows on 

rocky slopes, in sandy flats, and along roadsides, often with Acacia, Prosopsis, Fouquieria splendens, Juniperus, and Quercus, at 

480–1,900 m.

Specimens Examined. MEXICO. Chihuahua.

Chihuahua: Alrededores [surroundings] de la Cd. de Chihuahua, 

3 Sep 1996, 149 m, C. Yen & E. Estrada 5844 (ENCB); Rancho 

Experimental La Campana, 21 Oct 1981, pastizal [pastureland], 

1500 m, G. Melgoza 21 (CIIDIR); La Campana Experimental 

Station & Rancho El Arco Iris, 81–84 km along Pan American 

Hwy to Chihuahua City, Jun 1977, 1500 m, J.K. Meents & 

W.H. Moir 130 (NMC); Rancho Experimental La Campana, 13 

Sep 73, Jardines de observación [observation gardens], 1500 m, 

Valdés-Reyna VR–238 (RELC); Rancho Experimental La Campana, 82 km al N de Chihuahua, 26 Aug 1978, pastizal, 1500 m, 

M.A Bernal & F. Cardenas s/n (MEXU).

Eriochloa Kunth

Annual or perennial; caespitose, sometimes with short rhizomes or stolons, not producing subterranean spikelets. Culms 

20–250 cm tall, erect or decumbent, usually with 2–5 nodes. 

Sheaths open; auricles absent; ligules membranous, ciliate. Inflorescences terminal, panicles of spikelike branches on elongate 

rachises; branches with many pedicellate, loosely appressed 

spikelets, terminating in a spikelet, without stiff bristles or flat 

bracts, spikelets in pairs, triplets, or solitary, often solitary distally when in pairs or triplets at the middle of the branches; 

pedicels terminating in a well-developed disk; disarticulation 

below the glume(s). Spikelets with 2 florets, lower florets usually 

sterile, upper florets bisexual. Lower glumes typically reduced 

(sometimes absent) and fused with the glabrous callus to form a 

cuplike structure; upper glumes lanceolate to ovate, glabrous or 

variously pubescent, 3- to 9-veined, unawned or awned; lower 

lemmas similar to the upper glumes in length, shape, venation, 

FIGURE 113. Eragrostis superba. A. Habit. B. Culm 

and inflorescence. C. Spikelet. D. Floret. E. Palea. 

Drawn by Linda Ann Vorobik and Cindy Roché; 

copyright Utah State University.
162 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

and pubescence, unawned; lower paleas absent to fully developed; upper lemmas lanceolate to ovate, indurate, rugose, dull, 

glabrous, rounded on the back, veins not pronounced, margins 

involute; anthers 3; lodicules 2, papery; styles with 2 branches, 

purple, plumose. Caryopsis not longitudinally grooved; endosperm solid. x = 9. 

Eriochloa, a genus of about 37 species, grows in tropical, 

subtropical, and warm-temperate areas of the world.

KEY TO SPECIES OF ERIOCHLOA

1. Blades copiously pilose; spikelets 5–8 mm long, unawned and muticous, including the callus; upper lemma lacking a terminal mucro . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. nelsonii

1. Blades glabrous or almost glabrous; spikelets 3.5–7 mm long (including the callus and awns), awned or mucronate; upper 

lemma with a terminal mucro of 0.1–0.8 mm long or short-awned, the awn up to 1.5 mm long.

2. Spikelets 5.5–7 mm long (not including the awn); glumes usually acuminate and awned, the awns 1–4 mm long . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. aristata

2. Spikelets 3.5–5 mm long (not including the awn); glumes acute, usually mucronate, the mucro up to 1 mm long.

3. Blades 5–15 mm wide, puberulent or lanose-pubescent abaxially; racemes 5–20 cm long.

4. Racemes 5–20 cm long, simple, ascending, puberulent; pedicels puberulent . . . . . . . . . . . . . . . . . . E. acuminata

4. Racemes 3–5 cm long, soft and lax, rachis lanose-pubescent; pedicels with several long hairs besides the lanose 

pubescence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. lemmonii

3. Blades 1–5 mm wide, glabrous or scabrous-pubescent abaxially; racemes 1–1.5(2) cm long. 

5. Spikelets 4–5 mm long; upper lemma 2.3–3.3 mm long, mucronate, the mucro 0.1–0.3 mm long . . . . . . . . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. acuminata

5. Spikelets 3.5–4 mm long; upper lemma 2–2.5 mm long, mucronate or awned, the awn up to 1.1 mm long . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. contracta

153. Eriochloa acuminata (J. Presl.) Kunth, Enum. Pl. 1: 72. 

1833. Piptatherum acuminatum J. Presl, Rel. Haenk. 

1(4–5): 221. 1830.

Eriochloa gracilis (E. Fourn.) Hitchc., J. Wash. Acad. Sci. 23: 455. 1933.

Caespitose annual. Culms 30–120 cm long, erect or decumbent, sometimes rooting at the lower nodes; internodes glabrous 

or with scattered hairs; nodes glabrous or pilose. Sheaths sometimes conspicuously inflated, glabrous or pubescent; ligules 0.2–

1.2 mm long; blades 5–12(18) cm long, (2)5–12(16) mm wide, 

linear, flat or folded, straight or lax, glabrous or sparsely pubescent adaxially. Panicles 7–16 cm long, 1–6 cm wide, loosely contracted; rachises scabrous or hairy; branches 5–20, 1–5 cm long, 

0.4–0.6 mm wide, appressed to divergent, pubescent, sometimes 

setose, not winged, with 20–36 spikelets, spikelets mostly in 

unequally pedicellate pairs, solitary distally; pedicels 0.1–1 mm 

long, hairy. Spikelets 3.8–5(6) mm long, 1.1–1.4 mm wide, lanceolate to ovate. Lower glumes absent; upper glumes equaling 

the lower lemmas, lanceolate to ovate, hairy, 5(7)-veined, acuminate to acute, unawned or awned, awns to 1.2 mm; lower 

lemmas 3.6–5 mm long, 1.1–1.4 mm wide, lanceolate to ovate, 

setose, 5(7)-veined, acuminate to acute, unawned; lower paleas 

absent; anthers absent; upper lemmas 2.3–3.3 mm long, 0.7–0.9 

times as long as the lower lemmas, indurate, elliptic, rounded, 

5-veined, mucronate, the mucros 0.1–0.3 mm long; upper paleas 

indurate, blunt, rugose. 2n = 36.

Distribution and Habitat. Eriochloa acuminata is native to the southern United States and northern Mexico 

and has become established outside this region.

KEY TO VARIETIES OF ERIOCHLOA ACUMINATA

1. Spikelets 4–6 mm long, long-acuminate or narrowed into a short awn; blades usually glabrous but occasionally pubescent 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. acuminata var. acuminata

1. Spikelets less than 4 mm long, acute; blades usually pubescent but occasionally glabrous . . . . . . . E. acuminata var. minor

Eriochloa acuminata (J. Presl.) Kunth var. acuminata.

Specimens Examined. MEXICO. Chihuahua.

Balleza: 10 mi SW of El Ojito, 12 Sep 2006, 1902 m, P.M. Peterson 20022, F. Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, 

US). Camargo: Sierra de los Organos, 9 Aug 1936, LeSueur 

0171 (US). Carichi: Sánchez, 12 Oct 1910, Hitchcock 7703 (US). 

Chihuahua: near Chihuahua, 20 Oct 1936, LeSueur 0118 (US); 

10 Oct 1935, LeSueur Mex-064 (US); 16 Sep 1886, C.G. Pringle 

812 (US); 4 Sep 1885, C.G. Pringle 481 (US); Base de la Sierra 

de La Campana, 80 km al N de Chihuahua, ladera riolítica con 

pastizal & encinos [rhyolitic slopes with pastureland and oaks], 

19 Oct 1974, 1700 m, Rzedowski 32343 (ENCB). Cuauhtémoc: 

4 mi E of General Trias, mesquites and acacias, 14 Sep 1960, 

5300 ft, Reeder, C. Reeder & Soderstrom 3462 (ARIZ, ENCB). 

Hidalgo del Parral: About 5 mi N of Parral on road to Chihuahua City, Mesquite savanna, 14 Aug 1950, Reeder, C. Reeder 

& Goodding 1687 (ENCB). Janos: Chihuahua–Sonora border, Rancho Carretas, 22 Aug 1939, 1460 m, L. H. Harvey 
NUMBER 107 • 163

1622 (ENCB, US). Julimes: Camino entre carr. [path between 

hwy] Panamericana & Baños de San Diego, cañada [glen] con 

Xanthium–Hilaria–Prosopis, 30 Jul 1976, 1200 m, S. González 

& J.M. Peña 350 (ENCB). Matamoros: 19.3 km S of Villa Matamoros on hwy 45 to Durango, 3 Oct 1989, grassland, 1910 m, 

P.M. Peterson & R.M. King 8252 (US). Práxedis G. Guerrero: 

aprox. 3 km al NW del Porvenir, por la carr. Juárez–Porvenir, 

a los lados de cultivo de algodón [near cultivated cotton], 8 Sep 

1994, 1090 m, R. Corral, Bye, A. Domínguez, K. Chico & 

P. Yañez RCD5403 (UACJ). Saucillo: along Isla de Perla road 

4 mi E of cd. Delicias, cultivated and irrigated valley, 11 Jul 

1950, Reeder, C. Reeder & Goodding 1258, 1261 (ENCB).

Eriochloa acuminata var. minor (Vasey) R. B. Shaw

Specimens Examined. MEXICO. Chihuahua.

Chihuahua: near Chihuahua, 14 Oct 1910, Hitchc. 7778 (US).

Guachochi: Barranca de Basihuare, 28 Aug 2003, bosque de 

encino [oak forest], 1700 m, P.M. Peterson & P. Catalán 17586

(CIIDIR, US). Guerrero: Miñaca, 13 Oct 1910, Hitchc. 7753 (US).

154. Eriochloa aristata Vasey, Bull. Torrey Bot. Club 13(12): 

229. 1886.

FIGURE 114

Annual; caespitose, not rhizomatous. Culms 40–100 cm 

tall, erect or decumbent, sometimes rooting at the lower nodes; 

internodes glabrous; nodes 3–10, puberulent. Sheaths glabrous; 

ligules 0.5–0.8(2) mm long; blades 6–20 cm long, 6–20 mm 

wide, linear to lanceolate, flat or folded, straight or lax, glabrous (rarely sparsely pubescent) adaxially. Panicles 5–20 cm 

long, 1–3 cm wide, loosely contracted; rachises hairy; branches 

16–30, 20–35 mm long, 0.3–0.5 mm wide, divergent to spreading, setose, not winged, with 20–35 spikelets in unequally pedicellate pairs; pedicels 0.5–3 mm long, hairy, with some hairs 

0.5–2.5 mm long, at least distally. Spikelets 4–8.8 mm long, 

1.1–1.6 mm wide, lanceolate.; upper glumes 1–1.1 times as 

long as the lower lemmas, lanceolate, pilose or scabrous above, 

5-veined, acuminate and awned, the awns 1–4 mm long; lower 

florets sterile; lower lemmas 4–8 mm long, 1.1–1.6 mm wide, 

lanceolate, setose, 3- to 7-veined, acuminate, mucronate, mucro 

less than 0.4 mm long; lower paleas absent; anthers absent; 

upper lemmas (2)3–4(6) mm long, 0.4–0.6 times as long as the 

lower lemmas, indurate, elliptic, acute to rounded, 5-veined, 

mucronate, the mucro 0.2–0.8 mm long; upper paleas indurate, 

rugose. 2n = 36.

FIGURE 114. Eriochloa aristida. A. Habit. B. Spikelet. C. Upper floret. Drawn by Linda 

Ann Vorobik and Cindy Roché; copyright Utah State University.
164 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Distribution and Habitat. Eriochloa aristata

is a weed of moist swales, roadsides, and irrigated fields in the 

southwestern United States. Its range extends through Mexico 

and Central America to Colombia.

Specimens Examined. MEXICO. Chihuahua. Chihuahua: Chihuahua, Aug 1885, E. Palmer 110e (US); Río Bonito, 

25 Aug 1936, LeSueur Mex-094 (US). Hidalgo del Parral: about 

5 mi N of Parral on road to Chihuahua City, Mesquite savanna, 

14 Aug 1950, Reeder, C. Reeder & Goodding 1686 (ENCB).

155. Eriochloa contracta* Hitchc., Proc. Biol. Soc. Washington 

41: 163. 1928.

FIGURE 115

Caespitose annual. Culms 20–100 cm tall, erect or decumbent, sometimes rooting at the lower nodes; internodes pilose 

or pubescent; nodes pubescent to puberulent. Sheaths sparsely 

to densely pubescent; ligules 0.4–1.1 mm long; blades 6–12(22) 

cm long, 2–8 mm wide, linear, flat to conduplicate, straight, appressed to divergent, both surfaces sparsely to densely pubescent 

with short, evenly spaced hairs. Panicles 6–20 cm long, 0.3–

1.2 cm wide; rachises pilose, longer hairs 0.1–0.8 mm; branches 

10–20(28), 15–45(60) mm long, 0.2–0.4 mm wide, appressed, 

pubescent to setose, not winged, with 8–16 mostly solitary 

spikelets, occasionally paired at the base of the branches; pedicels 0.2–1 mm long, variously hirsute below, apex with fewer 

than 10 hairs more than 0.5 mm long. Spikelets (3.1)3.5–4.5(5) 

mm long, 1.2–1.7 mm wide, lanceolate; upper glumes as long as 

the lower lemmas, with sparsely appressed pubescence on the 

lower 2⁄3, scabrous or glabrous distally, 3- to 9-veined, acuminate and awned, awns 0.4–1 mm; lower florets sterile; lower 

lemmas 3–4.3 mm long, 1.2–1.7 mm wide, lanceolate, setose, 

3- to 7-veined, acuminate, unawned or mucronate; lower paleas 

absent; upper lemmas 2–2.5 mm long, indurate, elliptic, 5- to 

7-veined, acute to rounded and mucronate to awned, mucro/

awns 0.4–1.1 mm long; upper paleas indurate, faintly rugose, 

blunt. 2n = 36.

Distribution and Habitat. Eriochloa contracta grows in fields, ditches, and other disturbed areas. It is 

native and common in the central United States and adventive to 

the east and southwest.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 16.1 km W of Balleza and 77.9 km E of Guachochi, 

18 Sep 1991, bosque de encino [oak forest], 1990 m, P.M. Peterson, Annable & Valdés-Reyna 10744 (CIIDIR).

156. Eriochloa lemmonii Vasey & Scribn., Bot. Gaz. 9(12): 185, 

pl. 2. 1884.

FIGURE 116

Caespitose annual. Culms 20–80 cm tall, erect or decumbent, sometimes rooting at the lower nodes; internodes densely 

pubescent to pilose; nodes pubescent to pilose. Sheaths from 

conspicuously inflated to not inflated, glabrous or pubescent to 

pilose; ligules 0.5–1 mm long; blades 5–15 cm long, 6–20 mm 

wide, lanceolate, flat, straight, diverging or ascending, velvety pubescent adaxially. Panicles 5–15 cm long, 0.5–4 cm wide, spreading or contracted; rachises hairy; branches (2)3–8(10), 1–4 cm 

long, 0.4–0.6 mm wide, appressed or reflexed and spreading, 

velvety pubescent, not winged, with 10–14 spikelets, spikelets in 

unequally pedicellate pairs at the middle of the branches, solitary 

distally; pedicels 0.5–1 mm long, pilose, apex hairy or glabrous. 

Spikelets 3–4.5(4.9) mm long, 1.2–1.7 mm wide, elliptic; upper 

glumes equaling the lower lemmas, nearly glabrous or sparsely 

to densely pilose, elliptic, 5- to 7-veined, acute, unawned; lower 

lemmas 2.7–4 mm long, 1.2–1.7 mm wide, elliptic, setose to 

pilose, 5-veined, acute, unawned; lower paleas 1–4 mm long, 

hyaline; anthers absent or 3; upper lemmas 2.3–3.3 mm long, 

elliptic, indurate, dull, rough, occasionally with a few long hairs, 

acute to rounded, sometimes mucronate; upper paleas indurate. 

2n = 36.

Distribution and Habitat. Eriochloa lemmonii, a rare species, grows in canyons and on rocky slopes in Pima 

County, Arizona, Hidalgo County, New Mexico, and adjacent 

Mexico.

FIGURE 115. Eriochloa contracta. A. Inflorescence and leaf blades. 

B. Ligule. C. Spikelet. D. Upper floret. Drawn by Linda Ann Vorobik 

and Cindy Roché; copyright Utah State University.
NUMBER 107 • 165

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: SW Chihuahua, Aug 1885, E. Palmer 110-A (US); Intersección Arroyo de Santiago con el Río Batopilas, 6 km antes 

del pueblo [before town] de Batopilas, 10 Sep 1999, 600 m, 

T. Lebgue, G. Quintana & E. Estrada 2362 (NMC). Bocoyna: 

entre [between] barranca del Cobre & Bacahipare, bosque bajo 

de leguminosas [low legume forest], 17 Aug 1976, 1010 m, J.M. 

Peña & S. González 728 (ENCB). Ocampo: Ca 1 km W of W 

boundary of Parque Nacional “Cascada de Basaseachic,” 18 km 

from the Cahuisori–Ocampo road on the road to Candamena, 

7.5 km below Cruz, 24 Sep 1994, 1260 m, Spellenberg, Corral 

& Estrada 12193 (NMC).

157. Eriochloa nelsonii Scribn. & J. G. Sm., Bull. Div. Agrostol. 

U.S.D.A. 4: 12–13. 1897.

Annual. Culms 30–150 cm tall, erect or decumbent, pubescent. Sheaths pilose; ligule 0.3–1.5 mm long, a ring of hairs; 

blades 7–19 cm long, 5–17 mm wide, flat, pilose. Inflorescence 

6–12 cm long,1.5–4 cm wide, main axis pilose, branches 1.2–3.5 

cm long, (1)3–7(10) per culm with 10–40 spikelets per branch, 

divergent from rachis, the branches with hairs 3–8 mm long. 

Spikelets 5–8 mm long, 1.5–2 mm wide, lanceolate, in pairs; 

upper glumes equaling the lower lemmas, lanceolate, 5- to 

9-veined, pilose, glabrous toward the apex, acute to obtuse, muticous; lower lemma 4.8–7.8 mm long, 1.5–2 mm wide, lanceolate, 5(7)-veined, pilose, glabrous toward the apex, acute and 

muticous; palea vestigial or absent; upper lemma 3.2–4.4 mm 

long, 5-veined, acute to rounded or acute with a small mucro. 

2n = 18, 36.

Distribution and Habitat. Eriochloa nelsonii

has two varieties; only Eriochloa nelsonii var. nelsonii is present 

in Chihuahua. It ranges from Mexico to Central America.

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000).

158. Eriochloa punctata (L.) Desv. ex Ham., Prodr. Pl. Ind. 

Occid. 5. 1825.

FIGURE 117

Perennial; rhizomatous, often flowering the first year and 

resembling an annual. Culms 30–150 cm tall, erect or decumbent, not rooting at the lower nodes; internodes glabrous; nodes 

3–10, glabrate. Sheaths occasionally inflated, glabrous (rarely 

puberulent), often purplish at maturity; ligules 0.4–1 mm long; 

blades 10–50 cm long, (2)4–10(13) mm wide, linear, flat, straight, 

spreading, glabrous (rarely puberulent) on both surfaces. Panicles 

9–22 cm long, 1–10 cm wide, contracted, rarely open; rachises 

scabrous to densely pubescent; branches (4)8–20(27), 1–6 cm 

long, 0.3–0.5 mm wide, appressed or divergent, glabrous, not 

winged, with 28–60 spikelets, spikelets mostly in unequally 

pedicellate pairs, solitary distally; pedicels 0.1–0.7 mm long, uniformly pubescent, hairs about 0.1 mm. Spikelets (4)4.5–5.7 mm 

long, 0.9–1.4 mm wide; upper glumes equaling the lower lemmas, 

FIGURE 116. Eriochloa lemmonii. A. Habit. B. Inflorescence and 

leaf blade. C. Spikelet. D. Upper floret. Drawn by Linda Ann Vorobik and Cindy Roché; copyright Utah State University.
166 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

lanceolate, sparsely appressed pilose, 5- to 7-veined, acuminate, 

sometimes mucronate, mucro shorter than 0.5 mm; lower lemmas 4.3–5.5 mm long, 0.9–1.4 mm wide, lanceolate, setose, 

5- to 7-veined, acuminate, unawned or mucronate; lower paleas 

absent; anthers absent; upper lemmas 2–3.5 mm (excluding the 

awn), 0.4–0.6 times as long as the lower lemmas, indurate, elliptic, 5-veined, rounded, awned, awns 0.6–1.5 mm long; upper 

paleas 0.5–1.2 mm long, indurate, blunt. 2n = 36.

Distribution and Habitat. Eriochloa punctata grows in coastal marshes, along water courses, and in moist 

swales and ditches of the coastal plain from Texas and Louisiana 

south through Mexico to Central and South America.

Specimens Examined. MEXICO. Chihuahua. 

Camargo: 20 km S of Camargo, 2 Aug 1939, 1220 m, L. H. 

Harvey 1385 (ENCB, US); 5 km W of Cd. Camargo, 5 Aug 

1939, L. H. Harvey 1416 (US). Gran Morelos: 4 mi E of General Trias, 14 Sep 1960, Reeder, C. Reeder & Soderstrom 3462

(US). Valle de Zaragoza: 58 km N of Parral on Mex 24 towards 

Chihuahua, 14 Sep 1989, grassland, 1500 m, P.M. Peterson & 

Annable 8097 (US).

Erioneuron Nash

Perennial; usually caespitose, occasionally stoloniferous. Culms 6–65 cm long, erect. Leaves mostly basal; sheaths 

smooth, glabrous, striate, margins hyaline, collars with tufts 

of 1–3 mm hairs; blades usually folded, pilose basally, margins 

white, cartilaginous, apex acute but not sharp. Inflorescences 

terminal, simple panicles (racemes in depauperate specimens), 

exserted well above the leaves. Spikelets laterally compressed, 

with 3–20 florets, distal florets staminate or sterile; disarticulation above the glumes and between the florets. Glumes thin, 

membranous, 1-veined, acute to acuminate; calluses with hairs; 

lemmas rounded on the back, 3-veined, veins conspicuously 

pilose, at least basally, apex toothed or obtusely 2-lobed, midveins often extended into awns, awns to 4 mm long, lateral 

veins sometimes extended as small mucros; paleas shorter than 

the lemmas, keels ciliate, intercostal regions pilose basally; lodicules 2, adnate to the bases of the paleas; anthers 1 or 3. Caryopsis glossy, translucent; embryos more than 1⁄2 as long as the 

caryopsis. x = 8.

Erioneuron is an American genus of three species, all in 

Chihuahua.

FIGURE 117. Eriochloa punctata. A. Habit. B. Spikelet. C. Upper 

floret. Drawn by Linda Ann Vorobik and Cindy Roché; copyright 

Utah State University.
NUMBER 107 • 167

KEY TO SPECIES OF ERIONEURON

1. Lemmas 2-lobed, with a cleft of 1–2.5 mm deep, central veins extended into an awn 1–4 mm long; glumes (at least the 

upper) as long as or longer than the inferior florets.

2. Lemma lobes obtuse to broadly acute,1–2 mm deep; lateral veins never excurrent into small mucros; plants tufted, 10–40 cm 

tall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. avenaceum 

2. Lemma lobes rounded to truncate, 1.5–2.5 mm deep; lateral veins of lemma excurrent into small mucros up to 1 mm 

long; plants generally taller, 25–65 cm tall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. nealleyi

1. Lemmas entire, without a cleft or if present, only 0.1–0.5 mm deep; central veins extended into a small awn 0.5–2(2.5) mm 

long; glumes shorter than the inferior florets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. pilosum

159. Erioneuron avenaceum (Kunth) Tateoka, Amer. J. Bot. 

48(7): 572. 1961. Triodia avenacea Kunth, Nov. Gen. Sp. 

(quarto ed.)1: 156. T. 48. 1815. Tridens avenaceus (Kunth) 

Hitchc., Contr. U.S. Natl. Herb. 17(3): 357. 1913.

Erioneuron avenaceum var. grandiflorum (Vasey) Gould.

FIGURE 118

Culms (7)10–30(40) cm tall, (0.4)0.7–1 mm thick, glabrous; 

nodes glabrous or villous. Ligules to 0.5 mm long; blades (1.5)3–

5(8) cm long, (0.5)1–1.5(2.5) mm wide, both surfaces sparsely 

pilose. Panicles 2–8(10) cm long; branches with 2–10(16) shortly 

pedicellate spikelets. Spikelets 6–8(10) mm long, purplish, with 

(4)6–12(20) florets; lower glumes 4–7 mm long; upper glumes 

6–9 mm long, equaling or exceeding the lowest florets; lemmas 

4–7 mm long, purplish-green, awned from between the lobes, 

awns 2–4 mm long, apex bilobed, lobes 1–2 mm long, obtuse to 

acute; anthers 0.4–1 mm long or (when monandrous) to 1.3 mm 

long. Caryopsis 1–1.4 mm long. 2n = 16, 32.

Distribution and Habitat. Erioneuron avenaceum var. avenaceum is common in rocky areas from the southwestern United States to central Mexico; it also grows in Bolivia 

and Argentina.

Specimens Examined. MEXICO. Chihuahua. 

Aldama: 17 (rd) mi NE of Aldama along Hwy 16 at Puerto de 

Gómez, 14 Sep 1972, 1450 m, J. Henrickson 7543 (MEXU, 

NMC); 4 km (airline) SE of Placer de Guadalupe, 23 Oct 1972, 

matorral desértico [desert scrub], 1500 m, F. Chiang, T. Wendt & 

M.C. Johnston 9851A (MEXU). Ascensión: Sierra de Bismarck, 

21 Aug 1972, 1500–1850 m, F. Chiang, T. Wendt & M.C. Johnston 8765 (MEXU). Chihuahua: near Chihuahua, 12 Aug 1885, 

C.G. Pringle s.n. (US). Hidalgo del Parral: 4 mi E of Parral, 13 Sep 

1960, Reeder & C. Reeder 3458 (US); 14 mi E of Parral, 6 Sep 

1967, Reeder & C. Reeder 4876 (ARIZ, US). Jiménez: Santa Eulalia, 12 Aug 1885, Limestone ledges, C.G. Pringle 406 (MEXU, 

US); 1885, E. Wilkinson s.n. (US). Matamoros: 84.6 km SE of 

Villa Matamoros and 1.6 km N of Ejido Revolución on Mex 45, 

1900 m, P.M. Peterson, Annable & Valdés-Reyna 10871 (US).

160. Erioneuron nealleyi (Vasey) Tateoka, Amer. J. Bot. 48(7): 

572. 1961. Triodia nealleyi Vasey, Bull. Torrey Bot. Club 

15: 49. 1890.

FIGURE 119

Culms (15)30–65 cm tall, 0.8–2 mm thick, glabrous or hirsute; nodes glabrous or densely villous. Ligules 0.2–0.6 mm long; 

blades 5–10 cm long, 2–2.5 mm wide, flat in moist conditions, 

both surfaces pilose to villous, green. Panicles compact (rarely 

FIGURE 118. Erioneuron avenaceum. A. Spikelet. B. Floret. Drawn 

by Linda Ann Vorobik and Karen Klitz; copyright Utah State 

University.

FIGURE 119. Erioneuron nealleyi. A. Spikelet. B. Floret. Drawn by 

Linda Ann Vorobik and Karen Klitz; copyright Utah State University.
168 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

open), 5–10 cm long, 1–3 cm wide, usually 2–4(6) times longer than wide, occasionally interrupted in the lower 1⁄2; branches 

with 5–17 shortly pedicellate spikelets. Spikelets 7–11 mm long, 

purplish to pale, with 3–15 florets; lower glumes 5–7 mm; upper 

glumes 6–9 mm long, generally equaling or exceeding the lowest 

florets; lemmas 4–6 mm long, awned from between the lobes, 

awns 1–3.5 mm long, apex bilobed, lobes 1.5–2.5 mm long, 

rounded to truncate, lateral veins forming a mucro to 1 mm long; 

anthers 1, 1–1.5 mm long. Caryopsis 1.3–1.5 mm long. 2n = 16.

Distribution and Habitat. Erioneuron nealleyi is found on rocky slopes in the southwestern United States 

and central Mexico. Stoloniferous plants are known only from 

central Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Aquiles Serdán: Camino a Santa Eulalia–San Guillermo, 30 Aug 

1996, matorral xerófilo [xerophilous scrub], 1500 m, E. Estrada 

& C. Yen 5783 (CIIDIR). Hidalgo del Parral: 4 mi E of Parral, 

13 Sep 1960, 5700 ft, Reeder, C. Reeder & Soderstrom 3458

(ARIZ, ENCB). Jiménez: N end of Sierra de las Pampas on road 

from Las Pampas NW to Camargo, 24 Aug 1972, matorral 

desértico [desert scrub], 1400 m, M.C. Johnston, T. Wendt & 

F. Chiang 8803 (MEXU).

161. Erioneuron pilosum (Buckley) Nash, Fl. S.E. U.S. 144: 

1327, 1903. Uralepis pilosa Buckley, Proc. Acad. Nat. Sci. 

Philadelphia 14: 94. 1862.

FIGURE 120

Culms (6)10–30(40) cm tall, (0.3)0.6–1(2.5) mm thick, glabrous or hirsute. Ligules 2–3.5 mm long; blades (1)3–6(9) cm 

long, (0.5)1–1.5(2.5) mm wide, both surfaces sparsely pilose or 

glabrous, grayish-green. Panicles 1–4(6) cm long; branches with 

3–9 shortly pedicellate spikelets. Spikelets 6–12(15) mm long, 

with (5)6–12(20) florets; glumes exceeded by the lowest florets, 

pale; lower glumes 4–7 mm long; upper glumes 4–7 mm long; lemmas 3–6 mm long, green or purplish-green when young, becoming stramineous at maturity, awned, awns 0.5–2.5 mm long, apex 

acute, entire or bidentate, teeth 0.3–0.5 mm long; stamens usually 

3, anthers 0.3–1 mm long. Caryopsis 1–1.5 mm long. 2n = 16.

Distribution and Habitat. Erioneuron pilosum grows on dry, rocky hills and mesas, often in oak and 

pinyon–juniper woodlands. In North America, it is represented 

by Erioneuron pilosum var. pilosum. This variety differs from 

the other two varieties, both of which are restricted to Argentina, 

in its longer, less equal glumes and shorter awns.

Specimens Examined. MEXICO. Chihuahua. 

Samples not seen during the present revision but reported in Espejo Serna et al. (2000).

Festuca L. [Vulpia C. C. Gmel.]

Perennial and annual; bisexual; usually densely to loosely 

caespitose, with or without rhizomes, occasionally stoloniferous. Culms usually glabrous and smooth throughout, sometimes 

scabrous or densely pubescent below the inflorescences. Sheaths

from open to the base to closed almost to the top, in some species 

sheaths of previous years persisting and the blades usually deciduous, in other species the senescent sheaths rapidly shredding into fibers and decaying between the veins and the blades not deciduous; 

collars inconspicuous or absent, usually glabrous; ligules membranous, truncate to acute, ciliate to erose; blades flat, conduplicate, 

involute, or convolute, sometimes glaucous or pruinose, glabrous 

FIGURE 120. Erioneuron pilosum. A. Habit. B. Spikelet. C. Floret. 

Drawn by Linda Ann Vorobik and Karen Klitz; copyright Utah State 

University.
NUMBER 107 • 169

or scabrous, sometimes hirsute or puberulent. Inflorescences open 

or contracted panicles, sometimes reduced to racemes, usually 

with 1–2(3) branches at the lower nodes. Spikelets with (1)2–10 

mostly bisexual florets, distal florets reduced or abortive; disarticulation above the glumes, beneath the florets. Glumes subequal or 

unequal, usually exceeded by the florets, ovate to lanceolate, acute 

to acuminate; lower glumes from shorter than to about equal to 

the adjacent lemmas, 1(3)-veined; upper glumes 3(5)-veined; lemmas usually chartaceous, sometimes coriaceous, bases more or 

less rounded dorsally, slightly or distinctly keeled distally, veins 

5(7), prominent or obscure, apex acute to attenuate, sometimes 

minutely bidentate, usually terminally or subterminally awned or 

mucronate; paleas from shorter than to slightly longer than the 

lemmas, veins sparsely to densely scabrous-ciliate, bidentate; anthers 1 or 3. Caryopsis obovoid-oblong, adaxially grooved, usually free of the lemmas and paleas, sometimes adhering along the 

groove, sometimes adhering more broadly. x = 7. 

Festuca is a widespread genus, with about 610 species 

(Soreng et al., 2017b). The species grow in alpine, temperate, 

and polar regions on all continents except Antarctica. 

KEY TO SPECIES OF FESTUCA

1. Plants annual.

2. Lower glumes less than 1⁄2 the length of the upper glumes; spikelets 5–12 mm long, with 3–7 florets; rachilla internodes 

0.75–1(1.9) mm; lemma awns 5–15(22) mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F. myuros

2. Lower glumes 1⁄2 or more the length of the upper glumes; spikelets 4–10(13) mm long, with (4)5–11(17) florets; rachilla 

internodes 0.5–0.7 mm long; lemma awns 0.3–9 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F. octoflora

1. Plants perennial.

3. Leaf blades flat, occasionaly conduplicate, 5–15(18) mm wide; lemmas awned. 

4. Lemma awn 0.5–4 mm long; ligules 2.5–7 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F. lugens

4. Lemma awn 1–2 mm long; ligules 0.8–1.1(2) mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F. amplissima

3. Leaf blades 1–2.5(3) mm wide, permanently enrolled or involute, when flat no wider than 3 mm; lemmas unawned to 

short-awned.

5. Lemma apex bidentate, sometimes only emarginate, lemma awn 0.5–3(3.7) mm long, emerging between the teeth or 

emerging a little lower than the apex when emerginate; ligules 1.5–3.2(4.6) mm long . . . . . . . . . . . . . . F. tolucensis

5. Lemma apex entire, unawned or awned emerging in the apex; ligules 0.5 mm long.

6. Plants loosely caespitose, often with short rhizomes; culms decumbent, much branched near the base; sheaths margins closed up to halfway; lemmas awned, awns 2–3 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F. rubra

6. Plants densely caespitose, lacking rhizomes; culms erect, unbranched near the base; sheath margins closed up to 1⁄3

of the way from the base; lemmas unawned or apically mucronate, the mucro less than 1 mm long.

7. Anthers in the lowest floret usually abortive, anthers from the upper florets well-developed, 3–4.2 mm long 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F. diclina

7. Anthers in the lowest floret not abortive, all anthers approximately the same length, 1.6–6 mm long.

8. Leaf blades always folded (conduplicate or convolute), 0.5–1 mm wide, with 5–7(9) veins; panicle branches 

erect to spreading; apex of ovaries glabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F. rosei

8. Leaf blades flat to loosely folded, 2.5–3 mm wide, with 9–11 veins; panicles branches lax and loosely spreading, divaricate, basally naked and with the spikelets toward the apex; apex of ovaries pilose . . . . F. pringlei

162. Festuca amplissima Rupr. ex Fourn., Mex. Pl. 2: 125. 1881.

FIGURE 121

Perennial; strong. Culms 110–150 cm tall, erect, not 

branched, with the base hardened, nodes obscure. Leaves basal, 

numerous; sheaths fibrous, slightly scabrous, ligules 0.5–1.8 mm 

long, membranous, the basal very short; blades 20–50 cm long, 

7–8 mm wide, stiff and erect, scabrous, apex attenuate to involute. Panicle solitary, terminal, exserted to 40 cm long, narrowly 

elliptic; branches up to 5 per node, 10–12 cm long, ascending, 

naked several centimeters near the base, rachis, branches, and 

angular pedicels scabrous on the margins. Spikelets 8.5–10 mm 

long, laterally compressed, plicate along the branches, pedicels 

generally short; lower glumes 3–4.5 mm long, linear, 1-veined, 

upper glume 4.8–6 mm long, 3-veined, lanceolate; florets 3–5, 

often with a short terminal rudiment; lemmas 5.5–7 mm long, 

lanceolate, scabrous, 5-veined, keeled, unawned, acuminate, 

often purple over the back, bronzing near the apex; paleas almost as long as the lemmas, exserted abruptly to a point, scabrous between the keels; rachilla slender, scabrous; stamens 3, 

anthers 2.0–2.8 mm long, purple.

Distribution and Habitat. Festuca amplissima

is a rare species known only from clearings in forests with Pinus

and Quercus. It is reported from Mexico, Central America, and 

South America (Stančík and Peterson 2007).

Specimens Examined. MEXICO. Chihuahua.

Chihuahua: Canyons of the Sierra Madre, 16 Sep 1887, C.G. 

Pringle 1438 (MEXU) Isotype. Guachochi: Steep slopes above 

Barranca Basihuare, 28 Aug 2003, forest with oaks and pines, 

1815 m, P.M. Peterson & P. Catalán 17573 (US).
170 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

163. Festuca diclina Darbysh., Novon 5(2): 129, f. 1A–F, 2A–C. 

1995.

Perennial; delicate, densely caespitose, without rhizomes. 

Culms 30–90 cm long, erect, light green, with black or brown 

nodes, glabrous, not branched from base. Sheaths fibrous when 

mature, margins closed less than 1⁄3 from the base; ligules 0.2–

0.5 mm long, acute to truncate, sometimes lacerate, sparsely 

retrorse-scabrous; blades 1.2–1.5 mm wide (in the flat part), 

permanently inrolled or involute. Panicles 8–15 cm long, pyramidal, branches a little flexuous or sinuose-undulate, 1 or 2 per 

FIGURE 121. Festuca amplissima. A. Stylized growth form. B. Habit. C. Spikelet. D. Glumes. 

E. Lemma. F. Leaf blade cross-section. Drawn by Anna Skoumalová for Smithsonian Institution, 

Department of Botany.
NUMBER 107 • 171

node, glabrous to sparsely scabrous in the angles, the inferior 

5–9 cm long. Spikelets 8–12 mm long, in the distal part of the 

branches with (2)3–4(5) florets; glumes ovate-lanceolate, the 

margin hyaline and wide, glabrous to scabrous over the keels 

(apically), lower glumes 2.4–4 mm long, 1-veined, upper glumes 

3.5–5 mm long, (1)3-veined, rachilla with hairs of 0.1–0.3 mm; 

lemmas 6–8 mm long, narrowly lanceolate, glabrous or apically 

scabrous-hirsute, 1- to 3(5)-veined, apex entire, unawned or 

with a small mucro to 1 mm; paleas 5.5–7 mm long, 2-toothed, 

apically pilose-hirsute, hairs 0.1–0.2 mm long; anthers of the 

most inferior floret usually abortive, anthers of the upper florets 

3–4.2 mm long, well-developed. 

Distribution and Habitat. Festuca diclina is 

endemic to Chihuahua and is found on steep, rocky, volcanic 

slopes with Pinus, Quercus, Arctostaphylos, and Picea at 2,620–

3,300 m.

Specimens Examined. MEXICO. Chihuahua.

Guachochi: 61.3 km W of Balleza and 33.8 km E of Guachochi, 2620 m, 18 Sep 1991, P.M. Peterson, C.R. Annable & J. 

Valdés Reyna 10774 (US). Guadalupe y Calvo: Summit of Sierra 

Mohinora, 16 Oct 1959, Correll & Gentry 23178 (US); N side 

of Cerro Mohinora, ca. 13 mi SW of Guadalupe y Calvo, 20 

Aug 1988, Open pine–fir Woods with scattered spruce, 2950 m, 

G. Neson & A. Mc Donald 6473 (MEXU); Cerro Mohinora, 

rocks on the NW side of the hill top, 3 Nov 2007, Juniperus,

Type locality, 3290 m, D. Stancik & S. González 6188, 6189

(MEXU); Sierra Mohinora, 13 Sep 2006, bosque de pino [pine 

forest], 3076 m, P.M. Peterson, F. Sánchez Alvarado & E.P. 

Gómez Ruíz 20051 (CIIDIR).

163. Festuca lugens (E. Fourn.) Hitchc. ex Hern.-Xol., Bol. Soc. 

Bot. México 23: 165. 1958. Uniola lugens E. Fourn., Mexic. 

Pl. 2: 123. 1886.

Festuca mirabilis Piper.

Perennial; densely tufted with extravaginal innovations 

and rhizomes not elongated. Culms 100–200 cm tall, glabrous. 

Sheaths scabrous, straw color, not fibrous, margins free, auricles absent; ligule 2.5–7 mm long, ciliolate; blades 50–80 cm 

long, 3–6 mm wide, flat or folded, scabrous. Panicles 20–30 cm 

long, 5–10 cm wide, spread, lax; axis basally glabrous, apically 

scabrous, inferior branches 8–18 cm long, generally paired, 

widely spreading, naked in the inferior 1⁄2; pedicels scabrous. 

Spikelets 15–20 mm long, with 5–7 florets; lower glumes 

5.5–8 mm long, subulate, 1-veined, upper glumes 8–10 mm 

long; lemmas 12–15 mm long, scabrous, 2-toothed, with awns 

1–4 mm long, scabrous; anthers 3.8–5.5 mm long; ovary glabrous. 2n = 28.

Distribution and Habitat. Festuca lugens

grows in open areas of Pinus–Quercus forests. It is a Mexican 

species known from Chiapas, Chihuahua, Guanajuato, Hidalgo, 

Jalisco, México, Morelos, Nayarit, Oaxaca, Puebla, Querétaro, 

San Luis Potosí, Tamaulipas, Tlaxcala, and Veracruz.

Specimens Examined. MEXICO. Chihuahua. 

Carichi: Sánchez, 12 Oct 1910, Hitchcock 7683 (US).

164. Festuca myuros* L., Sp. Pl. 1: 74–75. 1753. Vulpia myuros

(L.) C. C. Gmel., Fl. Bad. 1: 8. 1805.

Annual. Culms 10–75(90) cm tall, solitary or loosely tufted, 

branched or unbranched distally. Sheaths usually glabrous; ligules 0.3–0.5 mm long; blades 2.4–10.5(17) cm long, 0.4–3 mm 

wide, usually rolled, occasionally flat, usually glabrous. Inflorescences 3–25 cm long, 0.5–1.5(2) cm wide, dense panicles 

or spikelike racemes, with 1 branch per node, often partially 

enclosed in the uppermost sheaths at maturity, pulvini absent; 

branches spreading or appressed to erect. Spikelets 5–12 mm 

long with 3–7 florets; rachilla internodes 0.75–1(1.9) mm long; 

glumes glabrous; lower glumes 0.5–2 mm long, 1⁄5–1⁄2 the length 

of the upper glumes; upper glumes 2.5–5.5 mm long; lemmas 

4.5–7 mm long, 5-veined, usually scabrous distally, glabrous except the margins sometimes ciliate, apex entire, awned, the awns 

5–15(22) mm long; paleas 4.7–6.4 mm long, minutely bifid; anthers 0.5–1(2) mm long. Caryopsis 3–5 mm long, fusiform, glabrous. 2n = 14, 42.

Distribution and Habitat. Festuca myuros

grows in well-drained, sandy soils and disturbed sites. It is native 

to Europe and North Africa and once thought to be native to 

North America.

Specimens Examined. MEXICO. Chihuahua. 

Práxedis G. Guerrero: Sierra San Ignacio, 7.5 km al W de Col. 

Esperanza, 18 Mar 1995, en lecho [bed] de arroyo, 1190 m, 

R. Corral, P. Olivas & E. Pérez RCD6042 (UACJ).

165. Festuca octoflora Walter, Fl. Carol. 81. 1788. Vulpia octoflora (Walter) Rydb., Bull. Torrey Bot. Club 36: 538. 1909.

FIGURE 122

Annual. Culms 5–60 cm tall, solitary or loosely tufted, 

glabrous or pubescent. Sheaths glabrous or pubescent; ligules

0.3–1 mm long; blades to 10 cm long, 0.5–1 mm wide, flat or 

rolled, glabrous or pubescent. Panicles 1–7(20) cm long, 0.5–

1.5 cm wide, with 1–2 branches per node; branches appressed 

to spreading. Spikelets 4–10(13) mm long, with (4)5–11(17) florets; rachilla internodes 0.5–0.7 mm long; lower glumes 1.7–4.5 

mm long, 1⁄2–2⁄3 the length of the upper glumes; upper glumes

2.5–7.2 mm long; lemmas 2.7–6.5 mm long, 5-veined, smooth, 

scabrous, or pubescent, apex entire, no more pubescent than the 

bases, awns of the lowermost lemma in each spikelet 0.3–9 mm 

long; paleas slightly shorter than the lemmas, apex entire or minutely bifid, teeth shorter than 0.2 mm long; anthers 0.3–1.5 mm 

long. Caryopsis 1.7–3.7 mm long. 2n = 14.

Distribution and Habitat. Festuca octoflora is 

a widespread native species growing in grasslands, sagebrush, 

and open woodlands, as well as in disturbed habitats and areas of 

secondary succession, such as old fields, roadsides, and ditches. 

It is known from United States to Mexico in Baja California, 

Baja California Sur, and Chihuahua.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: Cerca del Río Chih., 7 Abr [Apr] 1886, C.G. Pringle s/n (MEXU). Janos: Ca. 8.2 km (by road), Sierra de Cal (La 
172 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Biznaga), 25 Mar 2007, Chihuahuan desert scrub, A.L. Reina & 

T.R. Van Devender 2007-307 (ARIZ).

166. Festuca pringlei St.-Yves, Candollea 2: 305. 1925.

Perennial; caespitose, not rhizomatous. Culms to 1.5 m tall, 

glabrous, erect, unbranched from the base. Leaves of 2 forms, 

the basal convolute, filiform, the cauline flat and involute toward the apex; basal sheaths fibrous, disintegrated at maturity, 

sheaths margin closed less than 1⁄3 from the base, lacking auricles; 

ligules 0.5 mm long, membranous and pilose; blades 20–30 cm 

long, 2.5–3 mm wide, flat to loosely folded with 9–11 veins. 

Panicles 15–22 cm long, lax and loosely spreading, divaricate, 

basally naked and with the spikelets toward the apex. Spikelets 10–15 mm long, with 4–5 flattened florets, widely spaced; 

glumes glabrous and apiculate; lower glumes 4–4.5 mm long; 

upper glumes 5–6.5 mm long, wider; lemma 6.5–8 mm long, 

smooth on the back, apex entire, unawned or with an apical 

mucro, less than 1 mm; palea equal or less than lemma; anthers 

1.6–6 mm long from the inferior florets, not abortive, all about 

equal; ovaries pilose toward the apex. 

Distribution and Habitat. Festuca pringlei is 

an uncommon species that grows in pinyon forests; it is a Mexican species known from Aguascalientes, Chihuahua, Durango, 

and Jalisco.

Specimens Examined. MEXICO. Chihuahua.

Guadalupe y Calvo: Mt. Mohinora, SW Chihuahua, 2820 m, 

1 Sep 1898, E.W. Nelson 4900 (US); near Cumbre Mohinora, 13 

Sep 2006, 3300 m, P.M. Peterson, F. Sánchez Alvarado & E.P. 

Gómez Ruíz 20046 (CIIDIR, US).

167. Festuca rosei Piper, Contr. U.S. Natl. Herb. 10: 45. 1906.

Perennial; caespitose, not rhizomatous. Culms 70–150 cm 

tall, glabrous, the culms several or many together. Sheaths persistent with shredded bases below; ligules 0.3–0.6 mm long, 

ciliolate; blades (10)20–40 cm long, 0.5–1 mm wide, filiform, 

tightly involute, terete or angled, margins scabrous with 5–7(9) 

prominent veins on the upper surface. Panicles 15–30 cm long, 

2–5 cm wide with erect to spreading branches 3–5(10) cm long 

inserted solitary at a node. Spikelets (7)9–12 mm long, 3- to 

6-flowered; glumes 3–7 mm long; lower glumes 3–4.5(5.5) mm 

long, 1-veined, subulate; upper glumes 4–7 mm long, 3-veined, 

wider than lower; lemmas (5.7)6–7 mm long, subulate, glabrous, 

margins involute, apex scabrous sometimes mucronate; paleas 

a little shorter or longer than the lemma, apex bifid; anthers 

(2.7)3–4 mm long, yellow; apex of ovaries glabrous. 

Distribution and Habitat. Festuca rosei occurs on steep, rocky, volcanic slopes with Pinus, Quercus, 

and Arctostaphylos at 2,500–3,100 m. This is the first report 

of F. rosei from Chihuahua, a species known from throughout 

western Mexico to Guatemala.

Specimens Examined. MEXICO. Chihuahua. 

Guachochi: 61.3 km W of Balleza and 33.8 km E of Guachochi, 

2620 m, P.M. Peterson, Annable & Valdés-Reyna 10775 (US). 

FIGURE 122. Festuca octoflora. A. Habit. B. Spikelet. C. Floret. 

Drawn by Linda Ann Vorobik and Hana Pazdírková; copyright 

Utah State University.
NUMBER 107 • 173

168. Festuca rubra L., Sp. Pl. 1: 74. 1753.

FIGURE 123

Perennial; usually rhizomatous and loosely to densely caespitose, culms sometimes single and widely spaced, sometimes stoloniferous. Culms (8)10–120 (130) cm tall, erect or decumbent, 

glabrous and smooth. Sheaths closed for about 3⁄4 their length 

when young, readily splitting with age, usually pubescent, at 

least distally, hairs retrorse or antrorse, sometimes glabrous, not 

persistent, older vegetative shoot sheaths shredding into fibers; 

collars glabrous; ligules 0.1–0.5 mm long; blades usually conduplicate or convolute and 0.3–2.5 mm in diameter, sometimes 

flat and 1.5–7 mm wide, abaxial surfaces glabrous, smooth or 

scabrous, adaxial surfaces scabrous or pubescent, veins 5–9(13), 

ribs (3)5–7(9), usually conspicuous. Panicles (2)3.5–25(30) cm 

long, usually open or loosely contracted panicles, occasionally 

racemes, with 1–3 branches per node, lower branches with 2 or 

more spikelets; branches erect or spreading, stiff or lax, glabrous, 

scabrous, or pubescent. Spikelets (6)7–17 mm long, with 3–10 

florets; glumes ovate-lanceolate to lanceolate, exceeded by the 

distal florets; lower glumes (1.5)2–6(7) mm long; upper glumes

(3)3.5–8.5 mm long; lemmas 4–9.5 mm long, usually glabrous 

and smooth, sometimes scabrous toward the apex, sometimes 

densely pubescent throughout, attenuate or acuminate in side 

view, awned, awns (0.1)0.4–4.5 mm long; paleas slightly shorter 

than to about equaling the lemmas, intercostal region puberulent 

distally; anthers 1.8–4.5 mm long; ovary apex glabrous. 2n = 28, 

42, 56, 70.

Distribution and Habitat. Festuca rubra is interpreted here as a morphologically diverse polyploid complex 

that is widely distributed in the arctic and temperate zones of 

Europe, Asia, and North America to Mexico, where it is known 

from Chihuahua, Coahuila, Distrito Federal, Durango, México, 

Nuevo León, Puebla, Querétaro, Tamaulipas, and Veracruz. 

Specimens Examined. MEXICO. Chihuahua. 

Madera: Sierra Madre near Col. Garcia, 5 Jul 1899, bosque de 

encino [oak forest], 2300 m, C.H.T. Townsend & F.L. Scribner 

s.n. (NMC, US). Ocampo: Parque Nacional Cascada de Basaseachic, within barranca [canyon], 25 Jun 1991, 2000 m, M. Mahrt 

& Spellenberg 124 (NMC); Parque Nacional Cascada de Basaseachic, ca. 130 air km W of Cuauhtemoc, along river at base of 

falls, 25 Abr [Apr] 1987, 1600 m, Spellenberg, Muldavin & Corral 9057 (NMC); Parque Nacional Cascada de Basaseachic, at 

base falls, 26 Abr 1985, 1570 m, Spellenberg, R Soreng & R. Corral 8020 (MEXU, NMC); Parque Nacional Cascada de Basaseachic, ca. 130 air km W of Cuauhtemoc, 25 Jun 1991, 1600 m, 

Spellenberg & P. Martin 10793 (NMC); Parque Nacional Cascada 

de Basaseachic, 26 Abr 1985, 1570 m, R. Spellemberg, Soreng, 

R. Corral, J. Cornelius, C. Spurrier & T. Todsen 8020 (MEXU).

169. Festuca tolucensis Kunth, Nov. Gen. Sp. (quarto ed.) 1: 

153. 1815.

FIGURE 124

Perennial; caespitose, forming dense tufts. Culms 60–100 

cm tall, erect, not branched, nodes obscure, contracted, internodes glabrous, leaves mainly basal; sheaths glabrous, rugosegranular; ligule 1.5–3.2(4.6) mm long, slender, membranous, 

blades 18–25 cm long, 1–2.5 mm wide, scabrous, permanently 

inrolled or involute, if flat no more than 3 mm wide, scaberulous, superior portion of culms almost leafless. Inflorescence solitary, terminal, exserted to 30 cm long, panicles 11–20 cm long, 

spread but narrow, sparsely floreted, branches in pairs or solitary. Spikeletrs 9–14 cm long, usually purple, florets 6–8; lower 

glumes 4.5–6.3 mm long, narrowly triangular, 1-veined, upper 

glumes 6–7.4 mm long, ovate, acute, 3-veined; lemma 6–8 mm 

long, narrowly ovate, lemma apex 2-toothed, sometimes only 

emarginate, lemma awn 0.5–3(3.7) mm long, arising between the 

tooth or a lttle below the apex when emarginate, scaberulous; 

palea slightly shorter, 2-toothed in the apex; stamens 3, anthers 

2.8–3.4 mm long, yellow.

Distribution and Habitat. Festuca tolucensis

is known from Mexico, Central America, and South America

Specimens Examined. MEXICO. Chihuahua.

Guachochi: 8 km al W de Cabórachi, 12 Aug 1982, bosque de 

FIGURE 123. Festuca rubra. A. Ligule. B. Inflorescence. C. Spikelet. 

Drawn by Cindy Roché; copyright Utah State University.
174 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

FIGURE 124. Festuca tolucensis. A. Stylized growth form. B. Habit. C. Ligule. D. Spikelet. E. Glumes. F. Lemma. 

G. Lemma with palea and rachilla. H. Leaf blade cross-section. Drawn by Anna Skoumalová for Smithsonian 

Institution, Department of Botany.
NUMBER 107 • 175

pino–encino [pine–oak forest], 2100 m, R. Hernández 8752

(CIIDIR, MEXU). Mpio.?: NW of Fraile, 29 Dec 1940, L.R. 

Stanford, K. Retherford & R. Nortcraft 405 (US).

Glyceria R. Br.

Plants usually perennial, rarely annual; rhizomatous. Culms

erect or decumbent, freely rooting at the lower nodes, not cormous based. Sheaths closed for at least 3⁄4 their length, often almost entirely closed; ligules scarious, erose to lacerate; blades flat 

or folded. Inflorescences terminal, usually panicles, sometimes 

racemes in depauperate specimens, branches appressed to divergent or reflexed. Spikelets cylindrical and terete or oval and 

laterally compressed, with 2–16 florets, terminal floret in each 

spikelet sterile, reduced; disarticulation above the glumes, below 

the florets. Glumes less than to equaling the adjacent lemmas, 

1-veined, obtuse or acute, often erose; lower glumes 0.3–4.5 mm 

long; upper glumes 0.6–7 mm long; calluses glabrous; lemmas membranous to thinly coriaceous, rounded over the back, 

smooth or scabrous, glabrous or hairy, hairs to about 0.1 mm 

long, 5- to 11-veined, veins usually evident, often prominent and 

ridged, not or sparsely converging distally, apical margins hyaline, sometimes with a purplish band below the hyaline portion, 

apex acute to rounded or truncate, entire, erose, or irregularly 

lobed, unawned; paleas from shorter than to longer than the 

lemmas, keeled, keels sometimes winged; lodicules thick, sometimes connate, not winged; anthers (1)2–3; ovaries glabrous; 

styles 2-branched, branches divergent to recurved, plumose distally. x = 10.

Glyceria includes approximately 48 species, all of which 

grow in wet areas. All but five species are native to the Northern 

Hemisphere. 

KEY TO SPECIES OF GLYCERIA

1. Florets 6–12; lower glumes 1–2 mm long, upper glumes 2–2.5(3) mm long; lemma of inferior floret 3–4 mm long; panicle 

narrow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G. borealis

1. Florets 3–7; lower glumes 0.5–1 mm long, upper glumes 1–1.5 mm long, lemma of inferior floret 2–2.5 mm long; panicle 

ovoid, spreading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G. striata

170. Glyceria borealis (Nash) Batch., Proc. Manchester Inst. 

Arts Sci. 1: 74. 1900.

FIGURE 125

Perennial. Culms 60–100 cm tall, 1.5–5 mm thick, often 

decumbent and rooting at the lower nodes. Sheaths glabrous, 

keeled; ligules 4–12 mm long; blades 9–25 cm long, 2–7 mm 

wide, often floating, abaxial surfaces smooth, adaxial surfaces of 

the midcauline leaves densely papillose, glabrous. Panicles 18–

40(50) cm long, 0.5–2(5) cm wide, arching, usually narrow, open 

at anthesis, bases often enclosed in the upper leaf sheath at maturity; branches 5–10(15) cm long, usually 1–3(5) per node, usually 

appressed to strongly ascending, occasionally spreading, longer 

branches with 3–6 spikelets; pedicels 1.2–5 mm long. Spikelets

9–22 mm long, 0.8–2.5 mm wide, cylindrical and terete, except 

at anthesis when slightly laterally compressed, rectangular in side 

view, with 8–12 florets; glumes elliptic, apex rounded to obtuse, 

sometimes erose; lower glumes 1.2–2.2 mm long; upper glumes

2–3.8 mm long, rounded; rachilla internodes 0.6–3.5 mm long; 

lemmas 2.7–5.4 mm long, veins raised, scaberulous or smooth, 

intercostal regions usually smooth, sometimes scaberulous, midvein terminating about (0.1)0.2 mm short of the apical margin, 

apex usually acute, sometimes obtuse, usually entire; paleas usually shorter than or equaling the lemmas, sometimes exceeding 

them by up to 0.5 mm long, keels narrowly winged, apex bifid, 

teeth to 0.2 mm long, parallel to weakly incurved; stamens 3, 

anthers 0.4–1.5 mm long. Caryopsis 1.2–2 mm long. 2n = 20.

Distribution and Habitat. Glyceria borealis is 

a widespread native species that grows in the North America 

through the western mountains of the United States to Chihuahua, Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Madera: Lake near Chuichupa, 22 Aug 1937, LeSueur 0203 (US).

171. Glyceria striata (Lam.) Hitchc., Proc. Biol. Soc., Washington 41: 157. 1928.

FIGURE 126

Perennial. Culms 20–80 (100) cm tall, (1.5)2–3.5 mm 

thick, not or only slightly spongy, sometimes rooting at the 

lower nodes. Sheaths smooth to scaberulous, keeled, sometimes weakly so; ligules 1–4 mm long, usually rounded, sometimes acute to mucronate, erose-lacerate; blades 12–30 cm long, 

2–6 mm wide, smooth or scaberulous. Panicles 6–25 cm long, 

2.5–21 cm wide, pyramidal, open, nodding; branches 5–13 cm 

long, straight to lax, with 15–50 spikelets, these often confined 

to the distal 2⁄3; pedicels 0.5–7 mm long. Spikelets 1.8–4 mm 

long, 1.2–2.9 mm wide, laterally compressed, oval in side view, 

with 3–7 florets; glumes ovate, 1–1.5 times longer than wide, 

narrowing from midlength or above, veins terminating below 

the apical margins, apex often splitting with age; lower glumes

0.5–1.2 mm long, rounded to obtuse; upper glumes 0.6–1.2 mm 

long, acute or rounded; rachilla internodes 0.1–0.6 mm long; 

lemmas 1.2–2 mm long, ovate in dorsal view, veins raised, scaberulous over and between the veins, apex acute, prow-shaped; 

paleas slightly shorter than to equaling the lemma in length, 

1.5–3 times wider than the glumes, keeled, keels not winged, 

tips pointing toward each other, apex narrowly notched between 
176 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

the keels; stamens 2, anthers (0.2)0.4–0.6 mm long, purple or 

yellow. Caryopsis 0.5–2 mm long. 2n = 20 (reports of 28 are 

questionable).

Distribution and Habitat. Glyceria striata

grows in bogs, along lakes and streams, and in other wet places. 

It range extends from Canada and the United States to Mexico. 

There are two varieties; Glyceria striata var. striata is found in 

Chihuahua. 

Specimens Examined. MEXICO. Chihuahua. 

Madera: Sierra Madre near Col. Garcia, 6 Jul 1899, C.H.T. 

Townsend & C.M. Barber 112 (NMC, US).

Hackelochloa Kuntze

Perennial; caespitose. Culms solid, very branched. Sheaths 

carinate; ligules a ciliate membrane; blades widely linear, flat. 

Inflorescence a solitary raceme, racemes terminal and axillary, 

exserted, aggregated into a spathate false panicle; rachis articulate, flattened, glabrous, spikelets in pairs, the 2 spikelets and 

the internodes of rachis falling as a unit. Spikelets dimorphic, 

unawned, sessile and pedicelate. Sessile spikelets globose, rigid, 

with 2 florets; callus truncate, with a short cylindrical projection; lower glumes very inflated, the superior portion rounded, 

blackish, 13- to 15-veined, the surface covered with squares 

sculpted in transverse rows or punctuate on rows between the 

veins; upper glumes appressed to the internodes of rachis, oblong, 3-veined, obtuse, slightly carinate, chartaceous; inferior 

florets sterile; inferior lemma hyaline, inferior palea missing; 

superior florets bisexual, staminate, or sterile, superior lemma 

and palea hyaline, veinless, entire; stamens 3. Pedicelate spikelets 

herbaceous, sterile, rarely staminate; pedicel adnate to the rachis 

internodes; lower glumes ovate, acute, green, 7- to 9-veined, enclosing the margins of upper glumes by 2 borders; rudimentary 

florets missing or when present the inferior rudiment sterile, the 

superior floret staminate. 

Hackelochloa includes two species from the tropics of Asia 

and a single species naturalized in Mexico (Clayton et al., 2006).

172. Hackelochloa granularis* (L.) Kuntze, Revis. Gen. Pl. 2: 

776. 189. Cenchrus granularis L., Mant. Pl. 2: 575. 1771. 

Mnesithea granularis (L.) de Koning & Sosef., Blumea 

31(2): 295. 1986.

FIGURE 127

Perennial. Culms 10–120 cm tall. Sheaths inflated, hispid with 

tubercle-based hairs; ligules 0.8–1.5 mm long; blades 2–20 cm 

long, 4–15 mm wide, hispid with tubercle-based hairs. Racemes 

7–15 mm long. Sessile spikelets 1–1.7 mm long; lower glumes 

1.3–1.7 mm long, with the surface covered with squares sculpted 

in transverse rows; upper glumes 0.8–1 mm long; superior lemma 

and palea 0.8–1 mm long; anthers 0.2–0.4 mm long; pedicelate 

spikelets 1–1.9 mm long; anthers 0.3–0.5 mm long. 2n = 14.

Distribution and Habitat. Hackelochla granularis occurs in grasslands, thorn scrub, and tropical forests at 

FIGURE 125. Glyceria borealis. A. Upper leaf surface. B. Papillose 

hairs, magnified. C. Inflorescence. D. Spikelet. E. Glumes. F. Floret, 

side view. G. Floret, dorsal view. H. Floret, ventral view showing 

palea and rachilla. Drawn by Cindy Roché; copyright Utah State 

University.
NUMBER 107 • 177

FIGURE 126. Glyceria striata. A. Habit. B. Culm and inflorescence. C. Spikelet. D. Glumes. 

E. Floret. F. Floret, dorsal view. G. Floret, ventral view. Drawn by Cindy Roché; copyright 

Utah State University.
178 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

1,100–1,980 m. It is native to the Eastern Hemisphere, introduced in the Americas.

Specimens Examined. MEXICO. Chihuahua. 

Near hwy, 20 km N of Chihuahua City, 9 Oct 1941, R. Stewart & I.M. Johnson 2128 (US); N Chihuahua, 18 Sep 1886, 

C.G. Pringle 1057 (US). Balleza: 10 mi SW of El Ojito, 12 Sep 

2006, 1902 m, P.M. Peterson 20021, F. Sánchez Alvarado & 

E.P. Gómez Ruíz (CIIDIR, US). Cuauhtemoc: 11 mi E of Cuauhtémoc, 14 Sep 1960, Reeder, C. Reeder & Soderstrom 3465

(US). Guachochi: 39.2 km S of Creel on road to Batopilas at the 

Barranca El Cobre, 10 Sep 1989, 1930 m, P.M. Peterson, Annable & Y. Herrera 8022 (US). Ocampo: Cascada Basaseachic, 

on N side of barranca, 12 Sep 1987, 1800 m, J.T. Columbus, 

R.S. Spellenberg & D. Jewell 1783 (NMC); Ca 1 km W of W 

boundary of Parque Nacional “Cascada de Basaseachic,” 18 km 

from the Cahuisori–Ocampo road on the road to Candamena, 

7.5 km below Cruz, 24 Sep 1994, 1260 m, Spellenberg, Corral 

& Estrada 12187-B (NMC).

Hesperostipa (M. K. Elias) Barkworth

Perennial; caespitose, not rhizomatous. Culms erect, not 

branching at the upper nodes; prophylls shorter than the sheaths. 

Leaves not overwintering, not basally concentrated; cleistogenes 

not developed; sheaths smooth, auricles absent; ligules membranous, frequently ciliate; blades usually tightly involute, adaxial 

surfaces conspicuously ridged, apex narrowly acute, not sharp. 

Inflorescences terminal panicles, contracted or open. Spikelets 

with 1 floret; rachillas not prolonged beyond the base of the 

floret, disarticulation above the glumes and beneath the floret. 

Glumes tapering from near the base to a hairlike tip; florets narrowly cylindrical; calluses 2–6 mm long, sharp, densely strigose 

distally; lemmas indurate, smooth, margins flat, slightly overlapping at maturity, the upper portion fused into a papillose, ciliate 

crown, awned, lemma–awn junction distinct, awns persistent, 

twice-geniculate, often weakly so, lower segments twisted and 

scabrous to pilose, terminal segment not twisted, usually scaberulous or pilose; paleas equal to the lemmas, flat, pubescent, coriaceous, 2-veined, veins terminating at the apex, apex indurate, 

prow-tipped; anthers 3. Caryopsis fusiform, not ribbed. x = 11.

Hesperostipa is a North American endemic genus that resembles the Eurasian Stipa sensu stricto (s.s.) in overall morphology but is probably more closely related to the primarily 

South American genera Piptochaetium, Anatherostipa (Hack. 

FIGURE 127. Hackelochloa granularis. A. Habit. B. Culm and Inflorescence. C. Inflorescence. D. Spikelet pair. E. Spikelet pair, rotated 180°. 

Drawn by Linda Ann Vorobik and Cindy Roché; copyright Utah State 

University.
NUMBER 107 • 179

ex Kuntze) Peñail., Aciachne Benth., and Lorenzochloa Reeder 

& C. Reeder (Romaschenko et al., 2012). Hesperostipa differs 

from Stipa s.s. in having indurate palea apex and an unordered 

saw-like lemma epidermal pattern (Romaschenko et al., 2012).

173. Hesperostipa neomexicana (Thurb.) Barkworth, Phytologia 74(1): 16. 1993. Stipa pennata var. neomexicana

Thurb., Man. Bot. Rocky Mt. 408. 1885. Stipa neomexicana (Thurb.) Barkworth, Phytologia 74(1): 16. 1993.

FIGURE 128

Culms 40–100 cm tall; lower nodes glabrous. Lower sheaths 

glabrous or puberulent, not ciliate; ligules of lower leaves 0.5–1 

mm long, thickly membranous, rounded; ligules of upper leaves 

to 3 mm long, scarious, acute; blades 0.5–1 mm wide. Panicles 

10–30 cm long; glumes 30–60 mm long, subequal; florets 15–18 

mm long; calluses 4–5 mm long; lemmas evenly pubescent, hairs 

shorter than 1 mm long; awns 12–22 cm long, first 2 segments 

hairy, hairs mostly 0.2–1 mm long, terminal segment flexible, 

pilose, the hairs 1–3 mm long. 2n = 44.

Distribution and Habitat. Hesperostipa neomexicana grows in grassland, oak, and pinyon pine associations, 

usually in well-drained, rocky areas in the southwestern United 

States and adjacent Mexico; at 800 to 2,400 m.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: Sierra San Martin de Borracho, Rancho Carrizozo 

on the north side, 15 Jun 1973, Izotal on midslopes, chaparral on top, 1500–2195 m, M.C. Johnston & F. Chiang 11341 

(MEXU).

Heteropogon Pers.

Annual or perennial; caespitose. Culms simple or branched. 

Leaves sometimes aromatic and smelling of lemon oil or citronella; 

sheaths keeled, sometimes with a row of glandular depressions on 

the keel; ligules membranous, glabrous or ciliate. Inflorescences 

terminal and axillary; peduncles usually with 1 rame, sometimes 

with several in a digitate cluster; rames with 3–10 homogamous, 

unawned, sessile-pedicellate spikelet pairs on the lower 1⁄4–2⁄3 and 

heterogamous, awned, sessile-pedicellate spikelet pairs distally, 

axes slender, without a translucent median groove; disarticulation 

in the rames, beneath the sessile spikelets of the heterogamous 

spikelet pairs, sometimes also below their pedicellate spikelets. Homogamous spikelet units sterile or staminate; calluses poorly developed; glumes membranous, many-veined, keels winged above. 

Heterogamous spikelet units: sessile spikelets bisexual, terete; 

FIGURE 128. Hesperostipa neomexicana. A. Ligule. B. Glumes. C. Floret. D. Floret, magnified. Drawn 

by Cindy Roché and Annaliese Miller; copyright Utah State University.
180 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

calluses sharp, antrorsely strigose, hairs golden brown; glumes coriaceous, pubescent, concealing the florets; lower glumes enclosing 

the upper glumes, obscurely 5- to 9-veined; upper glumes sulcate, 

3-veined; lower florets sterile, reduced to a hyaline lemma; upper 

florets bisexual, lemmas with conspicuous, geniculate awns; awns 

with hairs. Caryopsis lanceolate, sulcate on 1 side. Pedicels short, 

free of the rame axes, not grooved; pedicellate spikelets sterile or 

staminate, larger than the sessile spikelets; calluses long, glabrous, 

functioning as pedicels; glumes membranous, many-veined, keels 

winged above. x = 10, 11. 

Heteropogon is a pantropical genus of five species (Clayton 

et al., 2006). Probably both species that occur in the Western 

Hemisphere and here in Chihuahua are introduced (Barkworth, 

2003a).

KEY TO SPECIES OF HETEROPOGON

1. Sesile and pedicelate spikelets 8–10 mm long, with stiff pubescence; glumes of the pedicellate spikelets lacking a row of 

glandular pits along the midvein; perennial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H. contortus

1. Sesile and pedicelate spikelets 15–20 mm long, glabrous; glumes of the pedicellate spikelets with a row of glandular pits 

along the midvein; annual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H. melanocarpus

174. Heteropogon contortus* (L.) P. Beauv. ex Roem. & Schult., 

Syst. Veg. 2: 836. 1817. Andropogon contortus L., Sp. Pl. 

2: 1045. 1753.

FIGURE 129

Perennial. Culms 20–150 cm tall, erect. Sheaths smooth, 

reddish; ligules 0.5–0.8 mm long, cilia 0.2–0.5 mm long; blades 

10–15 cm long, 2–7 mm wide, flat or folded, glabrous or pubescent. Rames 3–7 cm long, secund, with 12–22 sessile-pedicellate 

spikelet pairs, brown to reddish-brown. Homogamous spikelets 

6–10 mm long. Heterogamous spikelets: sessile spikelets 5–10 

mm long, brown, awned; calluses 1.8–2 mm long, strigose; awns 

6–10 cm long; pedicellate spikelets 6–10 mm long, unawned; 

glumes ovate-lanceolate, glabrous or with papillose-based hairs 

distally, without glandular pits, greenish to purplish-brown, becoming stramineous when dry. 2n = 40, 50, 60.

Distribution and Habitat. Heteropogon 

contortus grows on rocky hills and canyons in the southern 

United States, occupying a variety of different habitats, including disturbed sites. It is found in tropical and subtropical areas 

throughout the world.

Specimens Examined. MEXICO. Chihuahua. 

Aldama: 13.3 (rd) mi NE of Aldama along Chihuahua Hwy 

16, 14 Sep 1972, 1400 m, J. Henrickson 7532 (NMC). Balleza: 

16.1 km W of Balleza and 77.9 km E of Guachochi, 18 Sep 1991, 

bosque de encino [oak forest], 1990 m, P.M. Peterson, Annable 

& Valdés-Reyna 10743 (CIIDIR). Batopilas: SW Chihuahua, 

Aug 1885, E. Palmer 115B (US); 14.5 km N of Batopilas on 

road to La Bufa, 12 Sep 1989, 850 m, P.M. Peterson, Annable 

& Y. Herrera 8063 (ENCB, US). Buenaventura: 10 km al sur 

[S] de San Buenaventura, 23 Oct 73, Matorral [scrub], 1400 m, 

Valdés-Reyna VR-734 (RELC). Chihuahua: Chihuahua, 14 Oct 

1910, Hitchcock 7800 (US); Guazaremos, Río Mayo, 28 Sep 

1936, Gentry 2890 (US). near Chihuahua, 6 Sep 1885, C.G. 

Pringle 480 (US); Rancho Experimental La Campana, 16 Oct 

1980, pastizal [pastureland], 1500 m, A. Melgoza 634 (CIIDIR); 

Cerro Grande, 4 km al SO [SW] de Cd. Chihuahua, 11 Aug 

1996, 1650 m, E. Estrada & C. Yen 4956 (NMC); 87 km N 

Chihuahua, 1 km S Arco Iris on Hwy 45, 5 Oct 1986, 1500 m, 

FIGURE 129. Heteropogon contortus. A. Habit. B. Culms with 

Inflorescences. C. Inflorescence. D. Lower glume of the pedicellate 

spikelet. E. Sessile spikelet. Drawn by Linda Ann Vorobik and Hana 

Pazdírková; copyright Utah State University.
NUMBER 107 • 181

Spellenberg, Soreng & R. Corral 8905 (NMC); La Campana, 

Potrero La Sierra, 3 km Pte. carr. [hwy] Panamericana, 7 Sep 

73, pastizal con encino, 1600 m, Valdés-Reyna VR-133 (RELC). 

Guachochi: W of Munérachi, 7 Sep 2003, bosque tropical, 1200 

m, P.M. Peterson & P. Catalán 17716 (US). Janos: Chihuahua–

Sonora border, Rancho Carretas, 27 Aug 1939, 1460 m, L. H. 

Harvey 1618 (US). Jiménez 10 km SW of Cd. Jiménez, 30 Jul 

1939, L. H. Harvey 1340 (US). Madera: Paraje Sirupa, ejido 

Cebollitas, 16 Oct 1990, bosque de encino, 1200 m, O. Bravo 

1924 (CIIDIR); Paraje Agua Caliente, predio particular [private 

property] El Chorrito, 17 Oct 1990, bosque de encino, 1500 m, 

A. Benitez 2009 (CIIDIR). Manuel Benavides: km 1773 carr. a 

Cd. Juárez, 15 Sep 55, Hern.-Xol & V. Mathus N-1806 (US); 

entre [between] Manuel Benavides & Pocitos, 2 Aug 76, pastizal, 1342 m, S. González & J.M. Peña 453 (RELC). Matamoros: 19.3 km S of Villa Matamoros on hwy 45 to Durango, 27 

Sep 1988, grassland, 1800 m, P.M. Peterson & Annable 5980

(ENCB, US); P.M. Peterson & R.M. King 8260 (US). Riva Palacio: Nuevo Majalca, approx. 14.5 km W of Hwy 45, N of 

Chihuahua, 22 Sep 1988, 1700 m, P.M. Peterson & Annable 

5766 (US).

175. Heteropogon melanocarpus* (Elliott) Benth., J. Linn. Soc., 

Bot. 19(115–116): 71. 1881. Andropogon melanocarpus Elliott, Sketch Bot. S. Carolina 1: 146. 1816.

Annual. Culms 50–200 tall, often with prop roots, freely 

branching above the base. Sheaths glabrous, with a row of glandular depressions along the keel; ligules 2–4 mm long, erose to 

lacerate, glabrous; blades 30–50 cm long, 3–12 mm wide, usually folded, abaxial surfaces with dark glandular depressions 

along the keel, adaxial surfaces with scattered papillose-based 

hairs near the base, scabrous elsewhere. Rames 2.5–6.5 cm long. 

Homogamous spikelets 10–14 mm long, green; lower glumes 

glabrous, unawned. Heterogamous spikelets: sessile spikelets 

8–11.5 mm long, dark brown, awned; calluses about 3 mm long, 

the awns 10–15 cm long; pedicellate spikelets 16–21 mm long, 

unawned; lower glumes scabrous or sparsely ciliate distally, midveins glandular, pitted. 2n = 20.

Distribution and Habitat. Heteropogon 

melanocarpus is found in tropical regions throughout the world.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: Puente Río Batopilas hacia [toward] la Hierbabuena, 

24 Mar 2003, 1942 m, Tenorio, R. Alvarado & M. Hilerio

22848 (US). Chihuahua: Mapula Mts., Oct 1886, C.G. Pringle 

8201 (US). Guachochi: Parque Nacional Barranca del Cobre, 

3.8 km NE of La Bufa and 9.6 km S of Kirare, 1240 m, P.M. 

Peterson, Annable & Valdés-Reyna 10835 (US).

Hilaria Kunth

Perennial or annual; tufted or caespitose, sometimes stoloniferous, perennial species sometimes rhizomatous. Culms erect 

or decumbent; nodes usually villous or pilose, particularly the 

upper nodes. Sheaths open, glabrous or pilose, lower sheaths 

often glabrous basally and pilose distally, margins sometimes villous or pilose, upper sheaths often glabrous even if the lower 

sheaths are pilose; ligules membranous, lacerate or ciliate. Inflorescences terminal, spikelike panicles of reduced, disarticulating 

branches, exceeding the upper leaves; branches with 3 spikelets, 

appressed to the rachises, bases straight, seated in a ciliate, cuplike structure, sometimes with a callus, calluses pilose, axes not 

extending past the distal florets; disarticulation at the base of the 

branches, leaving the zigzag rachises. Lateral spikelets of each 

branch shortly pedicellate, with 1–4(5) sterile or staminate florets; glumes almost as long as the florets, deeply cleft into 2 or 

more lobes, with 1 or more dorsal awns; lemmas membranous, 

hyaline. Central spikelets sessile, with 1 pistillate or bisexual 

floret; glumes shorter than the florets, rigid, indurate and fused 

basally, apex with 2 or more lobes; lemmas membranous, awned 

or unawned. x = 9.

Hilaria is a genus of 10 species that ranges from the southwestern United States to northern Guatemala. Based on molecular DNA studies, Hilaria can be divided into two subgenera, H. 

subg. Pleuraphis (Torr.) Columbus, which includes H. mutica

and H. rigida, and H. subg. Hilaria, which includes H. belangeri, 

H. cenchroides, and H. ciliata (Peterson et al., 2016). 

KEY TO SPECIES OF HILARIA

1. Glumes hyaline and fimbriate at the apex; plants forming colonies from the growing rhizomes, the rhizomes indurate and 

scaly.

2. Culms tomentose pubescent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H. rigida

2. Culms glabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H.mutica

1. Glumes firm, not fimbriate at the apex; plants forming simple mats united by slender stolons, arched, not rhizomatous.

3. Glumes of lateral spikelets as long as the lemmas; glomerules 6–8 mm long . . . . . . . . . . . . . . . . . . . . . . . . H. swallenii

3. Glumes of lateral spikelets much shorter than lemmas; glomerules 3.5–6.5 mm long. 

4. Spikelets whitish or pallid, occasionally pinkish or purple; lateral spikelets 5–6 mm long, central spikelets (3.5)4–5 mm; 

glumes with black glands lacking or not abundant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H. belangeri

4. Spikelets generally gray or black; lateral spikelets 4.5–5.6 mm long, central spikelets 5–6 mm long; glumes with 

numerous and conspicuous black glands.

5. Glume awns of the central spikelet about 1 mm long, with short cilia; ligules 2–2.5 mm long . . . . . . . H. ciliata

5. Glume awns of the central spikelet about 3 mm long, scabrous; ligules 1.5–2 mm long . . . . . . . . H. cenchroides
182 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

176. Hilaria belangeri (Steud.) Nash, N. Amer. Fl. 17(2): 135. 

1912.

Perennial; caespitose, usually stoloniferous. Culms 5–35 cm 

tall, erect; nodes villous. Sheaths striate, glabrous; ligules 1–3 mm 

long, often lacerate; blades 3–15 cm long, 1–3.5 mm wide, adaxial surfaces sparsely pilose, hairs papillose-based, margins 

sparsely pilose basally, with similar hairs. Panicles 2–4 cm long; 

involucres 5–8 mm long. Lateral spikelets with 2(3) staminate 

florets, or 1 sterile floret; glumes unequal, thick, indurate, and 

conspicuously fused basally, thinner distally, asymmetrically 

lobed, scabrous, pale to purplish, bases sometimes spotted with 

a few dark glands, margins wide, hyaline, awns 1 or more, attached below midlength, equaling or exceeding the central spikelets, antrorsely scabrous; lower glumes wider, more deeply lobed, 

with longer awn(s) than the upper glumes; stamens 3, anthers 

3–3.7 mm long. Central spikelets as long as or longer than the 

lateral spikelets, with 1 pistillate floret; glumes terminating in 1 

or more antrorsely scabrous awns. 2n = 36, 72, 74.

Distribution and Habitat. Hilaria belangeri 

ranges from the United States to Mexico in Aguascalientes, Baja 

California, Baja California Sur, Chihuahua, Coahuila, Guanajuato, Guerrero, México, Michoacán, Morelos, Nuevo León, 

Oaxaca, Puebla, Querétaro, Sonora, and Tamaulipas. It has two 

varieties, only the typical variety is found in Chihuahua.

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000) and Herrera Arrieta and 

Cortés Ortiz (2010).

177. Hilaria cenchroides Kunth, Nov. Gen. Sp. (quarto ed.) 1: 

117, t. 37. 1815.

Perennial; caespitose, stoloniferous. Culms 5–60 cm long, 

erect, nodes bearded. Sheaths longer than adjacent culm internode, striately veined, outer margin hairy; ligules 1.5–2 mm long, 

an eciliate membrane, lacerate; blades 3–10 cm long, 2–4 mm 

wide, flat or involute, stiff, surface ribbed, rough on both sides, 

glabrous or pilose. margins scabrous. Panicles composed of racemes; racemes 0.4–0.8 cm long, borne along a central axis; 

closely spaced; in a multilateral false spike, cuneate, unilateral, 

axis 2–6 cm; deciduous from axis, spikelets 1 fertile and 2 sterile, sessile. Sterile spikelets 3–5 mm long, 2–4-flowered; lemmas 

as long as the bisexual spikelets, empty or male, oblong, asymmetrical, dorsally compressed, exserted from the glumes, apex 

muticous; glumes 1.5–4 mm long, 5- to 11-veined, scabrous, 

united below, coriaceous, 2-lobed, truncate or obtuse, both 

glumes awned, the awn 1–2 mm long, lemmas 2–4, exserted 

from glumes. Bisexual spikelets 4–7.5 mm long, 1-flowered, oblong, laterally compressed, falling entire and with sterile spikelets; glumes 4–5 mm long, ovate, coriaceous, black, 1-keeled, 

7-veined, scabrous, equal, connate along margins below, shorter 

and firmer than fertile lemmas, apex 2-lobed, truncate or obtuse, 1-awned, the awn about 3 mm long; lemmas 5–6 mm long, 

ovate, laterally compressed, cartilaginous, keeled, 3-veined, apex 

caudate; stamens 3, anthers 3–3.5 mm long. 2n = 44.

Distribution and Habitat. Hilaria cenchroides is distributed in the grasslands of Mexico and Central America. This species grows on dry slopes, flats, and along gravelly 

drainages in desert scrub and pine–oak woodlands commonly 

associated with Acacia, Quercus intricata Trel., Pinus cembroides, Rhus virens Lindh. ex A. Gray, Bouteloua dactyloides,

Juniperus deppeana Steud., Baccharis, Opuntia, Stevia, and

Viguiera.

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000). 

178. Hilaria ciliata (Scribn.) Nash, N. Amer. Fl. 17(2): 136. 1912.

Perennial; caespitose, stolons present. Culms 20–45 cm 

tall, tufted, erect, bearded below inferior nodes. Sheaths striate, 

mostly shorter than internodes, glabrous, the inferior sparsely 

papillose-pilose over the collar; ligules 2–2.5 mm long, eciliate 

membrane, sparsely pilose; blades 1.5–15(20) cm long, 3–5 mm 

wide, scabrous, sometimes with some papillose hairs on margins. Panicles composed of racemes, the racemes 3–5 cm long, 

in a multilateral false spike, cuneate, rachis pilose; glomerules 

or false involucres 3.5–5(5.8) mm long with 1 fertile spikelet 

and 2 sessile and sterile spikelets. Sterile spikelets 3–4 mm 

long, as long as bisexual spikelets, well-developed, male, oblong, asymmetrical, laterally compressed; glumes united below, 

coriaceous, 5-veined, scabrous, ciliolate on margins, muticous; 

lemmas 3, exserted from glumes, apex muticous. Bisexual 

spikelets 4–7.5 mm long, 1-flowered, oblong, laterally compressed, falling entire and with sterile florets; glumes shorter 

than the spikelet, asymmetrical, coriaceous, pallid, 1-keeled, 

scabrous, connate along the margins below, the margins ciliolate, apex 2-lobed, awned, the awn 1 mm long; lower glumes 

1.2–2 mm long, 3-veined, awned; upper glumes 2.8–3.8 mm 

long, 5-veined; fertile lemma 3–4 mm long, ovate, laterally 

compressed, cartilaginous, keeled, 3-veined, apex caudate; stamens 3, anthers 3–3.5 mm long. 2n = 36.

Distribution and Habitat. Hilaria ciliata is 

a Mexican species cited from Baja California, Baja California 

Sur, Chihuahua, Colima, Guanajuato, Guerrero, Jalisco, Michoacán, Nayarit, Oaxaca, Quéretaro, San Luis Potosí, Sonora, and 

Veracruz.

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000) and Herrera Arrieta and 

Cortés Ortiz (2010).

179. Hilaria mutica (Buckley) Benth., J. Linn. Soc., Bot. 19: 62. 

1881. Pleuraphis mutica Buckley, Proc. Acad. Nat. Sci. Philadelphia 14: 95. 1862.

FIGURE 130

Perennial; caespitose, rhizomatous. Culms 30–60 cm tall, 

erect, geniculate at the middle nodes; nodes glabrous or pubescent, hairs to 0.3 mm. Sheaths glabrous or sparsely pilose on 

the margins; ligules 0.5–2 mm long, lacerate; blades 2–15 cm 
NUMBER 107 • 183

long, 2–4 mm wide, mostly scabrous on both surfaces, with 

papillose-based hairs behind the ligules. Panicles 4–8 cm long; 

involucres 5–8 mm long. Lateral spikelets with 1 or 2(4) staminate florets; glumes not conspicuously fused basally, thin, 

hyaline, papery, flabellate, dorsally awned, awns not exceeding 

the apex, apical lobes rounded, ciliate to finely laciniate, veins 

not or sparsely excurrent; anthers 3, 2.5–3.5 mm long. Central 

spikelets with 1 bisexual floret; glumes with 1 or more divergent, dorsal awns, apical lobes, ciliate to finely laciniate, veins 

excurrent; lemmas exceeding the glumes, bilobed, mucronate. 

2n = 36, 54.

Distribution and Habitat. Hilaria mutica 

grows in alkaline flats, level upland areas, and desert valleys 

subject to occasional flooding but lacking permanent streams. 

Its range extends from southwestern United States to northern 

Mexico in Baja California Sur, Chihuahua, Coahuila, Durango, 

Nuevo León, Sonora, and Zacatecas. 

Specimens Examined. MEXICO. Chihuahua.

Aldama: Rancho El torreño # 3, 25 Sep 1982, matorral inerme 

parvifolio [unarmed small-leaved scrub], 1150 m, G. Melgosa 

36 (CIIDIR). Camargo: Rancho San Francisco, 21 Sep 76, matorral, 1300 m, S. González 479 (RELC); 1 mi S of Camargo, 

6 Sep 1967, Reeder & C. Reeder 4868 (ARIZ, US); 21 mi N of 

Camargo, 5 Sep 1967, Reeder & C. Reeder 4863 (ARIZ, US); 

3 mi N of Cd. Camargo on Hwy 45, 18 Aug 1959, D. Marsh 

1904 (US); Preson Ortega, 31 mi NE of Camargo, 25 Sep 1938, 

F. Shreve 8895 (US). Chihuahua: near Chihuahua, 2 Sep 1885, 

C.G. Pringle 485 (US); S of Chihuahua, 1 Aug 1936, LeSueur 

0132 (US); 13 mi SE of Cd. Chihuahua, 5 Sep 1967, 1478 m, 

Reeder & C. Reeder 4862 (ARIZ, US); 80 km de Chihuahua 

hacia Cd. Juárez, 11 oct 1980, pastizal amacollado [grass pasture], 1550 m, Valdés-Reyna s.n. (CIIDIR); 7 km Ote. [W] 

del Rancho el 45, 26 Sep 73, 1480 m, Valdés-Reyna VR-364

(RELC); km 54 carr. [hwy] Panamericana Chihuahua–Cd. 

Juárez, 14 Oct 74, matorral, 1500 m, Valdés-Reyna VR-637

(RELC). Cuauhtémoc: 23 mi NW of Zavalza, 3 Oct 1966, 4800 

ft, Reeder & C. Reeder 4578 (ARIZ). Delicias: 7 mi S of Delicias along Hwy 45, 24 Sep 1972, J. Henrickson 7991 (NMC). 

General Trías: km 40 carr. Chihuahua–Cuahutémoc, 12 Aug 

76, lomeríos [lorries], 1693 m, S. González & J.M. Peña 540

(RELC). Janos: Chihuahua–Sonora border, Rancho Carretas, 

29 Aug 1939, 1460 m, L. H. Harvey 1534 (US). Jiménez: 5 mi 

E of Carrillo, C.H. Muller 3321 (US); 11 mi N of Jiménez, 3 

Sep 1967, Reeder & C. Reeder 4870 (ARIZ, US); 14 mi SE of 

Jiménez, 3 Sep 1967, Reeder & C. Reeder 4839 (ARIZ, US); 

Sta. Eulalia plains, 2 Sep 1885, E. Wilkinson 557 (US); 33 mi 

SE of Jiménez, 27 Sep 1963, Reeder & C. Reeder 3843 (ARIZ, 

US); 10 km E of Jimenez, 31 Jul 1939, L. H. Harvey 1348 (US); 

Reserva de la Biosfera de Mapimí, Rancho La Soledad, 6 Jul 

1997, vegetación secundaria [secondary vegetation], 1113 m, 

A. García 2645 (CIIDIR); El Hugo, Torreoncitos, 13 Aug 2010, 

terrenos de cultivo [farmland], 1355 m, D. Ramírez & M.L. 

Juárez 3378 (CIIDIR); 50 km al S de Jiménez, 15 Aug 2010, 

FIGURE 130. Hilaria mutica. A. Habit. B. Inflorescence branch (fascicle of spikelets). C. Lateral spikelets. D. Central spikelet. Drawn by Linda Ann Vorobik 

and Karen Klitz; copyright Utah State University.
184 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

1442 m, D. Ramírez & M.L. Juárez 3415 (CIIDIR). Meoqui: Meoqui, 24 Jun 1935, LeSueur Mex 040 (US). Saucillo: 

19 mi NW of Naica, Dto. de Saucillo, 30 Jul 1937, F. Shreve 

8080 (US).

180. Hilaria rigida (Thurb.) Benth. ex Scribn., Bull. Torrey Bot. 

Club 9(3): 33. 1882. Pleuraphis rigida Thurb., Bot. California 2: 293–294. 1880. 

FIGURE 131

Perennial; with hard rhizomatous base. Culms 1.5–2.5 

m tall, in large groups, rigid, branched, tomentose pubescent. 

Sheaths overlapping, scabrous; ligule 1 mm long, a row of fine 

hairs; blades 2–5 cm long, 2–4 mm wide, slightly involute, escabrous. Panicles 3–9 cm long, involucres 6–12 mm long, densely 

barbed on the base; lateral spikelets staminate with 2–4 florets, 

superior floret sterile; glumes thin, fimbriate, hyaline, 7-veined, 

almost always 2- to 4-lobed on the apex, apex wide, 1–3 veins 

that terminate in slender awns, or the veins are inconspicuous 

and sparsely excurrent (variable in the same inflorescence). 

Central spikelets bisexual, 1-flowered, equal or longer than the 

lateral spikelets; glumes narrow, fimbriate, hyaline with several 

awns and 2 or more lobes deeply notched; lemma frequently longer than the glumes, slender, ciliate, 2- to 4-lobed, the midvein 

excurrent into a short awn. 2n = 54.

Distribution and Habitat. Hilaria rigida 

grows in pine forests; it ranges from the United States to Mexico 

in Baja California, Chihuahua, Oaxaca, and Sonora.

Specimens Examined. MEXICO. Chihuahua. Casas Grandes: Col. Díaz, 30 Mar 1894, E.A. Mearns 

2848/406 (US).

181. Hilaria swallenii Cory, Wrightia 1: 215. 1948.

Perennial; stoloniferous. Culms 10–35 cm long, erect; nodes 

villous. Sheaths slightly scabrous; ligules 2–2.2 mm long; blades 

to 8 cm long, 1–2 mm wide, mostly basal, both surfaces scabrous, sometimes also sparsely pilose. Panicles 1–4 cm long, 

with 2–8 involucres; involucres 6.5–8 mm long. Lateral spikelets 

2-flowered, lowest florets usually sterile, distal florets staminate; 

glumes unequal, thick, indurate, and conspicuously fused basally, mostly gray to dark brown, evenly and sparsely to densely 

spotted with dark glands, awned from above midlength, margins hyaline; stamens 3, anthers 3–3.5 mm long. Central spikelets with 1 pistillate floret; lemmas elliptic basally, narrower and 

parallel-sided distally. 2n = 54, 72.

Distribution and Habitat. Hilaria swallenii

grows on dry plains and rocky mesas in New Mexico, Texas, 

and northern Mexico in Chihuahua, Coahuila, Durango, Nuevo 

León, San Luis Potosí, and Zacatecas.

Specimens Examined. MEXICO. Chihuahua. Bocoyna: Sánchez, 12 Oct 1910, Hitchcock 7694 (US). Chihuahua: 

near Chihuahua, 23 Aug 1885, C.G. Pringle 493 (US); La Campana, Potrero del Plan, 3 km Ote. [W] carr. [hwy] Panamericana, 

FIGURE 131. Hilaria rigida. A. Habit. B. Inflorescence branch (fascicle of spikelets). Drawn by Linda Ann Vorobik and Karen Klitz; 

copyright Utah State University.
NUMBER 107 • 185

13 Sep 73, pastizal [pastureland], 1500 m, Valdés-Reyna VR236 (RELC); 4 km al Ote. carr. Panamericana, 1 Sep 74, pastizal, 

1500 m, Valdés-Reyna VR-604 (RELC).

Holcus L.

Plants usually perennial, rarely annual; caespitose or rhizomatous, rarely both caespitose and rhizomatous. Culms glabrous or pubescent; nodes glabrous or retrorsely pubescent. 

Sheaths open; auricles absent; ligules membranous, entire or 

erose-ciliate, glabrous or puberulent; blades flat, pubescent. Inflorescences terminal panicles, contracted to open. Spikelets laterally compressed, with 2(3) florets, lower florets bisexual, upper 

floret(s) staminate or sterile; rachillas curved below the lowest 

florets, sometimes prolonged beyond the uppermost florets; disarticulation below the glumes. Glumes equaling to exceeding the 

florets, strongly keeled; lower glumes 1-veined; upper glumes 

3-veined; calluses glabrous or pubescent; lemmas firm, shining, 

glabrous or pubescent, obscurely 3- to 5-veined, often bidentate; 

lower lemmas unawned; upper lemmas awned from below the 

apex, awns hooked or geniculate; paleas thin, subequal to the 

lemmas; lodicules 2, glabrous, toothed or not toothed; anthers 3; 

ovaries glabrous. Caryopsis glabrous. x = 4, 7. 

Holcus, a genus of eight species, is native to Europe, North 

Africa, and the Middle East.

182. Holcus lanatus* L., Sp. Pl. 2: 1048. 1753.

FIGURE 132

Perennial; caespitose, not rhizomatous. Culms 20–100 cm 

tall, erect, sometimes decumbent, lower internodes densely 

pilose, with hairs to 1 mm long, uppermost internode often 

glabrous. Sheaths densely pubescent; ligules 1–4 mm long, truncate, erose-ciliolate; blades 2–20 cm long, (3)5–10 mm wide, 

densely soft-pubescent. Panicles 3–15(20) cm long, 1–8 cm wide; 

branches hirsute; pedicels 0.2–1.6(4) mm long, pilose, hairs 

to 0.3 mm. Spikelets 3–6 mm; rachillas 0.4–0.5 mm long, glabrous; glumes exceeding and enclosing the florets, membranous, 

ciliate on the keels and veins, usually scabrous, puberulent, or 

villous between the veins, especially toward the apex, whitishgreen, often purple over the veins and toward the apex; lower 

glumes lanceolate, narrow, acute; upper glumes ovate, wider 

and longer than the lower glumes, midveins often prolonged 

as an awn to 1.5 mm long, apex obtuse, somewhat bifid; calluses sparsely hirsute; lemmas 1.7–2.5 mm long, acute, eroseciliate; upper lemmas shallowly bifid, awns 1–2 mm long, often 

FIGURE 132. Holcus lanatus. A. Habit. B. Ligule. C. Glumes. 

D. Florets. E. Caryopsis. Drawn by Linda Ann Vorobik and Hana 

Pazdírková; copyright Utah State University.
186 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

purple-tipped, slightly twisted and strongly hooked at maturity; 

anthers (1.2)2–2.5 mm long. 2n = 14.

Distribution and Habitat. Holcus lanatus

grows in disturbed sites, moist waste places, lawns, and pastures 

in a wide range of edaphic conditions; 0–2,300 m. A native of 

Europe, Holcus lanatus was widely distributed in North America 

by 1800.

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000) and Herrera Arrieta and 

Cortés Ortiz (2010).

Hopia Zuloaga & Morrone

Perennial; short rhizomatous and long stoloniferous. Culms 

not cormous at the base, not branched above the base; nodes swollen, villous, particularly on the stolons. Ligules membranous, papery; blades linear-lanceolate, cross sections with Kranz anatomy 

with a single mestome sheath surrounding the vascular bundles 

and in contact with the metaxylem vessels. Panicles contracted; 

branches spikelike, appressed, 1-sided, spikelets borne in pairs. 

Spikelets ellipsoid to obovoid. Lower glumes 3⁄4–4⁄5 as long as the 

spikelets, 5- to 7-veined; upper glumes subequal to the lower lemmas, 7- to 11-veined, blunt; lower florets staminate; lower paleas 

well-developed; upper florets obovoid, indurate, smooth, with microhairs and simple papillae near the base and tip. x = 10.

Hopia is a unispecific genus that extends from the southwestern United States into northern Mexico. 

183. Hopia obtusa (Kunth) Zuloaga & Morrone, Taxon 56: 

151. 2007. Panicum obtusum Kunth, Nov. Gen. Sp. (quarto 

ed.) 1: 98–99. 1815.

FIGURE 133

Perennial; usually from long slender stolons or shallow rhizomes with swollen, villous nodes. Culms 20–80 cm tall, often 

in small clumps, compressed, erect or decumbent, glaucous; 

lower nodes pubescent; upper nodes glabrous. Lower sheaths 

ascending, pubescent to pilose; upper sheaths glabrous; ligules 

0.2–2 mm long, membranous, truncate, irregularly denticulate; 

blades 3–26 cm long, 2–7 mm wide, ascending, firm, glaucous, 

sparsely pilose near the base, often scabrous on the margins, involute toward the apex. Panicles 5–15 cm long, 0.8–1.5 cm wide; 

branches 2–6, spikelike, erect, puberulent, 3-angled; ultimate 

branchlets 1-sided; pedicels paired, congested, shorter pedicels 

0.1–1 mm long, longer pedicels 1.5–2.5 mm long. Spikelets 2.8–

4.4 mm long, ellipsoid, terete to slightly laterally compressed, 

glabrous, obtuse; lower glumes about 3⁄4 as long as the spikelets, 5- to 7-veined; upper glumes and lower lemmas equaling the 

spikelets, 5- to 9-veined; lower florets staminate; lower paleas 

2.5–3.5 mm long; upper florets puberulent at the bases and apex. 

2n = 20, 36, 40.

Distribution and Habitat. Hopia obtusa 

grows in seasonally wet sand or gravel, especially on stream 

banks, ditches, roadsides, wet pastures, and rangeland. 

Specimens Examined. MEXICO. Chihuahua. 

Ascensión: alrededores del cruce del río [around the river crossing] Casas Grandes con la carr. [hwy] Juárez–Ascensión, 11 Jun 

2005, 1180 m, R. Corral, M. Vargas & H. Gutiérrez RCD 7154

(UACJ). Casas Grandes: El Alamito, Col. Cuauhtémoc, 12 Aug 

1996, P. Olivas, R. Rivas, I. Enríquez & A. Márquez POS838

(UACJ). Chihuahua: S of Chihuahua, 1 Aug 1936, LeSueur 131

(US); near Chihuahua, 20 Sep 1885, C.G. Pringle 476 (US); 

4 km al W de Sacramento, 10 Aug 1971, matorral [scrub] de 

Prosopis, 1550 m, F. Jiménez 84 (ENCB); La Campana, Potrero 

La Reserva, 14 km Ote. [W] carr. Panamericana, 26 Aug 1973, 

pastizal halófito [halophyte grassland], 1480 m, Valdés-Reyna 

VR-25 (RELC). Potrero El Plan, 4 km Ote. carr. Panamericana, 

6 Sep 73, orilla de lotes de producción de semilla [edge of seedproduction lots], 1500 m, Valdés-Reyna VR-93 (RELC). Cuauhtémoc: 21 km W of Cuauhtemoc, on Hwy 16, 23 Aug 1990, 

2000 m, P.M. Peterson & Annable 9597 (US). Cusihuiriáchi: Río 

Papigochic, 40 km de Cuahutémoc, carr. Cuahutémoc–Ocampo, 

FIGURE 133. Hopia obtusa. A. Habit. B. Spikeket. C. Upper floret. 

Drawn by Linda Ann Vorobik and Cindy Roché; copyright Utah 

State University.
NUMBER 107 • 187

8 Aug 1976, pastizal, 2100 m, J.M. Peña JMP-88 (RELC). Guadalupe: NE Chihuahua, vicinity of Rancho El Pino, ca 10 km 

SE of Sierra Rica, 23 Sep 1942, Stewart 2398 (US). Gran Morelos: 10 mi W of General Trias off hwy 16, 19 jul 1975, scrub 

junipers on rocky alluvium, 5850 ft, Ellis, Dunn & Wallace 937

(ENCB). Janos: Chihuahua–Sonora border, Rancho Carretas, 

27Aug 1939, 1450 m, L. H. Harvey 1630 (ENCB, US). Jiménez: 

5 mi N of Jiménez on Mex 45, 30 Aug 1971, 4400 ft, L. H. Harvey 8899 (ENCB); 10 km E of cd. Jiménez, 31 Jul 1939, 1340 

m, L. H. Harvey 1349 (ENCB); El Hugo, Torreoncitos, 13 Aug 

2010, terrenos de cultivo [farmland], 1355 m, D. Ramírez & 

M.L. Juárez 3380 (CIIDIR). Riva Palacio: 40 km W of Chihuahua, 20 Aug 1939, 1735 m, L. H. Harvey 1551 (US).Temosachi: 

About 2 mi of Natachic, 9 Jul 1950, on the flood plain of a small 

river, Reeder, C. Reeder & Goodding 1241 (ENCB).

Hordeum L.

Plants summer or winter annuals or perennials; caespitose, 

sometimes short rhizomatous. Culms to 135(150) cm long, erect, 

geniculate, or decumbent; nodes glabrous or pubescent. Sheaths 

open, pubescent or glabrous; auricles present or absent; ligules 

hyaline, truncate, erose; blades flat to more or less involute, more 

or less pubescent on both sides. Inflorescences usually spikelike 

racemes, sometimes spikes, all customarily called spikes, with 

3 spikelets at each node, central spikelets usually sessile, sometimes pedicellate, pedicels to 2 mm long, lateral spikelets usually 

pedicellate, pedicels curved or straight, sometimes all 3 spikelets 

sessile in cultivated plants; disarticulation usually in the rachises, 

the spikelets falling in triplets, cultivated forms generally not 

disarticulating. Spikelets with 1 floret; glumes awn-like, usually 

exceeding the floret. Lateral spikelets usually sterile or staminate, 

often bisexual in cultivated forms; florets pedicellate, usually reduced; lemmas awned or unawned. Central spikelets bisexual; 

florets sessile; rachillas prolonged beyond the floret; lemmas 

ovate, glabrous to pubescent, 5-veined, usually awned, rarely 

unawned; paleas almost equal to the lemmas, narrowly ovate, 

keeled; lodicules 2, broadly lanceolate, margins ciliate; anthers 

3, usually yellowish. Caryopsis usually tightly enclosed in the 

lemma and palea at maturity. 2n = 14, 28, 42.

Hordeum is a genus of 43 species that grow in temperate 

and subtropical areas at elevations from 0 to 4,500 m. The genus 

is native to Eurasia, the Americas, and Africa and has been introduced to Austral Asia.

KEY TO SPECIES OF HORDEUM

1. Auricles to 8 mm long, well-developed even on the upper leaves; lemmas of the lateral florets 6–15 mm long.

2. Rachises disarticulating at maturity; glumes of the central spikelets ciliate; lemmas of the central florets to 2 mm wide, 

with awns 20–40 mm long; lateral spikelets staminate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H. murinum

2. Rachises usually not disarticulating at maturity; glumes of the central spikelets pubescent; lemmas of the central florets 

at least 3 mm wide, unawned or with awns 30–180 mm long; usually 1 or both lateral spikelets at a node seed-forming 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H. vulgare

1. Auricles usually absent or to 0.3 mm long; lemmas of the lateral florets 1.7–8.5 mm long.

3. Lemmas of the lateral spikelets 7–11 mm long, with awns 3–8 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . H. murinum

3. Lemmas of the lateral spikelets 2.5–5.7 mm long, with awns up to 1.8 mm long . . . . . . . . . . . . . . . . . . . . H. pusillum

184. Hordeum murinum* L., Sp. Pl 1: 85. 1753.

FIGURE 134

Annual; loosely tufted. Culms to 110 cm tall, usually erect, 

sometimes almost prostrate; nodes glabrous. Lower sheaths often 

completely surrounding the culms, glabrous or somewhat pilose; 

ligules 1–4 mm long; auricles to 8 mm long, well-developed 

even on the upper leaves; blades to 28 cm long, usually flat, occasionally with involute margins, glabrous or sparsely pilose, 

sometimes scabrous. Spikes 3–8 cm long, 7–16 mm wide, pale 

green to distinctly reddish, especially the awns; rachises disarticulating at maturity. Central spikelets sessile, florets sessile 

or pedicellate, pedicels to 2 mm long; glumes 11–25 mm long, 

0.8–1.8 mm wide, flattened, margins usually distinctly ciliate; 

lemmas 8–14 mm long, to 2 mm wide, more or less smooth, 

awned, awns 20–40 mm; lodicules glabrous or with 1+ cilia; anthers 0.2–3.2 mm long, gray to yellow, sometimes with purple 

spots. Lateral spikelets staminate, floret sessile; glumes flattened, 

margins ciliate; lemmas 8–15 mm long, awned, awns 20–50 mm 

long; paleas 8–15 mm long; rachillas 2.5–6.5 mm long, slender 

or gibbous, yellow. 2n = 14, 28, 42.

Distribution and Habitat. Hordeum murinum is native to Eurasia, where it is a common weed in areas 

of human disturbance. It is thought to have been introduced to 

the Western Hemisphere along seasides, sandy riverbanks, and 

animal watering holes. It is now an established weed in southwestern North America and other scattered locations.

Specimens Examined. MEXICO. Chihuahua. 

Juárez: en el Parque “El Chamizal”, maleza de prados & canales de riego [grass meadows and irrigation canals], 7 Sep 1995, 

1120 m, R. Corral RCD6285 (UACJ); Univ. Autónoma de Cd. 

Juárez, Campus ICB, 15 Abr [Apr] 2005, 1118 m, R. Corral, 

M. Vargas & D. Alvarado RCD7102 (UACJ); Cd. Juárez, planta 

tratadora de agua [water treatment plant] entre la calle [between 

streets] Julia & Ana, Frac. Puerta del Sol, 26 Mar 1996, P. Olivas & R. Durán POS728 (UACJ). Práxedis G. Guerrero (San 

Ignacio): a 2 km al S del poblado del mismo nombre [village of 

the same name], Rancho Escuela de la Univ. Autónoma de Cd. 
188 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Juárez, 18 Mar 1995, 1090 m, R. Corral, P. Olivas & E. Pérez 

RCD6029 (UACJ).

185. Hordeum pusillum Nutt., Gen. N. Amer. Pl. 1: 87. 1818.

Annual; loosely tufted. Culms 10–60 cm long, erect, geniculate, or ascending; nodes glabrous. Sheaths glabrous or slightly 

pubescent; ligules 0.2–0.8 mm long; auricles absent; blades to 

10.5 cm long, to 4.5 mm wide, sparsely to densely pubescent 

on both sides. Spikes 2–9 cm long, 3–7 mm wide, erect, often 

partially enclosed at maturity, pale green. Glumes straight, not 

divergent at maturity. Central spikelets: glumes 8–17 mm long, 

0.5–1.5 mm wide, distinctly flattened near the base; lemmas 

5–8.5 mm long, usually glabrous, sometimes sparsely to densely 

pubescent, awned, the awns 3.5–9.5 mm long; anthers 0.7–

1.8 mm long. Lateral spikelets usually sterile; glumes to 18 mm 

long; lower glumes distinctly flattened, more or less winged basally; lemmas 2.5–5.7 mm long, usually awned, awns to 1.8 mm 

long, rarely unawned; anthers 0.6–1.2 mm long. 2n = 14.

Distribution and Habitat. Hordeum pusillum grows in open grasslands, pastures, the borders of marshes, 

and disturbed places such as roadsides and waste places, often 

in alkaline soil. It is native, widespread, and often common 

in much of the United States to northern Mexico, where it is 

uncommon. 

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: La Campana, 26 May 76, Jardines de observación 

[observation gardens], 1540 m, S. González 833 (RELC).

186. Hordeum vulgare* L., Sp. Pl. 1: 84-85. 1753.

FIGURE 135

Plants summer or winter annual; loosely tufted. Culms

to 100(150) cm long, usually erect; nodes glabrous. Lower 

sheaths pilose, upper sheaths glabrous, auricles to 6 mm long, 

well-developed even on the upper leaves; blades to 30 cm long, 

5–15 mm wide, flat, scabrous or glabrous. Spikes 5–10 cm long, 

0.8–2 cm wide, green to purplish or blackish; nodes 10–30, with 

3 spikelets per node, 0–2 lateral spikelets, in addition to the central spikelets, forming seed at maturity (resulting in 2-, 4-, and 

6-rowed barley); rachises usually not disarticulating at maturity. 

FIGURE 134. Hordeum murinum. A. Habit. B. Ligule and auricles. C. Inflorescence. D. Spikelet fascicle with three spikelets. Drawn by Cindy Roché and Annaliese Miller; copyright Utah State University.
NUMBER 107 • 189

Central spikelets sessile; glumes 10–30 mm long, pubescent, 

flattened near the base; lemmas 6–12 mm long, 3+ mm wide, 

glabrous, sometimes scabrous, particularly distally, unawned 

or awned, awns 30–180 mm long, usually scabrous; anthers

6–10 mm long, yellowish. Lateral spikelets usually sessile if seedforming, pedicellate if sterile; pedicels up to 3 mm long; lemmas

usually 6–15 mm long, awned when fertile, obtuse to acute when 

sterile. 2n = 14 (28).

Distribution and Habitat. Hordeum vulgare

is native to Eurasia. Plants in Mexico belong to the cultivated 

subspecies, Hordeum vulgare subsp. vulgare, and are found as 

an adventive in fields, roadsides, and disturbed habitats.

Specimens Examined. MEXICO. Chihuahua. 

Práxedis G. Guerrero (San Ignacio): a 2 km al S del poblado del 

mismo nombre [village of the same name], Rancho Escuela de la 

Univ. Autónoma de Cd. Juárez, 18 Mar 1995, 1090 m, R. Corral, P. Olivas & E. Pérez RCD6032 (UACJ).

Imperata Cirillo

Perennial; strongly rhizomatous. Culms mostly erect and unbranched, usually with 3–4 nodes. Leaves not aromatic; sheaths 

open, ciliate at the margins of the collars; ligules membranous; 

blades of the basal leaves linear to lanceolate, sometimes ciliate 

basally, those of the cauline leaves reduced. Inflorescences terminal, cylindrical to conical panicles with an evident rachis; rachises 

often with numerous long hairs; inflorescence branches usually 

shorter than the rachises, with spikelets in unequally pedicellate 

pairs; disarticulation below the glumes. Spikelets homogamous 

and homomorphic, unawned; calluses very short, hairy. Glumes 

equal to subequal, membranous, 3- to 9-veined, with hairs longer 

than the florets over at least the lower 1⁄2; lower florets reduced 

to hyaline or membranous lemmas; upper florets bisexual, lemmas, if present, hyaline, unawned; anthers 1–2, yellow to brown; 

stigmas elongate, purple to brown; styles connate or free. Pedicels 

not fused to the branch axes, terminating in cuplike tips. Caryopsis ovate to obovate, light to dark brown. x = 10.

Imperata has 13 species and is widely distributed in warm 

regions of both hemispheres.

187. Imperata brevifolia Vasey, Bull. Torrey Bot. Club 13(2): 

26. 1886.

FIGURE 136

Culms 51–129 cm tall. Ligules 0.7–2.9 mm long; blades 

7–14 mm wide, linear to lanceolate, abaxial surfaces smooth, 

adaxial surfaces sometimes densely pilose basally, otherwise scabrous. Panicles 16–34 cm long, dense; lower branches 2–5 cm 

long, divergent. Spikelets with callus hairs 8–12 mm long; 

glumes 2.7–4.1 mm long; lower lemmas 2.5–3.9 mm long, membranous, glume-like; upper lemmas 1.4–2.4 mm long, completely 

surrounding the ovary; stamens 1, filaments dilated at the base; 

anthers 1.3–2.3 mm long, yellow to orange; styles 0.9–2.4 mm 

long; stigmas 2.1–4 mm long, purple to brown. 2n = 20.

FIGURE 135. Hordeum vulgare. A. Habit. B. Inflorescence, awned 

form. C. Inflorescence, unawned form. D. Spikelet fascicle with three 

spikelets. Drawn by Cindy Roché and Annaliese Miller; copyright 

Utah State University.
190 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Distribution and Habitat. Imperata brevifolia is native to wet or moist sites in the southwestern deserts of 

California, Nevada, and Utah to western Texas. Our only record 

of this species is a LeSueur collection (Mex-099), and we cannot 

verify its locality. We do know that his next number, Mex-0100 

(Andropogon glomeratus var. pumilus), was collected on the 

same date and locality.

Specimens Examined. MEXICO. Chihuahua. 

Rio Bonito hot country, 26 Aug 1936, H. LeSueur 099 (US).

Kalinia H. L. Bell & Columbus

Robust perennial; with long, glabrous stolons and thick, 

tan to golden rhizomes with imbricate scales dehiscing to form 

distinctive scars. Culms erect; ligule a line of short hairs; leaf 

blades rigid, conspicuously orthodistichous, with markedly 

pungent tips. Inflorescence a narrow to open panicle. Spikelets 

with 4–12-hermaphroditic florets, the distal floret occasionally 

reduced; lemmas 3-veined, glabrous, with an obtuse to slightly 

pointed tip, sometimes erose, fringed, or mucronate from the 

central vein.

Kalinia is a new monotypic genus and subtribe to house 

Eragrostis obtusiflora (E. Fourn.) Scribn., a long-misplaced species that is sister to the Monanthochloinae + Boutelouinae (Bell 

et al., 2012; Peterson and Valdés-Reyna, 2005; Peterson et al., 

2016, 2017).

188. Kalinia obtusiflora (E. Fourn.) H. L. Bell & Columbus, 

Aliso 30(2): 91. 2012. Brizopyrum obtusiflorum E. Fourn.,

Mexic. Pl. 2: 120. 1886. Eragrostis obtusiflora (E. Fourn.) 

Scribn., Bull. Div. Agrostol. U.S.D.A. 8: 10, t. 5. 1897.

FIGURE 137

Perennial; with scaly, sharp-pointed rhizomes, with innovations, sometimes stoloniferous, the sharp-tipped rhizomes 

4–8 mm thick. Culms 15–40(50) cm tall, stiff, hard, glaucous 

below the nodes. Sheaths hairy at the apex, hairs to 2 mm; ligules 

0.2–0.4 mm long; blades 2–15 cm long, (1)2–4 mm wide, involute, arcuate, glabrous abaxially, scabrous adaxially, apex sharply 

pointed. Panicles 6–20(24) cm long, 2–8(12) cm wide, ovate, 

open or contracted; primary branches 1–8(15) cm long, appressed or diverging up to 50° from the rachises; pulvini glabrous 

or not; pedicels 0–8 mm long, appressed, lower pedicels on each 

branch shorter than 1 mm long. Spikelets 8–14 mm long, 1.4–3 

mm wide, ovate to lanceolate, stramineous with a reddish-purple 

tinge; disarticulation basipetal, glumes persistent; glumes unequal, chartaceous; lower glumes 2.4–3.6 mm long; upper glumes 

3–4.5 mm long, sometimes 3-veined; lemmas 3.8–4.5 mm long, 

ovate, leathery, lateral veins evident, greenish, upper margins 

hyaline, apex acute to obtuse, usually erose; paleas 3.8–4.5 mm 

long, membranous, keels scaberulous, apex obtuse to truncate; 

stamens 3; anthers 2–2.4 mm long, purplish to yellowish. Caryopsis 1.6–2 mm long, ellipsoid, dorsally flattened, with a shallow 

adaxial groove, striate, reddish-brown. 2n = 40.

Distribution and Habitat. Kalinia obtusiflora

is native to the southwestern United States and Mexico. It grows 

in dry or wet alkali flats, often in association with Distichlis spicata, at 900–1,400 m. 

Specimens Examined. MEXICO. Chihuahua. 

Ascensión: Laguna Ascension, near La Ascension, 13 Sep 1939, 

L. H. Harvey 1750 (US). Chihuahua: La Campana, Potrero La 

Reserva; 12 km carr. [hwy] Panamericana, 25 Aug 73, pastizal 

halófito abierto [open halophyte grassland], 1480 m, ValdésReyna VR–08 (RELC). Galeana: 4 mi NW of Galeana, 2 Sep 

FIGURE 136. Imperata brevifolia. A. Habit. B. Spikelet. Drawn by 

Linda Ann Vorobik and Hana Pazdírková; copyright Utah State 

University.
NUMBER 107 • 191

1958, alkali flat, 1524 m, Reeder & C. Reeder 3201 (ENCB). 

Hidalgo del Parral: 13 mi N of Parrita, 16 Sep 1960, alkali flat 

in desert pastizal–Mesquite area, 4800 ft, Reeder, C. Reeder & 

Soderstrom 3489 (ARIZ, ENCB).

Koeleria Pers.

Perennial; usually caespitose, sometimes short rhizomatous. 

Culm erect. Sheaths open; auricles absent; ligules membranous; 

blades flat to involute, pubescent or glabrous. Inflorescences 

panicles, usually dense and spikelike, sometimes lax, stiffly and 

narrowly pyramidal at anthesis; main rachis and branches pubescent. Spikelets laterally compressed, with 2–4 florets; rachillas to 

1 mm long, glabrous or pubescent, usually prolonged beyond 

the distal florets, or bearing a vestigial floret; disarticulation 

above the glumes and beneath the florets. Glumes subequal to or 

slightly exceeding the lemmas, membranous, scabrous to tomentose, keels sometimes ciliate; lower glumes 1-veined, somewhat 

narrower and shorter than the upper glumes; upper glumes obscurely 3(5)-veined; calluses with or without hairs; lemmas thin, 

membranous, 5-veined, margins shining, scarious, apex acute, 

sometimes mucronate or awned; paleas equaling or subequal to 

the lemmas, hyaline; lodicules 2, glabrous, toothed; anthers 3; 

ovaries glabrous. Caryopsis glabrous. x = 7.

Koeleria is a cosmopolitan genus of about 49 species that 

grow in dry grasslands and rocky soils; a single species is native 

to North America.

189. Koeleria pyramidata (Lam.) P. Beauv., Ess. Agrostogr. 84: 

166, 175. 1812. Poa pyramidata Lam., Tabl. Encycl. 1: 183. 

1791. 

Koeleria macrantha (Ledeb.) Schult., Koeleria cristata Pers., Koeleria californica (Domin) Beetle.

FIGURE 138

Plants loosely caespitose, sometimes rhizomatous. Culms 

(20)20–90(130) cm tall, glabrous or puberulent above. Sheaths 

sparsely sericeous to densely pubescent, old sheaths persistent, disintegrating into wavy, curled, or arched fibers; ligules 

0.5–2 mm long; blades 2–24 cm long, (0.5)1–5 mm wide, flat, 

often involute when dry, glabrous or hairy, scaberulous, margins of the basal blades often ciliate below, with hairs usually 

more than 2 mm. Panicles 4–27 cm long, (0.5)1–3(5) cm wide; 

branches finely pubescent to villous. Spikelets 2.5–10 mm long, 

with 2–4(5) florets; rachillas with scattered pubescence; glumes 

2.5–6 mm long, glabrous, smooth or scabrous, apex acute; 

lower glumes 2.5–5 mm long, 1-veined; upper glumes generally 

FIGURE 137. Kalinia obtusiflora. A. Rhizome. B. Habit. C. Florets. Drawn by Linda Ann 

Vorobik and Cindy Roché; copyright Utah State University.
192 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

4–6 mm long, 3-veined; calluses broadly rounded, pubescent; 

lemmas (2.5)4–6.5 mm long, glabrous or puberulent, rarely 

ciliate, sometimes scabrous, green when young, stramineous at 

maturity, sometimes purplish-tinged, apex acuminate to mucronate; anthers 1–2.5(3) mm long. Caryopsis 2.5–3.8 mm long. 

2n = 14, 28.

Koeleria pyramidata, as interpreted here, is a highly polymorphic species complex and has been treated as Koeleria pyramidata subsp. pyramidata by Quintanar and Castroviejo 

(2014), who studied the genus in the western Mediterranean 

Basin and Macaronesia. They found variability in organ size 

and hairiness. In addition, we have preliminary DNA sequence 

data (P. Barberá at Real Jardín Botánico, and K. Romaschenko, 

P. M. Peterson and R. J. Soreng at Smithsonian Institution; unpublished) confirming the highly variable nature of accessions 

previously referred to as K. pyramidata or K. macrantha. 

Distribution and Habitat. Koeleria pyramidata is widely distributed in temperate regions of North America 

and Eurasia. In North America it grows in semi-arid to mesic 

conditions on dry prairies or in grassy woods, generally in sandy 

soil, at 1,500–3,900 m. 

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 32 km W of hwy 45 towards Benito Juárez, 17 Oct 

1992, pinyon–juniper woodlands, 2110 m, P.M. Peterson & 

Annable 12549 (US). Batopilas: 16.1 km E of jct to Batopilas on road to Guachochi, 13 Sep 1989, pine forest, 2500 m, 

P.M. Peterson, Annable & Y. Herrera 8074 (ENCB, US); P.M. 

Peterson, Annable & Y. Herrera 974 (CIIDIR). Madera: near 

Col. García, 1–20 Aug 1899, E.W. Nelson 6198 (US). Guadalupe y Calvo: near Cumbre Mohinora, 13 Sep 2006, 3300 m, 

P.M. Peterson 20045, F.Sánchez Alvarado & E.P. Gómez Ruíz

(CIIDIR, US).

Lasiacis (Griseb.) Hitchc.

Perennial (rarely annual); caespitose. Culms weakly lignified, erect, arching, climbing, or decumbent, rooting at the 

nodes. Sheaths open; ligules membranous, sometimes ciliate; 

pseudopetioles sometimes present; blades linear to ovate, bases 

slightly to strongly asymmetric. Inflorescences open or contracted panicles, rachises usually visible, even distally, spikelets 

attached obliquely to the pedicels; disarticulation below the 

glumes. Spikelets subglobose to globose, with 2 florets. Glumes 

membranous, apex lanate pubescent, abruptly apiculate; lower 

glumes 1⁄3–2⁄3 as long as the spikelets, 5- to 13-veined, bases saccate, margins overlapping; upper glumes about as long as the 

upper florets, not saccate, 7- to 15-veined; lower florets sterile or 

staminate; lower lemmas membranous, apex lanate pubescent, 

abruptly apiculate; lower paleas present, sometimes reduced; 

upper florets stipitate, bisexual, appearing to be mucronate or 

acuminate; upper lemmas indurate, usually broadly elliptic to 

obovate, margins enclosing the edges of the paleas, apex obtuse, somewhat woolly pubescent, usually dark brown at maturity; upper paleas similar to the lemmas, but saccate below 

FIGURE 138. Koeleria pyramidata. A. Habit. B. Inflorescence 

branches. C. Glumes. D. Floret. Drawn by Linda Ann Vorobik and 

Hana Pazdírková; copyright Utah State University.
NUMBER 107 • 193

and gibbous above. Caryopsis plano-convex, ovoid, or nearly 

orbicular; embryo about 1⁄2 as long as the caryopsis; hila oblong 

to nearly round. x = 9. 

Lasiacis is a neotropical genus of 17 species that extends 

from southern Florida to Peru and Argentina; it is uncommon 

in Mexico.

190. Lasiacis ruscifolia (Kunth) Hitchc., Proc. Biol. Soc. Washington 24: 145. 1911. Panicum ruscifolium Kunth, Nov. 

Gen. Sp. (quarto ed.) 1: 101–102. 1815.

FIGURE 139

Caespitose perennial. Culms 1–8 m long, 5–12 mm thick, 

hollow, arching or clambering. Sheaths glabrous, puberulent, or hirsute with papillose-based hairs, margins ciliate; ligules 0.2–1 mm long, glabrous or ciliate; blades 2–16 cm long, 

8–56 mm wide, ovate to ovate-lanceolate. Panicles 2–22 cm 

long; lower branches to 9 cm long, divergent. Spikelets 2.6–4 mm 

long, globose; lower glumes 1.2–2.2 mm long, 9- to 13-veined; 

lower florets sterile; upper glumes 11- to 13-veined; upper florets 

2.8–3.6 mm long, 2–2.9 mm wide, dark brown to grayish-black 

at maturity; upper lemmas usually with a distinct shelf at the 

base, from which a sterile projection often arises; upper paleas 

usually deeply concave; anthers 1.4–2.3 mm long, white; stigmas 

white. Caryopsis 2–2.5 mm long. 2n = 36.

Distribution and Habitat. Lasiacis ruscifolia

extends from southern Florida to Peru.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: SW Chihuahua, Aug 1885, E. Palmer 10, 10/519

(US); 2.5 km de Satevo en brecha [gap] a San José, 12 Sep 

2003, P. tenorio, J. Rodríguez, M. Hilerio & E. Zarate 23278

(US). Guazapares: among rocks at Temoris station on Chihuahua al Pacifico RR, 7 Aug 1964, 1025 m, I.W. Knobloch 2087

(ENCB). Uruachi: Guasaremos, Río Mayo, 20 Aug, 1936, Gentry 2402 (US).

Leersia Sw.

Plants usually perennial, rarely annual; terrestrial or 

aquatic; rhizomatous or caespitose; synoecious. Culms erect or 

decumbent, often rooting at the nodes, branched or unbranched. 

Leaves equitably distributed along the culm; sheaths open; auricles absent; ligules membranous; pseudopetioles absent; blades

aerial, linear to broadly lanceolate, flat or folded, sometimes 

involute when dry. Inflorescences terminal panicles, usually exserted, axillary panicles sometimes also present; disarticulation

beneath the spikelets. Spikelets bisexual, with 1 floret; florets

laterally compressed, linear to suborbicular in sideview; glumes

absent; calluses not stipelike, glabrous; lemmas and paleas subequal, chartaceous to coriaceous, ciliate-hirsute or glabrous, 

tightly clasping along the margins; lemmas 5-veined, obtuse or 

acute to acuminate, sometimes mucronate, usually unawned; paleas 3-veined, unawned; lodicules 2; anthers 1, 2, 3, or 6; styles

2, bases fused, stigmas laterally exserted, plumose. Caryopsis

laterally compressed; embryos about 1⁄3 as long as the caryopsis; 

hila linear. x = 12.

Leersia is a genus of about 18 aquatic to mesophytic species, growing primarily in tropical and warm-temperate regions. 

Five species are native to North America, and three are found in 

Mexico.

191. Leersia hexandra Sw. Prodr. 21. 1788.

FIGURE 140

Perennial; rhizomatous, rhizomes elongate, not scaly. Culms

25–150 cm tall, 1–1.5 mm thick, decumbent, rooting at the 

nodes, terminal portions erect, often floating, branched or unbranched; nodes pubescent, adjacent portions of the internodes 

glabrous or coarsely scabrous. Sheaths glabrous or coarsely scabrous, margins often ciliate; ligules 1–3 mm long; blades 5–25 cm 

long, 3–15 mm wide, ascending, glabrous or pubescent. Panicles

5–15 cm long, exserted at maturity, with 1(2) branches per node; 

branches 3–10 cm long, appressed to ascending, spikelet-bearing 

to near the base, spikelets appressed to slightly divergent, slightly 

imbricate. Spikelets 3.2–4.7(5) mm long, 0.5–2 mm wide, ovate 

to elliptic. Lemmas ciliate on the keels and margins, short hirsute 

or glabrous elsewhere, apex acute to acuminate; paleas ciliate on 

the keels; stamens 6, anthers 2–3.2 mm long. Caryopsis about 

2mm long, usually not developed. 2n = 48.

FIGURE 139. Lasiacis ruscifolia. A. Habit. Drawn by Linda Ann 

Vorobik and Hana Pazdírková; copyright Utah State University.
194 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Distribution and Habitat. Leersia hexandra

is found in wet areas, usually in freshwater along streams and 

ponds, where it sometimes forms floating mats. It grows in the 

Americas throughout much of the neotropics.

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000).

Leptochloa P. Beauv.

Perennial; caespitose, sometimes stoloniferous. Culms herbaceous, solid, glabrous. Sheaths open, rounded; ligules membranous, ciliate, cilia longer than the membranous base, conspicuous 

tufts of stiff hairs present on either side of the ligules; blades 

linear, flat or folded. Inflorescences terminal, panicles of nondisarticulating spikelike branches, exceeding the leaves; branches 

in 1 or more whorl(s), spikelets in 2 rows on the abaxial side of 

the branches, axes terminating in a functional spikelet. Spikelets 

laterally or dorsally compressed, with 2–5 florets, lowest 1–2 florets bisexual, distal 1–3 florets progressively reduced and sterile; 

disarticulation above the glumes, all the florets falling as a unit; 

glumes much shorter than the spikelets, membranous; lower 

glumes linear, acuminate; upper glumes lanceolate-ovate, awned; 

calluses bearded; lowest lemmas linear-lanceolate, 3-veined, 

veins prolonged into 3 awns; central awns longer than lateral 

awns; paleas 2-keeled, acute; distal floret(s) 1- to 3-awned; lodicules 2; anthers 2 or 3. Caryopsis sulcate; embryos 1⁄2 as long as 

the caryopsis; hila punctate. x = 10.

Leptochloa has seven species, two of them are native to the 

Americas (Peterson et al., 2015). Both species of Leptochloa in 

Chihuahua have a disjunct distribution with populations in North 

America being widely separated from those in South America.

KEY TO SPECIES OF LEPTOCHLOA

1. Lowest lemma awns subequal, the central awns 8–12 mm long, equaling or slightly longer than the lateral awns . . . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L. crinita

1. Lowest lemma awns unequal, the central awns 8–12 mm long, the lateral awns 0.5–1.5 mm long . . . . . . . . L. pluriflora

192. Leptochloa crinita (Lag.) P. M. Peterson & N. Snow, Ann. 

Bot. 109: 1327. 2012. Chloris crinita Lag., Varied. Ci. 2(4): 

143. 1805. Trichloris crinita (Lag.) Parodi, Revista Argent. 

Agron. 14(1): 63. 1947. 

Perennial; caespitose, sometimes stoloniferous. Culms to 

100 cm tall. Sheaths glabrous or sparsely hirsute; ligules to 3 mm; 

blades to 20 cm long, 5–10 mm wide, scabrous. Panicles with 

6–20 branches in several closely spaced whorls, appearing as a 

single terminal cluster; branches to 15 cm long, erect, with 7–9 

spikelets per cm. Spikelets with 1 bisexual and 1(2) sterile floret(s); 

lower glumes 0.8–1.1 mm long; upper glumes 2–2.5 mm long, 

awned, awns to 2 mm; lowest lemmas 2.4–3.8 mm long, about 

0.5 mm wide, narrowly lanceolate to elliptic, scabrous, particularly distally, apex bilobed and 3-awned, central awns 8–12 mm 

long, equaling or slightly longer than the 5–12 mm lateral awns; 

first sterile florets 1–1.5 mm long, narrowing to 3 subequal 5–7 

mm awns; second sterile florets, if present, similar but smaller. 

Caryopsis 1.7–2.3 mm long, strongly dorsally flattened. 2n = 40.

FIGURE 140. Leersia hexandra. A. Culm and inflorescence. B. Two spikelets. Drawn by Linda Ann 

Vorobik; copyright Utah State University.
NUMBER 107 • 195

Distribution and Habitat. Leptochloa crinita

is a native species that grows in the southwestern United States 

and northern Mexico, and it is disjunct in northern Argentina.

Specimens Examined. MEXICO. Chihuahua.

Ahumada: aprox. 25 km al N del poblado [village] Flores Magón, 

7 Oct 1995, 1140 m, R. Corral, P. Olivas & J.O. Torres RCD6482

(UACJ). Chihuahua: Valley near Chihuahua, 20 Sep 1885, C.G. 

Pringle 475 (US); near El Carmen, 10 Oct 1935, LeSueur Mex070 (US). Jiménez: Western margin of the Laguna de Palomas, 18 

Aug 1972, 1230 m, F. Chiang, T. Wendt, & M.C. Johnston 8652

(MEXU). Juárez: Medanos de Samalayuca, 13 Oct 1997, km 70, 

I. Enríquez, S. Ordoñez & J. Leyva IEA21 (UACJ). Meoqui: In 

town of Meoqui, along hwy 45, SE of city of Chihuahua, 25 Sep 

2004, 1140 m, R.M. King & R.M. Garvey 13463 (CIIDIR).

193. Leptochloa pluriflora (E. Fourn.) P. M. Peterson & N. Snow, 

Ann. Bot. 109: 1327. 2012. Trichloris pluriflora E. Fourn., 

Mexic. Pl. 2: 142. 1886. Chloris pluriflora (E. Fourn.) Clayton, Kew Bull. 21: 102. 1967.

Perennial; stoloniferous or caespitose. Culms to 150 cm 

tall. Sheaths glabrous or sparsely hirsute; ligules to 3 mm; blades 

to 30 cm long, to 10 mm wide, scabrous or sparsely hirsute. 

Panicles with 7–20 branches in a few, evidently separate whorls; 

branches to 20 cm long, ascending, with 7–9 spikelets per centimeter. Spikelets with 1–2 bisexual florets, a third floret with 

a rudimentary pistil and stamens sometimes present below the 

(1)2–3 sterile florets; lower glumes 2–3 mm long; upper glumes 

3–5 mm long; lowest lemmas 3–5 mm long, mostly glabrous, 

margins short-ciliate near the middle, sparsely scabrous distally, 

apex 3-awned, central awns 8–12 mm long, lateral awns 0.5–

1.5 mm long; lowest sterile florets 1.5–3 mm long, about 0.3 mm 

wide, mostly glabrous, margins sometimes short-ciliate near the 

middle, apex 3-awned, central awns to 8 mm long, lateral awns 

mucronate. Caryopsis 1.8–2.2 mm long, strongly dorsally compressed to trigonous in transverse section. 2n = 80.

Distribution and Habitat. Leptochloa pluriflora is native from southern Texas to Guatemala and disjunct in 

Ecuador to Argentina.

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000) and Herrera Arrieta and 

Cortés Ortiz (2010). 

Lolium L.

Annual or perennial; caespitose, sometimes short rhizomatous. Culms slender to stout, erect to decumbent, rarely prostrate. Sheaths open, rounded, glabrous, sometimes scabrous; 

ligules membranous, glabrous; auricles sometimes present; 

blades flat, linear. Inflorescences distichous spikelike or paniculate. Inflorescence a spike, with solitary spikelets oriented 

edgewise to the rachis, perpendicular to the rachis concavities or panicles, open and much branched. Spikelets laterally 

compressed, with 2–22 florets, distal florets reduced; rachillas

glabrous; disarticulation above the glumes. Glumes usually 1 

or 2, lanceolate to oblong, rounded over the midvein, membranous to indurate, 3- to 9-veined, unawned; lower glumes

absent from all but the terminal spikelet in plants with spike 

inflorescences or both glumes present in plants with open panicles; calluses short, blunt, glabrous or sparsely hairy; lemmas

lanceolate, ovate or oblong, rounded over the midvein, membranous, chartaceous, 3- to 7-veined, apex sometimes hyaline, 

unawned or awned, awns subterminal, more or less straight; 

paleas membranous, usually smooth, keels ciliolate; lodicules

2, free, lanceolate to ovate; anthers 3; ovaries glabrous. Caryopsis dorsally compressed, oblong, broadly elliptic or ovate, 

longitudinally sulcate; hila linear, in the furrow; embryos 1⁄5–1⁄3

as long as the caryopsis. x = 7.

Lolium comprises 11 species that are native to Europe, temperate Asia, and northern Africa. All have been introduced to 

North America, often as forage grasses.

KEY TO SPECIES OF LOLIUM

1. Inflorescence an open panicle with numerous branches; all spikelets with 2 well-developed glumes; summit of leaf sheaths 

with auricles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L. arundinaceum

1. Inflorescence a spike with solitary spikelets oriented edgewise to the rachises; most spikelets, except the very terminal ones, 

with a single glume; summit of leaf sheaths without auricles.

2. Plants long-lived perennials; 2–10 florets per spikelet; lemmas unawned or awned, awns to about 8 mm long . . . . . L. perenne

2. Annual or short-lived perennials; 10–22 florets per spikelet; lemmas usually awned, awns to 15 mm long, rarely unawned

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L. multiflorum

194. Lolium arundinaceum* (Schreb.) Darbysh., Novon 3(3): 

241. 1993. Festuca arundinacea Schreb., Spic. Fl. Lips. 57. 

1771. Schedonorus arundinaceus (Schreb.) Dumort., Observ. Gramin. Belg. 106. 1824.

FIGURE 141

Perennial; sometimes rhizomatous. Culms to 1.5(2) m tall. 

Leaves convolute in young shoots; auricles ciliate, having at 

least 1 or 2 hairs along the margins; ligules 1(2) mm long; blades

11–30 cm long, 4–12 mm wide. Panicles 10–35 cm; branches

at the lowest node usually 2, shorter branch with (1)2–9(13) 

spikelets, longer branch with (3)4–13(19) spikelets. Spikelets

8–15.5 mm long, 2–3.5 mm wide, with 3–6(9) florets; lower 

glumes 3–6 mm long; upper glumes 4.5–7(9) mm long; lemmas

(4)5–9(11.5) mm long, usually scabrous or hirsute, at least distally, rarely smooth, awns absent or to 4 mm long, terminal or 
196 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

attached up to 0.4 mm below the apex; paleas slightly shorter 

than to slightly longer than the lemmas; anthers 2.5–4 mm long. 

Caryopsis 2–4 mm long, 0.9–1.6 mm wide. 2n = 28, 42, 56, 

63, 70.

Distribution and Habitat. Lolium arundinaceum is a Eurasian species that has been introduced to North 

America. It is grown for forage, soil stabilization, and coarse 

turf. It is now cultivated in all but the coldest and most arid parts 

of North America and often escapes. 

Specimens Examined. MEXICO. Chihuahua. 

Ocampo: Near Mirador de Cascada de Basaseachic, 7 Sep 

2008, slopes with Pinus, 2022 m, P.M. Peterson & J.M. Saarela 

22100 (US).

195. Lolium multiflorum* Lam., Fl. Franc. 3: 621. 1779.

FIGURE 142

Annual or short-lived perennial. Culms to 150 cm. Leaves

rolled in the bud; blades usually 10–30 cm long, (2)3–8 (13) 

mm wide. Spikes 15–45 cm long, with 5–38 spikelets; rachises

0.8–2 mm thick at the nodes, not flexuous. Spikelets 8–31 mm 

long, 2–10 mm wide, with (10)11–22 florets; glumes 5–18 mm 

long, 1⁄4–1⁄2 as long as the florets, membranous to indurate; lemmas 4–8.2 mm long, 1–2 mm wide, usually awned, awns to 15 

mm long, attached 0.2–0.7 mm below the apex, rarely unawned; 

paleas shorter than to slightly longer than the lemmas; anthers

FIGURE 141. Lolium arundinaceum. A. Inflorescence. B. Ligule. 

C. Spikelet. D. Lemma. Drawn by Annaliese Miller; copyright Utah 

State University.

FIGURE 142. Lolium multiflorum. A. Spikelet. B. Florets. Drawn by 

Cindy Roché; copyright Utah State University.
NUMBER 107 • 197

(2.5)3–4.5(5) mm long. Caryopsis 2.5–4 mm long, 0.7–1.5 mm 

wide, 3 or more times longer than wide. 2n = 14.

Distribution and Habitat. Lolium multiflorum, a European species, now grows in most of North America. It is planted as a cover crop, as a temporary lawn grass, for 

roadside restoration, and for soil or forage enrichment; it often 

escapes from cultivation, becoming established in disturbed sites.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: La Campana, Ojo del Arco, 11 Sep 1973, 1500 m, 

Valdés-Reyna VR-188 (ENCB, RELC); Rancho Experimental La 

Campana, Jardín de observación de zacates [grass observation 

garden], 17 May 1975, 1500 m, Valdés-Reyna VR-902 (ENCB, 

RELC).

196. Lolium perenne* L., Sp. Pl. 1: 83. 1753.

FIGURE 143

Plants long-lived perennial. Culms to 100 cm. Leaves

folded in the bud; blades usually 10–30 cm long, (1)2–4(6) mm 

wide. Spikes 3–30 cm long, with 5–37 spikelets; rachises 0.5–

2.5 mm thick at the nodes, often flexuous. Spikelets 5–22 mm 

long, 1–7 mm wide, with (2)5–9(10) florets; glumes 3.5–15 mm 

long, (1⁄3)1⁄2–3⁄4 as long as to slightly exceeding the distal florets, 

membranous to indurate; lemmas 3.5–9 mm long, 0.8–2 mm 

wide, unawned or awned, awns to about 8 mm long, attached 

0.2–0.7 mm below the apex; paleas shorter than to slightly longer than the lemmas; anthers 2–4.2 mm long. Caryopsis 3–5.5 

mm long, 0.7–1.5 mm wide, 3 or more times longer than wide. 

2n =14.

Distribution and Habitat. Lolium perenne, a 

Eurasian species, is now established in disturbed areas throughout much of North America. It is commercially important, being 

included in lawn seed mixtures as well as being used for forage 

and erosion prevention.

Specimens Examined. MEXICO. Chihuahua. 

Práxedis G. Guerrero (San Ignacio): a 2 km al S del poblado del 

mismo nombre [village of the same name], Rancho Escuela de la 

Univ. Autónoma de Cd. Juárez, 5 May 1995, 1090 m, R. Corral, 

P. Olivas, E. Pérez, K. Chico & A. Soutyrine RCD6078 (UACJ); 

Rancho Escuela, 16 Aug 1997, I. Enriquez, S. Ordoñez, L. Sushii, S. Carrasco, A. Perales & N. Loya IEA7 (UACJ). 

Luziola Juss

Perennial; aquatic, usually rooted, sometimes floating; stoloniferous, sometimes mat-forming; monoecious. Culms erect 

or prostrate, sometimes rooting at the nodes, branched, emergent or immersed. Leaves cauline; sheaths open, not inflated 

or somewhat inflated; ligules hyaline; pseudopetioles present 

or absent; blades flat, linear to lanceolate or narrowly elliptic, 

glabrous, pubescent, or scabrous. Inflorescences panicles, racemes, or spikes, exserted or enclosed, staminate and pistillate 

spikelets usually in separate inflorescences, pistillate inflorescences at the lower or middle nodes, staminate inflorescences 

FIGURE 143. Lolium perenne. A. Habit. B. Inflorescence. C. Spikelet. D. Floret. Drawn by Cindy Roché; copyright Utah State 

University.
198 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

usually terminal; disarticulation below the spikelets. Spikelets

unisexual, laterally compressed to subterete, with 1 floret; 

glumes absent; calluses glabrous; lemmas and paleas subequal, ovate or lanceolate, membranous or hyaline, unawned; 

lodicules 2; staminate lemmas and paleas obscurely few- to 

several-veined; anthers 6–16; pistillate lemmas 5- to 14-veined, 

margins not clasping the margins of the paleas, unawned; paleas 3- to 10-veined; styles 2, bases fused, stigmas laterally or 

terminally exserted, plumose. Fruits achenes, ovoid, ellipsoid, 

or subglobose, beaked by the persistent style bases; pericarps

shell-like, partially free from the seed, smooth or striate, crustaceous; seeds ovoid to subglobose; embryos basal; hila linear. 

x = 12.

Luziola is a genus of 11 species that range from the southeastern United States to Argentina (Clayton et al., 2006). Only 

L. fluitans is native to North America.

197. Luziola fluitans (Michx.) Terrell & H. Rob., Bull. Torrey 

Bot. Club 101(5): 244. 1974. Zizania fluitans Michx., Fl. 

Bor.-Amer. 1: 75. 1803.

Hydrochloa caroliniensis P. Beauv.

FIGURE 144

Plants stoloniferous; mostly immersed. Culms to 1+ m long, 

to 2 mm thick; bases prostrate and rooting at the nodes. Leaves

mainly cauline, usually crowded distally, streaming in the current 

FIGURE 144. Luziola fluitans. A. Habit. B. Culm. C. Staminate floret. D. Immature pistillate floret. E. Mature pistillate floret. F. Achene. Drawn by Sandy Long; copyright Utah State University.
NUMBER 107 • 199

or floating on the surface, distal leaves sometimes emergent; 

sheaths glabrous; ligules 0.5–2 mm long, subtriangular to truncate, sometimes erose; pseudopetioles sometimes present; blades

1–5(8) cm long, 1–4 mm wide, glabrous, sometimes pilose basally, 

scaberulous. Inflorescences spikes or racemes, spikelets sessile or 

shortly pedicellate. Staminate inflorescences 1–2 cm long, terminal, partially exserted from the sheaths, emergent at anthesis, with 

2–4 spikelets; staminate florets 3–5 mm long; lemmas narrowly 

ovate, usually 5-veined; paleas similar, usually 3-veined; stamens 

6, anthers 2–3.7 mm long, linear. Pistillate inflorescences 0.5–2 cm 

long, mostly included in the subtending sheaths, only the stigmas 

visible, with 2–4 spikelets; pistillate florets 1.4–3 mm long, caducous; lemmas 5- to 9-veined, acuminate; paleas similar to the 

lemmas, 3- to 7-veined; stigmas 3–6 mm long. Achenes 1.3–2 mm 

long, ovoid, asymmetrical, minutely striate, lustrous. 2n = 24.

Distribution and Habitat. Luziola fluitans

grows in fresh to slightly saline lakes and streams in the southeastern United States and Mexico. 

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000) and Herrera Arrieta and 

Cortés Ortiz (2010). 

Melica L.

Perennial; caespitose or soboliferous, not or only short rhizomatous. Culms sometimes forming a basal corm; nodes and 

internodes usually glabrous. Sheaths closed almost to the top; 

auricles sometimes present; ligules thinly membranous, erose to 

lacerate, usually glabrous, those of the lower leaves shorter than 

those of the upper leaves; blades flat or folded, glabrous or hairy, 

particularly on the adaxial surfaces, sometimes scabrous. Inflorescences terminal panicles; primary branches often appressed; 

secondary branches appressed or divergent; pedicels either more 

or less straight or sharply bent below the spikelets, scabrous 

to strigose distally; disarticulation below the glumes in species 

with sharply bent pedicels, above the glumes in other species. 

Spikelets with 1–7 bisexual florets, terminating in a sterile structure, the rudiment, composed of 1–4 sterile florets; rudiments

sometimes morphologically distinct from the bisexual florets, 

sometimes similar but smaller; glumes chartaceous or papery, 

distal margins wide, translucent; lower glumes 1- to 9-veined; 

upper glumes 1- to 11-veined; calluses glabrous; lemmas membranous basally, sometimes becoming coriaceous at maturity, 

glabrous or with hairs, (4)5- to 15-veined, usually unawned, 

sometimes awned, awns to 12 mm long, straight; paleas from 1⁄2

as long as to almost equaling the lemmas, keels usually ciliate; 

lodicules fused into a single, collarlike structure extending 1⁄2–2⁄3

around the base of the ovaries; anthers (2)3. Caryopsis smooth, 

glabrous, longitudinally furrowed, falling from the floret when 

mature. x = 9.

Melica includes 92 species, which grow in temperate regions 

of the world but is absent from Australia (Soreng et al., 2017b).

KEY TO SPECIES OF MELICA

1. Spikelets 6–8 mm long, with 1 bisexual and 1 rudimentary florets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. montezumae

1. Spikelets 8–16 mm long, with 4 bisexual and 1 rudimentary florets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. porteri

198. Melica montezumae Piper, Proc. Biol. Soc. Wash. 18: 144. 

1905.

FIGURE 145

Plants caespitose, not rhizomatous. Culms 14–100 cm tall, 

not forming corms; internodes smooth. Sheaths glabrous or 

scabrous; ligules 2.5–7 mm long; blades 1.2–3 mm wide, abaxial surfaces glabrous, scaberulous, adaxial surfaces puberulent. Panicles 5–25 cm long; branches 1–5 cm long, appressed 

to reflexed, straight, with 2–9 spikelets; pedicels sharply bent 

below the spikelets; disarticulation below the glumes. Spikelets

6–8 mm long, with 1 bisexual floret; lower glumes 5.5–8 mm 

long, 1.8–3 mm wide, 5-veined; upper glumes 5–8 mm long, 

0.7–1.5 mm wide, 3- to 5-veined; lemmas 4.5–8 mm long, 9- to 

15-veined, veins prominent, tuberculate, proximal portion with 

flat, twisted hairs, distal portion glabrous, chartaceous, apex 

emarginate to acute, unawned; paleas about 3⁄4 the length of the 

lemmas; anthers 1.5–3 mm long; rudiments 2–3 mm long, obovoid or obconic, clublike, not resembling the bisexual florets. 

2n = 18.

Distribution and Habitat. Melica montezumae grows primarily in shady locations in the mountains of west 

Texas and adjacent Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: Chihuahua, 1885, E. Wilkinson 342 (US). Jiménez: 

Santa Eulalia Mts, 6 Apr 1885, C.G. Pringle 430 (US). 

199. Melica porteri Scribn., Proc. Acad. Nat. Sci. Philadelphia 

37: 44, t. 1, f. 17–18. 1885.

FIGURE 146

Plants not or loosely caespitose, short rhizomatous. Culms

55–100 cm tall, not forming corms; internodes smooth, basal internodes not thickened. Sheaths often scabrous on the keels, otherwise smooth; ligules 1–7 mm long; blades 2–5 mm wide, both 

surfaces glabrous, scaberulous. Panicles 13–25 cm; branches

1–9 cm long, straight and appressed or flexible and ascending 

to strongly divergent, with 1–12 spikelets; pedicels sharply bent 

below the spikelets; disarticulation below the glumes. Spikelets 8–16 mm long, 1.5–5 mm wide, parallel-sided when mature, with 2–5 bisexual florets; rachilla internodes 1.9–2.1 mm 

long; glumes green, pale, or purplish-tinged; lower glumes 3.5–6 

mm long, 2–3 mm wide, 3- to 5-veined; upper glumes 5–8 mm 

long, 2–3 mm wide, 5-veined; lemmas 6–10 mm long, glabrous, 

chartaceous on the distal 1⁄3, 5- to 11-veined, veins conspicuous, 

apex rounded to acute, unawned; paleas about 2⁄3 the length of 
200 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

the lemmas; anthers 1–2.5 mm long; rudiments 1.8–5 mm long, 

acute to acuminate, resembling the bisexual florets. 2n = 18.

Distribution and Habitat. Melica porteri

grows on rocky slopes and in open woods, often near streams. It 

grows from Colorado and Arizona to central Texas and northern 

Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: Chihuahua, 9 Oct 1888, C.G. Pringle 2045 (US).

Melinis P. Beauv.

Annual or perennial; habit various. Culms erect, decumbent, or prostrate. Sheaths open; ligules of hairs or membranous 

and ciliate. Inflorescences terminal, simple panicles or panicles 

of spikelike primary branches, usually with capillary secondary 

branches and pedicels; disarticulation below the glumes, sometimes also below the upper florets, the upper florets then falling 

first. Spikelets with 2 florets; lower glumes present or absent, 

0- to 1-veined, unawned; upper glumes equaling or exceeding the 

florets, sometimes gibbous basally, 5- to 7-veined, emarginate to 

bilobed, awned or unawned; lower florets staminate or sterile; 

lower lemmas similar to the upper glumes, but not gibbous; upper 

florets bisexual, laterally compressed; upper lemmas subcoriaceous, glabrous, smooth, unawned; upper paleas resembling the 

upper lemmas; lodicules 2, fleshy or membranous. x = 9.

Melinis is an African and western Asian genus of 22 species 

that grow in savannahs, open grasslands, and disturbed places.

200. Melinis repens* (Willd.) Zizka, Biblioth. Bot. 138: 55. 1988. 

Saccharum repens Willd., Sp. Pl. 1: 322. 1797. RhynchelyFIGURE 145. Melica montezumae. A. Habit. B. Florets. C. Flat, 

twisted hairs. Drawn by Linda Ann Vorobik; copyright Utah State 

University.

FIGURE 146. Melica porteri. A. Habit. B. Spikelet. C. Glumes. 

D. Spikelets. E. Floret. Drawn by Linda Ann Vorobik; copyright 

Utah State University.
NUMBER 107 • 201

trum repens (Willd.) C. E. Hubb., Bull. Misc. Inform. Kew 

1934(3): 110.1934. 

FIGURE 147

Annual or short-lived perennial. Culms (20)40–150 cm 

long, decumbent, usually rooting at the lower nodes; nodes pubescent; internodes glabrous or with papillose-based hairs, hairs 

to 4.7 mm long. Sheaths glabrous or with papillose-based hairs, 

hairs 0.5–4.7 mm; ligules 0.7–2.2 mm long, of hairs; blades 

3.6–27 cm long, 2–9(14) mm wide, flat, glabrous or pubescent, 

with or without papillose-based hairs. Panicles (4)6–22 cm long, 

(1.5)2.5–12 cm wide; primary branches to 11 cm long, ends of 

the primary branches, secondary branches, and pedicels capillary; pedicels 0.6–5.3 mm long, usually hairy distally, hairs to 

6.3 mm. Spikelets 2–5.7 mm; callus hairs to 4 mm long; lower 

glumes 0–1.7 mm long, pubescent, sometimes with papillosebased hairs, apex rounded, truncate, or slightly cleft; upper 

glumes (1.9)2.3–4.9 mm long, enclosing the upper florets, gibbous basally, densely pubescent, the hairs to 7 mm long, sometimes papillose-based, varying from white to rose or darkish 

purple, apex tapering, beaked, glabrous, unawned or awned, 

awns to 4.1 mm; lower florets staminate or sterile; lower lemmas 1.9–4.8 mm long, unawned or with awns to 4.2 mm; lower 

paleas 0.9–4 mm long; anthers (0.8)1.5–2.6 mm long, orangebrown to orange; upper lemmas 1.8–2.7 mm long, glabrous; anthers 3, 1.2–1.7 mm long, orange-brown to orange. Caryopsis 

1.3–1.9 mm long, 0.6–0.9 mm wide. 2n = 36.

Distribution and Habitat. Melinis repens is 

native to Africa and western Asia. It is now established throughout the subtropics, including the southern portion of North 

America and northern Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: terracería [dirt road] Batopilas–La Bufa, 1.4 km del 

entronque [junction] Mesa de la Yerbabuena, 14 Feb 2003, R.Bye 

& col. 31361 (US); Parque Nacional Barranca del Cobre, 3.2 km 

S of La Bufa on road to Batopilas, tropical forest, 1050 m, P.M. 

Peterson, Annable & Valdés-Reyna 10859 (US). Madera: Mesa 

del Yerbanís, ejido El Largo, 12 Oct 1990, bosque [forest] de 

Quercus, 1900 m, O. Bravo 1854 (CIIDIR, MEXU); Ciénega 

Ojo de la Vibora, ejido El Largo, 14 Aug 1990, bosque de encino 

[oak], 1800 m, A. Benítez 1919 (CIIDIR, MEXU). Matamoros: 

19.3 km S of Villa Matamoros on hwy 45 to Durango, 27 Sep 

1988, grassland, 1800 m, P.M. Peterson & Annable 5979 (ENCB, 

US). Ocampo: Ca 1 km W of W boundary of Parque Nacional 

“Cascada de Basaseachic,” 13 km from the Cahuisori–Ocampo 

road on the road to Candamena, 2.25 km below Cruz, 23 Sep 

1994, 1570 m, Spellenberg, Corral & Estrada 12145 (NMC). Temosachi: Nabogame, 5 Aug 1988, 1800 m, Laferr. 1623 (NMC).

Microchloa R. Br.

Perennial (rarely annual); erect and caespitose, or decumbent and mat-forming. Culms 5–60 cm; nodes glabrous. Leaves 

mostly basal; ligules membranous and ciliate or of hairs; blades 

FIGURE 147. Melinis repens. A. Habit. B. Culm and inflorescence. 

C. Spikelet. D. Upper floret. Drawn by Linda Ann Vorobik and 

Karen Klitz; copyright Utah State University.
202 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

often stiff, convolute. Inflorescences terminal, panicles with 

a solitary (rarely 2), slender, spikelike branch; rachises curved 

or falcate, semicircular or crescentic in cross section. Spikelets 

solitary, with 1(2) floret, terete to dorsally compressed; florets 

bisexual; disarticulation above the glumes; glumes subequal, exceeding the florets, 1-veined; lower glumes asymmetric, keeled, 

keels somewhat twisted; upper glumes symmetric, flat, midveins 

straight; lemmas membranous or hyaline, 3-veined, veins hairy; 

paleas with 2 pubescent keels. Caryopsis 0.9–1.5 mm long, glabrous. x = 10, 12.

Microchloa includes six species that occur throughout the 

tropics (Cope 1999; Peterson et al., 2015). Most species grow in 

open mesic to xeric habitats, often in shallow, hard soils.

201. Microchloa kunthii Desv., Mém. Soc. Agric. Angers 1: 179. 

1831.

Perennial; forming small, dense tufts. Culms 5–30 cm long. 

Sheaths generally shorter than the internodes; ligules 1–1.5 mm 

long, ciliate; blades 1–1.5 mm wide, flat or folded, with thick, 

scabrous, white margins; cauline blades 1–2.5 cm long; innovation blades to 6 cm. Panicle branches 6–15 cm long; rachises 

ciliate. Spikelets 2.5–3.5 mm long; lemmas 2–2.5 mm long, keels 

pilose, margins densely pilose, hairs 0.2–1 mm long. 2n = 24, 40.

Distribution and Habitat. Microchloa kunthii grows on granitic outcrops on rocky slopes. Its range extends 

southward from the mountains in Arizona and the Big Bend region of Texas through Mexico to Guatemala.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: Ejido de Guazarachic, 9 Aug 1974, pinyon woodlands, 

2250 m, M.F. Robert 3216 (ENCB); 56.4 km W of Parral on 

road to Balleza and 35.5 km S of Balleza on Mex 432, near 

Corral de Duarte, 18 Sep 1991, pine–oak forest, 2210 m, P.M. 

Peterson, Annable & Valdés-Reyna 10703 (CIIDIR, US). Batopilas: Arroyo Baqueachi, at 1/2 km E of small villaje [village], 

28 Aug 2003, grassland, 2004 m, P.M. Peterson & P. Catalán 

17571 (US). Bocoyna: 18.7 mi S of San Juanito on road to 

Creel, 2200 m, P.M. Peterson & Annable 5862b (US). Chinipas: Sierra Saguarivo, 1.3 mi W of Curahui, 9 Sep 2008, tropical deciduous forest, 1001 m, P.M. Peterson & J.M. Saarela 

22152 (US). Chihuahua: Dry gravelly soil, hills and plains near 

Chihuahua, 6 Aug 1885, C.G. Pringle 425 (ENCB, US); 40 km 

W of Chihuahua, 20 Aug 1939, 1735 m, L. H. Harvey 1550

(US); km 28 Cd. Chihuahua–Cd. Cuauhtémoc, 27 Oct 1954, 

Hern.-Xol. & C. Tapia N-281 (US); La Campana Experimental 

Station & Rancho El Arco Iris, 81–84 km along Pan American Hwy to Chihuahua City, Oct 1977, J.K. Meents & W.H. 

Moir 100 (NMC); La Campana, Potrero El Plan, 4 km sureste 

[SE] carr. [hwy] Panamericana, 11 Sep 73, pastizal [pastureland], 1500 m, Valdés-Reyna VR-206 (RELC); Gravelly plains 

near Chihuahua, 6 Sep 1888, C.G. Pringle 1100 (MEXU). Cuauhtémoc: 16 mi W of Cuauhtémoc, 31 Aug 1958, Reeder & 

C. Reeder 3133 (US). Cusihuiriáchi: 4 km al sur de Estación 

Cusihuiriáchic, 10 Aug 1975, bosque de pino–encino [pine–oak 

forest], 2140 m, J.M. Peña JMP-125 (RELC). Guachochi: NW 

of Norogachic, ca. 3 road miles; airport near locality called 

to Achiachic, 23 Aug 1978, pine forest, 2500 m, Bye 8808

(MEXU). Guerrero: 35.4 km SW of La Junta and approx. 74 

km N of Creel, 24 Sep 1988, pine woods, 2200 m, P.M. Peterson & Annable 5839 (ENCB, US); 32.3 km SW of La Junta on 

road to Creel, 10 Sep 1989, pine forest, 2310 m, P.M. Peterson, 

Annable & Y. Herrera 7988 (ENCB, US); carr. la Junta–San 

Juanito, 17 km, 22 Sep 1997, 2290 m, B. Tah V. 2 (MEXU). 

Manuel benavides: E Chihuahua, vicinity of Pirámide, 12 Aug 

1941, I.M. Johnston 8120 (MEXU, US). Matamoros: 5 km al S 

de Villa Matamoros, carr. Parral–Durango, 14 Sep 1991, pastizal, 2000 m, J.L. Reyes s/n (MEXU); 18.2 km SE of Villa Matamoros on Mex 45 to Durango, 1780 m, oaks, 22 Sep 1991, 

P.M. Peterson, Annable & Valdés-Reyna 10866 (US). Riva Palacio: Majalca (Pilares), 11 Aug 1939, L. H. Harvey 1452 (US); 

Col. Cumbres de Majalca, 33.8 km W of Mex 45, N of Chihuahua City, 7 Sep 1989, pine forest, 2190 m, P.M. Peterson, 

Annable & Y. Herrera 7954 (ENCB, US). San Francisco del 

Oro: 21 km W of Parral and approx. 3.2 km N on dirt road to 

Torrencillo, 26 Sep 1988, grassland, 2000 m, P.M. Peterson & 

Annable 5962 (ENCB, US). 

Muhlenbergia Schreb.

Annual or perennial; hermaphrodites or occasionally monoecious; often caespitose, sometimes mat-forming, usually rhizomatous, rarely stoloniferous. Culms 2–300 cm tall, erect, 

geniculate, or decumbent, usually herbaceous, sometimes becoming woody; internodes solid or hollow. Sheaths open, auricles absent; ligules membranous or hyaline, sometimes firm or 

coriaceous, acuminate to truncate, sometimes minutely ciliolate, 

sometimes with lateral lobes longer than the central portion; 

blades narrow, flat, folded, or involute, sometimes arcuate. Inflorescences terminal, sometimes also axillary, open to contracted 

or spikelike panicles; disarticulation usually above the glumes, 

occasionally below the pedicels. Spikelets 1(2–3)-flowered, laterally compressed or terete; glumes subequal in length, mostly 

shorter than the lemmas, or as long as or exceeding the lemmas, usually (0)1(2 or 3)-veined, apex entire, erose, or toothed, 

truncate to acuminate, sometimes mucronate or awned; lower 

glumes sometimes rudimentary or absent, occasionally bifid; 

upper glumes shorter than to longer than the florets; lemmas 

membranous or rather firm, glabrous, scabrous, or with short 

hairs, 3-veined (occasionally appearing 5-veined), callus glabrous or hairy, apex awned, mucronate, or awnless; awns, if 

present, straight, flexuous, sinuous, or curled, sometimes borne 

between 2 minute teeth; paleas membranous or rather firm, welldeveloped, about as long as or shorter than the lemma, 2-veined, 

rounded on the back; lodicules 2, short, fleshy, truncate; lateral 

margins thin; ovary glabrous, styles free to their bases, stigmas 2; 

stamens (1 or 2)3, anthers purple, orange, yellow, or olivaceous. 

Caryopsis elongate, fusiform or ellipsoid, slightly dorsally compressed, usually not falling free from the lemma and palea. Cleistogamous panicles sometimes present in the axils of the lower 

cauline leaves, enclosed by a tightly rolled, somewhat indurate 

sheath. Chromosome number x = 8, 9, 10.
NUMBER 107 • 203

Muhlenbergia contains approximately 182 species, most of 

them native to the Americas; 6 species occur in southeastern 

Asia (Peterson and Annable 1990, 1991, 1992; Herrera Arriata 

1998; Peterson 2003b; Herrera Arrieta and Peterson 2007; Wu 

and Peterson, 2006; Peterson et al., 2007, 2010; Soreng et al., 

2017b).

KEY TO SPECIES OF MUHLENBERGIA

1. Spikelets in clusters of 3 to 5 or more; lemmas usually with veins (lateral or central) excurrent into awns.

2. Spikelets subtended by bristles on 1 side, clustered; leaves with prominent auricles . . . . . . . . . . . . . . . . . M. pereilema

2. Spkelets in varied inflorescences, never subtended by bristles on 1 side; leaves without auricles.

3. Central spikelet sessile to short-pedicellate, pedicels up to 0.5 mm long; glumes lobes acute or awned, the awn 

terminal, 2–4 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. cenchroides

3. Spikelets all pedicellate, pedicels 0.5–3 mm long; glumes lobes obtuse or rounded, wide and papiraceous; unawned 

or with a mucro 0.5–1 mm long. 

4. Fertile floret mucronate or with an awn less than 1.5 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . M. imperfecta

4. Fertile lemma awned, the awn 3–8(11) mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. uniseta

1. Spikelets not in clusters of 3, if in clusters then in pairs; lemmas with veins not excurrent into awns.

5. Inflorescence 1-sided raceme-like panicles; branches 1 per node; spikelets in pairs, at the end of branches . . . . . . . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. tarahumara

5. Inflorescence several-sided panicles or raceme-like, never 1-sided; branches 1 or more per node; spikelets never in 

pairs.

6. Lemma veins densely silky-pubescent.

7. Annual plants, erect to geniculate; lemma 1.3–1.7(1.9) mm long; pedicels of terminal spikelet on each branch 

nodding to reflexed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. shepherdii

7. Perennial plants, densely tufted, erect; lemma 2.3–3.2(3.8) mm long; pedicels of the terminal spikelet on each 

branch straight, flexuous to occasionally nodding to reflexed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. tricholepis

6. Lemma veins not densely silky-pubescent. 

8. Spikelets usually 2-flowered, the perfect floret sessile and the pedicellate floret staminate to neutral, plumbeous.

9. Annual plants; ligules 1.6–3.2 mm long; palea veins usually extended into awns . . . . . . . . . . . M. decumbens

9. Perennial plants; ligules 6–10 mm long; palea veins not extended into awns . . . . . . . . . . . . . . . . . M. ligulata

8. Spikelets 1-flowered, with variable colors and textures.

10. Annual plants.

11. Glumes and lemmas awnless, the lemma sometimes mucronate.

12. Lemmas 2.6–3.2 mm long, with prominent veins, somewhat dorsally compressed, oblong-ellipsoid; 

culms 30–80 cm tall, stout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. schmitzii

12. Lemmas up to 2.5 mm long, with inconspicuous veins, rounded, narrowly lanceolate to elliptic-oblong; 

culms up to 40 cm tall, slender.

13. Glumes longer than the lemma, acuminate.

14. Lemma appressed-pubescent at margins and midvein, 1.4–1.7 mm long, apex acute; pedicels 

erect; palea appressed-pubescent on the proximal 3⁄4, 1.4–1.7 mm long; glumes 1.6–2.1 mm 

long; auricles absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. annua

14. Lemma glabrous, 1–1.2 mm long, apex rounded or obtuse; pedicels nodding or reflexed, 

at least in the terminal spikelet of each branch; palea glabrous, 1–1.2 mm long; glumes 

1.2–1.5 mm long; auricles present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. majalcensis

13. Glumes shorter than the lemma, obtuse to acuminate.

15. Glumes pubescent at least at the apex, short-pilose to villous.

16. Pedicels nodding or reflexed, at least in the terminal spikelet of each branch; anthers 

olivaceous, 0.6–1.2 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. sinuosa

16. Pedicels ascending, at least in the terminal spikelet of each branch; anthers purple, up to 

0.7 mm long.

17. Lemma 0.8–1.5 mm long, obtuse to subacute, awnless . . . . . . . . . M. minutissima

17. Lemma 1.3–2 mm long, acuminate, mucronate to short-awned, the mucro or awn 

0.1–1(2) mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. texana

15. Glumes glabrous or minutely scabrous close to the apex. 

18. Panicle branches capillary, spreading, open to reflexed; inflorescence 3.5–11 cm wide; 

blade margins and midveins prominent, whitish and thickened. 
204 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

19. Pedicels nodding or reflexed, at least in the terminal spikelet of each branch; lemma 

1.3–1.8 mm long, glabrous; anthers 0.6–1.3 mm long . . . . . . . . . . . . . M. capillipes

19. Pedicels all erect; lemma 1–1.2 mm long, densely short-pubescent on the margins and 

midnerve or glabrous; anthers 0.3–0.5 mm long . . . . . . . . . . . . . . . . . . . M. fragilis

18. Panicle branches not capillary, closely appressed or widely spreading; inflorescence 0.6–

3.4 cm wide; blade margins and midveins never prominent, whitish and thickened.

20. Panicle contracted, narrow, often partially included in the uppermost sheath, 0.2–0.7 

cm wide; branches ascending or appresed; culms geniculate or decumbent, often 

rooting at the lower nodes.

21. Panicle long-exserted; branches 9–12 mm long, closely appressed at maturity; 

blades mostly basal, numerous . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. filiformis

21. Panicle partially included in the superior sheath; branches 3–10 mm long, ascending or appressed; blades mostly cauline . . . . . . . . . . . . . . . . . . . . . M. vaginata

20. Panicle loosely contracted, exserted, 0.6–2.5 cm wide; branches usually open, extended or reflexed to closely appressed; culms erect or spreading, not rooting at the 

lower nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. ramulosa

11. Glumes or lemmas, or both, awned, the awns 1.3–40 mm long.

22. Lemmas deeply bilobed, the lobe apex rounded to obtuse, the lobes 1–1.4 mm long, lateral veins prominent on the lower 1⁄2, scarce to densely appressed villous pubescence, the brownish hairs 0.5–0.7 mm 

long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. biloba 

22. Lemmas not deeply bilobed, sometimes minutely bifid, then the teeth usually acuminate to aristate, 

the teeth less than 1 mm long, lateral veins evident along entire length, pubescence, when present, not 

as above.

23. Lemma 1.3–2.5 mm long.

24. Upper glumes apex wide and truncate, usually 2- to 3-toothed.

25. Lemma awn sinuous-undulate, crisped and flexuous, olive-green; lemma inflated near the 

central part, lanceolate, 1.7–2.2 mm long . . . . . . . . . . . . . . . . . . . . . . . . . M. crispiseta

25. Lemma awn irregularly flexuous, purplish; lemma narrowly lanceolate, 1.4–4.2 mm long 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. peruviana

24. Upper glumes apex acute, acuminate or subulate, often awned.

26. Glumes pubescent near the apex, short-pilose to villous; lemma awn up to 3.5 mm long.

 27. Lemma 1.3–2 mm long, lemma awn 0.1–1(2) mm long; caryopsis 0.8–1 mm long; 

pedicels 2–7 mm long, usually longer than florets; palea 1.3–2 mm long, minutely 

appressed-pubescent at proximal half . . . . . . . . . . . . . . . . . . . . . . . . . . . M. texana

 27. Lemma (1.7)1.9–2.5 mm long, lemma awn 1.2–3.5 mm long; caryopsis 1.3–2.3 mm 

long; pedicels 1–2(3) mm long, usually shorter than florets; palea glabrous, 1.8–

2.4 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. eludens

26. Glumes glabrous or minutely scabrous; lemma awn up to 32 mm long.

 28. Lemma awn 1–3 mm long, lemma somewhat dorsally compressed, oblong ellipsoid, 

shortly and densely pubescent over the veins, yellowish . . . . . . . . . . . . . M. flavida

 28. Lemma awn more than 3 mm long; lemma not dorsally compressed, lanceolate or 

subulate, generally glabrous or if pubescent, the hairs elongate toward the apex, 

usually green or purple.

 29. Ligules 1.2–3(5) mm long; lower glumes 1.2–2 mm long, upper glumes 1.5–

2.8 mm long; panicles 7–20 cm long . . . . . . . . . . . . . . . . . . . . . . M. tenuifolia

 29. Ligules 0.3–0.5 mm long; lower glumes 0.7–1.5 mm long, upper glumes 1–1.8 mm 

long; panicles 4–12 cm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. ciliata

23. Lemma greater than 2.5 mm long.

30. Upper glumes apex wide and truncate, usually 2- to 3-toothed; lemma awn flexuous, purple 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. peruviana

30. Upper glumes apex obtuse, acute or acuminate, often awned; lemma awn straight to flexuous, 

brown-greenish to purple.

31. Panicle contracted, narrow, the branches ascending and close-appressed, up to 2 cm wide 

at maturity.
NUMBER 107 • 205

32. Lemma awn 1–3 mm long, lemma somewhat dorsally compressed, oblong-ellipsoid, 

with prominent veins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. strictior

32. Lemma awn 7–20 mm long; lemma subulate to lanceolate, veins never prominent.

33. Glumes elliptical, oblong or lanceolate, up to 2 mm long, excluding the awn; 

lower glumes 1-veined, apex bifid; spikelets borne singly. 

 34. Ligules 0.3–0.9 mm long, lemma 3–4.5(5) mm long, subulate to lanceolate, 

not rounded, glabrous to antrorsely scabrous, appearing 5-veined; cleistogamous spikelets usually absent in the axils of proximal branches . . . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. pectinata

 34. Ligules 1–3 mm long; lemma 2.5–3.5(4) mm long, narrowly lanceolate, 

rounded, scabrous, 3-veined; cleistogamous spikelets usually present in the 

axils of proximal branches . . . . . . . . . . . . . . . . . . . . . . . . M. microsperma

33. Glumes of superior spikelets of each branch subulate, 2–5 mm long; lower glumes 

2-veined, with 2 small awned teeth, awns 0.8–1.3 mm long; spikelets generally 

borne in pairs, 1 sessile and 1 pedicellate. 

35. Glumes equal or longer than the lemma; lemmas 2.5–4.5 mm long, awn 

7–15 mm long in the distal spikelet of each branch . . . . . . M. depauperata

35. Glumes 1⁄2 or less as long as the lemmas; lemmas 4–5(6) mm long, the awn 

10–20 mm long in the distal spikelet of each branch . . . . . . . . . . M. brevis

31. Panicle open with spreading branches, more than 2 cm wide at maturity.

36. Lemma awn 1–3 mm long; lemma somewhat dorsally compressed, oblong-ellipsoid 

with prominent veins. 

37. Lemma 2.2–3 mm long; panicle branches broadly ascending, sparsely flowered, 

naked toward base . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. flavida

37. Lemma 3–4.2 mm long; panicle branches narrowly ascending, appressed, flowered from the base . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. strictior

36. Lemma awn 5–30 mm long, lemma generally rounded.

38. Glumes obtuse to acute, 0.2–0.7 mm long.

 39. Glumes dimorphic, those from proximal spikelets of each branch often awnless, those of distal spikelets often 1 or both awned; ligules up to 0.8 mm 

long; inflorescence appearing secund or placed on 1 side of main axes . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. diversiglumis

 39. Glumes similar in all spikelets, awnless; ligules 1–2.5(3) mm long; inflorescence not secund.

 40. Inflorescence diffuse at maturity; pedicels capillary, thin and flexuous, 

glabrous; cleistogamous spikelets absent; lemmas scabrous on and among 

veins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. implicata

 40. Inflorescence not diffuse; pedicels short and thick, antrorsely scabrous; 

cleistogamous spikelets usually present at the axils of inferior branches; 

lemmas scabrous, with short hairs, appressed on veins close to the base 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. microsperma

38. Glumes mostly acute or awned, 0.8–2(3) mm long.

 41. Glumes dimorphic, those from proximal spikelets of each branch often awnless, 0.2–0.7 mm long, those from distal spikelets often 1 or both awned; 

inflorescence appearing secund or inserted on 1 side of the main axes . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. diversiglumis

 41. Glumes similar in all spikelets; inflorescence not secund.

 42. Ligules 1.2–3(5) mm long; anthers 0.9–1.6 mm long; lemma scabrous 

and rugose, 2–3.5(4) mm long, veins inconspicuous . . . . M. tenuifolia

 42. Ligules 0.3–0.9 mm long; anthers 0.3–0.6 mm long; lemma delicate 

and not scabrous-rugose, 3–4.5(5) mm long, with conspicuous, greenish 

veins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. pectinata

10. Perennial plants.

 43. Plants rhizomatous, rhizomes often stout, scaly, and creeping.
206 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

44. Blades articulated at base and early deciduous, culms much branched and lignified, bamboo-like, 

covered by cylindrical sheaths, the apex truncate; culms 100–300 cm tall; rhizomes 2–5 mm thick 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. dumosa

44. Blades not articulated, persistent, occasionally constricted at the base but without a lineal abscission, if 

belatedly deciduous, then the sheaths apex breaking irregularly; culms usually less than 100 cm tall, if 

occasionally bamboo-like, then the culms at base (or stolons) 1–2 mm thick and rooting at the nodes.

45. Lemmas awned, the awns (1)3–20(25) mm long; rhizomes short, inconspicuous.

46. Lemma awns 0.1–3(5) mm long, straight; panicle 1–3 mm wide; sheaths longer than the 

internodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. glauca

46. Lemma awns 10–20(25) mm long, flexuous; panicle (6)10–20 mm wide; sheaths mostly 

shorter than internodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. polycaulis

45. Lemmas unawned or mucronate, the mucros 0.1–0.8 mm long; rhizomes elongate and conspicuous.

47. Panicles narrow to open, 4–16 cm wide.

48. Ligules 1–3 mm long.

49. Culms nodulose-rugose; lemma 2–3 mm long, almost cylindrical . . . . . . . . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. richardsonis

49. Culms smooth, lemma 2–2.5 mm long, never cylindrical . . . . . . . . . . . M. vaginata

48. Ligules 0.5–1(2) mm long.

50. Ligules 0.5–2 mm long, hyaline, with well-developed lateral lobes or auricles; blade margins 

and midveins prominent, whitish, thickened . . . . . . . . . . . . . . . . . . . . . . . . . . M. arenacea

50. Ligules 0.2–1 mm long, ciliate, without lateral lobes or auricles; blade margins and midveins 

not conspicuously thickened, greenish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. asperifolia

47. Panicles contracted, narrow, 0.1–3.9 cm wide.

51. Spikelets 1.4–2.5 mm long.

52. Lemmas and paleas densely villous, the hairs 0.4–1 mm long; sheaths 5–15 cm long; 

panicles usually on an exserted peduncle; ligules apex acute . . . . . . . M. villiflora

52. Lemmas and paleas glabrous or with minute appressed pubescence, the hairs 

about 0.1 mm long; sheaths 0.3–2.4 cm long; panicles partially included in the 

upper sheaths; ligules apex obtuse or truncate.

 53. Panicle 1–5 cm long, 0.1–0.4 cm wide; lemma awnless, minutely pubescent 

along margins and at base, the lemma green or purplish . . . . . . . . M. utilis

 53. Panicle 0.5–3 cm long, 0.3–0.7 cm wide; lemma mucronate, the mucro about 

0.2 mm long, sparsely short-pubescent over the proximal 1⁄2, with conspicuous dark olivaceous spots . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. vaginata

51. Spikelets 2.4–8 mm long.

 54. Lemmas with tawny hairs up to 0.6 mm long on the lower 1⁄2 along the midveins 

and margins; leaf blades 4–12 cm long, not arcuate; anthers 1.8–2.4 mm long, 

orange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. glauca

 54. Lemmas glabrous or with minute appressed pubescence along margins and the 

base, the hairs less than 0.1 mm long; leaf blades 0.4–6 cm long, somewhat arcuate spreading; anthers 0.7–1.4 mm long, yellow to purplish . . . . . . . M. repens

43. Plants caespitose, rhizomes absent.

55. Upper glumes 3-veined; old sheaths flattened below and sometimes spirally twisted near base.

56. Upper glumes apex 3-toothed and 3-awned, the teeth usually awned (including the awns) 1⁄3 to 1⁄2

the length of the glumes, and the awns up to 1.7 mm long . . . . . . . . . . . . . . . . . . . M. montana

56. Upper glumes apex entire or 2- to 4-toothed, the teeth small and unawned, less than 1⁄6 the length 

of the glumes.

57. Panicles 2–5 cm long; ligules 0.2–0.5 mm long, apex truncate; culms 20–30 cm tall . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. flaviseta

57. Panicles 5–25 cm long; ligules 2–20 mm long, apex acuminate; culms 10–80(100) cm tall. 

58. Sheath becoming flat, ribbonlike or papery and conspicuously spirally twisted near base; 

upper glumes apex entire and acute; spikelets light grayish-green to white; ligules (6)10–

20 mm long, hyaline, not brownish below . . . . . . . . . . . . . . . . . . . . . . . . . M. virescens
NUMBER 107 • 207

58. Sheaths flat below but usually not spirally twisted near base; upper glumes apex often 

with 3 or 4 small teeth and truncate; spikelets plumbeous; ligules 2–8 mm long, membranous to hyaline and often brownish below . . . . . . . . . . . . . . . . . . . . M. quadridentata

55. Upper glumes usually 1-veined (rarely 2- or 3-veined); old sheaths usually not flat or spirally twisted 

near base.

59. Culms (65)80–230(300) cm tall; leaf blades 20–100 cm long, 2–7 mm wide, flat or folded.

60. Lemmas unawned, mucronate (mucros less than 1 mm long), or awned, with awns 1–4 mm long.

61. Panicle 35–100 cm long, (8)15–30 cm wide, purple or brown,; branches 6–25 cm long, 

naked at base; spikelets 1.3–2.6 mm long . . . . . . . . . . . . . . . . . . . . . . . . . M. gigantea

61. Panicle 15–55 cm long, 0.6–15 cm wide, green with some purple spots; branches 0.5–

13 cm long, flowered almost from base; spikelets 2–4.6 mm long.

62. Ligules 10–35 mm long, stiff, decurrent, brown basally; lemmas glabrous to sparsely 

puberulent at base.

63. Lemmas awnless or the awn up to 4 mm long; basal sheaths strongly compressedkeeled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. lindheimeri

63. Lemmas awnless or the awn up to 2 mm long; basal sheaths rounded to gently 

compressed-keeled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. longiligula

62. Ligules 2–15 mm long, lemma pilose over the proximal half or entire surface.

 64. Plants sparsely to densely pilose on culms, leaves, and spikelets; lemma (2)2.4–

2.6(3) mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. pubescens

 64. Plants glabrous to scabrous on culms, leaves, and spikelets; lemma 2.2–3.5 mm 

long.

 65. Leaf sheath auricles absent; ligules 10–25 mm long; lemmas pubescent along 

the midvein and margins on lower 1⁄2–3⁄4 . . . . . . . . . . . . . . . . . M. emersleyi

 65. Leaf sheath auricles present, (1)2–4(10) mm long, linear subulate to broadly 

triangular, longer above, straight or twisted, firm below; ligules 2–10(12) mm 

long; lemmas glabrous or pubescent with scattered hairs on the lower 1⁄2

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. robusta

60. Lemmas awned, with awns 5–30(40) mm long.

66. Sheath auricles present, long and pointed, 10–20 mm long, lemma awn 10–15 mm long 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. distichophylla

66. Sheath auricles absent or rudimentary, rarely more than 2 mm long.

67. Spikelets 1.2–2.2 mm long, generally reddish to purple; glumes as long as or shorter 

than lemma.

 68. Branches and leaves woolly pubescent; glumes the same length as the lemma, 

apex obtuse, awnless . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. speciosa

 68. Branches and leaves glabrous to scaberulous; glumes shorter than the lemma, 

unequal, apex acuminate, awned, awn up to 1 mm long . . . . . . . . M. scoparia

67. Spikelets 2.2–3.2 mm long, green-grayish; glumes longer than lemma . . . . . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. emersleyi

59. Culms 10–70 cm tall; leaf blades 1–16 cm long, 0.3–2.5 mm wide, filiform, involute, flat or folded.

69. Panicles broad, open, loosely contracted to diffuse, (2)3–20 cm wide; panicle branches usually widely spreading to loosely ascending.

70. Lemmas unawned; spikelet pedicels flexuous nodding or reflexed; lemmas with a thick 

covering of tawny to shiny silky hairs located on the midvein and margins; paleas densely 

villous between the veins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. tricholepis

70. Lemmas with awns 0.5–40 mm long; spikelet pedicels erect, not flexuous nodding or reflexed; lemmas without a thick covering of tawny to shiny silky hairs on the midvein and 

margins but with appressed pubescence, the hairs scattered; paleas sparsely pubescent 

between the veins.

71. Plants decumbent or geniculate, generally short, culms 15–60(80) cm tall, leaf blades 

2–10 cm long (occasionally up to 16 cm long in M. arenicola and M. argentea).

72. Plants conspicuously branched, especially from the middle and lower nodes, 

loosely caespitose; culms decumbent, geniculate, or erect.
208 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

 73. Plants distinctly bushy in appearance; perennial with a wiry and knotty base; 

panicles 6–15 cm wide; anthers 1.5–2.3 mm long; caryopsis ellipsoid, compressed, yellowish brown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. porteri

 73. Plants not distinctly bushy in appearance; plants short-lived perennials to annuals with delicate bases; panicles 1–6.5 cm wide; anthers 0.9–1.5 mm long; 

caryopsis narrowly fusiform, terete, brownish . . . . . . . . . . . . M. tenuifolia

72. Plants not conspicuously branched, caespitose; culms erect to rarely slightly decumbent near the base.

 74. Spikelets silvery-olive to reddish; panicles 0.7–3.5 cm wide; lemma awns 

5–10 mm long; anthers 1–1.6 mm long, green-yellowish . . . . . M. argentea

 74. Spikelets never silvery-olive to reddish, mostly green; panicles 3–20 cm wide; 

lemma mucronate or awned 0.5–4 mm long; anthers 1.2–2.1 mm long, greenish or purplish.

 75. Plant base not rhizomatous; leaf blades 4–7 cm long, with margins and 

midvein whitish, hardened, cartilaginous . . . . . . . . . . . . . . M. arizonica

 75. Plant base rhizomatous, the rhizomes short, leaf blades 5–10(16) cm long, 

margins and midvein not prominent, not cartilaginous, green.

 76. Leaf blades not arcuate, 1–2.2 mm wide, 4–10(16) cm long; 1 or more 

culm nodes exposed; leaf blades reaching 1⁄4–1⁄2 of the plant height 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. arenicola

 76. Leaf blades arcuate, 0.3–0.9 mm wide, 1–3(5) cm long; usually lacking exposed culm nodes; most leaf blades reaching less than 1⁄5 of the 

plant height . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. torreyi

71. Plants erect, of medium height, culms (25)50–120 cm tall, leaf blades 10–50 cm long.

77. Panicle elongated, loosely contracted, generally longer than wide.

 78. Lemma hyaline, densely villous, widely ovate-lanceolate, apex bifid, teeth 

1 mm long, subacute, midvein prominent, reddish, continuous with an geniculate awn 10–12 mm long that is twisted near base . . . . . . . . . . M. lucida

 78. Lemma glabrous, not transparent, narrowly lanceolate, apex entire, midvein 

not prominent or reddish, awn flexuous, not twisted at the base.

 79. Spikelets silvery-olive to reddish, 3–3.5 mm long; lemma awn 5–10 mm 

long; anthers 1–1.6 mm long . . . . . . . . . . . . . . . . . . . . . . . M. argentea

 79. Spikelets never silvery-olive to reddish, 4.5–5 mm; lemma mucro or awn 

different in size; anthers 1.4–2.6 mm long.

 80. Panicle 8–20(25) cm long; pedicels 3–20 mm long, capillary; lemma 

awn 2–7(10) mm long . . . . . . . . . . . . . . . . . . . . . . . . . . M. setifolia

 80. Panicle 15–50 cm long; pedicels 1–3 mm long, not capillary; lemma 

awn 10–40 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . M. elongata

77. Panicles almost as long as wide, open, loosely to densely flowered.

81. Spikelets 3.5–5.1 mm long; lemmas 3.5–5.1 mm long; paleas 3.5–5.1 mm 

long.

82. Lemmas scaberulous to scabrous, not smooth and shining, purple; leaf 

blades 1–3 mm wide, flat or involute, not falcate; culms usually with a 

single node; anthers purplish.

83. Lemma awned, awn 10–22 mm long; glumes 1–1.7(2) mm long, apex 

obtuse to subacute, sometimes erose . . . . . . . . . . . . . . . . . M. rigida

83. Lemma mucronate or shortly awned, awn or mucros 0.5–1(2) mm 

long; acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. mucronata

82. Lemmas glabrous, smooth and shining, stramineous; leaf blades 1–2.5 mm 

wide, tightly involute to falcate; culms usually with 2–4 nodes; anthers 

greenish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. setifolia

81. Spikelets (2)2.4–3.6 mm long; lemmas 2.3–3.6 mm long; paleas (2)2.4–

3.6 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. purpusii

69. Panicles narrow, contracted to loosely contracted, 0.2–3 cm wide; panicle branches usually 

closely appressed to loosely spreading.
NUMBER 107 • 209

84. Panicles spikelike, 0.2–1.2 cm wide, densely flowered, sometimes interrupted near the 

base; primary branches tightly appressed, the branches 0.1–4 cm long.

85. Culms (35)50–200 cm tall; panicles 15–60 cm long; sheaths rounded near the base.

 86. Glumes 3.4–5.6 mm long, usually longer than the lemma, apex unawned and not 

mucronate; ligules (5)8–40(50) mm long; anthers 1.5–2.2, dark greenish . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. macroura

 86. Glumes 1.8–3.2 mm long, shorter than the lemma, apex sometimes mucronate 

or short-awned, the awn up to 1.7 mm long; ligules 0.5–2(3) mm long; anthers 

1.3–1.8 mm long, yellow to purple . . . . . . . . . . . . . . . . . . . . . . . . . . M. rigens

85. Culms 15–60 cm tall; panicles (2)4–16 cm long; sheaths compressed-keeled near the 

base.

 87. Lower glumes all 1-veined, unawned or mucronate, the mucros 0.5–1 mm long; 

branches with a single spikelet, or if in pairs, the upper and lower spikelets both 

perfect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. wrightii

87. Lower glumes 2- or 3-veined and awned, the awns 1–5 mm long; branched with 

paired spikelets, the lower spikelet staminate or sterile and the upper spikelet 

perfect.

88. Upper leaf blades acuminate with slender awnlike seta 3–8(10) mm long; ligules (2)3–12 mm long; culms erect . . . . . . . . . . . . . . . . . . M. alopecuroides

88. Upper leaf blades acute sometimes with a narrow bristle 0.5–3 mm long; ligules 0.5–3 mm long; culms erect to decumbent.

89. Ligules 0.5–1 mm long, truncate; blades generally short with navicular 

apex, obtuse to subacute . . . . . . . . . . . . . . . . . . . . . . . . . M. phalaroides

89. Ligules 2–3 mm long, acuminate and erose, usually auriculate with triangular lateral lobes 0.5–2.5 mm long; blades apex acute to mucronate, 

sometimes extending up to 3 mm as a slender seta . . . . . . . M. phleoides 

84. Panicles narrow, (0.6)1–3 cm wide, loosely contracted to narrowly open; primary branches 

loosely appressed to spreading up to 70o from the rachises, the branches 0.4–8.5 cm long.

90. Lemmas unawned, mucronate (mucros less than 1 mm long), or awned, the awns 

1–6 mm long.

91. Spikelet pedicels flexuous nodding to reflexed, capillary; lemmas with a thick 

covering of tawny to shiny silky hairs located on the midvein and margins; 

ligules(0.3)0.7–2(2.7) mm long, hyaline to opaque throughout . . . . M. tricholepis 

91. Spikelet pedicels erect, not flexuous nodding to reflexed or capillary; lemmas 

without a thick covering of tawny to shiny silky hairs on the midvein and margins, usually glabrous, puberulent throughout, or densely villous only on the margins below; ligules 4–35 mm long, firm below and often brownish.

92. Spikelets 3.8–5 mm long; basal sheaths terete; anthers 1.5–2.2 mm long, 

greenish; ligules not decurrent and brownish below.

93. Glumes 1.8–2.5 mm long, apex obtuse, veins inconspicuous, less than 1⁄2

the length of the spikelet; lemma awn 0.5–6 mm long . . . . . . M. dubia

93. Glumes 2.5–3 mm long, apex acuminate to mucronate, 1⁄2 or more the 

length of the spikelet, lemma awn 5–10 mm long . . . . . . . . . M. palmeri

92. Spikelets 2.4–3.5 mm long; basal sheaths compressed-keeled or flat; anthers 

1.1–1.6 mm long, yellowish or purplish; ligules deccurent, brownish below.

94. Glumes longer than the florets, glabrous and without hairs, scabrous or 

smooth; lemmas glabrous, scabrous or smooth, rarely puberulent; ligules 

10–35 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. lindheimeri

94. Glumes shorter than the florets, pubescent especially near the base; lemmas villous on the lower 1⁄2 and margins below; ligules 5–13 mm long

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. pubigluma

90. Lemmas awned, the awns 8–40 mm long (5–10 mm in M. argentea).

95. Leaf blades 20–50 cm long, mostly involute.

 96. Ligules 2–8 mm long, firm below, membranous at the apex, obtuse to acute; 

panicle green or tawny . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. elongata
210 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

 96. Ligules 1–3 mm long, firm, truncate, membranous, minutely ciliolate; panicles with purple spots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. palmeri 

95. Leaf blades 2–20 cm long, flat to involute.

 97. Panicles loosely spreading, ovoid or pyramidal, 6–20 cm long, branches 

spreading; anthers 0.9–1.6 mm long.

 98. Spikelets silvery-olive to reddish . . . . . . . . . . . . . . . . . . . . M. argentea

 98. Spikelets never silvery-olive to reddish.

 99. Plants decumbent, wiry, delicate; lemma awn 10–30 mm long; glumes 

1⁄2–3⁄4 as long as the lemma . . . . . . . . . . . . . . . . . . . . . M. tenuifolia

 99. Plants erect, never decumbent, nor wiry, nor delicate; lemma awn 

(5)10–20 mm long; glumes less than 1⁄2 as long as the lemma . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. alamosae

 97. Panicles narrow, spiciform, 2–15 cm long, branches appressed or ascending; 

anthers 1.5–3 mm long.

 100. Lemma and palea generally glabrous; ligules with lateral lobes 1.5–3 

mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. pauciflora

 100. Lemma appressed-pubescent on the central vein and margins, paleas 

appressed-pubescent between the veins; ligules without lateral lobes.

 101. Glumes 0.3–1.1 mm long, less than 1⁄2 as long as the lemma, apex 

obtuse to acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. purpusii

 101. Glumes (1)1.2–2.8 mm long, more than 1⁄2 as long as the lemma (at 

least the upper glumes), apex acute to acuminate.

 102. Anthers 1.5–2 mm long, orange; lemmas elliptic, widest near the 

middle; culms strigulose below the nodes . . . . . M. polycaulis

 102. Anthers 0.9–1.5 mm long, yellowish; lemmas lanceolate, widest near the base; culms scaberulous below the nodes . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. tenuifolia

202. Muhlenbergia alamosae Vasey, Bot. Gaz. 16(5): 146–147. 

1891.

Perennial plant; erect. Culms 30–70 cm tall, glabrous. 

Sheaths 3.5–6.5 cm long, rounded; ligules 1–4 mm long, membranous, hyaline; blades 5–15 cm long, 1–3 mm wide, flat. 

Panicles 6–12 cm long, 2.5–3.5 cm wide, partially included in 

the superior sheath, ovoid, spreading with ascending ramifications, twigs 3.5–5 cm long, lateral pedicels shorter than spikelets. 

Spikelets 2–3.2 mm long, hyaline with prominent veins, green 

to purple; glumes 1–2 mm long, glabrous, 1-veined, veins green 

to purple, ovate-lanceolate, mucronate, lower glumes 1–1.5 mm 

long, the mucro 0.5 mm long; upper glumes 1.5–2 mm long, the 

mucro 0.5–1 mm long; lemma 2–3.2 mm long, subulate, pilose 

only at the base, scabrous at the apex, 3-veined, veins green, 

lemma awn (5)10–20 mm long; palea equal to lemma; anthers 

1–1.2 mm long, yellow. Caryopsis 1–1.2 mm long, 0.3–0.4 mm 

wide, fusiform.

Distribution and Habitat. Muhlenbergia alamosae grows in grasslands and pine–oak forests at elevations of 

1,150–2,450 m. It occurs in Mexico in Aguascalientes, Baja California Sur, Chihuahua, Durango, Guanajuato, Jalisco, México, 

Morelos, Puebla, Sinaloa, and Sonora.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: Rancho Byarly, Sierra Charuco, 17–25 Apr 1948, 

1700 m, Gentry 8089 (MEXU, US). Guachochi: 20.3 km NE 

of La Bufa and 3.2 km S of Basigochi, 2180 m, P.M. Peterson 

& Annable 10807 (US); Parque Nacional Barranca del Cobre, 

13.6 mi NE of La Bufa on road towards Samachique, 2240 

m, P.M. Peterson, M.B. Knowles, C.H. Dietrich & S.M. Braxton 13573 (US). Madera: Puerto de El Tenedor, ejido El Long, 

2450 m, O. Bravo 1929 (CHAPA, CIIDIR). Ocampo: overlook 

of Cascada de Basaseachic, approx. 37 mi W of Tomochic, 22 

Sep 1986, 2200 m, P.M. Peterson & Annable 4548 (US); Parque 

Nacional Cascada de Basaseachic, 1620 m, Spellenberg, Soreng, 

R. Corral & T. Lebegue 8038 (CIIDIR); 5.25 km NW of Pinos 

Altos on road to Las Baterías, at the crossing of río Haciendita, 

1700 m, Spellenberg & P.S. Martin s.n. (MEXU). Temósachi: 

Nabogame, 2200 m, Laferr. 1396 (MEXU).

203. Muhlenbergia alopecuroides (Griseb.) P. M. Peterson & 

Columbus, Madroño 55(2): 159. 2008.

Lycurus setosus (Nutt.) C. Reeder.

FIGURE 148

Caespitose perennial. Culms 30–60 cm tall, erect, scabrous 

to puberulent just above or below the nodes. Sheaths usually 1–5 

cm long, glabrous to pubescent, compressed-keeled near base; 

ligules (2)3–12 mm long, acuminate to erose, sometimes with 

lateral lobes the same length as the ligule, the lateral lobes decurrent below; blades 4–10(2) cm long, 1–2.5 mm wide, flat or 

folded, glabrous to puberulent below and puberulent to hirsute 

above, margins and midvein whitish-thickened, apex acuminate 
NUMBER 107 • 211

with slender awnlike seta, 3–8(10) mm on the upper blades. Panicles (2)4–10 cm long, 4–8 mm wide, contracted, narrow, densely 

flowered, and spikelike; primary branches 0.1–0.3 cm long, 

tightly appressed. Spikelets 3–4 mm long, 1–flowered; glumes 

1–2 mm long, scaberulous near apex, awned, the awns 1–5 mm; 

lower glumes usually 2(3)-veined; upper glumes 1-veined, awns 

2–5 mm; lemmas 3–4 mm long, puberulent along the margins, 

awned, the awns 1–3 mm; paleas 3–4 mm long, puberulent between the veins; anthers 1.5–2 mm long, yellow. Caryopsis 1.8–

2.2 mm long, brownish. 2n = 40.

Distribution and Habitat. Muhlenbergia 

alopecuroides grows in wooded canyons, rocky slopes, desert 

grasslands, and rock outcrops with Pinus spp., Quercus spp., 

Cupressus spp., Abies spp., Cornus stolonifera, Ceanothus spp., 

and Yucca spp. It occurs in northwestern Mexico in Baja California, Chihuahua, Durango, and Sonora, extends into the southwestern United States, and is disjunct in northwestern Argentina 

and Bolivia; 1,400–2,500 m.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 10 km al S de Moctezuma, 30 Jul 1994, 1200 m, 

R. Corral, E. Pérez, A. Domínguez & F. Félix RCD5366

(UACJ); 10 km del entronque [junction] a Casas Grandes carr 

[hwy] Chih.–Cd. Juárez, 8 Aug 1979, pastizal [pastureland], 

1525 m, M.E. Siqueiros 267 (MEXU). Balleza: 56.4 km W of 

Parral on road to Balleza and 35.5 km S of Balleza, 18 Sep 1991, 

pine forest–encino [oak], 2210 m, P.M. Peterson, Annable & 

Valdés-Reyna 10707 (CIIDIR); 10 mi SW of El Ojito, 12 Sep 

2006, 1902 m, P.M. Peterson 20024, F. Sánchez Alvarado & 

E.P. Gómez Ruíz (CIIDIR, US). Batopilas: Yamuco at 1 km E 

of Hwy towards Basihuare and Creel, N of Rio Urique crossing, 

26 Aug 2003, pine forest, 1891 m, P.M. Peterson & P. Catalán 

17533 (US). Casas Grandes: Valle de las Cuevas al S del Ejido 

Ignacio Zaragoza, pine forest, 25 Sep 1982, 1760 m, Tenorio 

1707 & Romero (ENCB, MEXU); 0.5 mi E of Cuesta Blanca, 

W of Casas Grandes, 4 Sep 1958, Reeder, C. Reeder 3229 (US); 

9 mi NE of Cuesta Blanca, W of Casas Grandes, 18 Sep 1960, 

Reeder, C. Reeder & Soderstrom 3554 (ARIZ, US); Rancho Tapiecitas de Casas Grandes a Col. Hidalgo aprox 20 km desviar a 

la derecha por terracería [divert right by dirt road] 12 km, 3 Oct 

2000, pastizal, G. Gómez 112 (MEXU). Chihuahua: Mapula 

Mts, 11 Nov 1886, C.G. Pringle 904 (MEXU); Sierra Azul, (Sierra Mapula), 10 Sep 1934, Pennell 18648 (US); 6.1 mi W of 

Hwy 45 on dirt road towards Santa Clara, 18 Oct 1992, bosque 

de encino [oak forest], 1640 m, P.M. Peterson & Annable 12584

(US); 16.7 mi W of Hwy 45 on road up Los Prietos Canyon, 

18 Oct 1992, pine forest, 2120 m, P.M. Peterson & Annable 

12595 (US); 13 km al N de la Cd. de Chihuahua carr. Chih.–Cd. 

Juárez, encinar–pastizal [oak grove–pastureland], 18 Aug 1996, 

C. Yen & E. Estrada 5484 (ENCB); Base de la Sierra de La Campana, 80 km al N de Chihuahua, ladera riolítica [rhyolitic hillside] con pastizal & encinos, 19 Oct 1974, 1700 m, Rzedowski 

32309 (ENCB); Ejido col Ocampo, 13 Jul 1976, pastizal, 1500 

m, Blanco35 (MEXU); Rancho Tepehuanes de Chihuahua hacia 

[toward] Namiquipa desviar en Campo 73 a la derecha terracería 6 km, 11 Oct 2000, pastizal, G. Gómez 306 (MEXU); Rancho Aguja de Chihuahua hacia Namiquipa desviar en Campo 73 

a la derecha terracería 6 km, 12 Oct 2000, pastizal, G. Gómez 

321 (MEXU). Cuauhtémoc: about 11 mi W of Cuauhtémoc, 

5 Oct 1966, steep mountain slope with pines, oaks, and junipers. 

7600 ft, Reeder & C. Reeder 4596 (ENCB, MEXU); 12 mi W 

of Cuauhtemoc, 5 Sep 1967, 7000 ft, Reeder & C. Reeder 4861

(ARIZ, ENCB); 32 km W of hwy 45 towards Benito Juárez, 17 

Oct 1992, pinyon woodlands, 2110 m, P.M. Peterson & Annable 12547 (US). Cusihuiriachic: Rancho El Coronel, 2 Sep 1981, 

bosque esclero-aciculifolio [narrow-leaved sclerophyllous forest], 2500 m, Loya & Méndez1506 (MEXU). Guachochi: 5.8 mi 

N of Creel on road (hwy 25) towards San Juanito, 5 Oct 2000, 

pine forest, 2480 m, P.M. Peterson & J. Cayouette 15365 (US); 

NW of Cusarare, 23 Aug 1973, pine–oak, 6900 ft, Bye 4746b

(MEXU). Guerrero: Girasol, on railroad NW of San Isidro, Sierra Madre Occidental, 18 Sep 1934, F.W. Pennel 18984 (US); 

35.4 km SW of La Junta and approx. 74 km N of Creel, 24 

Sep 1988, pine woods, 2200 m, P.M. Peterson & Annable 5835

(ENCB, US); 32.3 km SW of La Junta on road to Creel, 10 Sep 

1989, pine forest, 2310 m, P.M. Peterson, Annable & Y. Herrera 

7991 (ENCB, US). Gran Morelos: 47 mi W of Cd. Chihuahua 

on hwy 16, 7 Oct 1972, 6000 ft, L. H. Harvey & J.T. Witherspoon 9294 (ENCB). Hidalgo del Parral: 14 mi E of Parral, 6 

FIGURE 148. Muhlenbergia alopecuroides. A. Leaf blade apex. 

B. Ligule. Drawn by Linda Ann Vorobik and Karen Klitz; copyright 

Utah State University.
212 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Sep 1967, Reeder & C. Reeder 4877 (US); NE edge of Parral, 30 

Sep 1959, Correll 22683 (ENCB); 5 mi S of Parral, 7 Oct 1966, 

Reeder & C. Reeder 4814 (ARIZ). Ignacio Zaragoza: 20.3 km 

NE of Ignacio Zaragoza on Mex 23, 28 Sep 1989, pine woods, 

2400 m, P.M. Peterson & R.M. King 8148 (ENCB). Jiménez: 

20 mi NW of Chih.–Dgo. State line, along hwy 45, 7 Sep 1967, 

1737 m, Reeder & C. Reeder 4890 (US). Madera: Along railroad N of Madera, 19 Sep 1934, Pennell 18996 (US); Mesa del 

Yerbanís, ejido El Long, 12 Oct 1990, bosque de Quercus, 1900 

m, O. Bravo 1855 (CIIDIR, ENCB, MEXU). Proximidad a la 

Col. Chuichupa, 1 Sep 1990, pastizal & bosquete [grove] de Juniperus, 2240 m, A. Benítez 2165 (CIIDIR, ENCB). Matachic: 

SW of Matachic on slope on NW side of ridge near km 9.7 on 

Matachic–Cocomoarachic road, 29 Aug 1978, pine–oak, 1900 

m, Bye 9008 (MEXU). Matamoros: 9 mi S of Villa Matamoros, 

7 Sep 1967, Reeder & C. Reeder 4884 (US); 19.3 km S of Villa 

Matamoros on hwy 45 to Durango, 27 Sep 1988, grassland, 

1800 m, P.M. Peterson & Annable 5983 (ENCB, US). Riva Palacio: Nuevo Majalca, approx. 14.5 km W of Hwy 45, N of 

Chihuahua, 22 Sep 1988, 1700 m, P.M. Peterson & Annable 

5763 (US); 5776b (ENCB, US); 11.3 km W of Nuevo Majalca, 

25.7 km W on Hwy 45, 22 Sep 1988, 1800 m, P.M. Peterson & 

Annable 5786 (US). San Francisco del Oro: 21 km W of Parral 

and approx. 3.2 km N on dirt road to Torrencillo, 26 Sep 1988, 

grassland, 2000 m, P.M. Peterson & Annable 5959 (ENCB, US).

204. Muhlenbergia annua (Vasey) Swallen, Contr. U.S. Natl. 

Herb. 29(4): 204. 1947.

Annual; small plants. Culms 8–20 cm tall, erect, internodes 

short, 3–25 mm long, glabrous, scabrous below nodes. Sheaths 

2–25 mm long, glabrous to scabrous, margins hyaline; ligules 

1.6–2.5 mm long, hyaline, apex irregularly toothed to lacerate, 

acute, margins entire; blades 1–6 cm long, 0.8–1.5 mm wide, flat 

to involute, midvein evident, short-pubescent adaxially, scaberulous abaxially. Panicle 5–13 cm long, 1.4–6 cm wide; branches 

10–36 mm long, 1 or 2 per node, slender, scattered florets, ascending or extended; pedicels 3–8 mm long, slender, erect, nodes 

9–22 per inflorescence. Spikelets 1.4–2.2 mm long, with antocian spots when immature; glumes 1.5–2.1 mm long, equal in 

length and larger than lemma, glabrous, often with a central 

vein, prominent, apex acuminate to short-awned, awn not longer that 0.3 mm long; lemma 1.4–1.7 mm long, oblong-elliptic, 

densely appressed-pubescent on the midvein and margins; palea 

1.1–1.7 mm long, oblong-elliptic, densely appressed-pubescent 

on the lower 3⁄4, apex acute; anthers 0.5–0.6 mm long, purplish. 

Caryopsis 0.9–1.1 mm long, fusiform to ellipsoid, brownishgray. n = 10. 

Distribution and Habitat. Muhlenbergia 

annua grows on gravelly soils in pine–oak forests at elevations 

of 2,000–2,270 m. It is uncommon in Mexico, known from the 

Sierra Madre Occidental in Chihuahua, Durango, and Sonora. 

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 10 mi SW of El Ojito, 12 Sep 2006, 1902 m, P.M. Peterson 20022, F. Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, 

US). Bocoyna: 18.7 mi S of San Juanito on road to Creel, 

2200 m, P.M. Peterson & Annable 7999 (US). Casas Grandes: 

25 mi SW on Col. Juárez road to Hernández Javales, P.M. Peterson & Annable 4036 (TAES, US); About 43 mi SW of Casas 

Grandes, 2100 m, Reeder & C. Reeder 2691 (MEXU, US); 1 mi 

W of Cuesta Blanca, W of Casas Grandes, 2012 m, Reeder & 

C. Reeder 3223 (MEXU, US); 1 mi N of Cuesta Blanca, 25.4 mi 

from Col. Juárez, P.M. Peterson & Annable 4046 (US); 15.5 mi 

W of La Junta on road to Tomóchic, 15 km mark on Hwy 16, 

2100 m, P.M. Peterson & Annable 4053 (US). Chihuahua: Chihuahua, 1885, E. Palmer 4A (US), holotype. Guachochi: 10.6 

mi NE of La Bufa on road to Creel, P.M. Peterson & Annable 

8072 (US); 16.6 km NE of La Bufa and 6.7 km S of Basigochi, 

2130 m, P.M. Peterson, Annable & Valdés-Reyna 10814 (US); 

Norogachic, 2320 m, E. Palmer 4a (US); Flat rock outcrops at 

Napuchis, 2140 m, P.M. Peterson & P. Catalán 17672 (CIIDIR, 

US); Arroyo Baqueachi, at 5 km E of small village, 2004 m, P.M. 

Peterson & P. Catalán 17567 (CIIDIR, US). Guerrero: 15.5 mi 

W of La Junta on road to Tomóchic, 15 km mark on Hwy 16, 

4 Sep 1985, P.M. Peterson & Annable 4053 (US); 24 mi SW of 

La Junta on road to Creel, 2270 m, P.M. Peterson & Annable 

9612 (US); 18.7 mi N of San Juanito on road to Creel, 10 Sep 

1989, P.M. Peterson, Annable & Y. Herrera 7999 (US). 

205. Muhlenbergia arenacea (Buckley) Hitchc., Proc. Biol. Soc. 

Washington 41: 161. 1928.

FIGURE 149C–G

Rhizomatous perennial. Culms 10–30(40) cm tall, decumbent, terete to somewhat compressed-keeled near the base; internodes scaberulous below the nodes. Sheaths about 1⁄2 as long as 

the internodes, margins hyaline; ligules 0.5–2 mm long, hyaline, 

with lateral lobes or auricles 1–2 mm; blades 0.7–4(6) cm long, 

0.5–1.7 mm wide, flat, occasionally folded, tapering, scabrous 

abaxially, strigulose adaxially, margins and midveins thickened, 

whitish, apex narrow, often sharp, erose. Panicles 5–15 cm long, 

4–14 cm wide, broadly ovoid, open; primary branches 2–8 cm 

long, capillary, straight to slightly flexuous, diverging 45°–

80(100)° from the rachises, never appearing involucred, naked 

proximally; pedicels 1–11 mm long, usually longer than the 

spikelets. Spikelets 1.5–2.5 mm long, occasionally with 2 florets; 

glumes 0.9–2 mm long, equal, 1-veined, usually acute to acuminate, occasionally erose and mucronate, mucros to 0.2 mm; lemmas 1.5–2.5 mm long, lanceolate to oblong-elliptic, plumbeous 

to purplish, sparsely appressed-pubescent on the lower 1⁄2 of 

the margins and midveins, hairs to 0.3 mm long, apex acute 

to obtuse, sometimes shallowly bilobed, mucronate, mucros to 

0.3 mm; paleas 1.5–2.6 mm long, lanceolate, glabrous, obtuse to 

acute; anthers 1–1.5 mm long, yellowish to purplish. Caryopsis 

1–1.3 mm long, elliptic, brownish.

Distribution and Habitat. Muhlenbergia arenacea grows on sandy flats, plains, alluvial fans, washes, depressions, and alkaline mesas in open grasslands at elevations of 

1,000–2,200 m. It ranges from the southwestern United States to 
NUMBER 107 • 213

FIGURE 149. Muhlenbergia uniseta. A. Habit. B. Inflorescence branch. Muhlenbergia arenacea. 

C. Habit. D. Ligule. E. Glumes. F. Floret. G. Lodicules, pistil, and stamens. Drawn by Susan C. Escher 

and Elisabeth P. Roberts for Smithsonian Institution, Department of Botany.
214 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

northern Mexico in Chihuahua, Hidalgo, San Luis Potosí, and 

Zacatecas.

Specimens Examined. MEXICO. Chihuahua. Aldama: Rancho El Torreño, 1150 m, G. Melgoza 54 (CIIDIR). 

Ascensión: Al SE del rancho El Caballo, 1200 m, M.A. López 

s.n. (INEGI). Camargo: 15 mi W of Jiménez, 1398 m, Reeder & 

C. Reeder 4874 (ENCB); In arroyo 50 km N of Jiménez, 1 Aug 

1939, 1270 m, L. H. Harvey 1375 (TAES, US). Casas Grandes: 

20 km al SE de Nuevo Casas Grandes, 2100 m, Hern.-Xol–10438

(CHAPA); 7 km NW de Casas Grandes, faldas del cerro [hillsides] El Pajarito, 1900 m, Hern.-Xol–10441 (CHAPA). Jiménez: 10 mi E of Carrillo, 21 Sep 1938, F. Shreve 8863 (US).

206. Muhlenbergia arenicola Buckley, Proc. Acad. Nat. Sci. 

Philadelphia 14: 91. 1862.

FIGURE 150

Caespitose perennial. Culms (15)20–60(70) cm tall, somewhat 

decumbent, 1 or more nodes exposed; internodes hirsute below 

the nodes. Leaves somewhat basally concentrated, most blades 

not reaching more than 1⁄4−1⁄2 of the plant height; sheaths usually 

a little shorter than the internodes, not keeled, scaberulous, margins hyaline, basal sheaths rounded, not becoming spirally coiled 

when old; ligules 2–9 mm long, hyaline, acute, lacerate, often 

with lateral lobes; blades 4–10(16) cm long, 1–2.2 mm wide, not 

arcuate, flat, folded, or involute, scabrous, often glaucous, midveins and margins not thickened, green. Panicles 12–30 cm long, 

5–20 cm wide, diffuse; primary branches 1–10 cm long, diverging 30°–80° from the rachises, naked basally; pedicels 1–4(6) mm 

long, erect. Spikelets 2.5–4.2 mm long; glumes 1.4–2.5 mm long, 

equal, 1-veined, apex scaberulous, acute to acuminate, minutely 

erose, sometimes mucronate, the mucros to 1 mm long; lemmas 

2.5–4.2 mm long, narrowly elliptic, usually purplish, scabrous distally, appressed-pubescent on the lower 1⁄2–3⁄4 of the margins and 

midveins, apex acuminate, awned, awns 0.5–4 mm long; paleas 

2.5–3.5 mm long, narrowly elliptic, intercostal region sparsely pubescent, apex acuminate, with 2 short mucros 0.1–0.2 mm long; 

anthers 1.5–2.1 mm long, greenish. Caryopsis 1.9–2.3 mm long, 

fusiform, brownish. 2n = 80, 82.

Distribution and Habitat. Muhlenbergia arenicola grows on sandy mesas, limestone benches, and in open 

desert grasslands, associated with Bouteloua gracilis, B. uniflora, 

and Larrea tridentata, at elevations of 600–2,135 m. The range 

of M. arenicola extends to southwestern United States, and the 

species is disjunct in northwestern Argentina.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 7 km al W de Sueco carr. [hwy] Sueco–Buenaventura, 

1300 m, Valdés-Reyna VR-728 (ENCB). Camargo: 2 mi S of San 

Fernando, 40 mi NE of Camargo, 25 Sep 1938, I.M. Johnston 

7938 (US); In arroyo 50 km N of Jiménez, 1 Aug 1939, 1280 

m, L. H. Harvey 1370 (US). Chihuahua: Hills near Chihuahua, 

1800 m, C.G. Pringle 479 (US); 13 mi N of Parrita, 1460 m, 

Reeder, C. Reeder & Soderstrom 3488 (US); 12 mi N of Chihuahua, 1800 m, Hern.-Xol. & V. Mathus N-1747 (CHAPA). 

Jiménez: 8 mi SW of Jiménez, 1300 m, Reeder, C. Reeder & Soderstrom 3459 (US); 10 mi E of Carrillo, 21 Sep 1938, F. Shreve 

8847 (US); W slope, Sierra de Sta Eulalia, 1280 m, L. H. Harvey 

1537 (US). López: 15 mi W of Jiménez, 1398 m, J.R Reeder & 

C. Reeder 4875 (ENCB). Manuel Benavides: 1 mi E of Pozo de 

Villa on Coahuila bundary, along rd from Ojinaga to Castillón, 

1200 m, I.M. Johnston 8180 (US).

207. Muhlenbergia argentea Vasey, Bull. Torrey Bot. Club 

13(12): 232. 1886.

FIGURE 151A–E

Caespitose perennial. Culms 30–50 cm tall, decumbent near 

base, glabrous, strigulose below nodes. Sheaths 2–8 cm long, 

glabrous to strigulose, margin hyaline, old sheaths folded; ligules 5–9 mm long, hyaline, delicate, margin erose, apex lacerate; 

blades 2–16 cm long, 0.4–2 mm wide, flat to involute, occasionally folded, apically acuminate, strigulose adaxially, scabrous 

abaxially, central midvein and margins evidently hardened and 

whitish. Panicle 6–16 long, 0.7–3.5 cm wide, included to shortexserted, narrow to loosely spreading; branches 1–4.5 cm long, 

ascending, appressed or diverging up to 45° from rachis; rachis 

scabrous. Spikelet 3–3.5 mm long, silvery-olive to reddish, pedicels 

0.6–4.5 mm; glumes 1.5–2.3 mm long, green, subequal, glabrous 

to scabrous, oblong-lanceolate, 1-veined, mucronate, mucro 0.3–

0.6 mm long; lemma 2.8–3.7 mm long, oblong-elliptic, appressedpubescent along margins and midvein at the inferior 1⁄2, hairs to 

FIGURE 150. Muhlenbergia arenicola. A. Habit. B. Floret. 

C. Glumes. Drawn by Linda Ann Vorobik and Annaliese Miller; 

copyright Utah State University.
NUMBER 107 • 215

FIGURE 151. Muhlenbergia argentea. A. Habit. B. Ligule. C. Glumes. D. Lemma. E. Lodicules, pistil, and stamens. Muhlenbergia lucida. F. Ligule. G. Glumes. H. Lemma. I. Lodicules, pistil, and stamens. Drawn by Cathy Pasquale for Smithsonian 

Institution, Department of Botany.
216 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

0.7 mm long, silver-olive, occasionally purplish, apex deeply bilobed, 0.5–1 mm long, lobes rounded to obtuse, awn 5–10 mm 

long, emerging between 2 lobes, flexuous, scabrous, silvery-olive 

to reddish close to base; palea 2.8–3.7 mm long, narrowly oblongelliptic, pilose between veins toward the inferior 1⁄3, apex obtuse to 

truncate; anthers 1–1.6 mm long, oblong, yellow-greenish. Caryopsis 1.4–1.6 mm long, fusiform, stramineous to light brown. 

Distribution and Habitat. Muhlenbergia argentea grows below oak forests in rhyolitic rocks at elevations of 

1,780–2,100 m and is endemic to Chihuahua. The species should 

be searched for in northern Durango and eastern Sonora, where 

it might also occur.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: Hacienda San Miguel, near Batopilas, 2100 m, 

E. Palmer 160 (US); 8.9 km NE of La Bufa on road to Creel, 

1780 m, P.M. Peterson, Annable & Y. Herrera 8066 (US). Moris: 

NW Chihuahua, near Sonora border, on Hwy 16 towards Maycoba, 1900 m, P.M. Peterson & Annable 12482 (US). Guachochi: Parque Nacional Barranca del Cobre, 20.3 km NE of La 

Bufa and 3.2 km S of Basigochi, 2180 m, P.M. Peterson, Annable 

& Valdés-Reyna 10808, 10810 (US); 15.3 mi S of Mex 127 and 

6.9 mi NE of la Bufa, 2000 m, Y. Herrera, P.M. Peterson & Annable 971 (CIIDIR); 24.6 km S of Mex Hwy 127 and 11.1 km 

NE of La Bufa, 2000 m, P.M. Peterson, Annable & Y. Herrera 

8044 (US); Parque Nacional Barranca del Cobre, 13.6 mi NE of 

La Bufa on road towards Samachique, 2240 m, P.M. Peterson, 

M.B. Knowles, C.H. Dietrich & S.M. Braxton 13577 (US). Ocampo: 122.5 km W of La Junta and 56.7 km W of Tomochic 

in Parque Nacional Cascada de Basaseachic, 2100 m, P.M. Peterson & R.M. King 8248 (US); Along trail just above Cascada 

Basaseachic, 1880 m, P.M. Peterson & Annable 12526 (US); mirador [lookout] de Cascada Basaseachic, 7 Sep 2008, 2023 m, 

P.M. Peterson & Saarela 22095 (US). 

208. Muhlenbergia arizonica Scribn., Bull. Torrey Bot. Club 

15(1): 8, t. A, f. 1–6. 1888.

FIGURE 152

Caespitose perennial; non-rhizomatous. Culms 15–50 cm 

tall, erect to decumbent, hirsute to glabrous. Sheaths 0.8–6.5 cm 

long, rounded, hirsute basally, hyaline margin; ligules 1–2 mm 

long, hyaline, the apex obtuse, minutely erose; blades 4–7 cm 

long, 0.8–2 mm wide, flat to folded, midvein and margins hardened, white and cartilaginous, glabrous to scabrous. Panicle 

8–20 cm long, 4–15 cm wide, diffuse, branches 1–7.5 cm long, 

spreading or ascending, basally naked, pedicels 3–16 mm long, 

FIGURE 152. Muhlenbergia arizonica. A. Habit. B. Culm and inflorescence. C. Glumes. D. Floret. Drawn by Linda Ann Vorobik and 

Annaliese Miller; copyright Utah State University.
NUMBER 107 • 217

erect to flexuous. Spikelets 2–3.1 mm long, solitary at the end 

of branches and twigs; glumes 1–1.5 mm long, equal, 1-veined, 

scabrous to the apex, obtuse or acute, awnless; lemma 2–3.1 mm 

long, elliptic, purplish, appressed-pubescent in margins and midvein to the inferior 1⁄2, scabrous at superior 1⁄2, apex acute, lightly 

bifid, awn 0.5–1.1 mm; palea 2.1–3.1 mm long, elliptic, glabrous, apex acute; anthers 1.6–2.1 mm long, purplish. Caryopsis 

1.3–1.7 mm long, fusiform, dorsally grooved, brown. 2n = 20. 

Distribution and Habitat. Muhlenbergia arizonica grows in grasslands, xerophilous scrub, and edges of cultivated areas at elevations of 700–2,270 m. It ranges from the 

southwestern United States to northern Mexico.

Specimens Examined. MEXICO. Chihuahua. Balleza: 69.2 km al E de Guachochi and 25.7 km W of 

Balleza, 26 Sep 1988, 2100 m, P.M. Peterson & Annable 5940

(US); 56.4 km W of Parral on road to Balleza and 35.5 km S of 

Balleza, 2210 m, P.M. Peterson, Annable & Valdés-Reyna 10701

(US); 16.1 km W of Balleza and 77.9 km E of Guachochi, 1990 

m, P.M. Peterson, Annable & Valdés-Reyna 10741 (US); 11 mi 

SE of Balleza on road to Parral, 1800 m, P.M. Peterson, M.B. 

Knowles, C.H. Dietrich & S.M. Braxton 13531 (US). Chinipas: 

Sierra Saguarivo, 1.3 mi W of Curahui, 9 Sep 2008, 1001 m, 

P.M. Peterson & J.M. Saarela 22173 (US). Chihuahua: Rocky 

hills near Chihuahua, 2190 m, C.G. Pringle 402 (ENCB); Hills 

near Chihuahua, 1800 m, C.G. Pringle 964 (MEXU, US). Guerrero: 24 mi SW of La Junta on road to Creel, 2270 m, P.M. Peterson & Annable 9615 (US). Hidalgo del Parral: About 5 mi S of 

Parral, 1824 m, Reeder & C. Reeder 4612 (ENCB); 3 mi NE of 

Parral on Hwy 45 towards Chihuahua, 2000 m, M.E. Siqueiros 

1549 (MEXU). Janos: Chihuahua–Sonora border, Rancho Carretas, 1780, L. H. Harvey 1624 (TAES). Madera: 23.3 km SE 

of Madera on Mex 16 to La Junta, 29 Sep 1989, 2190 m, P.M. 

Peterson & R.M. King 8183 (US). Matamoros: 19.3 km S of 

Villa Matamoros on Hwy 45 to Dgo., 1988 m, P.M. Peterson & 

Annable 5981 (US); P.M. Peterson & R.M. King 8255 (US). Riva 

Palacio: 2.7 km W of Nuevo Majalca, 17.2 km W of Hwy 45, 

22 Sep 1988, 1700 m, P.M. Peterson & Annable 5777 (US). San 

Francisco del Oro: 21 km W of Parral and 3.2 km N of Torreoncillo, 26 Sep 1988, 2000 m, P.M. Peterson & Annable 5960 (US). 

209. Muhlenbergia asperifolia (Nees & Meyen ex Trin.) Parodi, Revista Fac. Agron. Veterin. (Buenos Aires) 6: 117, f.1. 

1928.

FIGURE 153

Rhizomatous perennial; occasionally stoloniferous. Culms 

10–60(100) cm tall, decumbent-ascending, bases somewhat 

compressed-keeled; internodes glabrous, shiny below the nodes. 

Sheaths glabrous, margins hyaline; ligules 0.2–1 mm long, firm, 

truncate, ciliate, without lateral lobes; blades 2–7(11) cm long, 

1–2.8(4) mm wide, flat, occasionally folded, smooth or scaberulous in both surfaces, margins and midveins not conspicuously 

thickened, greenish, apex acute, not sharp. Panicles 6–21 cm 

long, 4–16 cm wide, broadly ovoid, open; primary branches 

3–12 cm long, capillary, lower branches spreading 30°–90° from 

the rachises, never appearing involucred; pedicels 3–14 mm 

long, longer than the spikelets. Spikelets 1.2–2.1 mm long, occasionally with 2 or 3 florets; glumes 0.6–1.7 mm long, equal, 

purplish, scaberulous, particularly on the veins, 1-veined, apex 

acute; lemmas 1.2–2.1 mm long, lanceolate to oblong-elliptic, 

somewhat plumbeous, glabrous, usually smooth, occasionally 

scaberulous near the apex, apex acute, awnless or mucronate, 

mucros to 0.3 mm long; paleas 1.2–2.1 mm long, lanceolate, 

glabrous, acute; anthers 1–1.3 mm long, greenish-yellow to purplish at maturity. Caryopsis 0.8–1 mm long, fusiform, brownish. 2n = 20, 22, 28.

FIGURE 153. Muhlenbergia asperifolia. A. Habit. B. Ligule. 

C. Glumes. D. Lemma. Drawn by Elisabeth P. Roberts for Smithsonian Institution, Department of Botany.
218 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Distribution and Habitat. Muhlenbergia asperifolia grows in moist, often alkaline meadows, beach margins, and sandy washes, on grassy slopes, and around seeps and 

hot springs at elevations of 5–3,000 m. This species is common 

in the western United States and Canada and is also found in 

Argentina, Bolivia, and Chile. In Mexico M. asperifolia occurs 

in Baja California, Chihuahua, Durango, Jalisco, and San Luis 

Potosí.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: Presa Encinillas, 100 km al N de Chihuahua, 1600 

m, Rzedowski 32378 (MEXU); Base de la Sierra de La Campana, 80 km al N de Chihuahua, 1700 m, F.W. Gould 8912

(TAES). Delicias: About 9 mi N of Las Delicias, 1220 m, Reeder 

& C. Reeder 2615 (ENCB, MEXU, US). Guachochi: About 1 mi 

E of Boquilla Reservoir, 1277 m, Reeder & C. Reeder 4602

(ENCB, US). Madera: About 20 mi S of Madera, 2100 m, Reeder 

& C. Reeder 1240 (ENCB).

210. Muhlenbergia biloba Hitchc., Contr. U.S. Natl. Herb. 

17(3): 294. 1913. Bealia mexicana Scribn., True Grasses 

103–104, f. 45a. 1890. 

Annual; small plants, often caespitose. Culms 9–35 cm tall, 

very branched at the inferior nodes, scaberulous-pubescent, striate, glabrous to minutely pubescent below nodes, internodes 

2–10 mm long, hollow. Sheaths 2–7.5 cm long, keeled, usually 

striate, scaberulous to almost glabrous, longer than internodes, 

margin widely scarious; ligules 1.5–3.4 mm long, membranous, 

apex acute or rounded, irregularly toothed, margins entire, decurrent, ending in auricles, shorter than ligule; blades 1–7 cm 

long, 0.6–1.4 mm wide, flat, involute when dry, scaberulous 

abaxially, short-pubescent adaxially, midvein and margins 

white and hardened on adaxial surface. Panicles 3–10 cm long, 

1.5–3.2 cm wide, spreading, branches 1.8–4.5 cm long, sinuoseascending, 1(2) per node; pedicels 1–5.5 mm long, slender, dispersed, ascending, scabrous and minutely glandular, 6–16 nodes 

per inflorescence. Spikelets 3–4.8 mm long; glumes 3.2–4.8 mm 

long, 1-veined, equal, green-grayish, obtuse, sparingly pilose to 

villous, especially over proximal 2⁄3; lemma 2.9–3.5 mm long, 

sparingly to densely villous over the proximal 2⁄3, hairs 0.5–

0.7 mm long, lateral veins evident in the proximal 1⁄2, apex bilobed, the lobes 1–1.4 mm long, rounded obtuse, awn 4–6.5 mm 

long, emerging between the lobes, scabrous, curly to flexuous; 

palea 2.6–3.4 mm long, apex obtuse, pubescence similar to the 

lemma; anthers 1.2–2.3 mm long, purple. Caryopsis 1.5–1.8 mm 

long, fusiform, brown-olive. n = 8. 

Distribution and Habitat. Muhlenbergia biloba grows on sandy soils derived from calcareous rocks associated with pine forests at elevations of 1,780–2,300 m. It is an 

endemic species in Mexico found in Chihuahua, Durango, and 

Sonora.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 15 mi E of El Vergel on road to Parral, 21 Oct 1959, 

7500 ft, Correll & Gentry 23270 (ENCB, US). Chihuahua: near 

Chihuahua, Oct 1886, C.G. Pringle 819 (ARIZ, NMC, US). 

Matamoros: SE of Villa Matamoros on hwy 45 towards Durango, 22 Sep 1991, 1780 m, P.M. Peterson, Annable & ValdésReyna 10865 (US); 19.3 km S of Villa Matamoros on hwy 45 

to Durango, 27 Sep 1988, grassland, 1800 m, P.M. Peterson & 

Annable 5976 (ENCB, US); P.M. Peterson & R.M. King 8264 

(US). Riva Palacio: Col. Cumbres de Majalca, 33.8 km W of 

Mex 45, N of Chihuahua City, 7 Sep 1989, pine forest, 2190 

m, P.M. Peterson, Annable & Y. Herrera 7946 (ENCB, US); 37 

km W of Mex 45, and ca. 3.2 km W of Col. Cumbres de Majalca, 7 Sep 1989, pine forest, 2170 m, P.M. Peterson, Annable 

& Y. Herrera 7981 (ENCB, US); 23 mi W of Mex 45 and 2 mi 

W of Cumbre de Majalca, 8 Sep 1989, bosque de pino [pine 

forest], 2170 m, Y. Herrera, Peterson & Annable 915 (CIIDIR, 

ENCB); 1.2 mi W of Cumbres de Majalca, 22.6 mi W of hwy 45, 

20 Sep 1986, 2200 m, P.M. Peterson & Annable 4529 (ENCB, 

NMC, US); Col. Cumbres de Majalca, approx. 32.2 km W of 

Hwy 45 N of Chihuahua, 22 Sep 1988, 2200 m, P.M. Peterson 

& Annable 5800 (US); Majalca, 6 Sep 1935, 2080 m, LeSueur 

Mex-026 (US).

211. Muhlenbergia brevis C. O. Goodd., J. Wash. Acad. Sci. 31: 

505. 1941.

FIGURE 154

Caespitose annual. Culms 3–20 cm tall, erect, slender, 

very branched at the base, scabrous to hispidule. Sheaths striate, glabrous or scabrous; ligule 1–3 mm long, thin, lacerate, 

often auriculate; blades 1–4.5 cm long, 1–2 mm wide, flat or 

involute, scabrous, with midveins and margins cartilaginous. 

Panicles 3–12 cm long, 0.5–1.8 cm wide, often included on the 

base, densely flowered, light green tinted with purple, branches 

1–3.8 cm long, plicate-ascending, pedicels 0.2–8 mm. Spikelets 

4–5 mm long, slender, in pairs, 1 spikelet sessile and another 

pedicelled, disarticulating below the pair of spikelets; glumes 

scabrous, unequal, shorter than lemma; lower glume 2–3.5 mm 

long, 2-veined, subulate, minutely to deeply bifid, the teeth slender, occasionally short-awned, awn 1.6–1.8 mm long, upper 

glume 2.4–4 mm long, entire, narrow, acuminate to attenuate, 

1-veined, awned, awn to 2 mm; lemma 3.5–5 mm long, narrowly lanceolate, brown-green to purple, scabrous, appressedpubescent between veins to base, apex acuminate, sometimes 

2-teethed, awned, the awn 10–20 mm long, rigid to slightly flexuous, scabrous; palea similar to the lemma; anthers 0.5–0.9 mm 

long, purplish to yellowish. Caryopsis 2–2.8 mm long, narrow, 

fusiform, brown. 2n=20.

Distribution and Habitat. Muhlenbergia 

brevis grows on stony hills and gravel plains in grasslands and 

forests with Pinus, Cupressus, and Quercus at elevations of 

1,700–2,400 m. It ranges from the United States to northern 

Mexico.

Muhlenbergia brevis and M. depauperata share various 

characters with M. phalaroides, M. phleoides, and M. alopecuroides, for example, spikelets in pairs, lower glumes 2-veined and 

2-awned, upper glumes 1-veined and 1-awned, acuminate, 
NUMBER 107 • 219

lemmas with short-pubescent margins, and pubescent paleas. 

However, M. brevis and M. depauperata are sister found in the 

Muhlenbergia subg. Bealia (Scribn.) P. M. Peterson clade whereas 

the other three species are found in the M. subg. Pseudosporobolus (Parodi) P. M. Peterson clade (Peterson et al., 2010).

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 15.6 mi NE of El Vergel on Hwy 24, 2000 m, P.M. 

Peterson & Annable 4061 (US); 56.4 km W of Parral on road 

to Balleza and 35.5 km S of Balleza, 2210 m, P.M. Peterson, 

Annable & Valdés-Reyna 10706 (US). Carichi: Sánchez, 12 Oct 

1910, Hitchcock 7664 (US). Casas Grandes: 1 mi N of Cuesta 

Blanca, 25.4 mi from Col. Juárez, 2000 m, P.M. Peterson & Annable 4047 (US); Reeder & C. Reeder 3225 (US); 21 mi W of 

Col. Juárez, 2316 m, Reeder & C. Reeder 3210 (ENCB, US); 

21 mi SW of Col. Juárez on road to Hernández Javales, 2200 m, 

P.M. Peterson & Annable 4030 (US); W of Casas Grandes, 5 mi 

S of Hernández, 2200 m, Reeder & C. Reeder 3507 (MEXU, 

US); 3 mi S of Hernández Javales, 32 mi SW of Col. Juárez, 2200 

m, P.M. Peterson & Annable 4041 (US). Cuauhtemoc: 16 mi W 

of Cuauhtémoc, 2400 m, Reeder & C. Reeder 3468 (MEXU, 

US); 12 mi W of Cuauhtémoc, 2128 m, Reeder & C. Reeder 

2620, 3191 (CHAPA). Chihuahua: 39 km carr. [hwy] Chihuahua–Namiquipa, 2300 m, M. Vergara 179 (MEXU); 16.7 mi W 

of Hwy 45 on road up Los Prietos Canyon, 2120 m, P.M. Peterson & Annable 12589 (US). Guachochi: 10.6 mi NE of La Bufa 

on road to Creel, 2235 m, P.M. Peterson, Annable & Y. Herrera 

8069 (US); Flat rock outcrops at Napuchis, 2140 m, P.M. Peterson & P. Catalán 17669 (CIIDIR, US). Guerrero: 24 mi SW of 

La Junta on road to Creel, 2200 m, Y. Herrera, P.M. Peterson 

& Annable 955 (ENCB); 9614 (US); 24 mi SW of La Junta on 

road to Creel, 2200 m, P.M. Peterson & Annable 5837 (US); 

P.M. Peterson, Annable & Y. Herrera 7998 (US); 16 km SW of 

La Junta on road to Creel, 2270 m, P.M. Peterson 9614 (US). 

Hidalgo del Parral: 15.7 mi W of Parral on Hwy 24 towards El 

Vergel, 2100 m, P.M. Peterson & Annable 4558 (US). Ignacio 

Zaragoza: Near Ignacio Zaragoza, 2100 m, A.A. Beetle M-8034

(MEXU); 12.6 mi NE of Ignacio Zaragoza, 2400 m, P.M. Peterson & R.M. King 8151 (US). Madera: 12 mi SW of Madera of 

Hwy 16 towards Cuauhtémoc, 2100 m, P.M. Peterson & Annable 4051 (US); 2 mi N of Madera, 2165 m, Reeder & C. Reeder 

2645 (MEXU); About 17 mi NW of Madera, 2195 m, Reeder 

& C. Reeder 2658 (CHAPA); About 15 mi S of Madera, mpio. 

Madera, 2190 m, P.M. Peterson & R.M. King 8178 (US). Riva 

Palacio: 2.7 km W of Nuevo Majalca, 17.2 km W of Hwy 45, 

1700 m, P.M. Peterson & Annable 5774 (US); 0.9 km E of entrance to Parque Nacional, Col. Cumbres de Majalca, 2100 m, 

P.M. Peterson & Annable 5788 (US); 0.7 mi W of Nuevo Majalca, 8.5 mi W of Hwy 45, 1700 m, P.M. Peterson & Annable 

4512 (US); Cumbres de Majalca, 21.5 mi W of Hwy 45, 2200 m, 

P.M. Peterson, Annable & Y. Herrera 7941 (US).

212. Muhlenbergia capillipes (M. E. Jones) P. M. Peterson & 

Annable, Syst. Bot. Monogr. 31: 27. 1991. Sporobolus 

capillipes M. E. Jones, Contr. W. Bot. 14: 9. 1912.

FIGURE 155

Caespitose annual; fragile. Culms 15–40 cm tall, reddish, 

erect, glabrous, minutely scabrous below nodes. Sheaths glabrous 

to scabrous, margins hyaline; ligules 1.5–2.8 mm long, hyaline, 

apex toothed to lacerate, acute, occasionally with short auricles, 

decurrent; blades 3–12 cm long, 0.6–2 mm wide, flat to involute, 

midvein and margins hardened, short-pubescent to scabrous. 

Panicle 10–20 cm long, 3.5–8 cm wide; branches 1–5.5 cm long, 

1–3 per node, ascending or spreading, pedicels 3–8 mm long, 

slender, capillary, curved and reflexed. Spikelets 1.3–1.8 mm 

long, widely spaced in the branches, inclined to reflexed, reddish when immature; glumes 1–1.2 mm long, equal, shorter than 

the lemma, glabrous, 1-veined, reddish especially near the base, 

apex obtuse to rounded, often irregular and minutely ciliate; 

lemma 1.3–1.8 mm long, widely ovate to lanceolate, glabrous, 

apex widely rounded to acute, reddish to slightly brown; palea 

1.3–1.8 mm long, lanceolate, glabrous, apex rounded to acute; 

anthers 0.6–1.3 mm long, purplish. Caryopsis 1–1.2 mm long, 

fusiform, reddish-brown.

Distribution and Habitat. Muhlenbergia 

capillipes grows on sandy soils, rocky plains, and canyon walls 

in pine–oak forests at elevations of 1,400–2,400 m. It is an endemic species from Mexico growing in Chihuahua, Durango, 

and Sonora.

FIGURE 154. Muhlenbergia brevis. A. Habit. B. Glumes. C. Floret. 

Drawn by Linda Ann Vorobik and Annaliese Miller; copyright Utah 

State University.
220 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Muhlenbergia capillipes is morphologically similar to 

M. majalcensis, but the former differs in having glumes shorter 

than the lemma.

Specimens Examined. MEXICO. Chihuahua. 

Buenaventura: 0.5 mi W of Flores Magón, 1400 m, Reeder & C. 

Reeder 3496 (US). Casas Grandes: W of Casas Grandes, 2 mi NE 

of Cuesta Blanca, 1980 m, Reeder & C. Reeder 3539 (US). Chihuahua: San Diego Mt, Sierra Madre Mts, M.E. Jones s.n. (US), 

Type fragment. Guerrero: 24 mi SW of La Junta on road to Creel, 

2200 m, Y. Herrera, P.M. Peterson & Annable 953 (ENCB); 23 

mi SW of La Junta on road to Creel at the puente [bridge] Arroyo Ancho, 24 Sep 1988, 2230 m, P.M. Peterson, Annable & 

Y. Herrera 5858, 7993 (US); 35.4 mi W of La Junta on road to 

Parque Nacional Cascada de Basaseachic and 4.4 mi E of Tomochic, 30 Sep 1989, 2350 m, P.M. Peterson & R.M. King 8221

(US); 23 mi SW of La Junta on road to Creel at the puente Arroyo 

FIGURE 155. Muhlenbergia capillipes. A. Habit. B. Floret. 

C. Glumes. D. Ligule. Drawn by Alice R. Tangerini for Smithsonian Institution, Department of Botany.
NUMBER 107 • 221

Ancho, 2230 m, P.M. Peterson & Annable 9604 (US); 16 km SW 

of La Junta on road to Creel, 2270 m, P.M. Peterson & Annable 

9618 (US); 37 km SW of La Junta on road to Creel at Puente 

Arroyo Ancho, 2230 m, P.M. Peterson 9604 (US). Ignacio Zaragoza: 12.6 mi NE of Ignacio Zaragoza, 2400 m, P.M. Peterson & 

R.M. King 8157 (US). Madera: 22 mi SE of Chuhichupa on the 

road to Madera, 2130 m, Reeder & C. Reeder 2673 (US); 23.3 

km SE of Madera on Mex 16 to La Junta, 29 Sep 1989, 2190 

m, P.M. Peterson & R.M. King 8182 (US). Namiquipa: Rancho 

Teseachic, 2000 m, A.A. Beetle M-3266 (MEXU). Temosachic: 

Canyon Huahuatan, 10 mi SE of Madera, 22 Sep 1939, C.H. 

Muller 7417 (US). Uruáchi: 16 mi W of Maycoba on Hwy 16 to 

Yécora, 1520 m, Gentry & Bye 23353 (US).

213. Muhlenbergia cenchroides (Humb. & Bonpl. ex Willd.) 

P. M. Peterson, Caldasia 31(2): 280, f. 2C–D. 2009. Aegopogon cenchroides Humb. & Bonpl. ex Willd.

Muhlenbergia brevigluma (Scribn.) Columbus.

Caespitose annual; slender, sometimes producing stolons. 

Culms 30–40(50) cm tall, decumbent. Sheaths glabrous to puberulent; ligules 1.5–4.5 mm long, eciliate membrane; blades 2–11 

cm long, 1–2 mm wide, scabrous or puberulent. Panicles 2–8 cm 

long, spreading, composed of unilateral racemes, racemes born 

along a central axis, bearing a triad of spikelets. Spikelets 4-6 mm 

long, central spikelet perfect, 3.5–5.5 mm long, sessile or with a 

pedicel less than 0.5 mm long; lateral spikelets pediceled, staminate to rudimentary, pedicel a little longer, purple; glumes 3–5 

mm long, 1-veined, linear to oblong, lobed, lobes acute, awned 

on apex, awn 1–3 mm; fertile lemma 2–3 mm long, laterally compressed, glabrous, membranous, dark brown, keeled, 3-veined, 

lateral veins ribbed, lemma apex 3-lobed, lobes lanceolate, acuminate, 3-awned, outer lobes longer; principal lemma awn 4–7 

mm long; lateral lemma awns 1–2 mm long; palea 2.5–3 mm 

long, lanceolate, minute-pubescent dorsally, teeth awned, the awn 

0.5–2 mm long; anthers 0.5–2 mm long, yellow. 2n = 40, 60, 80.

Distribution and Habitat. Muhlenbergia cenchroides grows in humid areas in pine–oak forests at elevations 

of 1,600–2,320 m. It ranges from the United States and Mexico 

in Chiapas, Guerrero, Michoacán, Nayarit, Oaxaca, and Querétaro to Central and South America.

Specimens Examined. MEXICO. Chihuahua.

Balleza: 43.5 km W of Balleza and 51.6 km E of Guachochi, 18 

Sep 1991, bosque de pino [pine forest], 2320 m, P.M. Peterson, 

Annable & Valdés-Reyna 10758 (CIIDIR). Bocoyna: 3.2 km al 

SE de Bocoyna rumbo [course] a Creel, 14 Aug 1976, Bosque de 

pino, 2270 m, S. Gonzalez & J.M. Peña 674 (RELC). Chinipas: 

Saguarivo, 53 mi N of Alamos, 9 Sep 2008, slopes with oaks 

and pines, 1540 m, P.M. Peterson & J.M. Saarela 22137 (US). 

Chihuahua: 38 km W of hwy 45 on road towards Benito Juárez, 

17 Oct 1992, pinyon woodlands, 2230 m, P.M. Peterson & Annable 12573 (US). Guachochi: Yamuco, 1 mi E of hwy N of Rio 

Urique crossing towards Basihuare and Creel, 5 Sep 2008, 1890 

m, P.M. Peterson & J.M. Saarela 22045 (US); 39.2 km S of Creel 

on road to Batopilas at the Barranca El Cobre, 10 Sep 1989, 

oak forest, 1930 m, P.M. Peterson, Annable & Y. Herrera 8024

(ENCB, US); Guadalupe y Calvo: near Cumbre Mohinora, 13 

Sep 2006, 3300 m, P.M. Peterson 20034, F. Sánchez Alvarado & 

E.P. Gómez Ruíz (CIIDIR, US); 9.5 mi E of Guadalupe y Calvo 

on hwy 24, 14 Sep 2006, 2570 m, P.M. Peterson 20059, F. Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, US). Guerrero: 38.6 

km SW of La Junta and approx. 70.8 km N of Creel at p. Arroyo Ancho crossing, 21 km marker, 24 Sep 1988, pine woods, 

2200 m, P.M. Peterson & Annable 5850 (ENCB, US); 10 mi E of 

Tomochic, 13 Oct 1984, 2300 m, Spellenberg & M. Spellenberg 

7891 (NMC). Madera: proximidad a la Col. Chuichupa, 1 Nov 

1990, pastizal & bosquete [pastureland and trees] de Juniperus 

deppeana, 2240 m, A. Benítez 2184 (CIIDIR, ENCB); Laguna de 

Babícora, Arroyo El Jaral, 10 Sep 1994, 2300 m, G. Quintana & 

E. Estrada 3577 (NMC). Ocampo: Parque Nacional “Cascada 

de Basaseachic,” in the barranca [canyon] at the base of the falls, 

11 Nov 1989, 1600 m, M. Mahrt & Spellenberg 82 (NMC); 

Parque Nal. Cascada basaseachic, por los estacionamientos 

[parking lots], 22 Sep 1994, R. Corral, Spellenberg & E. Estrada 

RCD5452 (UACJ); Near Mirador of Cascada Basaseachic, 2022 

m, slopes with Pinus, 7 Sep 2008, P.M. Peterson & J.M. Saarela 

22091 (US). Riva Palacio: 11.3 km W of Nuevo Majalca, 25.7 

km W of hwy 45, N of Chihuahua, 22 Sep 1988, pine woods, 

1800 m, P.M. Peterson & Annable 5779 (ENCB, US); Col. Cumbres de Majalca, 33.8 km W of Mex 45, N of Chihuahua City, 

7 Sep 1989, pine forest, 2190 m, P.M. Peterson, Annable & 

Y. Herrera 7946b, 7957, 7968 (ENCB, US).

214. Muhlenbergia ciliata (Kunth) Trin., Gram. Unifl. Sesquifl. 

193, t. 5, f. 16. 1824. Muhlenbergia ciliata (Kunth) Kunth, 

Révis. Gramin. 1: 63. 1829.

Delicate annual plants. Culms (7)10–30 cm tall, slender, 

loose, glabrous, often branched from the inferior nodes. Sheaths 

1.5–5 cm long, rounded, glabrous or sparsely pilose; ligules 

0.3–0.9 mm long, membranous pilose and/or erose; blades 

1.5–4 cm long, 1–1.5(2) mm wide, folded or involute, glabrous 

to scattered pilose, often reflexed or spreading. Panicles 4–12 cm 

long, 1.8–5 cm wide; branches (1)1.5–2 cm long, some distant, 

widely spreading or reflexed, spikelet-bearing to the base. Spikelets 2–2.5 mm long, appressed to the branches and overlapping; 

glumes subequal, glabrous, acuminate or shortly awned, lower 

glumes 0.7–1.5 mm long, upper glumes 1–1.8 mm long; lemma 

2–2.2(2.5) mm long, lanceolate, 3-veined, often appearing 

5-veined, lateral veins ciliate to the apex, rarely only scabrous, 

the awn 5–7(10) mm long; palea 1.6–2.4 mm long, narrowly 

lanceolate; anthers 0.3–0.5 mm long, yellowish changing to 

pale with age. Caryopsis 0.8–1.8 mm long, narrowly fusiform, 

brown-reddish. n = 10.

Distribution and Habitat. Muhlenbergia ciliata grows in xerophilous scrub and pine or oak forests at elevations of 1,880–2,400 m. This species is widely distributed in 

Mexico, Central America, and South America.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 14.8 mi NE of El Vergel, 2100 m, P.M. Peterson & 
222 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Annable 4080 (US); 56.4 km W of Parral on road to Balleza and 

35.5 km S of Balleza, 2210 m, P.M. Peterson, Annable & ValdésReyna 10722 (US). Bocoyna: Cabecera de la cañada de Recogoata, 

2400 m, B. Tah V. 51 (MEXU). Chinipas: Sierra Milpillas, 24.1 mi 

E of Los Tanques on road to Milpillas, 2100 m, P.M. Peterson & 

Annable 4179 (US); 3.4 mi W of Saguarivo on road to Chinacas, 

10 Sep 2008, rocky slopes with Acacia, Opuntia, Quercus, 1617 

m, P.M. Peterson & J.M. Saarela 22172 (US). Guachochi: 28.3 

km S of Cusarare on road to Guachochi, entering Barranca del 

Cobre, 1900 m, P.M. Peterson & Annable 5901 (US); 24.3 mi S of 

Creel on road to Batopilas at Barranca del Cobre, 1930 m, P.M. 

Peterson, Annable & Y. Herrera 8017 (US); 15.3 mi S of Mex 127 

and 6.9 mi NE of la Bufa, 2000 m, P.M. Peterson, Annable & Y. 

Herrera 8047 (US); 20.3 km NE of La Bufa and 3.2 km S of Basigochi, 2180 m, P.M. Peterson, Annable & Valdés-Reyna 10809

(US); 11.3 km NE of La Bufa and 2.1 km S of Kirare, 1950 m, 

P.M. Peterson, Annable & Valdés-Reyna 10821 (US); 9 mi S of 

Guachochi at Barranca Río Green, 2470 m, P.M. Peterson & J. 

Cayouette 15376 (US). Guerrero: Arroyo Ancho, Sierra Madre, 

Sep 1887, C.G. Pringle 1435 (US); 4.5 mi W of Tomóchic on Hwy 

16, 2200 m, P.M. Peterson & Annable 4541 (ENCB, US). Estación 

Coru, 1900 m, C.G. Pringle 13245? (MEXU); Tomóchic, 2 km alrededor del poblado [around the village], 2100 m, M. Vergara 157

(MEXU). Ocampo: Along trail just above Cascada Basaseachic, 

1880 m, P.M. Peterson & Annable 12528 (US).

215. Muhlenbergia crispiseta Hitchc., N. Amer. Fl. 17(6): 440. 

1935.

FIGURE 156A–D

Caespitose annual. Culms 7–16 cm tall, erect, very branched 

in the inferior nodes. Sheaths glabrous, the inferior overlaped; 

ligules 1.3–2 mm long, membranous, rounded at the apex; blades 

1–5 cm long, 0.7–1.4 mm wide, flat to involute, pubescent to glabrous. Panicles 1.8–4.5 cm long, largely exserted, branches 1.5–

2.8 cm long, ascending, flowered from base, pedicels 0.5–2 mm 

long, often curved; glumes 1.2–1.8 mm long, pale, unequal, glabrous, lower glume 1.2–1.6 mm long, apex acute, 1-veined, upper 

glume 1.6–1.8 mm long, wider, oblong, 3-veined, apex truncate, 

3-toothed; lemma 1.7–2.2 mm long, cylindrical, lanceolate, 

densely pilose on the proximal 1⁄2, glabrous over the rest, apex 

2-toothed, lemma awn 8–18 mm long, slender, sinuose-undulate 

or crisped and flexuous, green-olive; palea 1.1–1.7 mm long, lanceolate, sparsely pilose between the veins in the proximal 1⁄2, apex 

acuminate; anthers 0.4–0.7 mm long, reddish-purple. Caryopsis 

0.5–1 mm long, elipsoid, brown. n = 10. 

Distribution and Habitat. Muhlenbergia 

crispiseta grows in oak or pine forests at elevations of 1,880–

2,680 m. It ranges from the United States to northern Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 12.1 mi NE of El Vergel on Hwy 24, SW of Parral, 2000 

m, P.M. Peterson & Annable 4063 (US); 10.9 mi NE of El Vergel 

on Hwy 24, SW of Parral, 2000 m, P.M. Peterson & Annable 

4067 (US); 56.4 km W of Parral on road to Balleza and 35.5 km 

FIGURE 156. Muhlenbergia crispiseta. A. Habit. B. Floret. 

C. Glumes. D. Ligule. Muhlenbergia peruviana. E. Habit. F. floret. G. Glumes. H. Ligule. Drawn by Midge Gillete for PMP.
NUMBER 107 • 223

S of Balleza, 2210 m, P.M. Peterson, Annable & Valdés-Reyna 

10721 (US); 56.4 km W of Balleza and 38.7 km E of Guachochi, 

2280 m, P.M. Peterson, Annable & Valdés-Reyna 10768 (US); 

45 mi W of Balleza on road towards Guachochi, 2560 m, P.M. 

Peterson, M.B. Knowles, C.H. Dietrich & S.M. Braxton 13551 

(US). Bocoyna: Cabecera de la cañada de Recogoata, 2400 m, 

B. Tah V. 42 (MEXU). Carichi: Sánchez, 12 Oct 1910, Hitchcock 

7663b (US). Cusihuiriáchi: SW of town Cusihuiriáchi on the top 

of La Bufa, 18 air km S of Cuauhtémoc, 2400 m, Spellenberg & 

D. Jewell s.n. (MEXU). Chihuahua: 39 km carr. [hwy] Chihuahua–Namiquipa, 2300 m, M. Vergara 182 (MEXU); Mapula 

Mts, C.G. Pringle 824 (US). Guachochi: 16 mi E of Guachochi 

on Mex 127 towards Balleza, 2680 m, Y. Herrera, P.M. Peterson 

& Annable 978 (CHAPA); 18 mi E of Guachochi on Mex 127 

towards Balleza, 2600 m, Y. Herrera, P.M. Peterson & Annable 

977 (CHAPA); 11 km al SW de Cuasarare, 2400 m, P.M. Peterson 

& Annable 5892 (US); 19.3 km E of Guachochi, 2300 m, P.M. 

Peterson & Annable 5927 (US); 18 mi E of Guachochi on Mex 

127 towards Balleza, 2680 m, P.M. Peterson, Annable & Y. Herrera 8080 (US); Parque Nacional Barranca del Cobre, 12 mi SE 

of Samachique on road towards Guachochi, 2150 m, P.M. Peterson, M.B. Knowles, C.H. Dietrich & S.M. Braxton 13588 (US). 

Guerrero: 18.7 mi N of San Juanito on road to Creel, 2335 m, Y. 

Herrera, P.M. Peterson & Annable 957 (CHAPA); 35.4 km SW 

of La Junta and 74 km N of Creel, 2200 m, P.M. Peterson & Annable 5834 (US); 29 mi W of La Junta on road to Parque Nacional 

Cascada Basaseachic, 2200 m, P.M. Peterson & R.M. King 8197

(US); 33.7 mi W of La Junta on road to Parque Nacional Cascada 

Basaseachic, 30 Sep 1989, 2260 m, P.M. Peterson & R.M. King 

8216 (US); Sierra Madre, porphyry ledges near Guerrero, 2200 m, 

Aug 1887, C.G. Pringle 1411 (MEXU, US); 23.6 mi W of Hwy 

jct at La Junta on road to Tomóchic, 18 mi E of Tomóchic, 2200 

m, P.M. Peterson & Annable 4534 (US). Matamoros: 12 mi S of 

Villa Matamoros on Hwy 45 towards Parral, 3 Oct 1989, 1910 

m, P.M. Peterson & R.M. King 8265 (US); 19.3 km S of Villa Matamoros on Hwy 45 to Dgo., 1800 m, P.M. Peterson & Annable 

5974 (US). Ocampo: Cascada de Basaseachic, 37 mi W Tomochic, 

2200 m, P.M. Peterson & Annable 4546 (US); Along trail just 

above Cascada Basaseachic, 1880 m, P.M. Peterson & Annable 

12527 (US). Parral: 24.9 km SE of Balleza, 22.5 km N of hwy 24, 

W of Parral, 1900 m, P.M. Peterson & Annable 5950 (US). Riva 

Palacio: Cumbres de Majalca, 21.5 mi W of Hwy 45, 2200 m, 

P.M. Peterson & Annable 4528 (US); Cumbres de Majalca, 21.5 

mi W of Hwy 45, 2200 m, P.M. Peterson & Annable 5791 (US); 

38 km W of Hwy 45 on road towards Benito Juárez, 2230 m, P.M. 

Peterson & Annable 12558 (US). Uruáchi: 17.6 mi E of Maycoba 

on hwy 16 towards Yepachic and 2 mi E of Sonora/Chihuahua 

boundary, 1540 m, P.M. Peterson & Annable 12517 (US).

216. Muhlenbergia decumbens Swallen, Bol. Soc. Bot. México 

23: 30–32, f. 4. 1959. Chaboissaea decumbens (Swallen) 

J. & C. Reeder, Phytologia 65(2): 156. 1988.

Annual; delicate. Culms 12–30 cm tall, decumbent, branched 

and rooting at the lower nodes. Sheaths 1⁄2 the length of internodes, 

glabrous with hyaline margins; ligules 1.6–2.5 mm long, hyaline, 

entire, the apex truncate; blades 2.5–8 cm long, 0.8–1.4 mm wide, 

flat, scaberulous, margins scabrous to the apex. Panicles (4)8–

11 cm long, 1.5–4.5 cm wide, narrow, branches 2.5–4.8 cm long, 

ascending; pedicels 1–3 mm long, rigid, scabrous. Spikelets 3–3.8 

mm long, 1- or 2-flowered, erect, plumbeous; glumes 1.8–3.2 mm 

long, subequal, grayish, glabrous and scabrous on midveins, apex 

acuminate to mucronate, the mucro 0.6 mm long, lower glume 

1.8–2.5 mm long, upper glume 2.4–3.2 mm long, wider than 

lower; lemma 3–3.8 mm long, lanceolate, compressed-keeled toward the apex, awned or awnless, appressed-pubescent on margins on the lower 1⁄3, dark green to gray with light greenish-white 

spots, apex long acuminate, the awns 0.2–3 mm long; palea similar to the lemma, veins extended into small mucros 0.3–0.6 mm 

long; anthers 0.9–1.1 mm long, greenish. Caryopsis 2–2.3 mm 

long, fusiform, brown. n = 16.

Distribution and Habitat. Muhlenbergia decumbens is endemic to Chihuahua and grows in sandy clay loam 

to dark clay soils along sloughs and wet depressions in pine–

oak–juniper woodlands (Peterson and Annable, 1992).

Specimens Examined. MEXICO. Chihuahua. 

Casas Grandes: W of Casas Grandes, 5 mi S of Hernández, 18 

Sep 1960, pine–oak region, 2100 m, Reeder, C. Reeder & Soderstrom 3510 (NMC, US). Cuauhtémoc: km 31 between Cuauhtémoc & V. Guerrero, 27 Oct 1954, Hern.-Xol.. & C. Tapia 

N-359 (US), holotype; 21 km W of Chauhtemoc on Hwy 16, 

23 Aug 1990, P.M. Peterson 9587 (US); 12.8 mi W of Cuauhtémoc on Mex 16, 9 Sep 1989, wet meadow in dark mud, 2000 

m, P.M. Peterson, Annable & Y. Herrera 952 (CIIDIR, ENCB); 

P.M. Peterson & Annable 5820 (MEXU, US); about 11 mi W of 

Cuauhtémoc, 5 Oct 1966, 7600 ft, Reeder & C. Reeder 4593, 

4599, 4601 (ENCB, MEXU, US); 4848 (US); 14.3 mi W of Cuauhtémoc on hwy 16, 21 Sep 1986, 2200 m, P.M. Peterson & 

Annable 4533 (ENCB, MEXU, NMC, US). Guerrero: 32 km SW 

of La Junta on road to Creel, 7 Sep 1989, flat open woods with 

Quercus, Pinus, Juniperus, 2310 m, P.M. Peterson, Annable & 

Y. Herrera 7983 (MEXU, US). Madera: 5 mi N of Long at the 

edge of a small lake in oak–pine zone, 12 Oct 1953, 2375 m, 

Reeder & C. Reeder 2683 (CIIDIR, ENCB).

217. Muhlenbergia depauperata Scribn., Bot. Gaz. 9: 187, f. 

1–2. 1884.

FIGURE 157

Caespitose annual. Culms 3–15 cm tall; internodes mostly 

scaberulous or pubescent, pubescent or strigose below the nodes, 

very branched at the lower nodes. Sheaths often longer than the 

internodes, somewhat inflated, smooth or scabrous, keeled, 

margins scarious; ligules 1.4–2.5 mm long, membranous, acute, 

with lateral lobes; blades 1–3 cm long, 0.6–1.5 mm wide, flat or 

involute, scabrous to strigose, midveins and margins thickened, 

whitish. Panicles 2.5–8.5 cm long, 0.5–0.7 cm wide, contracted; 

primary branches 1–2.2 cm long, appressed, spikelet-bearing to 

the base, spikelets borne in subsessile-pedicellate pairs; longer 
224 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

pedicels 3–6 mm long, scabrous; disarticulation beneath the 

spikelet pairs at the base of pedicel. Spikelets 2.5–4.5 mm long, 

appressed; glumes 2.3–5.1 mm long, equaling or exceeding the 

florets; lower glumes 2.3–4 mm long, subulate, 2-veined, minutely to deeply bifid, teeth awnless or with awns to 1.3 mm 

long; upper glumes 3–5.1 mm long, lanceolate, 1-veined, entire, 

acuminate; lemmas 2.5–4.5 mm long, narrowly lanceolate, light 

greenish-brown to purplish, scabrous, appressed-pubescent on 

the margins and midveins, apex acuminate, awned, the awns 

6–15 mm long, stiff; paleas 2.4–3.6 mm long, lanceolate, intercostal region appressed-pubescent, apex acuminate; anthers 

0.5–0.8 mm long, purplish to yellowish. Caryopsis 1.5–2.3 mm 

long, narrowly fusiform, brownish. 2n = 20.

Distribution and Habitat. Muhlenbergia 

depauperata grows in gravelly flats, rock outcrops, exposed 

bedrock, sandy banks, and grama grassland associations, usually on soils derived from calcareous parent materials, and associated with species of Selaginella, Hechtia, Opuntia, Salvia, 

and Juniperus at 1,530–2,400 m. Its range extends into the 

southwestern United States, and in Mexico this species occurs 

in Aguascalientes, Chihuahua, Distrito Federal, Durango, Guanajuato, Jalisco, México, Oaxaca, Puebla, San Luis Potosí, and 

Veracruz.

Specimens Examined. MEXICO. Chihuahua. 

Jiménez: Presón del Apache, upper part of Canyon del Apache, 

SE quadrant of Sierra del Diablón, 1650 m, F. Chiang, T. Wendt 

& M.C. Johnston 9028 (MEXU); Sta. Eulalia Mts, C.G. Pringle 

404 (US). Matamoros: Just N of Villa Matamoros on Hwy 45 

towards Parral, 1700 m, P.M. Peterson & Annable 4082, 4579

(ENCB, US); 12 mi S of Villa Matamoros on Hwy 45 towards 

Parral, 1900 m, P.M. Peterson & Annable 4082, 4083 (ENCB, 

US); Reeder & C. Reeder 4623, 4885 (ENCB, US); 19.3 km S 

of Villa Matamoros on Hwy 45 to Dgo., 1800 m, P.M. Peterson 

& Annable 5977, 10863 (US). Ocampo: Parque Nacional Cascada Basaseachic, 1 km airline S of Cascada, 2100 m, Tenorio & 

R. Torres 4511-a (IBUG).

218. Muhlenbergia distichophylla (J. Presl) Kunth, Enum. Pl. 1: 

202. 1833.

Caespitose perennial. Culms 100–180 cm tall, erect, glabrous to pubescent below the nodes; internodes glabrous. 

Sheaths 8–42 cm long, longer than basal internodes, glabrous, 

the keels prominent, sometimes coiled to shredded below, basal 

sheaths compressed-keeled; sheath auricles 0.4–2.6 cm long, 

on lower portions and to 6.4 cm above; ligules 4–15 mm long, 

membranous, apex finely lacerate sometimes almost to the base; 

blades 18–90 cm long, 2–7 mm wide, flat or folded, scaberulous 

to scabrous in boths sides, the margins and keel saw-toothed. 

Panicles 35–70 cm long, 4–15 cm wide, densely flowered, oblong, sometimes lax near apex, greenish-brown, sometimes 

reddish-purple; primary branches 2–15 cm long, without spikelets near the base, appressed to loosely spreading up to 60° from 

the rachises; pedicels 0.2–4 mm long, glabrous to scaberulous. 

Spikelets 1.5–2.8(3) mm long, erect, greenish-brown, to reddishpurple; glumes 1.2–2.8 mm long, longer, as long as, or a little 

shorter than the lemma, subequal, oblong to narrowly oblong, 

faintly 1-veined, hyaline, glabrous to scaberulous, usually with 

faint, widely scattered hairs, the hairs less than 0.1 mm long, 

apex acute to acuminate; upper glumes rarely mucronate, the 

mucro to 0.4 mm; lemmas 1.4–2.7 mm long, lanceolate to linearlanceolate, awned, glabrous or sometimes the margins on the 

lower 1⁄3 pubescent, the hairs to 0.2 mm long, rarely the lower 

1⁄3 with scattered hairs, callus usually short pilose, apex acute, 

minutely bifid, the teeth to 0.5 mm long, the awn 4–16 mm long, 

flexuous, often reddish-purple near base; paleas 1.3–2.7 mm 

long, glabrous or with few hairs between the veins on the lower 

1⁄3, apex acute; anthers 1.2–1.5 mm long, yellowish, sometimes 

reddish tinged. 

Distribution and Habitat. Muhlenbergia distichophylla occurs from central Mexico in Chiapas, Guerrero, 

Jalisco, México, and Oaxaca to Guatemala; found in open pine–

oak forests and tropical deciduous forests on rocky slopes, canyons, 

and ravines, with Pinus spp. and Quercus spp. at 400–2,000 m.

FIGURE 157. Muhlenbergia depauperata. A. Habit. B. Glumes. 

C. Floret. Drawn by Linda Ann Vorobik and Annaliese Miller; 

copyright Utah State University.
NUMBER 107 • 225

Specimens Examined. MEXICO. Chihuahua. 

Chinipas: 1 mi E of Saguarivo, 10 Sep 2008, small arroyo with 

oaks and pines, 1490 m, P.M. Peterson & J.M. Saarela 22160 

(US). Guachochi: Parque Nacional Barranca del Cobre, 13.6 

mi NE of La Bufa on road towards Samachique, 2240 m, P.M. 

Peterson, M.B. Knowles, C.H. Dietrich & S.M. Braxton 13564 

(US); Parque Nacional Barranca del Cobre, 1.6 km E of La Bufa, 

1950 m, P.M. Peterson & M.B. Knowles 13583 (US).

219. Muhlenbergia diversiglumis Trin., Mém. Acad. Imp. Sci. 

St.-Pétersbourg. Ser. 6, Sci. Math., Seconde Pt. Sci. Nat. 6, 

4(3–4): 298. 1841.

FIGURE 158A–D

Delicate, sprawling annual. Culms 20–50(70) cm tall, glabrous and glossy, inferior nodes retrorse-pilose, rooting at the 

lower nodes. Sheaths papillose-pilose to glabrous, the hairs up 

FIGURE 158. Muhlenbergia diversiglumis. A. Habit. B. Floret. C. Glumes. D. Ligule. Muhlenbergia implicata. E. Habit. F. Floret. G. Glumes. H. Ligule. Drawn by Midge Gillete for PMP.
226 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

to 3 mm long; ligules 0.5–1 mm long, apex erose; blades 1.5–

4(6) cm long, 1–1.5(2) mm wide, flat or loosely involute, glabrous, 

papillose-pilose near the base and margins. Panicle 4–10(15) cm 

long, 2–4.5 cm wide, pale green or sometimes purple; branches 

10–20 cm long, 1–2 cm wide, spreading at right angles to the culm 

and reflexed or secund, disarticulating at the base with spikelets 

appressed and falling as a unit. Spikelets dimorphic, 2–5 on each 

branch, pedicels 1–5 mm long, scabrous or short papillose-pilose; 

glumes 0.2–8 mm long, dimorphic; proximal spikelets of each 

branch 0.2–0.7 mm long, orbicular, apex irregularly toothed to 

erose, subequal; distal spikelets the glumes unequal; lower glumes 

5–8 mm long, ovate, apiculate, awned, the awn 1–2.5(7) mm long; 

upper glumes 0.2–0.7 mm long, orbicular, apiculate, occasionally 

awned; lemma 4–7.5 mm long, glabrous to papillose-scabrous 

with 3 prominent usually greenish veins, apex awned, the awn of 

5–19 mm long; palea 3.7–6.8 mm long, attenuate, the veins prominent, sometimes 2-toothed, scabrous between the veins; anthers 

0.4–0.8 mm long, yellowish. Caryopsis 1.8–3 mm long, oblongovoid, flattened, brown. n = 10. 

Distribution and Habitat. Muhlenbergia diversiglumis occurs in pine or oak forests at elevations of 1,700–

2,000 m. It ranges from Mexico to Central and South America.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: Sierra Charuco, Río Fuerte, 1700 m, Gentry 1761

(CHAPA). Chínipas: Sierra Milpillas, 24.1 mi E of Los Tanques 

on road to Milpillas, 2100 m, P.M. Peterson & Annable 4178

(US). Guachochi: 15.3 mi S of Mex 127 and 6.9 mi NE of la Bufa, 

2000 m, P.M. Peterson, Annable & Y. Herrera 8046 (US); Parque 

Nacional Barranca del Cobre, 11.3 km NE of La Bufa and 2.1 km 

S of Kirare, 1950 m, P.M. Peterson, Annable & Valdés-Reyna 

10819 (US). Uruáchi: 1.7 mi W of Maycoba on Hwy 16 towards 

Yécora, 1720 m, P.M. Peterson & J. Cayouette 15352 (US).

220. Muhlenbergia dubia E. Fourn., Biol. Cent.-Amer., Bot. 

3(29): 540. 1885.

FIGURE 159F–I

Densely caespitose perennial. Culms 30–100 cm tall, erect, 

not rooting at the lower nodes; internodes glabrous, minutely 

pubescent to hirtellous below the nodes. Leaf sheaths longer 

than the internodes, smooth or scaberulous, rounded basally; 

ligules 4–10 mm long, membranous, firm below, acute, lacerate, 

brownish; blades 10–60 cm long, 1–2 mm wide, usually involute 

(occasionally flat), scabrous abaxially, hirsute adaxially. Panicles 

10–40cm long, (0.6)1–2.4 cm wide, contracted, grayish-green; 

primary branches 0.6–7 cm long, diverging to 40° from the rachises, stiff, spikelet-bearing to the base; pedicels 0.1–6 mm long, 

strongly divergent, hirsute. Spikelets 3.8–5 mm long, grayishgreen; glumes (1.8)2–3 mm long, equal, shorter than the florets, 

glabrous and smooth proximally, scaberulous distally, faintly 

1-veined, acute; lemmas 3.8–5 mm long, narrowly lanceolate, 

calluses hairy, hairs to 0.5 mm long, lemma bodies glabrous 

and smooth below, scabrous distally, apex acuminate, awnless, 

mucronate or awned, the awns 1–6 mm long, straight; paleas 

3.8–5 mm long, narrowly lanceolate, glabrous below, acuminate; 

anthers 1.5–2.2 mm long, greenish. Caryopsis 2.5–3.5 mm long, 

fusiform, brownish. 2n = 40, 50.

Distribution and Habitat. Muhlenbergia dubia 

grows on steep slopes, ridge tops, limestone rock outcrops, and 

along draws with Juniperus flaccida, Quercus spp., and Pinus ponderosa at 1,500–3,200 m. Its range extends from western Texas 

and southern New Mexico to Mexico, where this species occurs 

in Aguascalientes, Chihuahua, Durango, Distrito Federal, Guanajuato, Hidalgo, Jalisco, México, Michoacán, Oaxaca, Puebla, 

Querétaro, San Luis Potosí, Tlaxcala, Veracruz, and Zacatecas.

Specimens Examined. MEXICO. Chihuahua. Bocoyna: Cabecera de la cañada de Recogoata, 2400 m, B. Tah V. 

63 (MEXU); 20 km S of San Juanito on road to Creel and 3 km S 

of Bocoyna, 10 Sep 1989, 2330 m, P.M. Peterson, Annable & Y. 

Herrera 8028 (US). Chihuahua: Hills near Chihuahua, 1800 m,

C.G. Pringle 403 (US); 12 mi N of Chihuahua, 1800 m, Soderstrom 931 (US). Cuauhtémoc: 12 mi W of Cuauhtémoc, 2128 m, 

Reeder & C. Reeder 4857 (ENCB). Guachochi: Parque Nacional 

Barranca del Cobre, 20.3 km NE of La Bufa and 3.2 km S of Basigochi, 2180 m, P.M. Peterson, Annable & Valdés-Reyna 10804 

(US); Entering Barranca El Cobre, approx. 25.7 km S of Cusarare 

on road to Guachochi, 25 Sep 1988, 2000 m, P.M. Peterson & 

Annable 5897 (US); 38.4 mi W of Guachochi on Mexico 127 

towards Creel, 2440 m, M.E. Siqueiros 1640 (MEXU); Parque 

Nacional Barranca del Cobre, 13.6 mi NE of La Bufa on road towards Samachique, 2240 m, P.M. Peterson, M.B. Knowles, C.H. 

Dietrich & S.M. Braxton 13565 (US); 30.2 km N of San Juanito 

on road to Creel, 10 Sep 1989, 2235 m, P.M. Peterson, Annable 

& Y. Herrera 8001 (US). Guerrero: Km 96 Yeporema–San José 

Babicora, al N de Vicente Guerrero, 2100 m, Hern.-Xol. & C. 

Tapia N-455 (CHAPA). Hidalgo del Parral: Minas Nuevas, 8 mi 

NW of Parral, 1829 m, Correll 22736 (US). Ignacio Zaragoza: 

72.5 km S of Ignacio Zaragoza on Mex 23, 28 Sep 1989, 2300 

m, P.M. Peterson & R.M. King 8175 (US). Madera: Guayanopa 

Canyon, Sierra Madre, Sep 1903, M.E. Jones s.n. (US) Type frag. 

Riva Palacio: Col. Cumbres de Majalca, approx. 32.2 km W of 

Hwy 45 N of Chihuahua, 23 Sep 1988, 2100 m, P.M. Peterson & 

Annable 5808 (US); Cumbres de Majalca, 21.5 mi W of Hwy 45, 

23 Sep 1988, 2200 m, P.M. Peterson & Annable 5809 (US); Col. 

Cumbres de Majalca, 33.8 km W of Mex 45, N of Chihuahua 

City, 2190 m, P.M. Peterson, Annable & Y. Herrera 7937 (US).

221. Muhlenbergia dumosa Scribn. ex Vasey, Contr. U.S. Natl. 

Herb. 3(1): 71. 1892.

FIGURE 160

Densely caespitose perennial; rhizomes elongated. Culms 

50–150(300) cm tall, bamboo-like, woody at base, emerging 

from a scaly rhizome 2–5 mm in diameter, freely branched at superior and central nodes, pubescent to glabrous below the nodes, 

branches fastigiated and numerous, central culm and proximal 

branches covered with sheaths until growth. Sheaths glabrous; 

ligules 0.3–0.5 mm long, truncate, erose; blades 2–5(10) cm 

long, 0.5–1.5 mm wide, flat or finely involute, articulate at the 

base and deciduous at the sheath apex. Panicles 1–3(4) cm long, 
NUMBER 107 • 227

0.3–1.3 cm wide, numerous and flexuous, pedicels 0.1–1.5 mm 

long. Spikelets 2.2–3.1 mm long, greenish or purplish; glumes 

1–1.7 mm long, shorter than spikelet, subequal, 1-veined, persistent; lower glumes 1–1.3 mm long, mucronate, the mucro 0.5–1 

mm long; upper glumes 1.3–1.7 mm long, mucronate or awned, 

the awn 0.6–2 mm long; lemma 2–2.2 mm long, membranous, 

pale or occasionally purplish, glabrous with green veins, awned, 

the awn (3)5–11 mm long; palea 2–2.2 mm long, similar to 

lemma; anthers 1.2–2 mm long, purple. Caryopsis 1.2–1.6 mm 

long, fusiform, reddish-brown. 2n = 40.

FIGURE 159. Muhlenbergia palmeri. A. Habit. B. Ligule. C. Glumes. D. Floret. E. Lodicules, pistil, and stamens. Muhlenbergia dubia. F. Ligule. G. Glumes. H. Floret. I. Lodicules, pistil, and stamens. Drawn by Elisabeth P. Roberts for Smithsonian Institution, Department of Botany.
228 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Distribution and Habitat. Muhlenbergia dumosa grows in pine–oak forests and tropical forests at elevations 

of 1,700–2,100 m. It ranges from the southwestern United States 

to Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 69.2 km al E de Guachochi and 25.7 km W of Balleza, 

26 Sep 1988, 2100 m, P.M. Peterson & Annable 5942 (US); 11 

mi SE of Balleza on road to Parral, 1800 m, P.M. Peterson, M.B. 

Knowles, C.H. Dietrich & S.M. Braxton 13526 (US). Batopilas: Rancho Byarly, Sierra Charuco, 17–25 Apr 1948, 1700 m, 

Gentry 8034 (MEXU, US). Guachochi: Parque Nacional Barranca del Cobre, 0.5 km E of La Bufa at the bridge crossing the 

Río Batopilas, 1000 m, P.M. Peterson, Annable & Valdés-Reyna 

10837 (US); West of Munérachi, 1200 m, P.M. Peterson & P. 

Catalán17718 (US).

222. Muhlenbergia elongata Scribn. ex Beal, Grass. N. Amer. 2: 

251. 1896.

FIGURE 161E–H

Caespitose perennial; never rhizomatous. Culms 40–120 cm 

tall, erect, not branched, glabrous, sometimes scabrous below 

the nodes. Sheaths glabrous to scabrous, rounded to base; ligules 

2–8 mm long, firm below, membranous to the apex, apex obtuse 

or acute; blades 15–50 cm long, 0.5–1.5 mm wide, flat to involute, 

glabrous to scabrous. Panicles 15–50 cm long, 1–7 cm wide, loosely 

contracted not dense, branches 1–8 cm long, appressed to barely 

divergent, naked basaly; pedicels 1.3–8 mm long, hirsute. Spikelets 3–4.2 mm long, straw-colored at maturity; glumes 2–3 mm 

long, slightly shorter than the lemma, subequal, glabrous at the 

base, minutely pubescent to scabrous near the apex, 1-veined, 

apex acuminate to acute, sometimes awned, the awn 1–1.6 mm 

long; lemma 2.8–4.2 mm long, narrow-lanceolate, glabrous at the 

base, scabrous near the apex, apex acuminate, awned, the awn 

10–40 mm long, straight to flexuous; palea 2.8–4.2 mm long, narrowly lanceolate, glabrous acuminate; anthers 1.4–2.2 mm long, 

yellow. Caryopsis 2–2.2 mm long, fusiform, brown. 

Distribution and Habitat. Muhlenbergia elongata grows in rhyolitic conglomerate or volcanic substrates on 

rocky slopes and canyon walls at elevations of 1,500–2,400 m. It 

ranges from the United States to Mexico in Chihuahua, Hidalgo, 

and Sonora.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: Hacienda San Miguel, near Batopilas, 2100 m, 

E. Palmer 159 (TAES, US); Batopilas, 2000 m, R. Fierros 1663

(MEXU); 14.5 km N of Batopilas on road to La Bufa, 12 Sep 

1989, 1850 m, P.M. Peterson, Annable & Y. Herrera 8064 (US); 

S side of Urique bridge, between Humirá and Napuchic, 1500 

m, Bye 6933 (TAES). Bocoyna: Cabecera de la cañada de Recogoata, 2400 m, B. Tah V. 65 (MEXU). Chinipas: 1 mi E of Saguarivo, 10 Sep 2008, small arroyo with oaks and pines, 1490 

m, P.M. Peterson & J.M. Saarela 22164 (US). Chihuahua: 12 

mi N of Chihuahua, 1800 m, Reeder, C. Reeder & Soderstrom 

3484 (ENCB); Cañón del 54, 1800 m, J. Peña s.n. (ENCB); Hills 

near Chihuahua, 1800 m, C.G. Pringle 398 (MEXU, US), type. 

Guachochi: Parque Nacional Barranca del Cobre, 0.5 km E of 

La Bufa at the bridge crossing the Río Batopilas, 1000 m, P.M. 

Peterson, Annable & Valdés-Reyna 10839, 10843 (US); Parque 

Nacional Barranca del Cobre, 3.8 km NE of La Bufa and 9.6 km 

S of Kirare, 1240 m, P.M. Peterson, Annable & Valdés-Reyna 

10833 (US); 39.2 km S of Creel on road to Batopilas at the Barranca El Cobre, 10 Sep 1989, 1930 m, P.M. Peterson, Annable 

& Y. Herrera 8026 (US); 24.6 km S of Mex 127 and 11.1 km 

NE of La Bufa, 11 Sep 1989, 2000 m, P.M. Peterson, Annable & 

Y. Herrera 8049 (US); 8.9 km NE of La Bufa on road to Creel, 

1780 m, P.M. Peterson, Annable & Y. Herrera 8067 (US). Hidalgo del Parral: NE edge of Parral, 2200 m, I.W. Knobloch 745

(TAES); Just S of Parral, 1950 m, Soderstrom 834 (US). Matamoros: 12 mi S of Villa Matamoros on Hwy 45 towards Parral, 

1900 m, Reeder & C. Reeder 4625, 4886 (ENCB, US). Ocampo: 

FIGURE 160. Muhlenbergia dumosa. A. Habit. B. Culm and inflorescence. C. Glumes. D. Floret. Drawn by Linda Ann Vorobik and 

Annaliese Miller; copyright Utah State University.
NUMBER 107 • 229

FIGURE 161. Muhlenbergia majalcensis. A. Habit. B. Floret. C. Glumes. D. Ligule. Muhlenbergia elongata. E. Habit. 

F. Ligule. G. Glumes. H. Floret. Drawn by Midge Gillete for PMP (A−D) and Susan C. Escher for Smithsonian Institution, Department of Botany (E−H).
230 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

122.5 km W of La Junta and 56.7 km W of Tomochic in Parque 

Nacional Cascada de Basaseachic, 1 Oct 1989, 2100 m, P.M. 

Peterson & R.M. King 8241, 8243 (US); Along trail just above 

Cascada de Basaseachic, 1880 m, P.M. Peterson & Annable 

12531 (US). Riva Palacio: 11.3 km W of Nuevo Majalca, 25.7 

km W of Hwy 45, N of Chihuahua, 22 Sep 1988, 1800 m, P.M. 

Peterson & Annable 5778 (US); Nuevo Majalca, approx. 14.5 

km W of Hwy 45, N of Chihuahua, 22 Sep 1988, 1700 m, P.M. 

Peterson & Annable 5762 (US); Nuevo Majalca, 11.6 km W of 

Mex 45 on road to Parque Nacional Cumbres de Majalca, 9 Sep 

1989, 1750 m, P.M. Peterson, Annable & Y. Herrera 7982 (US).

223. Muhlenbergia eludens C. Reeder, J. Wash. Acad. Sci. 39: 

365–366, f. 1B. 1949. 

Caespitose annual. Culms 10–40 cm tall, erect, strigulose 

below the nodes, internodes glabrous. Sheaths scabrous to puberulent, keeled, margins brown-yellowish; ligules 1.5–2.5 mm 

long, membranous, acute, lacerate to erose; blades 2–8 cm long, 

0.8–2 mm wide, involute, occasionally flat, minute-pilose to scabous. Panicles 14–24 cm long, 3–7 cm wide, spreading, open, 

narrowly pyramidal; branches 2–7 cm long, narrowly spreading and ascending, 1–3 per node; pedicels 1–2(3) mm long, usually shorter than the florets, slender, appressed to branches or 

occasionally erect. Spikelets 1.7–2.5 mm long; glumes 1.3–1.8 

mm long, subequal, 1-veined; lower glumes 1.3–1.6 mm long, 

acuminate to sometimes mucronate, mucros 0.5 mm long; upper 

glumes 1.4–1.8 mm long, acuminate, wider than the lower 

glume, apex acuminate; lemma 1.7–2.5 mm long, lanceolate, 

purple to yellowish or light brown, appressed silky-pubescent 

along the midvein and margins, the hairs 0.3–0.5 mm long, apex 

awned, the awn 1.2–3.5 mm long, delicate, emerging between 2 

small teeth; paleas 1.8–2.4 mm long, oblong-elliptic, glabrous; 

anthers 0.4–0.6 mm long, purplish. Caryopsis 1.3–2.3 mm long, 

fusiform, slightly compressed dorsally, light brownish. n = 20. 

Distribution and Habitat. Muhlenbergia 

eludens grows in grasslands and oak–pine forests at elevations 

of 1,800–2,680 m. It ranges from the United States to northern 

Mexico in Chihuahua, Durango, and Sonora.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 56.4 km W of Parral on road to Balleza and 35.5 km 

S of Balleza on Mex 432, near Corral de Duarte, 2210 m, P.M. 

Peterson, Annable & Valdés-Reyna 10708 (US); 56.4 km W of 

Balleza and 38.7 km E of Guachochi, 2480 m, P.M. Peterson, Annable & Valdés-Reyna 10769 (US). Bocoyna: Norogachi, 2350 

m, E. Palmer 3D (US). Carichi: Sánchez, 12 Oct 1910, 2400 

m, Hitchcock 7664.5 (CHAPA, US). Casas Grandes: 2 mi S of 

Hernández Javales, 31 mi SW of Col. Juárez, 2200 m, P.M. Peterson & Annable 4038, 4040 (US). Chihuahua: 39 km carr. [hwy] 

Chihuahua–Namiquipa, 2300 m, M. Vergara 177 (MEXU); Hills 

near Chihuahua, 1800 m, C.G. Pringle 3052 (TAES, US); Rocky 

hills near Chihuahua, C.G. Pringle 399, 400 (US); 38 km W of 

Hwy 45 on road towards Benito Juárez, 2230 m, P.M. Peterson 

& Annable 12561 (US); 9.1 mi W of Hwy 45 on dirt road towards Santa Clara, 1690 m, P.M. Peterson & Annable 12587 

(US). Cuauhtémoc: 10 mi W of Cuauhtémoc on hwy 16, 2000 

m, P.M. Peterson & Annable 4055 (US); 11 mi E of Cuauhtémoc, 21 Sep 1986, 1800 m, P.M. Peterson & Annable 4531 (US). 

Guachochi: 12 mi E of Guachochi, 2300 m, P.M. Peterson & 

Annable 5925 (US); 18 mi E of Guachochi on Mex 127 towards 

Balleza, 2680 m, P.M. Peterson & R.M. King 8085 (US); 5.5 mi 

S Cieneguita de Barranca on road towards Sorichique, 2125 m, 

P.M. Peterson, P. Catalán, C. López, & G. Villegar 7702 (US). 

Guerrero: Tomochic, 2 km alrededor del poblado [around the village], 2100 m, M. Vergara 153 (MEXU); Miñaca, 13 Oct 1910, 

Hitchcock 7768 (US), holotype; 24 mi SW of La Junta on road 

to Creel, 2200 m, P.M. Peterson & Annable 5851 (US); 25 mi 

W of La Junta on rd to Parque Nacional Cascada Basaseachic, 

2200 m, P.M. Peterson & R.M. King 8193 (US). Ignacio Zaragoza: 12.6 mi NE of Ignacio Zaragoza, 2400 m, P.M. Peterson 

& R.M. King 8158 (US). Madera: 14.5 mi SE of Madera on Mex 

16 to La Junta, 2200 m, P.M. Peterson & R.M. King 8176 (US). 

Namiquipa: 45 mi S of Ignacio Zaragoza, 2200 m, P.M. Peterson 

& R.M. King 8167 (US). Ocampo: Parque Nacional de Cascada 

Basaseachic, 1 km airline S of Cascada, 2100 m, P.M. Peterson 

& R.M. King 8212 (MEXU, US). Riva Palacio: Cumbres de Majalca, 21.5 mi W of Hwy 45, 22 Sep 1988, 2200 m, P.M. Peterson 

& Annable 4524, 5789, 5794, 5796 (MEXU, US); 0.9 km E of 

entrance to Parque Nacional, Col. Cumbres de Majalca, 2200 m, 

P.M. Peterson & Annable 4516 (US); 20.6 mi W of Hwy 45, 0.8 

mi E of Cumbres de Majalca, 2200 m, P.M. Peterson & Annable 

4517 (US); Cumbres de Majalca, 21.5 mi W of Hwy 45, 2200 m, 

P.M. Peterson, Annable & Y. Herrera 7939 (US).

224. Muhlenbergia emersleyi Vasey, Contr. U.S. Natl. Herb. 

3(1): 66. 1892.

FIGURE 162J–M

Densely caespitose perennial. Culms (65)80–150(200) cm 

tall, erect, stout, not conspicuously branched; internodes smooth 

for most of their length, smooth or scaberulous below the nodes. 

Sheaths 7–35 cm long, shorter or longer than the internodes, glabrous or puberulent, basal sheaths compressed-keeled, sheath auricles missing; ligules 10–25 mm long, membranous throughout, 

acuminate, lacerate, slightly firmer below; blades 20–50 cm long, 

2–6 mm wide, flat or folded, scabrous abaxially, smooth or scaberulous adaxially, margins coarsely scabrous. Panicles 20–45 cm 

long, 4–7(15) cm wide, loosely contracted to open, light purplish 

to light brownish; primary branches 9–17 cm long, lax, loosely 

appressed or diverging to 70° from the rachises, naked basally; 

pedicels 0.5–3 mm long, erect, smooth or scaberulous. Spikelets 

2.2–3.2 mm long; glumes 2.2–3.2 mm long, longer or as long as 

the lemma, subequal, scaberulous to scabrous, faintly 1-veined, 

acute to obtuse, usually unawned, occasionally mucronate, mucro 

to 0.2 mm long; lemmas 2–3 mm long, oblong-elliptic, pubescent 

along the midvein and margins on the lower 1⁄2–3⁄4, apex acute, 

usually awned, sometimes awnless or mucronate, awns generally 

(1)6–15 mm long, flexuous, purplish; paleas 1.8–2.9 mm long, 

oblong-elliptic, acute; anthers 1.2–1.6 mm long, yellowish to purplish. Caryopsis 1.3–1.6 mm long, fusiform, reddish-brown. 2n = 

24, 26, 28, 30, 40, 42, 46, 60, 64.
NUMBER 107 • 231

FIGURE 162. Muhlenbergia lindheimeri. A. Habit. B. Ligule. C. Glumes. D. Floret. E. Lodicules, pistil, and stamens. Muhlenbergia longiligula. F. Ligule, G. Glumes. H. Floret. I. Lodicules, pistil, and stamens. Muhlenbergia 

emersleyi. J. Ligule. K. Glumes. M. Lodicules, pistil, and stamens. Drawn by Cathy Pasquale for Smithsonian 

Institution, Department of Botany.
232 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Distribution and Habitat. Muhlenbergia 

emersleyi grows on rocky slopes, gravelly washes, canyons, 

and cliffs, and along streams often derived from limestone parent material associated with oak–pinyon–juniper woodlands at 

1,200–2,600 m. It occurs in western Texas, New Mexico, and 

Arizona and is common throughout Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 11 mi SE of Balleza on road to Parral, 1800, P.M. Peterson, M.B. Knowles, C.H. Dietrich, S.M. Braxton 13516, 13517

(US); 56.4 km W of Balleza and 38.7 km E of Guachochi, 2280 

m, P.M. Peterson, Annable & Valdés-Reyna 10766 (US); 19.3 km 

SE of Balleza towards Parral, 26 Sep 1988, 1800 m, P.M. Peterson & Annable 5945 (US); 16.1 km W of Balleza and 77.9 km E 

of Guachochi, 1990 m, P.M. Peterson, Annable & Valdés-Reyna 

10749 (US); 56.4 km W of Balleza and 38.7 km E of Guachochi, 

2280 m, P.M. Peterson, Annable & Valdés-Reyna 10765 (US); 10 

mi SW of El Ojito, 12 Sep 2006, 1902 m, P.M. Peterson 20014, 

20015, 20031, F. Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, 

US). Batopilas: Just S of Napuchis along ridgetop with Schizachyrium and scattered Pinus, 2162 m, P.M. Peterson & P. Catalán 

17664 (US); 22 km al S de Humira, 21.8 km al SW de la desv. A 

La Bufa, 2070 m, Tenorio & R. Torres 3700 (MEXU); Brecha 

[gap] Samachique–Batopilas, 1400 m, A. Rodríguez & S. Manrique 1606 (MEXU); Between La Bufa and Quirare, on N side of 

Barranca Batopilas, Bye 5709 (MEXU). Bocoyna: 24.7 mi N of 

San Juanito on road towards Cuauhtemoc, 5 Sep 2008, 2233 m, 

P.M. Peterson & J.M. Saarela 22024, 22035 (US); Cabecera de la 

cañada de Recogoata, 2400 m, B. Tah V. 52 (MEXU). Buenaventura: 15 mi W of Flores Magón, 1829 m, Reeder, C. Reeder & 

Soderstrom 3499 (CHAPA, US); Hills near Buenaventura, 1950 

m, A.A. Beetle M-7877 (MEXU). Carichi: Sánchez, 12 Oct 1910, 

Hitchcock 7669, 7714, 7720 (US). Casas Grandes: Arroyo de Los 

Nogales 20 km, al S de Col. Juárez,1450 m, Tenorio & Romero 

1622 (ENCB, US); About 38 mi SW of Casas Grandes, 2040 m, 

Reeder & C. Reeder 2695 (ENCB); 1 mi W of Cuesta Blanca, W 

of Casas Grandes, 1976 m, Reeder, C. Reeder & Soderstrom 

3349 (ENCB); W of Casas Grandes, 3 mi NE of Cuesta Blanca, 

1976 m, Reeder, C. Reeder & Soderstrom 3449,3542, 3543, 

3548 (ENCB, US); 1 mi W of Cuesta Blanca, W of Casas Grandes, 

2012 m, Reeder & C. Reeder 3227 (ENCB); W of Casas Grandes, 

12 mi W of Col. Juárez, 1763 m, Reeder, C. Reeder & Soderstrom 3503 (ENCB, US); W of Casas Grandes, 5 mi S of Hernández, 2200 m, Reeder, C. Reeder & Soderstrom 3524 (ENCB, US); 

9 mi NE of Cuesta Blanca, W of Casas Grandes, 2200 m, Reeder, 

C. Reeder & Soderstrom 3555 (ENCB); Rancho Palanganas 

(Mesa El Cuervo), 2020 m, R. Fierros 130 (MEXU); Near Casas 

Grandes, C.W. Towsend 357 (US); Soderstrom 734 (US); Río Piedras Green al SE del Ejido Ignacio Zaragoza, 1700 m, Tenorio & 

Romero 1695 (MEXU); W of Casas Grandes, 12 mi W of Col. 

Juárez, 1763 m, Reeder & C. Reeder 3502 (US); W of Casas 

Grandes, 3 mi NE of Cuesta Blanca, 1976 m, Reeder & C. Reeder 

3548, 3549 (US); W of Casas Grandes, just S of Hernández, 

Reeder & C. Reeder 3533 (US). Cuauhtémoc: 10 mi W of Cuauhtémoc on Hwy 16, 5 Sep 1985, 2100 m, P.M. Peterson & Annable 4058 (US); 12 mi W of Cuauhtémoc, 2128 m, Reeder & 

C. Reeder 3190, 4859 (ENCB); F.W. Gould 8946 (TAES); 11 mi 

E of Cuauhtémoc, 1824 m, Reeder, C. Reeder & Soderstrom 

3467, 3469 (ENCB, US); Rancho La Estancia, 2300 m, 

R. Guzmán 4911 (MEXU); 16 mi W of Cuauhtémoc, 2300 m, 

Reeder & C. Reeder 3470, 3471, 3472 (US). Chihuahua: Base de 

la Sierra de La Campana, 80 km al N de Chihuahua, 1700 m, 

Rzedowski 32318 (ENCB); Base de la Sierra de La Campana, 80 

km al N de Chihuahua, 1700 m, Valdés-Reyna VR-144 (TAES); 

12 mi N of Chihuahua, Reeder & C. Reeder 3482 (US); Soderstrom 930 (US); 13 mi SW of Chihuahua on road to Cuauhtémoc, 

Soderstrom 917, 918 (US); Mts. NW of Chihuahua, 1800 m, 

LeSueur 149 (US); 87.7 km N of Parral on Mex 24 towards Chihuahua, 14 Sep 1989, 1620 m, P.M. Peterson, Annable & Y. Herrera 8106 (US); 9.1 mi W of Hwy 45 on dirt road towards Santa 

Clara, 1690 m, P.M. Peterson & Annable 12588 (US); 38 km W 

of Hwy 45 on road towards Benito Juárez, 2230 m, P.M. Peterson & Annable 12568 (US). Chínipas: Saguarivo, 53 mi N of Alamos, 9 Sep 2008, slopes with oaks and pines, 1540 m, P.M. 

Peterson & J.M. Saarela 22123 (US); Sierra Milpillas, 24.1 mi E 

of Los Tanques on road to Milpillas, 2100 m, A.A. Beetle, R. Alcaráz & R. Cuadra 8054, 8114 (TAES). Guachochi: 5.5 mi S of 

Cieneguita de Barranca on road towards Sorichique, 2125 m, 

P.M. Peterson, P. Catalán, C.López & G. Villegar 17705 (US); 

1–2 km south of Rio Osichi and Rio Basihuare jct along river bottom in rocks and slopes with Quercus and Pinus, 1600 m, P.M. 

Peterson & P. Catalán 17631 (US); Along Rio Corareáchi, slopes 

with oak–pinyon–Cupressus–Arbutus, and Juniperus, 1840 m, 

P.M. Peterson & P. Catalán 17595, 17606, 17607 (US); Arroyo 

Baqueachi, at 0.5 km E of small village, 2004 m, P.M. Peterson & 

P. Catalán 17568 (US); Steep slopes above Barranca Basihuare 

with Quercus spp., Pinus ponderosa, P. chihuahuana, 1815 m, 

P.M. Peterson & P. Catalán 17582 (US); Parque Nacional Barranca del Cobre, 8.8 km NE of La Bufa and 4.8 km S of Kirare, 

1730 m, P.M. Peterson, Annable & Valdés-Reyna 10826, 10828 

(US); Parque Nacional Barranca del Cobre, 20.3 km NE of La 

Bufa and 3.2 km S of Basigochi, 2180 m, P.M. Peterson, Annable 

& Valdés-Reyna 10805 (US); S side of Barranca El Cobre, 29.4 

km S of Cusarare on road to Guachochi, 25 Sep 1988, 1800 m, 

P.M. Peterson & Annable 5909 (US); Entering Barranca El Cobre, 

28.3 km S of Cusarare on road to Guachochi, 25 Sep 1988, 1900 

m, P.M. Peterson & Annable 5900, 5905 (US); 8.5 km S of Cusarare on road to Guachochi, 25 Sep 1988, 2400 m, P.M. Peterson & Annable 5879, 5886 (US); Camino Guachochi–Creel, 5 

km antes del entronque [before junction] a la Bufa, 2400 m, M.E. 

Siqueiros 1619, 1626, 1639 (MEXU); Cusarare, just NW of the 

church, 2200 m, Bye 8099 (MEXU); 9 mi S of Guachochi at edge 

of Barranca Río Green, 2470 m, P.M. Peterson & J. Cayouette 

15381 (US); 26.7 mi S of Creel on road to Batopilas, 10 Sep 1989, 

2100 m, P.M. Peterson, Annable & Y. Herrera 8018 (US); Parque 

Nacional Barranca del Cobre, 12.6 mi NE La Bufa and 2 mi S 

Barsigochi, 2180 m, P.M. Peterson, Annable & Valdés-Reyna 

10805 (US); 39.2 km S of Creel on road to Batopilas at the Barranca El Cobre, 10 Sep 1989, 1930 m, P.M. Peterson, Annable & 

Y. Herrera 8021 (US); 43 km S of Creel on road to Batopilas, 11 

Sep 1989, P.M. Peterson, Annable & Y. Herrera 8035 (US); 24.6 
NUMBER 107 • 233

km S of Mex 127 and 11.1 km NE of La Bufa, 2000 m, P.M. 

Peterson, Annable & Y. Herrera 8050 (US). Guadalupe y Calvo: 

Between Guadalupe y Calvo and Tecolote, 18 Oct 1959, 2250 m, 

Correll 23237 (US); Rio Verde Crossing, 21 mi SW of El Vergel 

on hwy 24, 14 Sep 2006, 2330–2360 m, P.M. Peterson 20075, F. 

Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, US). Guerrero: 

33.5 km SW of La Junta on road to Creel, 2260 m, P.M. Peterson 

9609 (US); Carr. San Juanito–La Junta, 17 km, 2990 m, B. Tah 

V. 15 (MEXU); Km 193 carr. [hwy] Chihuahua–Hermosillo, 

tramo [section] San Pedro–Temochic, 2200 m, M.A. Vergara 173

(MEXU); Miñaca, 13 Oct 1910, Hitchcock 7742 (US); 33.5 km 

SW of La Junta on road to Creel, 2260 m, P.M. Peterson 9607

(US); Barranca Colorada, Sierra Gazachic, 35 km S of Miñaca, 

2500 m, Pennell 18957 (US). Hidalgo del Parral: 5 mi S of Parral, 

Reeder & C. Reeder 4617, 4618 (US); 1 mi S of Parral on road to 

México city, Soderstrom 828 (US); 4 mi E of Parral, Reeder & 

C. Reeder 3457 (US); 21 km W of Parral and approx. 0.8 km N 

on dirt road to Torrenocillo, 26 Sep 1988, 1900, P.M. Peterson & 

Annable 5969 (US). Ignacio Zaragoza: Ejido de León, 2100 m, 

Robert & Passini 6747 bis (ENCB); 27 km al SW de Buenaventura, 1578 m, J. Peña 776 (ENCB); 20.3 km NE of Ignacio Zaragoza on Mex 23, 28 Sep 1989, 2400 m, P.M. Peterson & R.M. 

King 8153 (US). Janos: Rancho Carretas, Chih.–Son. Border, 

1675 m, L. H. Harvey 1627 (US); Sierra El Medio, 1700 m, 

S. Ibarra s.n. (INEGI). Jiménez: Sta. Eulalia Mts, 1280 m, 

E. Wilkinson 58 (US). Madera: About 23 mi SE of Chuhichupa 

on the road to Madera, 2255 m, Reeder & C. Reeder 2670, 2671

(ENCB); About 15 mi S of Madera, 2165 m, Reeder & C. Reeder 

2640 (ENCB); Mesa de Yerbanís, ejido El Long, 1900 m, 

A. Benítez 1837, 2816, 2817 (CHAPA); Ejido El Long, 1900 m, 

O. Bravo 1293, 1931 (CHAPA); Ciénega Ojo de la Víbora, ejido 

El Long, 2300 m, A. Benítez 2864 (CHAPA); Rancho de Doroteo, 2100 m, J.M. Peña 815 (HUAA). Matamoros: 12 mi S of 

Villa Matamoros on Hwy 45 towrds Parral, 1900 m, Reeder & 

C. Reeder 4888 (ENCB); Minas Nuevas, 8 mi NW of Parral, 

1829 m, Correll 22736 (US); 19.3 km S of Villa Matamoros on 

Mex 45 to Durango, 1910 m, P.M. Peterson & R.M. King 8263 

(US). Moris: Yepachic, Chih., 1550 m, C.W. Peninngton 81 

(MEXU). Namiquipa: Sierra El Nido, coger part of Arroyo Mesteño, 2600 m, G.M. Christman 170 (TAES). Nuevo Casas 

Grandes: E de la sierra La Escondida, en el Cañón de La Madera, 

1840 m, M.A. López s.n. (INEGI). Ocampo: Parque Nacional de 

Cascada Basaseachic, 1 km airline S of Cascada, 1 Oct 1989, 

2100 m, P.M. Peterson & R.M. King 8244 (US); Along trail just 

above Cascada de Basaseachic, 1880 m, P.M. Peterson & Annable 12529 (US); Parque Nacional de Cascada Basaseachic, 1 km 

airline S of Cascada, 2100 m, Tenorio & R. Torres 3802, 4472

(MEXU); Along trail just above Cascada Basaseachic, 1880 m, 

P.M. Peterson & Annable 12533 (US); 40.3 km W of La Junta on 

road to Parque Nacional Cascada de Basaseachic, 29 Sep 1989, 

2390 m, P.M. Peterson & R.M. King 8192 (US). Riva Palacio: 38 

km W of Hwy 45 on road towards Benito Juárez, 2230 m, P.M. 

Peterson & Annable 12559 (US); Majalca, 2100 m, LeSueur 021 

(US); 11.3 km W of Nuevo Majalca, 25.7 km W of Hwy 45, N of 

Chihuahua, 22 Sep 1988, 1800 m, P.M. Peterson & Annable 

5780 (US); Col. Cumbres de Majalca, approx. 32.2 km W of 

Hwy 45 N of Chihuahua, 23 Sep 1988, P.M. Peterson & Annable 

5806 (US); Col. Cumbres de Majalca, 33.8 km W of Mex 45, N 

of Chihuahua City, 7 Sep 1989, 2190 m, P.M. Peterson, Annable 

& Y. Herrera 7958 (US). Ojinaga: Sierra Matosagua, 1400 m, 

G. García s.n. (INEGI). Temósachi: 71.7 km SE of Madera on 

Mex Hwy 16 and 1.6 km S of Temósachic, 29 Sep 1989, 2090 m, 

P.M. Peterson & R.M. King 8185 (US); Nabogame, 2200 m, Laferr. 732 (MEXU). San Francisco del Oro: San Francisco del Oro 

mines, 20 mi from Parral, Soderstrom 870, 871 (US). Santa Bárbara: Ejido Buenavista, 1950 m, S. Aguirre 2052 (MEXU); Rancho El Primero, 1820 m, S. Ojeda s.n. (INEGI). Uruáchi: 8.6 mi 

E of Yécora on Hwy 16 to Maycoba, 1880 m, P.M. Peterson & 

J. Cayouette 15324 (US); 20.2 mi W of Maycoba on Hwy 16 to 

Yécora, 1810 m, P.M. Peterson & J. Cayouette 15328 (US).

225. Muhlenbergia filiformis (Thurb. ex S. Wats.) Rydb., Bull. 

Torrey Bot. Club 32(11): 600. 1905.

Annual (often appearing perennial); tufted. Culms (3)5–

20(35) cm tall, erect or geniculate, often rooting at the lower 

nodes; internodes glabrous. Sheaths shorter or longer than the 

internodes, glabrous, smooth or scaberulous; ligules 1–3.5 mm 

long, hyaline to membranous, rounded to acute; blades 1–4(6) 

cm long, 0.6–1.6 mm wide, mostly basal, numerous, flat or 

involute, smooth or scaberulous abaxially, scabrous or pubescent adaxially. Panicles 1.6–6 cm long, 0.2–0.5 cm wide, spikelike, interrupted near the base, long-exserted; primary branches 

0.9–1.2 cm long, closely appressed at maturity; pedicels 1–3 mm 

long, scabrous. Spikelets 1.5–3.2 mm. Glumes greenish-gray, glabrous, 1-veined, rounded to subacute; lower glumes 0.6–1.4 mm; 

upper glumes 0.7–1.7 mm; lemmas (1.5)1.8–2.5(3.2) mm long, 

lanceolate, dark greenish, appressed-pubescent on the margins 

and midveins, hairs shorter than 0.3 mm long, apex scaberulous, 

acute to acuminate, unawned, sometimes mucronate, mucros 

shorter than 1 mm; paleas 1.6–2.6(3.1) mm long, lanceolate, scaberulous distally; anthers 0.5–1.2 mm long, purplish. Caryopsis 

0.9–1.5 mm long, fusiform, reddish-brown. 2n = 18.

Distribution and Habitat. Muhlenbergia filiformis grows in open, moist meadows, on gravelly lake shores, 

along stream banks, and in moist humus near thermal springs at 

elevations of 1,060–3,050 m. It is usually associated with yellow (three-needled) pine forests, but also grows in many other 

plant communities. It occurs in Canada, the United States, and 

extends into northern Mexico.

Specimens Examined. MEXICO. Chihuahua, 

Bocoyna: Sánchez, along railway, 21 Oct 1910, A.S. Hitchcock 

7720 (US).

226. Muhlenbergia flavida Vasey, Contr. U.S. Natl. Herb. 1(8): 

282. 1893. 

FIGURE 163A–D

Caespitose delicate annual. Culms 7–40 cm tall, erect, occasionally decumbent, strigulose below nodes. Sheaths glabrous 

to scaberulous, margins greenish-yellow; ligules 1.5–3 mm long, 
234 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

FIGURE 163. Muhlenbergia flavida. A. Habit. B. Lemma, C. Glumes. D. Ligule. Muhlenbergia schmitzii. E. Habit. 

F. Lemma. G. Glumes. H. Ligule. Drawn by Midge Gillete for PMP.
NUMBER 107 • 235

membranous, apex obtuse to acute, lacerate to erose; blades 

2–9 cm long, 0.4–1.8 mm wide, involute to folded, occasionally 

flat, sparsely minute-villous above, glabrous to sparsely scaberulous below. Panicles 10–16 cm long, (1)3–6.5 cm wide, narrowly 

pyramidal; branches 1.6–4 cm long, 1–3 per node, ascending or 

some divergent, naked to the base with scattered florets; pedicels 

0.7–1.5 mm long, slender, appressed, less than 1⁄2 as long as the 

floret. Spikelets 2.2–3 mm long, broad and dorsally flattened, 

stramineous to yellow, appressed along the branches; glumes 

1.5–2 mm long, almost equal, glabrous, 1-veined, ovate lanceolate, awned, awns to 0.8 mm long, lower glume gradually 

acuminate, upper glume generally abruptly acuminate; lemma 

2.2–3 mm long, membranous, yellowish when mature, oblongellipsoid, 3-veined, silky-pubescent on margins and midvein to 

the base, appressed hairs to 0.4 mm long, apex 2-toothed, teeth 

minute to 0.2 mm long, awn 1–3 mm long, delicate, emerging 

between lobes; palea 2.2–3 mm long, oblong-ellipsoid, glabrous, 

apex with 2 minute teeth to 0.2 mm; anthers 0.4–0.6 mm long, 

olive-green to light brown. Caryopsis 1–1.7 mm long, oblong, 

compressed, light brown to yellowish.

Distribution and Habitat. Muhlenbergia 

flavida grows in pine–oak forests at elevations of 1,900–2,100 

m. It is known from Mexico in Chihuahua, Durango, Hidalgo, 

Jalisco, Michoacán, Nayarit, Sinaloa, and Sonora.

Specimens Examined. MEXICO. Chihuahua. 

Chínipas: Sierra Milpillas 28.1 mi E of Los Tanques on road to 

Chínipas, 1.6 mi N of Los Chinicas, 2100 m, P.M. Peterson & 

Annable 4173, 4174 (MEXU, US). Guachochi: 15.3 mi S of Mex 

127 and 6.9 mi NE of la Bufa, 2000 m, M.E. Siqueiros 1647

(MEXU); S side of Barranca del Cobre, 18.3 mi S of Cusarare 

on rd to Guachochi, 1900 m, P.M. Peterson & Annable 5908

(US); 24.3 mi S of Creel on road to Batopilas at Barranca del 

Cobre, 1900 m, P.M. Peterson, Annable & Y. Herrera 8014 (US); 

15.3 mi S of Mex 127 and 6.9 mi NE of la Bufa, 2000 m, P.M. 

Peterson, Annable & Y. Herrera 8053 (US); Small spring below 

Napuchis, 1950 m, P.M. Peterson & P. Catalán 17659 (CIIDIR, 

US). Uruáchi: 20.2 mi W of Maycoba on Hwy 16 to Yécora, 

1800 m, P.M. Peterson & J. Cayouette 15343 (US). 

227. Muhlenbergia flaviseta Scribn., U.S.D.A. Div. Bot. Bull. 8: 

11, t. 7. 1897.

Caespitose perennial. Culms 20–30 cm tall, glabrous. Leaf 

blades mostly basal, sheaths puberulent to glabrous, papery with 

age; ligules 0.2–0.5 mm long, hyaline, truncate and fimbriate; 

blades 2–7(8.5) cm long, 1.5–2 mm wide, flat, glabrous to scabrous, apex largely acuminate. Panicles 2–5 cm long, 1–2 cm 

wide, long-exserted, very branched, branches 2.5–3 cm long, 

ascending, appressed, central axes flattened with 2 ribs, glabrous to scabrous. Spikelets 3.5–4 mm; glumes unequal, greenish, glabrous, oblong-lanceolate; lower glumes (0.5)1–1.8 mm 

long, 1-veined, mucronate; upper glumes (3)3.5–4.2 mm long, 

1- to 3-veined, 3-toothed; lemma (3)3.8–4 mm long, subulate, 

green to straw color, glabrous, apex entireand awned, the awn 

14–16 mm long, yellow, flexuous, scabrous at the base; palea 

2.8–3.2 mm long, straw-colored, glabrous; anthers 1.5–2 mm 

long, oblong, purplish. 2n = 20. 

Distribution and Habitat. Muhlenbergia flaviseta grows in pine–oak forests and grasslands with scattered 

oaks at elevations of 1,900–2,400 m. This Mexican endemic occurs in the Sierra Madre Occidental and is found in Chihuahua 

and Durango.

Specimens Examined. MEXICO. Chihuahua. 

Bocoyna: Cabecera de la cañada de Recogoata, 2400 m, B. Tah 

V. 43 (MEXU). Guachochi: 25.6 mi S of Creel on road to Batopilas, 2100 m, Y. Herrera 967 (CIIDIR); 42 km S of Creel on road 

to Batopilas, 10 Sep 1989, 2100 m, P.M. Peterson, Annable & 

Y. Herrera 8034 (US); 32.2 km S of Cusarare on road to Guachochi, S side of Barranca del Cobre, 25 Sep 1988, 2000 m, P.M. 

Peterson & Annable 5911 (US); Parque Nacional Barranca del 

Cobre, 11.3 km NE of La Bufa and 2.1 km S of Kirare, 1950 

m, P.M. Peterson, Annable & Valdés-Reyna 10820 (US). Guazapares: Between Tamares and Basoriachic, 2200 m, Bye 6127

(MEXU). Moris: Approx. 17.6 mi E of Maycoba on Hwy 16 

towards Yepachic and 2 mi E of Sonora/Chihuahua boundary, 

1540 m, P.M. Peterson & Annable 12513 (US). Ocampo: overlook of Casada de Basaseachic, approx. 37 mi W of Tomochic, 

2200 m, P.M. Peterson & Annable 4547 (US); Parque Nacional 

Cascada de Basaseachic, 1 km airline S of Cascada, 2100 m, 

Spellenberg & M. Mahrt 74 (MEXU); 122.5 km W of La Junta 

on road to Parque Nacional Cascada de Basaseachic and 56.7 

km W of Tomochic, 1 Oct 1989, 2100 m, P.M. Peterson & R.M. 

King 8224 (US); 122.5 km W of La Junta and 56.7 km W of 

Tomochic in Parque Nacional Cascada de Basaseachic, 1 Oct 

1989, 2100 m, P.M. Peterson & R.M. King 8235 (US); Parque 

Nacional Cascada de Basaseachic, 1 km airline S of Cascada, 

2100 m, M. Vergara 139 (MEXU).

228. Muhlenbergia fragilis Swallen, Contr. U.S. Natl. Herb. 

29(4): 206. 1947.

FIGURE 164

Caespitose annual. Culms 10–38 cm tall, erect or spreading; scabrous or strigulous below the nodes; internodes mostly 

glabrous, smooth or scaberulous. Sheaths 2.4–4.2 cm long, often 

longer than the internodes, scaberulous, margins hyaline; ligules 

1–3 mm long, hyaline, obtuse, irregularly toothed to lacerate, 

with lateral lobes extended into auricles; blades 1–10 cm long, 

0.4–2 mm wide, flat, scabrous abaxially, strigulose adaxially, 

margins and midveins whitish-thickened; panicles 10–24 cm 

long, 3.5–11 cm wide, diffuse; primary branches 2.2–6.2 cm 

long, capillary, diverging 80°–100° from the rachises, straight; 

pedicels 6–10 mm long, delicate. Spikelets 1–1.2 mm long, appressed to slightly divergent from branch axes; glumes 0.5–1 mm 

long, equal to subequal, 1-veined, glabrous throughout or obscurely puberulent, hairs about 0.06 mm long, apex obtuse or 

subacute; lemmas 1–1.2 mm long, oblong-elliptic, membranous, 

purplish to light brownish, not mottled, glabrous or densely 

appressed-puberulent on the margins and midveins, apex obtuse, 
236 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

awnless; paleas 0.9–1.2 mm long, oblong-elliptic, densely puberulent between the veins or glabrous, apex obtuse; anthers 

0.3–0.5 mm long, purplish. Caryopsis 0.7–0.9 mm long, elliptic, 

reddish-brown. 2n = 20.

Distribution and Habitat. Muhlenbergia fragilis grows on rocky talus slopes, cliffs, canyon walls, roadcuts, 

and sandy slopes, often on calcareous substrates, at elevations 

of 480–2,200 m from southeastern California to western Texas 

to south into Mexico in Baja California, Chiapas Chihuahua, 

Guanajuato, Guerrero, Jalisco, Michoacán, Morelos, Nayarit, 

Oaxaca, Puebla, Querétaro, San Luis Potosí, Sinaloa, Sonora, 

and Veracruz. It is usually found in oak–grama savannahs, 

thorn scrub forests, oak–yellow pine forests, and pinyon–juniper 

woodlands.

Specimens Examined. MEXICO. Chihuahua. 

Buenaventura: 0.5 mi W of Flores Magón, Reeder & C. Reeder 

3495 (US). Casas Grandes: 5 km al W de Casas Grandes, 1900 

m, Valdés-Reyna VR-751 (CHAPA). Cuauhtémoc: 11 mi E of 

Cuauhtémoc, 1824 m, Reeder & C. Reeder 2616 (ENCB); 3466

(US). Chihuahua: Base de la Sierra de La Campana, 80 km al 

N de Chihuahua, 1700 m, Rzedowski 32306 (ENCB); Km 43 

carr. [hwy] Chihuahua–Cd. Cuauhtémoc, 1600 m, Hern.-Xol. & 

C. Tapia N-298 (TAES, CHAPA); Hills near Chihuahua, 1800 

m, C.G. Pringle 482 (US); Chihuahua, 1800 m, 14 Oct 1910, 

Hitchcock 7783 (US); SW of Chihuahua, E. Palmer 76 (US); 6.1 

mi W of Hwy 45 on dirt road towards Santa Clara, 1640 m, P.M. 

Peterson & Annable 12578 (US). Chínipas: Sierra Milpillas, 18.2 

mi E of Los Tanques on rd to Milpillas, 2100 m, P.M. Peterson & 

Annable 4170 (US); 3.4 mi W of Saguarivo on road to Chinacas, 

10 Sep 2008, rocky slopes with Acacia, Opuntia, Quercus, 1617 

m, P.M. Peterson & J.M. Saarela 22171 (US). Guachochi: Parque 

Nacional Barranca del Cobre, 1.6 km E of La Bufa, 1950 m, P.M. 

Peterson & M.B. Knowles 13580 (US); 15.3 mi S of Mex 127 

and 6.9 mi NE of la Bufa, 2000 m, P.M. Peterson, Annable & 

Y. Herrera 8055 (US); Parque Nacional Barranca del Cobre, 8.8 

km NE of La Bufa and 4.8 km S of Kirare, 1730 m, P.M. Peterson, Annable & Valdés-Reyna 10824 (US); Parque Nacional Barranca del Cobre, 0.5 km E of La Bufa at the bridge crossing the 

Río Batopilas, 1000 m, P.M. Peterson, Annable & Valdés-Reyna 

10838 (US); Parque Nacional Barranca del Cobre, 6.7 km NE of 

Batopilas along the Río Batopilas at the Arroyo de Santiago, 690 

m, P.M. Peterson, Annable & Valdés-Reyna 10854 (US); West of 

Munérachi, 1200 m, P.M. Peterson & P. Catalán17712 (US). Hidalgo del Parral: 13.5 mi W of Parral on Hwy 24 towards El Vergel, 2000 m, P.M. Peterson & Annable 4554 (US). Janos: Rancho 

Carretas, Chih–Son. Border, 1675 m, L. H. Harvey 1623 (US). 

Jiménez: Sta. Eulalia Mts, E. Wilkinson 57 (US). Madera: About 

15 mi S of Madera, 2165 m, Reeder & C. Reeder 2631 (ENCB); 

FIGURE 164. Muhlenbergia fragilis. A. Habit. B. Ligule. C. Inflorescence. D. Glumes. E. Florets. Drawn by Linda 

Ann Vorobik and Annaliese Miller; copyright Utah State University.
NUMBER 107 • 237

Puerto de El Tenedor, ejido El Long. 2450 m, O. Bravo 1930

(ENCB); Zona Arqueológica “40 Casas”, 20 km al NW de Las 

Varas, 2140 m, Tenorio & Romero 1836 (ENCB); 12 mi SW of 

Madera of Hwy 16 towards Cuauhtémoc, 2100 m, P.M. Peterson 

& Annable 4050 (US); 14.5 mi SE of Madera on Mex 16 to La 

Junta, 2200 m, P.M. Peterson & R.M. King 8181 (US). Ocampo: 

Parque Nacional de Cascada Basaseachic, 1 km airline S of Cascada, 2100 m, Spellenberg, Soreng, R. Corral & T. Lebegue 8664

(ENCB); Parque Nacional Cascada Basaseachic, 1 km airline S of 

Cascada, 2100 m, Spellenberg, Soreng, R. Corral & T. Lebegue 

8683 (MEXU).

229. Muhlenbergia gigantea (E. Fourn.) Hitchc., N. Amer. Fl. 

17(6): 460. 1935.

FIGURE 165F–J

Strongly caespitose perennial. Culms 120–300 cm tall, 

erect, compressed-keeled near the base, glabrous below the 

nodes to sometimes scaberulous. Sheaths 12–32 cm long, shorter 

than internodes, sometimes purplish near base, often changing 

to brown with age, keels prominent and glabrous; ligules (5)8–

15 mm long, membranous, apex lacerate; blades 35–110 cm 

long, 5–10 mm wide, flat, scaberulous adaxially and glabrous 

abaxially, margins and keels serrate. Panicle 35–100 long, (8)15–

30 cm wide, purple or brown-purplish, branches ascending or 

pendulous spreading up to 60° from culm axis; pedicels 0.2–

2.5 mm long, generally shorter than spikelets, scaberulous; primary branches 6–25 cm long, naked near the base, pendulous to 

flexuous. Spikelets 1.3–2.6 mm long, erect, purple to brownishpurple; glumes 1.3–2.6 mm long, ovate, generally longer than 

florets, subequal, 1-veined, often transluscent, usually glabrous 

to scaberulous, apex acute to obtuse; lemma 1.3–2.3 mm long, 

oblong, awnless, rarely mucronate, glabrous; palea 1.3–2.3 mm 

long, glabrous, apex acute to obtuse; anthers 0.9–1.3 mm long, 

yellow to purplsih. Caryopsis 1–1.3 mm long, fusiform, reddishbrown. 2n = 20, 24.

Distribution and Habitat. Muhlenbergia gigantea grows in pines or pine–oak forests and tropical forests 

with Liquidambar, Nyssa, and Sabal, at elevations of 600–

2,300 m. In Mexico, this species is known to occuri in Chiapas, 

Chihuahua, Durango, Guanajuato, Guerrero, Hidalgo, Jalisco, 

México, Michoacán, Oaxaca, Puebla, San Luis Potosí, Sinaloa, 

and Veracruz.

Specimens Examined. MEXICO. Chihuahua. 

Uruáchi: 9 mi E of Yecora on Hwy 16 towards Maycoba and 

10.7 mi S on a dirt road towards Talayote, 1800 m, P.M. Peterson & Annable 12481 (US).

230. Muhlenbergia glauca (Nees) B. D. Jacks., Index Kew. 2: 

269. 1895.

FIGURE 166A–D

Perennial; with slender, creeping, well-developed rhizomes. Culms 25–60 cm tall, often decumbent, moderately stiff, 

sometimes erect; internodes mostly scabrous, retrorsely hirsute 

below the nodes. Sheaths longer than the internodes, scaberulous; ligules 0.5–2 mm long, truncate to obtuse, erose or lacerate; 

blades 4–12 cm long, 1–2.6 mm wide, flat to involute distally, 

not arcuate, scabrous abaxially, hirsute or scabrous adaxially. 

Panicles 4–12(17) cm long, 0.3–2.4 cm wide, contracted, interrupted below; primary branches 0.3–3 cm long, usually appressed, occasionally diverging to 30° from the rachises; pedicels 

0.1–1.2 mm long, scabrous to hirsute. Spikelets 2.4–3.5 mm 

long; glumes 1.5–3.5 mm long, 1⁄2 to about as long as the lemma, 

equal, 1-veined, veins scabrous, apex acute or acuminate, usually 

mucronate or awned, awns, if present, to 1.5 mm long; lemmas 

2.4–3.4 mm long, elliptic, pubescent on the lower 1⁄2 of the midveins and margins, hairs to 0.6 mm long, tawny, apex acuminate 

to acute, awned, awns 0.1–3(5) mm long, straight; paleas 2.2–

3.4 mm long, elliptic, intercostal region pubescent on the lower 

1⁄2, apex acuminate to acute; anthers 1.8–2.4 mm long, orange, 

rarely purplish. Caryopsis 1.7–2 mm long, fusiform, brownish. 

2n = 60.

Distribution and Habitat. Muhlenbergia 

glauca grows on calcareous rocky slopes, cliffs, canyon walls, 

table rocks, and volcanic rock outcrops in open vegetation associated with oak–pinyon–juniper woodlands at 1,200–2,780 m. 

It extends from southeastern Arizona, southern New Mexico, 

and southwestern Texas to northern Mexico in Aguascalientes, 

Chihuahua, Durango, Guanajuato, Hidalgo, Jalisco, México, 

Distrito Federal, Puebla, and San Luis Potosí,.

Specimens Examined. MEXICO. Chihuahua. 

Cuauhtémoc: 12 mi W of Cuauhtémoc, 2128 m, F.W. Gould 

8945 (TAES). Chihuahua: La Campana, 10 km W carr. [hwy] 

Panamericana, 1700 m, Valdés-Reyna VR–331 (TAES); Rocky 

hills near Chihuahua, 1800 m, C.G. Pringle 395, 418 (US); 14.5 

mi W of Hwy 45 on road up Los Prietos Canyon, 1910 m, P.M. 

Peterson & Annable 12602 (US); 38 km W of Hwy 45 on road 

towards Benito Juárez, 2230 m, P.M. Peterson & Annable 12564 

(US). Hidalgo del Parral: NE edge of Parral, 2200 m, I.W. Knobloch 744 (TAES). Matamoros: 12 mi S of Villa Matamoros on 

Hwy 45 towards Parral, 5600 ft, Reeder & C. Reeder 4628 (US). 

Ocampo: 122.5 km W of La Junta on road to Parque Nacional Cascada de Basaseachic and 56.7 km W of Tomochic, 1 Oct 

1989, 2100 m, P.M. Peterson & R.M. King 8237 (US). Riva Palacio: Majalca, Pennell 19298 (US); Col. Cumbres de Majalca, 

33.8 km W of Mex 45, N of Chihuahua City, 2190 m, P.M. Peterson, Annable & Y. Herrera 7940 (US). San Francisco del Oro: 

Ejido Corral de Duarte, 1950 m, E.S. Blanco 1552 (MEXU). 

Uruáchi: 20.2 mi W of Maycoba on Hwy 16 towards Yécora, 

1800 m, P.M. Peterson & J. Cayouette 15341 (US). 

231. Muhlenbergia imperfecta (Nash) Columbus, Aliso 28: 66. 

2010. Aegopogon imperfectus Nash, N. Amer. Fl. 17(2): 

138. 1912.

Aegopogon tenellus var. abortivus (E. Fourn.) Beetle.

Slender often sprawling, caespitose annual. Culms (2)6–

30 cm tall, glabrous below the nodes; internodes 0.6–6 cm long, 
238 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

FIGURE 165. Muhlenbergia scoparia. A. Habit. B. Ligule. C. Glumes. D. Floret. E. Lodicules, pistil, and stamens. Muhlenbergia gigantea. F. Habit. G. Ligule. H. Glumes. I. Lemma. J. Lodicules, pistil, and stamens. Drawn by Cathy Pasquale for 

Smithsonian Institution, Department of Botany.
NUMBER 107 • 239

glabrous to sparingly pubescent. Sheaths mostly 0.5–4.8 cm long, 

shorter than the internodes, glabrous to sparingly pilose; ligules 

0.6–1.5 mm long, apex mostly truncate, lacerate; blades 1.5–

4.5 cm long, 0.5–1.5 mm wide, flat, scaberulent and pubescent 

above, smooth beneath. Panicles 2–6 cm long, 0.5–1 cm wide, 

open, loosely flowered, racemose primary branches 3–5 mm 

long, 1 per node. Spikelets 1.5–3.2 mm long, often greenish or 

purplish, the clusters with 1 short-pedicelled spikelet (perfect), 

the pedicels 0.2–0.6 mm and the other 2 spikelets (staminate or 

sterile) short-pedicelled, the pedicels about 0.7–1.5 mm long; 

FIGURE 166. Muhlenbergia glauca. A. Ligule. B. Glumes. C. Floret. D. Lodicules, pistil, 

and stamens. Muhlenbergia polycaulis. E. Habit. F. Ligule. G. Glumes. H. Floret. I. Lodicules, pistil, and stamens. Drawn by Elisabeth P. Roberts for Smithsonian Institution, 

Department of Botany.
240 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

glumes (1)1.3–2 mm long, obovate and wider distally, apex 

shallowly notched, entire or mucronate, the mucro 0.1–0.4 mm 

long, lobes obtuse or rounded; lemmas 2.5–3.2 mm long, the 

lateral veins often mucronate, the central vein mucronate to 

short-awned, the awns never more than 1.5 mm long; paleas 

2.2–3 mm long, puberulent, apex 2-mucronate, the mucros less 

than 0.8 mm long; anthers 0.5–0.8 mm long, yellowish. Caryopsis 1.1–1.3 mm long, obovoid, light brownish. 

Distribution and Habitat. Muhlenbergia imperfecta grows on moist slopes, cliffs, canyons, and roadsides 

and along or near springs, usually in shaded areas associated 

with Pinus cooperi C. E. Blanco, P. lumholtzii spp., Quercus 

spp., Juniperus deppeana Steud., Arctostaphylos pungens, Rhus 

trilobata Nutt., and Cercocarpus at 1,300–2,860 m. It ranges 

from southern Arizona throughout most of Mexico and Central 

America.

Specimens Examined. MEXICO. Chihuahua. 

Casas Grandes: 21 mi SW of Col. Juárez on road to Hernández 

Javales, 2 Sep 1985, bosque de pino [pine forest], 2200 m, P.M. 

Peterson & Annable 4032 (ENCB, US). Guadalupe y Calvo: 

15.2 mi E of Ocote on hwy 24 towards El Vergel, rock outcrops 

in pine–oak woodlands, 14 Sep 2006, P.M. Peterson, Sánchez 

Alvarado & Gómez Ruíz 20062B (US); 9.5 mi E of Guadalupe 

y Calvo on hwy 24 and 5 mi W of Ocote, rocky slopes in pine–

oak–juniper woodlands, 14 Sep 2006, P.M. Peterson, Sánchez 

Alvarado & Gómez Ruíz 20060 (US). Guerrero: 38.6 km SW of 

La Junta and approx. 70.8 km N of Creel at puente [bridge] Arroyo Ancho crossing, 21 km marker, 24 Sep 1988, pine woods, 

2200 m, P.M. Peterson & Annable 5846 (ENCB, US). Riva Palacio: Col. Cumbres de Majalca, approx. 32.2 km W of hwy 45 N 

of Chihuahua, 22 Sep 1988, pine woods, 1800 m, P.M. Peterson 

& Annable 5798 (ENCB, US). Colonia Cumbres de Majalca, 

33.8 km W of Mex 45 N of Chihuahua City, table rock and 

rocky slopes, Pine–oak–juniper woodland, 7 Sep 1989, P.M. Peterson, Annable & Herrera Arrieta 7947 (US).

232. Muhlenbergia implicata (Kunth) Trin., Gram. Unifl. Sesquifl. 193, t. 5a, f. 26. 1824.

FIGURE 158E–H

Caespitose slender annual. Culms 15–50(70) cm tall, scaberulous to short-pubescent below the nodes. Sheaths glabrous to 

scaberulous; ligules 1–2.5(3) mm long, hyaline; blades 3–5(10) cm 

long, 1–2 mm wide, flat or loosely involute, short-pubescent 

above and glabrous below, margins scabrous. Panicle 7–12(20) 

cm long, 3–5(8) cm wide, diffuse, with the peduncle included in 

the sheath, axis scaberulous; branches ascending and spreading 

up to 90° from the culm axis; pedicels 7–11 mm long, capillary, 

flexuous, delicate, nodding to reflexed, mostly purplish. Spikelets 

2.5–3(4) mm long, purple; glumes 0.2–0.6 mm long, unequal, 

apex obtuse, often erose; lower glumes 0.2–0.3 mm long; upper 

glumes 0.3–0.6 mm; lemma 2.5–3(4) mm long, 3-veined, appearing 5-veined, scabrous, apex awned and 2-toothed, the teeth 

to 1 mm long, the awn 8–26 mm long; palea 2.9–4 mm long, 

narrowly lanceolate, glabrous; anthers 0.4–0.9 mm long, purple. 

Caryopsis 1.8–2.7 mm long, narrowly fusiform. 2n = 20. 

Distribution and Habitat. Muhlenbergia implicata grows on cliffs, on canyon walls, and in open vegetation 

associated with oak–pinyon–juniper woodlands at elevations of 

1,900–2,550 m. It ranges from Mexico to Central and South 

America.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 14.8 mi NE of El Vergel, 2100 m, P.M. Peterson & Annable 4079 (TAES, US); 56.4 km W of Parral on road to Balleza 

and 35.5 km S of Balleza on Mex 432, near Corral de Duarte, 

2210 m, P.M. Peterson, Annable & Valdés-Reyna 10717 (US). 

Guachochi: 19 mi E of Guachochi on rd to Balleza, 2100 m, 

P.M. Peterson & Annable 5938 (US). Guerrero: Villa Guerrero, 

2550 m, A.A. Beetle & R. Guzmán M-5808 (MEXU); 29 mi W 

of La Junta on road to Parque Nacional Cascada Basaseachic, 

2200 m, P.M. Peterson & R.M. King 8196 (US); Tomochi, 2 km 

alrededor del poblado [around the village], 2100 m, M. Vergara 

159 (MEXU). Hidalgo del Parral: 24.9 km SE of Balleza, 22.5 

km N of hwy 24, W of Parral, 2100 m, P.M. Peterson & Annable 

5059, 5951 (MEXU, US). Jiménez: Volcán La Alberca, near Villa 

Jiménez, 2100 m, Rzedowski 40805 (ENCB). Julimes: Potrero 

Mts, 12 Oct 1886, C.G. Pringle 818 (TAES, US). Matamoros: 

12 mi S of Villa Matamoros on Hwy 45 towards Parral, 1900 m, 

P.M. Peterson & Annable 4084, 5973 (US); P.M. Peterson & 

R.M. King 8250 (US); Reeder & C. Reeder 4629 (US); 18.2 km 

SE of Villa Matamoros on Mex 45 to Durango, 1780 m, P.M. 

Peterson, Annable & Valdés-Reyna 10868 (US). Riva Palacio: 21 

mi W of México 45, N of Chihuahua city, Col. Cumbres de Majalca, 2120 m, P.M. Peterson, Annable & Y. Herrera 7936 (US); 

0.7 mi W of Nuevo Majalca, 8.5 mi W of Hwy 45, 1700 m, P.M. 

Peterson & Annable 4514 (TAES, US); Cumbres de Majalca, 

21.5 mi W of Hwy 45, 2200 m, P.M. Peterson & Annable 4525

(US); 21 mi W of México 45, N of Chihuahua city, Col. Cumbres 

de Majalca, 2120 m, P.M. Peterson & Annable 5797 (US).

233. Muhlenbergia ligulata (E. Fourn.) Scribn. & Merr., Bull. 

Div. Agrostol. U.S.D.A. 24: 19. 1901. Chaboissaea ligulata

E. Fourn., Mexic. Pl. 2: 112, t. 1. 1886.

Caespitose perennial. Culms 20–70(90) cm tall, erect, glabrous 

and occasionally purple below the nodes. Sheaths (0.8)2.5–11(31) 

cm long, keeled, glabrous, margins hyaline; ligules 6–10 mm long, 

hyaline, apex acuminate, lacerate; blades 10–15(20) cm long, 

1–2.5 mm wide, flat to folded or involute, glabrous above and 

scaberulous below. Panicles 6–28 cm long, 1–10 cm wide, narrow, pyramidal; branches short, appressed or narrowly spreading 

less than 70° from the culm axis, 1 per node. Spikelets 2.8–3 mm 

long, 1 or 2(3)-flowered, plumbeous, proximal spikelet perfect 

and distal spikelet staminate or sterile; glumes 1–4 mm long, subequal, 1-veined, glabrous and scabrous along midveins, apex acute 

to acuminate, occasionally mucronate, the mucro up to 0.5 mm 

long; lower glume 1–3.2 mm long; upper glume 1.2–4 mm long; 

lemma 2.5–3.5(4) mm long, lanceolate, compressed-keeled, with 

appressed hairs on the midvein and margins on the proximal 1⁄2,
NUMBER 107 • 241

green-yellowish with gray spots, apex acuminate to acute, unawned, mucronate or awned, the awn up to 2 mm long; palea 

2.4–3.5 mm long, lanceolate, unawned, similar to the lemma, apex 

acute or obtuse; anthers 1–1.2 mm long, yellow to purple. Caryopsis 1.1–1.3 mm long, fusiform, brown. n = 8. 

Distribution and Habitat. Muhlenbergia ligulata grows in seasonally wet areas in grasslands and oak–pine 

forests at elevations of 2,000–2,616 m. It is known from Mexico 

in Aguascalientes, Chihuahua, Distrito Federal , Durango, Guanajuato, Jalisco, México, San Luis Potosí, and Zacatecas.

Specimens Examined. MEXICO. Chihuahua. 

Carichi: Sánchez, 12 Oct 1910, Hitchcock 7693 (US). Cuauhtémoc: 13.0 mi W of Cuauhtémoc on hwy 16, 20 Sep 1986, 

2200 m, P.M. Peterson & Annable 4532 (ENCB, US); 19 km W 

of Cuanuhtémoc on hwy 16, 23 Sep 1988, open meadow along 

roadside, 2000 m, P.M. Peterson & Annable 5819 (MEXU, US); 

9 km N of Cuanuhtémoc on hwy 23, 14 Sep 1989, drainage 

ditch in wet, blackish soil, 2120 m, P.M. Peterson & Annable 

8111 (MEXU, US). Guerrero: 15 mi E of Guerrero, 4 Sep 1967, 

Reeder & C. Reeder 4858 (ARIZ).

234. Muhlenbergia lindheimeri Hitchc., J. Wash. Acad. Sci. 

24(7): 291. 1934.

FIGURE 162A–E

Strongly caespitose perennial. Culms 50–150 cm tall, 

stout, erect, not rooting at the lower nodes; internodes mostly 

glabrous, sometimes puberulent below the nodes. Sheaths 

10–45 cm long, shorter or longer than the internodes, glabrous, 

basal sheaths compressed-keeled, not becoming spirally coiled 

when old, purplish-brown or yellowish; ligules 10–35 mm long, 

decurrent, firm and brown basally, membranous distally, acuminate; blades 25–55 cm long, 2–5 mm wide, flat or folded, 

firm, scaberulous abaxially, often involute near the apex, scabrous and shortly pubescent adaxially. Panicles 15–50 cm long, 

(0.6)1–2(3) cm wide, loosely contracted, often purplish-tinged; 

primary branches 0.5–7 cm long, appressed or strongly ascending, rarely spreading as much as 20° from the rachises; pedicels 

0.5–1.2 mm long, scabrous. Spikelets 2.4–3.5 mm long, light 

grayish; glumes 2–3.5 mm long, equal, longer than the florets, 

scabrous or smooth, 1-veined, obtuse to acute, occasionally 

bifid and the teeth to 0.3 mm long, awnless, rarely mucronate, 

mucros less than 0.2 mm long; lemmas 2.4–3.5 mm long, lanceolate, scabrous or smooth, rarely puberulent near the base, 

apex obtuse to acute, awned or unawned, the awns 1–4 mm 

long, straight; paleas 2.4–3.5 mm long, lanceolate, glabrous to 

puberulent between the veins on the proximal 1⁄4, apex obtuse; 

anthers 1.1–1.5 mm long, purplish. Caryopsis 1.2–1.6 mm long, 

fusiform, reddish-brown. 2n = 20, 26, 30.

Distribution and Habitat. Muhlenbergia 

lindheimeri grows in sandy draws or rocky, calcareous soils, 

generally in open areas, at elevations of 150–700 m. It is an uncommon species throughout its range, which includes northern 

Mexico and southern Texas.

Specimens Examined. MEXICO. Chihuahua. 

Madera: Ciénega Ojo de la Víbora, ejido El Largo, bosque de 

pino–encino [pine–oak forest], 2300 m, A. Benítez 2866, 2867 

(CIIDIR; MEXU); Puerto del Tenedor, ejido El Largo, bosque de 

pino-encino, 2450 m, A. Benítez 2918 (CIIDIR).

235. Muhlenbergia longiligula Hitchc., Amer. J. Bot. 21(3): 136. 

1934.

FIGURE 162F–I

Densely caespitose perennial. Culms 60–130 cm tall, robust, 

erect. Sheaths rounded, rarely compressed, but never keeled, 

glabrous to scabrous; ligule 20–30 mm long, firm, brown on 

the base, widely decurrent, membranous at the apex; blades 

20–65 cm long, 3–6 mm wide, flat or enrolled on margins, glabrous to scabrous, green changing to brown, firm, involute when 

mature. Panicle 15–55 cm long, 1–15 cm wide, green to purple; 

branches 3–13 cm long, ascending or divergent, flowering to the 

base; pedicels 0.1–2.5 mm long, shorter than florets, glabrous to 

scabrous. Spikelets 2–3.5 mm long; glumes 2–3.5 mm long, longer than the lemma, occasionally shorter, equal or the upper a little longer than the lower, scabrous or glabrous, 1-veined, acute to 

acuminate, awnless, sometimes decurrent in a small awn; lemma 

2–2.9 mm long, oblong-elliptic, green to purple, scabrous or glabrous, apex acute, often bifid, teeth to 0.2 mm long, awnless or 

rarely with a small awn of 2 mm; palea 2–3 mm long, a little 

longer than the lemma, glabrous, oblong-elliptic, scabrous to glabrous, acute; anthers 1–2 mm long, yellow to purple. Caryopsis 

1.1–1.5 mm long, fusiform, brown-reddish. 2n = 22, 24, 29, 30.

Distribution and Habitat. Muhlenbergia longiligula grows in pine or oak forests at elevations of 1,000–2,200 

m. It occurs from the United States to Mexico in Chihuahua, 

Durango, Jalisco, Puebla, and Sonora.

This species is very similar to Muhlenbergia emersleyi but 

differs in having rounded basal sheaths, glabrous lemmas, and 

panicle branches flowered to the base. It is also similar to M. 

lindheimeri but differs in having rounded basal sheaths.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 11 mi SE of Balleza on road to Parral, 1800, P.M. Peterson, M.B. Knowles, C.H. Dietrich, S.M. Braxton 13534 (US). 

Batopilas: White-tuff volcanic outcrops surrounding Napuchis 

with Pinus and many grasses, 2140 m, P.M. Peterson & P. Catalán 17682 (US). Bocoyna: 7 mi NE of San Rafael on road towards Creel, at Divisidero lookout, 5 Sep 2008, 2240 m, P.M. 

Peterson & J.M. Saarela 22039, 22040 (US). Buenaventura: 

Hills near Buenaventura, 1950 m, A.A. Beetle M-7877 (MEXU). 

Casas Grandes: 1 mi W of Cuesta Blanca, W of Casas Grandes, 

2073 m, Reeder & C. Reeder 3222 (ENCB); About 43 mi SW 

of Casas Grandes, 2100 m, Reeder & C. Reeder 2696 (ENCB); 

W of Casas Grandes, 5 mi S of Hernández, 2200 m, Reeder, 

C. Reeder & Soderstrom 3509 (ENCB, US); 3531 (US); About 

38 mi SW of Casas Grandes, 2040 m, Reeder & C. Reeder 2699

(ENCB); Near Casas Grandes, C.H. Towsend 357 (US); 2 mi S 

of Hernández, W of Casas Grandes, Reeder & C. Reeder 3505
242 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

(US). Carichi: Sánchez, 12 Oct 1910, Hitchcock 7667 (US). 

Guachochi: Yamuco, 1 mi E of hwy N of Rio Urique crossing 

towards Basihuare and Creel, 5 Sep 2008, 1890 m, P.M. Peterson & J.M. Saarela 22063 (US); Just S of Napuchis, 2162 m, 

P.M. Peterson & P. Catalán 17667 (CIIDIR, US); Approx. 22.5 

mi NE of Cieneguita de Barranca on road towards Creel, 2160 

m, P.M. Peterson, P. Catalán, C. López, & G. Villegar 17692, 

17693 (US); Parque Nacional Barranca del Cobre, 20.3 km NE 

of La Bufa and 3.2 km S of Basigochi, 2180 m, P.M. Peterson, 

Annable & Valdés-Reyna 10813A (US); Parque Nacional Barranca del Cobre, 34 mi S of Creel on road towards Samachique, 

2150 m, P.M. Peterson, M.B. Knowles, C.H. Dietrich, S.M. 

Braxton 13592 (US); Parque Nacional Barranca del Cobre, 13.6 

mi NE of La Bufa on road towards Samachique, 2240 m, P.M. 

Peterson, M.B. Knowles, C.H. Dietrich, S.M. Braxton 13567 

(US); 11.5 mi NW of Aboreachi on road towards Creel, 2500 

m, P.M. Peterson, M.B. Knowles, C.H. Dietrich, S.M. Braxton 

13558 (US). Guerrero: Arroyo ancho, 15 Oct 1887, C.G. Pringle 

1423 (US) Isotype; 33.7 mi W of La Junta on road to Parque 

Nacional Cascada Basaseachic, 30 Sep 1989, 2260 m, P.M. Peterson & Annable 8207 (US); 33.5 km W La Junta on road to 

Parque Nacional Cascada de Basaseachic, 2200 m, P.M. Peterson & Annable 9605 (US). Madera: About 15 mi S of Madera, 

2165 m, Reeder & C. Reeder 2639 (ENCB); About 27 mi NW 

Madera, 2195 m, Reeder & C. Reeder 2663 (ENCB, MEXU); 

Aserradero El Tres, al N de Cd. Madera, 1900 m, F. Martínez 

F-2477 (US). Matamoros: 19.3 km S of Villa Matamoros on hwy 

45 to Durango, 3 Oct 1989, grassland, 1910 m, P.M. Peterson 

& R.M. King 8263 (US). Ocampo: Along trail just above Cascada de Basaseachic, 1880 m, P.M. Peterson & Annable 12521, 

12535 (US); Parque Nacional de Cascada Basaseachic, 1 km airline S of Cascada, 2100 m, Tenorio & R. Torres 4472 (MEXU); 

122.5 km W of La Junta and 56.7 km W of Tomochic in Parque 

Nacional Cascada de Basaseachic, 1 Oct 1989, 2100 m, P.M. 

Peterson & R.M. King 8242 (US); Near Mirador of Cascada Basaseachic, 2022 m, slopes with Pinus, 7 Sep 2008, P.M. Peterson 

& J.M. Saarela 22096 (US). Riva Palacio: 33-35 km W of Hwy 

45 on road towards Benito Juárez, 2200 m, P.M. Peterson & Annable 12556 (US). Temósachi: 28.7 km al NE de Agua Caliente, 

2000 m, J. Morelos s.n. (INEGI). Uruáchi: 9 mi E of Yécora on 

Hwy 16 towards Maycoba and 5 mi SE on a dirt road towards 

Talayote, 1750 m, P.M. Peterson & Annable 12477 (US).

236. Muhlenbergia lucida Swallen, J. Wash. Acad. Sci. 26(5): 

208. 1936.

FIGURE 151F–I

Caespitose perennial. Culms(25)40–60 cm tall, erect, with 

short, appressed hairs. Sheaths glabrous to pubescent or scabrous, apex puberulent; ligules 3–6(7) mm long, firm to base, 

apex obtuse, margins entire, decurrent, and with auricles; blades 

15–30 cm long, 0.8–1.2 mm wide, firm, involute, flexuous, 

scabrous. Panicles 12–18 cm long, 6–12 cm wide, included to 

exserted, open, loosely flowered; branches 5–6 cm long, 1–2 

per node, divergent, filiform, flexuous, scabrous or pubescent, 

naked below, spikelets distant at the end of the branches; pedicels 5–8 mm long, filiform, flexuous. Spikelets 3.8–4.2 mm 

long, green pale changing to whitish when mature; glumes 

2.8–3.8 mm long, subequal, widely oblong-lanceolate, hyaline, 

veins inconspicuous, short-pubescent over the veins to the base; 

lower glumes 2.8–3.3 mm long; upper glumes 3.5–3.8 mm; lemmas 3.8–4.2 mm long, hyaline, densely villous, widely ovatelanceolate, apex bifid, teeth subacute, the teeth about 1 mm long, 

central vein prominent, reddish, turning into an awn, the awn 

10–12 mm long, somewhat geniculate and twisted in the inferior 

part; paleas 3.8–4.2 mm long, equal to the lemma but a little narrower; anthers 2.1–2.4 mm long, brown to purplish. Caryopsis 

2.5–2.8 mm long, fusiform, brown.

Distribution and Habitat. Muhlenbergia lucida occurs in pine–oak forests at elevations of 2,245–2,680 m. 

This Mexican endemic has been found in Chihuahua, Guanajuato, México, and Sonora.

Specimens Examined. MEXICO. Chihuahua. Balleza: 34 mi W of Balleza on road towards Guachochi, 

2500 m, pine–oaks woodlands, 29 Oct 1995, P.M. Peterson, 

M.B. Knowles, C.H. Dietrich & S.M. Braxton 13544 (US); 

56.4 km W of Balleza and 38.7 km E of Guachochi, 2480 m, 

P.M. Peterson, Annable & Valdés-Reyna 10773 (US). Batopilas: 

10.7 mi S of Mexico 127 on road to Batopilas, 2245 m, Y. Herrera, P.M. Peterson & Annable 946 (CIIDIR); 10.7 mi S of Mexico 127 on road to Batopilas, 2245 m, P.M. Peterson, Annable & 

Y. Herrera 8039 (US). Bocoyna: 7 mi NE of San Rafael on road 

towards Creel, at Divisidero lookout, 5 Sep 2008, 2240 m, P.M. 

Peterson & J.M. Saarela 22041 (US). Chinipas: 1 mi E of Saguarivo, 10 Sep 2008, small arroyo with oaks and pines, 1490 m, 

P.M. Peterson & J.M. Saarela 22163 (US). Guachochi: Yamuco, 

1 mi E of hwy N of Rio Urique crossing towards Basihuare and 

Creel, 5 Sep 2008, P.M. Peterson & J.M. Saarela 22047 (US); 16 

mi E of Guachochi on Mex 127 towards Balleza, 2680 m, P.M. 

Peterson, Annable & Y. Herrera 8083 (MEXU, US); 2 km W of 

Río Corareáchi and E of Osichi, 1960-2040 m, P.M. Peterson 

& P. Catalán 17623 (CIIDIR, US); White-tuff volcanic outcrops 

surrounding Napuchis, 2140 m, P.M. Peterson & P. Catalán 

17679 (CIIDIR, US); 8.5 km S of Cusarare on road to Guachochi, 2400 m, P.M. Peterson & M.B. Knowles 13561, 13572 (US); 

25.6 mi S of Creel on road to Batopilas, 2075 m, P.M. Peterson 

& Annable 8029, 8030 (US); 11 mi on road to La Bufa from jtn 

with Creel–Guachochi road, 2000 m, Spellenberg 8609 (US); 8.5 

km S of Cusarare on road to Guachochi, 2400 m, P.M. Peterson 

& Annable 5882 (US); 12.4 km S of Cusarare on road to Guachochi, 2400 m, P.M. Peterson & Annable 5896 (US); 19.3 km 

E of Guachochi, 2300 m, P.M. Peterson & Annable 5931 (US); 

Arroyo Baqueachi, at 1/2 km E of small village, 2004 m, P.M. 

Peterson & P. Catalán 17570 (US). Guerrero: 78 km de la Junta 

de Basaseachic, 2300 m, R. Fierros 1691 (MEXU); 33.7 mi W of 

La Junta on road to Parque Nacional Cascada Basaseachic, 30 

Sep 1989, 2260 m, P.M. Peterson & Annable 8210, 8217 (US); 

35 km al SW de Miñaca, Sierra Gazachic, Barranca Colorada, 
NUMBER 107 • 243

2300 m, Pennell 18955 (US), holotype. Moris: Approx. 17.6 mi 

E of Maycoba on Hwy 16 towards Yepachic and 2 mi E of Sonora/Chihuahua boundary, 1540 m, P.M. Peterson & Annable 

12515 (US). Ocampo: overlook of Casada de Basaseachic, approx. 37 mi W of Tomochic, 2200 m, P.M. Peterson & Annable 

4551 (US); 29 mi W of La Junta on road to Parque Nacional 

Cascada Basaseachic, 30 Sep 1989, 2260 m, P.M. Peterson & 

Annable 8202 (US); 76 mi W of La Junta and 35.2 mi W of 

Tomochic in Parque Nacional, 2200 m, P.M. Peterson & Annable 8228 (US); 122.5 km W of La Junta and 56.7 km W of 

Tomochic in Parque Nacional Cascada de Basaseachic, 2100 m, 

P.M. Peterson & R.M. King 8249 (US); Parque Nacional Cascada Basaseachic, 2100 m, Spellenberg 8656 (US); Along trail 

just above Cascada de Basaseachic, 1880 m, P.M. Peterson & 

Annable 12534 (US). Riva Palacio: Majalca, 2100 m, LeSueur 

022 (US); Col. Cumbres de Majalca, ca. 32.2 km W of Hwy 

45, N of Chih., P.M. Peterson & Annable 5803 (US); 21 mi W 

of México 45, N of Chihuahua city, Col. Cumbres de Majalca, 

2190 m, P.M. Peterson & Annable 7942, 7973 (US); 37 km W 

of Mex 45, and ca. 3.2 km W of Col. Cumbres de Majalca, 7 Sep 

1989, 2170 m, P.M. Peterson, Annable & Y. Herrera 7978 (US). 

Uruáchi: 20.2 mi W of Maycoba on Hwy 16 towards Yécora, 

1800 m, P.M. Peterson & J. Cayouette 15338 (US).

237. Muhlenbergia macroura (Kunth) Hitchc., N. Amer. Fl. 

17(6): 468. 1935.

Caespitose perennial. Culms 75–200 cm tall, erect, rounded 

near base, forming dense clumps of 100 culms or more and up to 

1 m in diameter, pubescent below the nodes, internodes mostly 

glabrous. Sheaths 15–40 cm long, shorter than the internodes, 

glabrous to scaberulous, the basal persistent and keeled with age; 

ligules (5)8–40(50) mm long, strongly decurrent, spliting into 

broad auricles, membranous to chartaceous above, brownish, 

firm, the veins evident below and near margins, apex truncate to 

obtuse; blades 20–60 cm long, 2–5 mm wide, mostly flat and apically involute, scabrous above and below. Panicles(15)20–40 cm 

long, 5–12 mm wide, dense, spikelike, erect, exserted and surpassing the blades in height, greenish to greenish-gray; primary 

branches 0.1–1.2 cm long, ascending and tightly appressed, unexposed, imbricate; pedicels 0.1–1.7 mm long, shorter than the 

spikelets, scaberulous. Spikelets 3.4–5.6 mm long, erect, strongly 

laterally compressed, greenish-gray; glumes 3.4–5.6 mm long, 

linear-elliptic to linear-ovate, usually longer than the lemma, 

1-veined, scabrous along the keel, subequal, awnless, the upper 

slightly longer, apex acute to acuminate, scabrous; lemmas 

3.4–5 mm long, elliptic to linear-elliptic, scabrous, greenishgray; callus pilose, the hairs 0.1–0.3 mm long, apex acute, rarely 

mucronate, the mucro less than 0.4 mm long; paleas 3.4–5 mm 

long, about as long as the lemma, scabrous, apex acute; anthers 

1.5–2.2 mm long, dark greenish. Caryopsis 2–3 mm long, fusiform, brownish. 2n = 20, 24, 28.

Distribution and Habitat. Muhlenbergia macroura occurs in the Sierra Madre Occidental in northern Mexico 

from Chihuahua to Chiapas, Guatemala, and Costa Rica; it is 

found on upland slopes, in mountain meadows, and in pine or 

pine–oak forests often in deep humid soils at 1,500–3,400 m.

Specimens Examined. MEXICO. Chihuahua. 

Bocoyna: Gonogochic region in Ejido San Ignacio Ararenco, 

Bye 5480 (US). Casas Grandes: Valle de las Cuevas S Ejido Ignacio Zaragoza, 1760 m, Tenorio & Romero 1708 (ENCB, US). 

Guachochi: 1–2 km S of Río Osichi and Río Basihuare junction, 1600 m, P.M. Peterson & P. Catalán 17636 (CIIDIR, US); 

Yamuco at 1 km E of hwy towards Basihuare and Creel, N of 

Rio Urique crossing, 1891 m, P.M. Peterson & P. Catalán 17545 

(US); Yamuco, 1 mi E of hwy N of Rio Urique crossing towards 

Basihuare and Creel, 5 Sep 2008, 1890 m, P.M. Peterson & J.M. 

Saarela 22062 (US). Ocampo: Parque Nacional Cascada Basaseachic, 2000 m, Tenorio & Romero 1939 (MEXU); Parque Nacional Cascada Basaseachic, 1 km airline S of Cascada, 2100 m, 

Spellenberg 7946 (TAES). Cascada de Basaseachic, 3 km al SE de 

Basaseachic, 1960 m, R. Tórres & Tenorio 3771 (US).

238. Muhlenbergia majalcensis P. M. Peterson, Syst. Bot. 14(3): 

316–318, f. 1. 1989.

FIGURE 161A–D

Caespitose delicate annual. Culms 15–36 cm tall, erect, reddish, scabrous, strigulous below the nodes. Sheaths 10–32 mm 

long, shorter than the internode, glabrous to scaberulous, margins hyaline; ligules 1.5–2.0 mm long, hyaline, apex dentate 

to lacerate, obtuse to rounded, decurrent and extended above 

to form auricles; blades 2–10 cm long, 0.7–1.4 mm wide, flat 

to involute, midvein prominent, short-pubescent above and 

scaberulous below. Panicles 9–15 cm long, 3.5–9.5 cm wide, 

branches 1–6 cm long, 1–3 per node, ascending to open, capillary; pedicels 3–8 mm long, slender, capillary, curved and reflexed; spikelets at the end of branches, reddish when immature; 

glumes 1.2–1.5 mm long, equal and longer than the lemma, acuminate, glabrous, faintly 1-veined; lemma 1–1.2 mm long, oval, 

glabrous, straw color, awnless, apex rounded or obtuse; palea 

1–1.2 mm long, oval, glabrous, apex rounded or obtuse; anthers 

0.4–0.5 mm long, purplish. Caryopsis 0.8–0.9 mm long, ellipsoid, reddish-brown.

Distribution and Habitat. Muhlenbergia majalcensis occurs in gravelly soils in pinyon–juniper forests at elevations of 2,140–2,200 m. This species is endemic to the Sierra 

Madre Occidental, known only from Chihuahua (Peterson, 

1989).

This species is superficially similar to M. annua but differs 

in having a glabrous lemma and palea, spikelets with curved to 

reflexed pedicels, and plants 18–36 cm tall in M. majalcensis and 

8–22 cm tall in M. annua. Muhlenbergia majalcensis is also similar to M. capillipes and can be separated from the latter in having 

glumes that are longer than lemma and palea, and anthers and 

caryopses shorter than those found in M. capillipes.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: 32 km W of Hwy 45 towards Benito Juárez, 2110 m, 

P.M. Peterson & Annable 12550 (US). Riva Palacio: 20 mi W of 
244 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

México 45 and about 1⁄2 mi E of Cumbres de Majalaca, 2180 

m, Y. Herrera, P.M. Peterson & Annable 949 (CIIDIR); 7974

(US); Cumbres de Majalca, 21.5 mi W of Hwy 45, 2200 m, P.M. 

Peterson & Annable 4573 (US); 21.1 mi W of Hwy 45, 0.4 mi E 

of Cumbres de Majalca, 20 Sep 1986, 2200 m, P.M. Peterson & 

Annable 4519 (US); 0.9 km E of entrance to Parque Nacional, 

Col. Cumbres de Majalca, 2200 m, P.M. Peterson & Annable 

5787 (US); 0.5 mi E of Cumbres de Majalca, 2200 m, P.M. Peterson & Annable 5815 (US). 

239. Muhlenbergia microsperma (DC.) Kunth, Révis. Gramin. 

1: 64. 1829.

FIGURE 167A–D

Caespitose annual; rarely appearing as short-lived perennial. Culms 10–80 cm tall, often geniculate at the base, slender, 

often striate, very branched near the base, scaberulous below 

the nodes; internodes 1.8–8.6 mm long, mostly scaberulous or 

smooth. Sheaths 2.2–6.6 mm long, commonly shorter than the internodes, glabrous, smooth or scaberulous; ligules 1–2 mm long, 

membranous to hyaline, decurrent, margins often extended, apex 

truncate to obtuse; blades 3–8.5(10) cm long, 1–2.5 mm wide, 

flat or loosely involute, scabrous below, strigulose above, often 

deciduous with age. Panicles 6.5–13.5 cm long, 1–6.5 cm wide, 

open and not densely flowered, often purplish; primary branches 

1.6–4 cm long, ascending or diverging to 80° from the rachises, 

spikelet-bearing to the base; pedicels 2–6 mm long, appressed 

to divaricate, antrorsely scabrous. Cleistogamous panicles with 

1–3 spikelets present in the axils of the lower sheaths. Spikelets 

2.5–5.5 mm long; glumes 0.4–1.3 mm long, exceeded by the florets, unequal, 1-veined, apex obtuse, often minutely erose; lower 

glumes 0.4–1 mm long; upper glumes 0.6–1.3 mm long; lemmas 

2.5–3.8(5.3) mm long, narrowly lanceolate, mostly smooth, scaberulous distally, hairy on the callus, lower 1⁄2 of the margins, and 

midveins, with hairs 0.2–0.5 mm long, apex acuminate, awned, 

the awns 10–30 mm long, straight to flexuous; paleas 2.2–4.8 

mm long, narrowly lanceolate, acuminate; anthers 0.3–1.2 mm 

long, purplish. Caryopsis 1.7–2.5 mm long, fusiform, reddishbrown. 2n = 20, 40, 60.

Distribution and Habitat. Muhlenbergia microsperma grows on sandy slopes, drainages, cliffs, rock outcrops, and disturbed roadsides, at elevations of up to 0–2,400 m. 

It is usually found in creosote scrub and oak–pinyon woodland 

associations. Its range extends from the southwestrn United 

States and Mexico in Aguascalientes, Baja California, Baja California Sur, Chiapas, Chihuahua, Durango, Guanajuato, Guerrero, Hidalgo, Jalisco, México, Michoacán, Morelos, Nayarit, 

Oaxaca, Querétero, Sinaloa, Sonora, Tlaxcala, Veracruz, and 

Zacatecas through Central and South America along the Andes.

Specimens Examined. MEXICO. Chihuahua. 

Chínipas: Sierra Milpillas, 24.1 mi E of Los Tanques on road to 

Milpillas, pinyon woodlands, 2100 m, P.M. Peterson & Annable 

4169 (ENCB, US). Guachochi: 6.3 mi S of Cusarare on road 

to Guachochi, 2420 m, P.M. Peterson & Annable 5888 (US); 

Parque Nacional Barranca del Cobre, 0.5 km E of La Bufa at the 

bridge crossing the Río Batopilas, 1000 m, P.M. Peterson, Annable & Valdés-Reyna 10842 (US). Moris: South-western Chihuahua, 2200 m, E. Palmer 158 (TAES. US), type; Río Bonito, 

Le Saueur 156 (US).

240. Muhlenbergia minutissima (Steud.) Swallen, Contr. U.S. 

Natl. Herb. 29(4): 207. 1947.

FIGURE 168

Delicate annual. Culms 5–40 cm tall, slender, erect or 

spreading; scaberulous or strigulose below the nodes; internodes 

mostly glabrous, scaberulous or smooth. Sheaths 0.4–5.2 cm 

long, shorter or longer than the internodes, smooth or scaberulous; ligules 1–2.6 mm long, hyaline, margins entire, rarely with 

lateral lobes or auricles not longer than the body of the ligule, 

apex truncate to obtuse; blades 0.5–4(10) cm long, 0.8–2 mm 

wide, flat or involute, scabrous below, puberulent above, margins and midveins not whitish-thickened. Panicles 5–16.2(21) 

cm long, 1.5–6.5 cm wide, open; primary branches 8–42 mm 

long, often capillary, diverging 25°–80° from the rachises; pedicels 2–7 mm long, straight or curved, but rarely curved as much 

as 90°; glumes 0.5–0.9 mm long, subequal, sparsely strigulose, 

at least near the apex, the hairs 0.1–0.3 mm long, 1-veined; 

lower glumes 0.5–0.8 mm long, obtuse to acute; upper glumes 

0.6–0.9 mm long, broader than the lower glumes, obtuse; lemmas 0.8–1.5 mm long, lanceolate, brownish to purplish, glabrous or the midveins and margins appressed-pubescent, apex 

obtuse to subacute, awnless; paleas 0.8–1.4 mm long, puberulent or glabrous; anthers 0.2–0.7 mm long, purplish. Caryopsis 

0.6–0.9 mm long, fusiform to elliptic, brownish. 2n = 60, 80.

Distribution and Habitat. Muhlenbergia 

minutissima grows in sandy and gravelly drainages, rocky slopes, 

flats, road cuts, and open sites. It is usually found in yellow pine 

and oak–pine forests, pinyon–juniper woodlands, thorn scrub 

forests, and oak–grama savannahs at elevations of 1,200–3,000 

m. It occurs in western North America to southern Texas and 

throughout Mexico to Guatemala.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 0.5 mi NE El Vergel, 2100 m, P.M. Peterson & Annable 

4068 (US); 16 mi SW of El Vergel on Hwy 24, Río Green, 2200 

m, P.M. Peterson & Annable 4075 (US); 43 mi E of Guachochi 

and 16 mi W of Balleza, 2100 m, P.M. Peterson & Annable 5935

(US); 56.4 km W of Parral on road to Balleza and 35.5 km S of 

Balleza on Mex 432, near Corral de Duarte, 2210 m, P.M. Peterson, Annable & Valdés-Reyna 10705 (US). Bocoyna: 20 km S of 

San Juanito on road to Creel and 3 km S of Bocoyna, 2330 m, 

Y. Herrera, P.M. Peterson & Annable 960 (CIIDIR); 5 km al N 

de Creel, 2200 m, Tenorio & R. Torres 4391 (MEXU); 20 km S 

of San Juanito on road to Creel and 3 km S of Bocoyna, 2350 m, 

P.M. Peterson, Annable & Y. Herrera 8003 (US); Cabecera de 

la cañada de Recogoata, 2400 m, B. Tah V. 44 (MEXU). Carichi: Mojarachic, 5 Sep 1938, I.W. Knobloch 5400 (US); Sánchez, 

Oct 1910, Hitchcock 7662 (US). Casas Grandes: W of Casas 
NUMBER 107 • 245

FIGURE 167. Muhlenbergia microsperma. A. Habit. B. Ligule. C. Glumes. D. Floret. Muhlenbergia pereilema. 

E. Habit. F. Ligule. G. Portion of inflorescence. H. Glumes. I. Floret. J. Lodicules, pistil, and stamens. Drawn by 

Midge Gillete for PMP (A−D) and Cathy Pasquale for Smithsonian Institution, Department of Botany (E−J).
246 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Grandes, 5 mi S of Hernández, 2200 m, Reeder & C. Reeder 

3515 (SLPM, US); 3502 (US); 3 mi S of Hernández Javales, 32 

mi SW of Col. Juárez, 2200 m, P.M. Peterson & Annable 4042

(US); 2 mi E of Cuesta Blanca, 26 mi W of Col. Juárez, 1950 m, 

Reeder & C. Reeder 3230 (US). Cuauhtémoc: 11 mi E of Cuauhtémoc, 21 Sep 1986, 1850 m, P.M. Peterson & Annable 4530

(US); 12 mi W of Cuauhtémoc, 2120 m, P.M. Peterson & Annable 5823 (US); 13 mi W of Cuauhtémoc, Reeder & C. Reeder 

4592 (US). 16 mi W of Cuauhtémoc, Reeder & C. Reeder 3473

(US). Chihuahua: Hills near Chihuahua, 1800 m, C.G. Pringle 

482 (US); 32 km W of Hwy 45 towards Benito Juárez, 2110 m, 

P.M. Peterson & Annable 12544 (US); 16.7 mi W of Hwy 45 on 

road up Los Prietos Canyon, 2120 m, P.M. Peterson & Annable 

12592 (US). Chinipas: Sierra Milpillas 28.1 mi E of Los Tanques 

on road to Chínipas, 1.6 mi N of Los Chinicas, 2200 m, P.M. 

Peterson & Annable 4176 (TAES, US). Guachochi: Parque Nacional Barranca del Cobre, 1.6 km E of La Bufa, 1950 m, P.M. 

Peterson & M.B. Knowles 13586 (US); 38.4 mi W of Guachochi 

on Mexico 127 towards Creel, 2440 m, P.M. Peterson & R.M. 

King 8079, 8173 (US); Parque Nacional Barranca del Cobre, 

20 mi NW of Aborreachi on road towards Creel, 2390 m, P.M. 

Peterson, M.B. Knowles, C.H. Dietrich & S.M. Braxton 13560 

(US); Cusarare, S of Creel, 220 m, Bye 5188 (US); Guachochi, 

2400 m, P.M. Peterson & Annable 5914 (US); 24.6 km W of 

Guachochi and 0.6 km S of Rocheachi, 2340 m, P.M. Peterson, 

Annable & Valdés-Reyna 10788 (US). Guadalupe y Calvo: Agua 

Amarilla, 5 mi NW of Chinatú, 10 Oct 1959, Correll & Gentry 

22986 (US); 15.2 mi E of Ocote on hwy 24 towards El Vergel, 

14 Sep 2006, 2580 m, P.M. Peterson 20061, F. Sánchez Alvarado 

& E.P. Gómez Ruíz (CIIDIR, US). Guerrero: Miñaca, 13 Oct 

1910, Hitchcock 7767 (US); 35 km al SW de Miñaca, Sierra 

Gazachic, Barranca Colorada, Pennell 18981 (US); 23.6 mi W 

of Hwy jct at La Junta on road to Tomochic, 18 mi E of Tomochic, 2200 m, P.M. Peterson & Annable 4536 (US); 35.2 mi 

W of Tomochic in Parque Nacional Cascada Basaseachic, 2200 

m, P.M. Peterson & R.M. King 8226 (US); 22 mi SW of La Junta 

on rd to Creel, 2200 m, P.M. Peterson & Annable 5828 (US); 

24 mi SW of La Junta on road to Creel, 2200 m, P.M. Peterson 

& Annable 5845 (US); 25 mi W of La Junta on rd to Parque 

Nacional Cascada Basaseachic, 2200 m, P.M. Peterson & R.M. 

King 8195 (US); 4.5 km W of Tomochic on Hwy 16, 2200 m, 

P.M. Peterson & Annable 4544 (ENCB, US). Madera: 1.5 km 

Col. Chuhichupa, 2240 m, F. Ramos 1892 (CHAP); 5 mi N of El 

Long at edge of small lake, 2375 m, Reeder & C. Reeder 2680, 

2681 (SLPM, US); 12 mi SW of Madera of Hwy 16 toward Cuauhtémoc, 4 Sep 1985, 2100 m, P.M. Peterson & Annable 4048

(US); 14.5 mi SE of Madera on Mex 16 to La Junta, 2200 m, 

P.M. Peterson & R.M. King 8180 (US). Ocampo: Along trail 

just above Cascada de Basaseachic, 1880 m, P.M. Peterson & 

Annable 12536 (US); Approx. 10 mi E of Basaseachic on Hwy 

towards La Junta, 2110 m, P.M. Peterson & Annable 12540 

(US). Riva Palacio: 9.1 mi E of Cumbres de Majalca, 2200 m, 

P.M. Peterson & Annable 4515 (US); 20.6 mi W of Hwy 45, 0.8 

mi E of Cumbres de Majalca, 2200 m, P.M. Peterson & Annable 

FIGURE 168. Muhlenbergia minutissima. A. Habit. B. Spikelet. 

C. Floret. Drawn by Linda Ann Vorobik and Annaliese Miller; 

copyright Utah State University.
NUMBER 107 • 247

4518 (US); 0.6 mi E of entrance to Parque Nacional Cumbres de 

Majalca, 2200 m, P.M. Peterson & Annable 5790 (US); Majalca, 

LeSueur 159 (US). Temósachi: Laguna de la Bavícora southside, 

2300 m, P.S. Martin s.n. (ENCB). Uruáchi: 7.6 mi E of Yécora 

on Hwy 16 towards Maycoba, 1840 m, P.M. Peterson & J. Cayouette 15318 (US).

241. Muhlenbergia montana (Nutt.) Hitchc., U.S.D.A. Bull. 

(1915–23) 772: 145, 147. 1920.

FIGURE 169

Densely caespitose perennial. Culms 10–80 cm tall, erect, 

rounded near base, glabrous below the strictly basal nodes; internodes mostly glabrous, occasionally glaucous. Sheaths 2–35 cm 

long, longer than the lower internode, glabrous to scaberulous, 

often glaucous, becoming flat, loose and papery, and occasionally spirally twisted near the base; ligules 4–14(20) mm long, 

membranous, decurrent, apex acute to acuminate, often lacerate; blades 6–25 cm long, 1–2.5 mm wide, flat becoming loosely 

involute to subfiliform, somewhat stiff, scabrous below and hirsute above. Panicles 5–25 cm long, (1)2–6 cm wide, narrow to 

somewhat open, loosely flowered, not dense; primary branches 

0.5–10 cm long, ascending, appressed or spreading to 40° from 

the rachises; pedicels 0.5–6.5 mm long, flattened, scabrous, occasionally stiffly reflexed. Spikelets 3–4.5(7) mm long, erect, occasionally reflexed; glumes (1)1.5–3.2(4) mm long, 1⁄3 to 2⁄3 as long 

as the lemma, subequal, glabrous to scaberulous above; lower 

glumes 1-veined, sometimes mucronate, the mucro less than 

1 mm long; upper glumes 3-veined, 3-toothed and 3-awned, the 

teeth (including the awns) 1⁄3 to 1⁄2 the length of the glume, and 

the awns up to 1.7 mm long, apex truncate to acute; lemmas 

3–4.5(7) mm long, lanceolate, awned, often greenish or yellowish with dark green or purple mottles, scaberulous above, loosely 

to densely appressed-pubescent to pilose along the midvein, margins, and proximal 1⁄2 to 4⁄5, the hairs up to 0.8 mm long, occasionally glabrous, apex acute to acuminate, the awn (2)6–25 mm 

long, flexuous; paleas 3–4.5(7) mm long, lanceolate, loosely to 

densely appressed-pubescent to pilose between the veins on the 

proximal 1⁄3 to 4⁄5, apex acute to acuminate, scaberulous; anthers 

1.5–2.3 mm long, purplish. Caryopsis 1.8–2 mm long, fusiform, 

light brown. 2n = 20, 40.

Distribution and Habitat. Muhlenbergia 

montana grows on rocky slopes, dry meadows, ridgetops, and 

open grasslands, primarily in upland and mountain habitats at 

elevations of 1,400–3,500 m. It ranges from the southwestern 

United States throughout western Mexico to Guatemala.

FIGURE 169. Muhlenbergia montana. A. Habit. B. Inflorescence. C. Glumes. 

D. Upper glume. E. Two florets. Drawn by Linda Ann Vorobik and Annaliese 

Miller; copyright Utah State University.
248 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 15 mi E of El Vergel, 2280 m, Correll 23253 (ENCB, 

US); 56.4 km W of Balleza and 38.7 km E of Guachochi, 2280 m, 

P.M. Peterson, Annable & Valdés-Reyna 10759 (US); 64.5 km W 

of Balleza and 30.6 km E of Guachochi, 2620 m, P.M. Peterson, 

Annable & Valdés-Reyna 10770 (US); 34 mi W of Balleza on 

road towards Guachochi, 2500 m, P.M. Peterson, M.B. Knowles, 

C.H. Dietrich & S.M. Braxton 13535, 13346 (US); 45 mi W of 

Balleza on road towards Guachochi, 2560 m, P.M. Peterson, 

M.B. Knowles, C.H. Dietrich & S.M. Braxton 13548 (US); 

33.8 km W of Parral on Hwy 24 towards El Vergel, 26 Sep 1988, 

2000 m, P.M. Peterson & Annable 5957 (US); 29 km E of Guachochi on Mex 127 towards Balleza, 13 Sep 1989, 2600 m, P.M. 

Peterson, Annable & Y. Herrera 8087 (US); 43.5 km W of Balleza 

and 51.6 km E of Guachochi, 2320 m, P.M. Peterson, Annable & 

Valdés-Reyna 10759 (US). Batopilas: Rancho Byarly, Sierra Charuco, 17–25 Apr 1948, Gentry 8055 (US); 10.7 mi S of Mexico 

127 on road to Batopilas, 2245 m, Y. Herrera, P.M. Peterson & 

Annable 972 (CIIDIR, US); 17.3 km S of Mex 127 on road to 

Batopilas, 11 Sep 1989, 2245 m, P.M. Peterson, Annable & 

Y. Herrera 8040 (US); Hacienda San Miguel, near Batopilas, 

2100 m, E. Palmer 10a (TAES, US). Bocoyna: Cabecera de la cañada de Recogoata, 2400 m, B. Tah V. 39, 58 (MEXU). Buenaventura: 15 mi W of Flores Magón, 1829 m, R. Guzmán 4938

(MEXU). Carichi: 1.5 km al SW del Cuiteco, 2060 m, J. Morelos 

s.n. (INEGI); Sánchez, 2400 m, Oct 1910, A.S. Hichcock 7668 

(US); 8.5 km al N de Carichi, 2100 m, J. Morelos s.n. (INEGI). 

Casas Grandes: W of Casas Grandes, 5 mi S of Hernández, 

2200 m, E. Palmer 168 (TAES); About 43 mi SW of Casas 

Grandes, 2100 m, J.M. Tucker 2586 (TAES). Cuauhtémoc: Rancho La Estancia, 2300 m, R. Guzmán 4918 (MEXU); 12 mi W of 

Cuauhtémoc, 2128 m, F.W. Gould & D. Watson 8927 (TAES, 

US). Chihuahua: Chihuahua, Sierra Madre, dry ledges, 7 Oct 

1887, Hitchcock 1413 (US); Mapula Mts, 2280 m, C.G. Pringle 

895 (US); 39 km carr. [hwy] Chihuahua–Namiquipa, 2300 m, 

M. Vergara 178 (MEXU); 16.7 mi W of Hwy 45 on road up Los 

Prietos Canyon, 2120 m, P.M. Peterson & Annable 12593 (US); 

Sand Dunes, 1300 m, LeSueur 057 (US); 17.5 mi W of Hwy 45 

on road up Los Prietos Canyon, 2120 m, P.M. Peterson & Annable 12600 (US). Guachochi: Yamuco, 1 mi E of hwy N of Rio 

Urique crossing towards Basihuare and Creel, 5 Sep 2008, P.M. 

Peterson & J.M. Saarela 22046 (US); Arroyo Baqueachi, at 

0.5 km E of small village, 2004 m, P.M. Peterson & P. Catalán 

17565 (US); 25.6 mi S of Creel on road to Batopilas, 2100 m, 

Y. Herrera, P.M. Peterson & Annable 968 (CIIDIR, US); 26.7 mi 

S of Creel on road to Batopilas, 2105 m, Y. Herrera, P.M. Peterson & Annable 970 (CIIDIR); 20 mi S of Creel on road to Batopilas, 2380 m, Y. Herrera, P.M. Peterson & Annable 964 (CIIDIR, 

US); 16 mi E of Guachochi on Mex 127 towards Balleza, 2680 m, 

Y. Herrera, P.M. Peterson & Annable 980 (CIIDIR); M.E. 

Siqueiros 1605 (MEXU); 38.4 mi W of Guachochi on Mexico 

127 towards Creel, 2440 m, M.E. Siqueiros 1594, 1630 (MEXU); 

18 mi E of Guachochi on Mex 127 towards Balleza, 2680 m, 

M.E. Siqueiros 1591 (MEXU); 25.6 mi S of Creel on road to 

Batopilas, 10 Sep 1989, 2100 m, P.M. Peterson, Annable & 

Y. Herrera 8033 (US); 9 mi S of Guachochi at edge of Barranca 

Río Green, 2470 m, P.M. Peterson & J. Cayouette 15377 (US); 

Cusarare, just NW of the church, 2200 m, Bye 8098 (US); Just S 

of Napuchis, 2162 m, P.M. Peterson & P. Catalán 17666 (CIIDIR, 

US); White-tuff volcanic outcrops surrounding Napuchis, 2140 

m, P.M. Peterson & P. Catalán 17681 (CIIDIR, US); Parque Nacional Barranca del Cobre, 13.6 mi NE of La Bufa on road towards Samachique, 2240 m, P.M. Peterson, M.B. Knowles, C.H. 

Dietrich & S.M. Braxton 13576 (US); Parque Nacional Barranca 

del Cobre, 12 mi SE of Samachique on road towards Guachochi, 

2150 m, P.M. Peterson, M.B. Knowles, C.H. Dietrich & S.M. 

Braxton 13589 (US); Parque Nacional Barranca del Cobre, 34 mi 

S of Creel on road towards Samachique, 2150 m, P.M. Peterson, 

M.B. Knowles, C.H. Dietrich & S.M. Braxton 13591 (US); 

12.4 km S of Cusarare on road to Guachochi, 25 Sep 1988, 2400 

m, P.M. Peterson & Annable 5894 (US); Entering Barranca El 

Cobre, approx. 25.7 km S of Cusarare on road to Guachochi, 25 

Sep 1988, 2000 m, P.M. Peterson & Annable 5899 (US); S side of 

Barranca El Cobre, approx. 32.2 km S of Cusarare on road to 

Guachochi, 2000 m, P.M. Peterson & Annable 5912 (US); Just N 

of Guachochi (1 km), 26 Sep 1988, 2500 m, P.M. Peterson & 

Annable 5920 (US); 19.3 km E of Guachochi, 26 Sep 1988, 2300 

m, P.M. Peterson & Annable 5930 (US); 32.3 km S of Creel on 

road to Batopilas, 10 Sep 1989, 2380 m, P.M.Peterson, Annable 

& Y. Herrera 8008 (US); 39.2 km S of Creel on road to Batopilas 

at the Barranca El Cobre, 10 Sep 1989, 1930 m, P.M. Peterson, 

Annable & Y. Herrera 8019 (US); Parque Nacional Barranca del 

Cobre, 24.8 km NE of La Bufa on road to Samachic, 2440 m, 

P.M. Peterson, Annable & Valdés-Reyna 10803 (US); Yamuco at 

1 km E of Hwy towards Basihuare and Creel, N of Rio Urique 

crossing, 1891 m, P.M. Peterson & P. Catalán 17539 (US). Guerrero: 24 mi SW of La Junta on road to Creel, 2200 m, Y. Herrera, 

P.M. Peterson & Annable 956 (CIIDIR, US); Km 25 carr. La 

Junta–Tomochi, 380 m, Valdés-Reyna VR-711A (ENCB); Km 25 

carr. La Junta–Tomochi, 2380 m, S. González 613 (TAES); 4.5 mi 

W of Tomochic on Hwy 16, 2200 m, M. Vergara 166 (MEXU); 

Carr. San Juanito–La Junta, 17 km, 2290 m, B. Tah V. 8 (MEXU); 

54.3 km W of La Junta on road to Parque Nacional Cascada 

Basaseachic, 30 Sep 1989, 2260 m, P.M. Peterson & R.M. King 

8214 (US); Miñaca, 13 Oct 1910, Hitchcock 7769 (US); 8 mi N 

of Santo Tomas, 2300 m, C.H. Muller 3396 (US); 38.6 km SW of 

La Junta and approx. 70.8 km N of Creel at P. Arroyo Ancho 

crossing, 21 km marker, 2200 m, P.M. Peterson & Annable 5847, 

5849 (US); 37 km SW of La Junta on road to Creel at the Puente 

Arroyo Ancho, 2230 m, P.M. Peterson, Annable & Y. Herrera 

7995 (US); 33.5 km SW of La Junta on road to Creel, 2260 m, 

P.M. Peterson 9608 (US); 40.3 km W of La Junta on road to 

Parque Nacional Cascada de Basaseachic, 29 Sep 1989, 2390 m, 

P.M. Peterson & R.M. King 8191 (US); 46.7 km W of La Junta 

on road to Parque Nacional Cascada de Basaseachic, 30 Sep 

1989, 2260 m, P.M. Peterson & R.M. King 8199 (US). Ignacio 

Zaragoza: Ejido de León, 2100 m, A.A. Beetle M-8032 (MEXU); 

72.5 km S of Ignacio Zaragoza on Mex 23, 28 Sep 1989, 2300 m, 
NUMBER 107 • 249

P.M. Peterson & R.M. King 8171 (US). Janos: Chihuahua–Sonora border, Rancho Carretas, 1730 m, L. H. Harvey 1639

(ENCB, US). Jiménez: Sta. Eulalia Mts, C.G. Pringle 392, 393 

(US). Madera: Mesa de Huracán, 2100 m, J. Peña 802 (CHAPA); 

Mesa de El Poleo, ejido El Long, 2400 m, E. Guízar 2683

(CIIDIR); 12 mi SW of Chuhichupa, 2260 m, Spellenberg & 

J. Zimmerman 8951 (ENCB); Mesa de Huracán, 2100 m, J. Peña 

s.n. (MEXU); Chuichupa, 2240 m, LeSueur 111 (US); 71.7 km SE 

of Madera on Mex 16 and 1.6 km S of Temosachici, 29 Sep 1989, 

2090 m, P.M. Peterson & R.M. King 8186 (US). Maguarichi: 

Maguarichi, 2100 m, Dávila, Tenorio & J.I. Solís 136 (MEXU). 

Moris: 17.6 mi E of Maycoba on Hwy 16 towards Yepachic and 

2 mi E of Sonora/Chihuahua boundary, 1540 m, P.M. Peterson & 

Annable 12514 (US); 9.6 mi E of Maycoba on Hwy 16 towards 

Yepachic, 1420 m, P.M. Peterson & Annable 12511 (US). Ocampo: overlook of Casada de Basaseachic, approx. 37 mi W of 

Tomochic, 22 Sep 1986, 2200 m, P.M. Peterson & Annable 4550 

(US); 122.5 km W of La Junta and 56.7 km W of Tomochic in 

Parque Nacional Cascada de Basaseachic, 1 Oct 1989, 2100 m, 

P.M. Peterson & R.M. King 8233 (US). Ojinaga: Sierra El Peguis, 

1640 m, G. García s.n. (INEGI). Riva Palacio: 23 mi W of México 

45 and about 2 mi W of Col. Cumbres de Majalca, 2000 m, Y. 

Herrera, P.M. Peterson & Annable 950 (CIIDIR,US); 21 mi W of 

México 45, N of Chihuahua city, Col. Cumbres de Majalca, 

2120 m, Y. Herrera, P.M. Peterson & Annable 947 (CIIDIR, US); 

Parque Cumbres de Majalca, 2120 m, E. Estrada s.n. (ENCB); 38 

km W of Hwy 45 on road towards Benito Juárez, 2230 m, P.M. 

Peterson & Annable 12552, 12566 (US); Majalca, 2100 m, Pennell 19315 (US); Col. Cumbres de Majalca, approx. 32.2 km W 

of Hwy 45 N of Chihuahua, P.M. Peterson & Annable 5799, 

5811 (US) ; 37 km W of Mex 45, and ca. 3.2 km W of Col. Cumbres de Majalca, 7 Sep 1989, 2170 m, P.M. Peterson, Annable & 

Y. Herrera 7980 (US). Temósachi: 28.7 km al NE de Agua Caliente, 2000 m, J. Morelos s.n. (INEGI). Uruáchi: 20.2 mi W of 

Maycoba on Hwy 16 towards Yécora, 1810 m, P.M. Peterson & 

J. Cayouette 15332 (US); 8.6 mi E of Yécora on Hwy 16 towards 

Maycoba, 1880 m, P.M. Peterson & J. Cayouette 15323 (US).

242. Muhlenbergia mucronata (Kunth) Trin., Gram. Unifl. Sesquifl. 194, t. 5, f. 23. 1824.

Muhlenbergia laxiflora Scribn.

FIGURE 170H

Densely caespitose perennial. Culms 75–100(120) cm tall, 

erect, scabrous or strigulous below the nodes. Sheaths shorter than 

internodes, glabrous or scaberulous, purplish in part, rounded 

below; ligules (2)5–8 mm long; blades 20–40 cm long, 2–3 mm 

wide, flat or loosely involute, attenuate into a long apex, scabrous abaxially, scabrous on ribs adaxially. Panicle (5)10–15(20) 

cm long, 1–3(6) cm wide, oblong-cylindrical, spreading, purple, 

rarely purple-greenish, branches 4–8(10) cm long, ascending 

or appressed. Spikelets (4)4.5–5 mm long, pedicels 1–5(6) mm 

long, slender, scabrous below spikelets; glumes 1.5–2 mm long, 

acute, subequal, scabrous near the apex; lemma (4)4.5–5 mm 

long, scaberulous between veins, mucronate or shortly awned 

from 2 minute teeth, the mucro or awn 0.5–1(2) mm long; palea 

scabrous between the veins, apex acute or acuminate; callus 

hairy, the hairs 0.5–0.7 mm long; anthers 2–2.2 mm long, purplish. Caryopsis 2–2.5 mm long, about 0.5 mm wide, ellipsoid, 

reddish-brown. 

Distribution and Habitat. Muhlenbergia mucronata grows in oak and pine forests at elevations of 2,050–

2,650 m. This Mexican endemic is known from Baja California, 

Chiapas, Chihuahua, Distrito Federal, Durango, Guanajuato, 

Mexico City, Oaxaca, Puebla, San Luis Potosí, Sinaloa, Veracruz, and Zacatecas.

Muhlenbergia mucronata is morphologically similar to 

M. rigida, differing in the mucronate to short-awned lemmas, 

narrower panicles, and usually shorter pedicels. 

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 19.3 km SE of Balleza towards Parral, 26 Sep 1988, 

1800 m, P.M. Peterson & Annable 5946 (US); 34 mi W of Balleza 

towards Guachochi, 2500, P.M. Peterson, M.B. Knowles, C.H. 

Dietrich, S.M. Braxton 13540 (US); 64.5 km W of Balleza and 

30.6 km E of Guachochi, 2650 m, P.M. Peterson, Annable & 

Valdés-Reyna 10778 (US). Bocoyna: 7 mi NE of San Rafael on 

road towards Creel, at Divisidero lookout, 5 Sep 2008, 2240 m, 

P.M. Peterson & J.M. Saarela 22038 (US). Carichi: Sánchez, 12 

Oct 1910, Hitchcock 7674, 9221 (US). Guachochi: Parque Nacional Barranca del Cobre, 20.3 km NE of La Bufa and 3.2 km 

S of Basigochi, 2180 m, P.M. Peterson, Annable & ValdésReyna 10813 (US); 24.6 km W of Guachochi and 0.6 km S of 

Rocheachi, 2340 m, P.M. Peterson, Annable & Valdés-Reyna 

10794 (US); 61.3 km W of Balleza and 33.8 km E of Guachochi, 

2620 m, P.M. Peterson, Annable & Valdés-Reyna 10776 (US); 

30.6 km E of Guachochi on road to Balleza, 26 Sep 1988, P.M. 

Peterson & Annable 5934 (US); 8.5 km S of Cusarare on road 

to Guachochi, 25 Sep 1988, 2400 m, P.M. Peterson & Annable 

5884, 5885 (US); 20 km S of San Juanito on road to Creel and 

3 km S of Bocoyna, 24 Sep 1988, 2200 m, P.M. Peterson & Annable 5875 (US); 11.5 mi NW of Aboreachi on road towards 

Creel, 2500 m, P.M. Peterson, M.B. Knowles, C.H. Dietrich, 

S.M. Braxton 13557 (US); Just S of Napuchis, 2162 m, P.M. 

Peterson & P. Catalán 17663 (CIIDIR, US); Approx. 22.5 mi 

NE of Cieneguita de Barranca on road towards Creel, 2160 m, 

P.M. Peterson, P. Catalán, C. López, & G. Villegar 17691 (US). 

Guadalupe y Calvo: Agua Amarilla, about 5 mi NW of Chinatú, 

10 Oct 1959, Correll & Gentry 22988 (US); Mt. Mohinora, SW 

Chihuahua, 2050 m, E.W. Nelson 4902, 4903 (US); 9.5 mi E of 

Guadalupe y Calvo on hwy 24, 14 Sep 2006, 2570 m, P.M. Peterson 20058, F. Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, 

US); Rio Verde Crossing, 21 mi SW of El Vergel on hwy 24, 

14 Sep 2006, 2330–2360 m, P.M. Peterson 20071, F. Sánchez 

Alvarado & E.P. Gómez Ruíz (CIIDIR, US). Guerrero: 35.4 km 

SW of La Junta and approx..74 km N of Creel, 24 Sep 1988, 

2200 m, P.M. Peterson & Annable 5833 (US); Sierra Madre, 

porphyry ledges near Guerrero, 27 Aug 1887, 2286 to 2591 m, 

C.G. Pringle 1412 (US).
250 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

243. Muhlenbergia palmeri Vasey, Bull. Torrey Bot. Club 13(12): 

231. 1886.

FIGURE 159A–E

Perennial; densely caespitose. Culms 35–100 cm tall, erect, 

glabrous. Sheaths rounded, glabrous to scabrous; ligule 1–3 mm 

long, firm, truncate, membranous, minutely ciliolate; blades 

15–50 cm long, 1–3.5 mm wide, flat or involute, glabrous or scabrous. Panicles 15–35 cm long, 0.5–2(3) cm wide, dense to loosely 

flowered, narrow, straight, rachis scabrous, branches 0.5–8 cm 

long, plicated, flowered from the base; pedicels 1–6 mm long, 

hispid. Spikelets 3–4.3 mm long, brown-yellowish to purplish; 

FIGURE 170. Muhlenbergia rigida. A. Habit. B. Inflorescence. C. Inflorescence. D. Ligule. E. Glumes. 

F. Floret. G. Lodicules, pistil, and stamens. Muhlenbergia mucronata. H. Floret. Drawn by Susan C. Escher 

for Smithsonian Institution, Department of Botany.
NUMBER 107 • 251

glumes (1.7) 2–3.1 mm long, subequal, 1-veined, apex acute to 

acuminate, awned, the awn 1.2–1.5 mm long, finely scabrous 

distally; lemmas 3–4.3 mm long, scabrous, lanceolate, apex acuminate, awned, the awns 5–10 mm long, straight, sometimes 

flexuous; palea 2.9–4.2 mm long, lanceolate, scabrous, apex 

acute to acuminate; anthers 1.5–2.5 mm long, yellow or spotted 

with purple. Caryopsis 2–3 mm long, fusiform, brown.

Distribution and Habitat. Muhlenbergia 

palmeri grows on rocky and sandy soils in oak and pine forests 

at elevations of 1,580–2,100 m. It ranges from the United States 

to Mexico in Chihuahua, Michoacán, and Sonora.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 16 mi E of Balleza on road towards Parral, 1950 m, P.M. 

Peterson & J. Cayouette 15385 (US); 11 mi SE of Balleza on 

road to Parral, 1800 m, P.M. Peterson, M.B. Knowles, C.H. Dietrich & S.M. Braxton 13529 (US); 7.4 km W of Balleza on road 

to Guachochi, 1660 m, P.M. Peterson, Annable & Valdés-Reyna 

10737 (US). Chihuahua: Cañón del 54, 1800 m, J. Peña s.n.

(TAES). Guachochi: Parque Nacional Barranca del Cobre, 1.6 

km E of La Bufa, 1950 m, P.M. Peterson & M.B. Knowles 13579

(US); 16 mi E of Guachochi on Mex 127 towards Balleza, 2680 

m, R. Fierros 1581 (MEXU); Along Río Corareáchi, 1840–1900 

m, P.M. Peterson & P. Catalán 17605 (CIIDIR, US); 1–2 km S 

of Río Osichi and Río Basihuare junction, 1600 m, P.M. Peterson & P. Catalán 17634 (CIIDIR, US); West of Munérachi along 

route (trail) to Sorichique, 1701 m, P.M. Peterson & P. Catalán 

17708 (US). Guerrero: Miñaca, 13 Oct 1910, Hitchcock 7750 

(US). Jiménez: 9 km NNE de El Chamizal, 11 km al SW de Bordo 

Los Valles, 1580 m, E. Juárez s.n. (INEGI). Madera: 10 km N 

of Madera, 2100 m, Valdés-Reyna VR-673, VR-667 (ENCB). 

Moris: SW Chihuahua, 1900 m, E. Palmer 16 (MEXU, US), 

type. Riva Palacio: Col. Cumbres de Majalca, approximately 

32.2 km W of Hwy 45 N of Chihuahua, 23 Sep 1988, 2100 m, 

P.M. Peterson & Annable 5812 (US); 17.7 km W of Nuevo Majalca on road to Cumbres de Majalea, Parque Nacional., 22 Sep 

1988, 2000 m, P.M. Peterson & Annable 5784 (US). Uruáchi: 

8.6 mi E of Yécora on Hwy 16 towards Maycoba, 1880 m, P.M. 

Peterson & J. Cayouette 15322 (US).

244. Muhlenbergia pauciflora Buckley, Proc. Acad. Nat. Sci. 

Philadelphia 14: 91. 1862.

FIGURE 171

Caespitose perennial. Culms 30–70 cm tall, decumbent, 

wiry, branching at the lower nodes. Sheaths rounded, becoming flat and spreading at maturity, glabrous or scabrous, usually 

with dark brown necrotic spots; ligules 1–2.5(5) mm long, hyaline, lacerate-ciliate, with auricles (lobes) 1.5–3 mm long; blades 

5–12(15) cm long, 0.5–1.5 mm wide, filiform, flat or involute, 

falling soon, scabrous, often with dark brown necrotic spots. Panicles (2)5–15 cm long, 5–18 mm wide, contracted, interrupted at 

the base; branches 1–4(6) cm long, appressed or some divergent, 

densely flowered from the base; pedicels 0.5–3 mm long, scabrous. Spikelets 3.5–5.5 mm long, purplish; glumes 1.5–3 mm 

long, subequal, glabrous, lanceolate, acuminate or awned, pale 

green, 1-veined, the veins prominent; lemma 3–5.5 mm long, 

glabrous, purple, 3-veined, scabrous on veins, awned, the awn 

of (7)10–20 mm long, slender, flexuous; palea 3–5.5 mm long, 

FIGURE 171. Muhlenbergia pauciflora. A. Habit. 

B. Inflorescence. C. Glumes. D. Floret. Drawn by 

Linda Ann Vorobik and Annaliese Miller; copyright 

Utah State University.
252 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

glabrous, scabrous on veins, purple; anthers 1.5–2.1 mm long, 

purple. Caryopsis 2–2.5 mm long, fusiform, brown.

Distribution and Habitat. Muhlenbergia 

pauciflora grows on calcareous and saline soils in xerophilous 

scrublands and oak forests, at elevations of 1,890–2,438 m. It 

ranges from the United States to northern Mexico in Baja California, Chihuahua, Coahuila, Jalisco, Nuevo León, and Sonora.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: 22 km al S de Humira, 21.8 km al SW de la dev. a 

La Bufa, 2070 m, Tenorio & R. Torres 3691A (MEXU, US). 

Bocoyna: 7 mi NE of San Rafael on road towards Creel, at Divisidero lookout, 5 Sep 2008, 2240 m, P.M. Peterson & J.M. 

Saarela 22043 (US). Carichi: Sánchez, 12 Oct 1910, Hitchcock 

7701 (US). Casas Grandes: 1⁄2 mi E of Cuesta Blanca, 1890 m, 

Reeder & C. Reeder 3228 (ENCB, US); 18 mi W of Col. Juárez, 

2073 m, Reeder & C. Reeder 3206 (ENCB); About 38 mi SW of 

Casas Grandes, 2040 m, Reeder & C. Reeder 2697 (ENCB, US). 

Chihuahua: 6.1 mi W of Hwy 45 on dirt road towards Santa 

Clara, 1640 m, P.M. Peterson & Annable 12580 (US). Cuauhtémoc: Rancho La Estancia, 2300 m, R. Guzmán 4913 (MEXU). 

Guachochi: Yamuco, 1 mi E of hwy N of Rio Urique crossing towards Basihuare and Creel, 5 Sep 2008, 1890 m, P.M. Peterson 

& J.M. Saarela 22048 (US); 10.8 km N of Creel on Mex 127 and 

20 km S of San Juanito, 10 Sep 1989, 2330 m, P.M. Peterson, 

Annable & Y. Herrera 8004 (US); 19.3 km E of Guachochi., 26 

Sep 1988, 2300 m, P.M. Peterson & Annable 5933 (US); 20 km S 

of San Juanito on road to Creel and 3 km S of Bocoyna, 2200 m, 

P.M. Peterson & Annable 5875-b (US). Guadalupe y Calvo: Rio 

Verde Crossing, 21 mi SW of El Vergel on hwy 24, 14 Sep 2006, 

2330–2360 m, P.M. Peterson 20077, 20079, F. Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, US). Guerrero: 54.3 km W 

of La Junta on road to Parque Nacional Cascada de Basaseachic, 

30 Sep 1989, 2260 m, P.M. Peterson & R.M. King 8209 (US). 

Ignacio Zaragoza: 20.3 km NE of Ignacio Zaragoza on Mex 23, 

28 Sep 1989, 2400 m, P.M. Peterson & R.M. King 8162 (US). 

Madera: 22 mi SE of Chuhichupa on the road to Madera, 2130 

m, Reeder & C. Reeder 2674 (ENCB, US); Chuichupa, 2240 m, 

LeSueur 0116 (US). Ocampo: Along trail just above Cascada de 

Basaseachic, 1880 m, P.M. Peterson & Annable 12522 (US).

245. Muhlenbergia pectinata C. O. Goodd., J. Wash. Acad. Sci. 

31(12): 505–506. 1941.

Annual; slender, delicate. Culms 10–35 cm tall, glabrous, 

filiform, erect or decumbent, branched. Sheaths glabrous, striate, 

margins sparsely pilose; ligules 0.3–0.9 mm long, hyaline, pilose; 

blades 1–6 cm long, 0.6–2 mm wide, flat to involute, appressed, 

sparsely pilose. Panicles 4–12 cm long, 0.5–2.6(4) cm wide, 

included or exserted in the upper sheath, terminal; branches 

2–3.5 cm long, ascending; pedicels 1–3 mm long, glabrous, 

appressed. Spikelets ascending or straight, overlapping, green 

with purple spots; glumes 0.8–2(3) mm long, subequal, awned 

or awnless, glabrous, 1-veined, apex acute or acuminate, awn 

to 1.5 mm long, lower glumes 0.8–1.7 mm long, upper glumes 

1–2(3) mm; lemmas 3–4.5(5) mm long, subulate to lanceolate, 

awn 10–30 mm long, slender, flexuous, glabrous to antrorsely 

scabrous, appearing 5-veined, veins greenish, lateral ones occasionally ciliate, the hairs flattened, swollen at the base; paleas 

2.5–4.5 mm long, narrowly lanceolate, glabrous, acuminate; anthers 0.3–0.6 mm long, yellowish. Caryopsis 0.6–3.1 mm long, 

narrowly fusiform, light brown. n = 10. 

Distribution and Habitat. Muhlenbergia pectinata grows in oak and pine forests at elevations of 1,750–2,000 

m. It ranges from the United States to Mexico in Chihuahua, Durango, Guerrero, Jalisco, México, Michoacán, Morelos, Nayarit, 

Oaxaca, Sinaloa, and Sonora.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: La Bufa, 21 mi S of Mex 127 on rd to Batopilas, 1750 

m, P.M. Peterson, Annable & Y. Herrera 8057 (US). Batopilas, 

E. Palmer (US). Chínipas: Sierra Milpillas, 24.1 mi E of Los 

Tanques on road to Milpillas, 2100 m, P.M. Peterson & Annable 

4280 (ENCB, US); Sierra Milpillas, 22.7 mi E of Los Tanques 

on road to Milpillas, 2100 m, P.M. Peterson & Annable 4171, 

4172 (US); Saguarivo, 53 mi N of Alamos, 9 Sep 2008, 1540 m, 

P.M. Peterson & J.M. Saarela 22138 (US). Curahui, 9 Sep 2008, 

tropical deciduous forest, 926 m, P.M. Peterson & J.M. Saarela 

22143A (US). El Tule: 12 mi SE of Balleza towards Parral, 2000 

m, P.M. Peterson & Annable 5948 (US). Guachochi: Parque Nacional Barranca del Cobre, 0.6 km W of La Bufa and 22.5 km 

NE of Batopilas, 1100 m, 20 Sep 1991, P.M. Peterson, Annable 

& Valdés-Reyna 10844 (US); West of Munérachi along route 

(trail) to Sorichique, 1701 m, P.M. Peterson & P. Catalán 17707 

(US). Guadalupe y Calvo: Río Salado, aprox. 3 mi S of Tahonas, 

Sierra Mohinora, 2300 m, P.M. Peterson & Annable 4578 (US). 

Uruáchi: 20.2 mi W of Maycoba on Hwy 16 towards Yécora, 

1800 m, P.M. Peterson & J. Cayouette 15342 (US).

246. Muhlenbergia pereilema P. M. Peterson, Caldasia 31(2): 

293–294, f. 6E–J. 2009. Pereilema crinitum J. Presl, Reliq. 

Haenk. 1(4–5): 233, t. 37, f. a–f. 1830.

FIGURE 167E–J

Delicate, caespitose annual. Culms 15–90 cm tall, decumbent, rooting from lower nodes. Sheaths with oral hairs ciliate, 

auricles 1–1.5 mm long, falcate; ligules 0.5–1 mm long, membranous, eciliate, irregularly erose; blades 5–15 cm long, 2–3 mm 

wide, flat, acuminate. Panicles 5–20 cm long, 2–3 cm wide, spiciform, linear, continuous or interrupted; branches 0.5–3.5 cm 

long, appressed. Spikelets with 1 or 2 perfect spikelets and 2 or 

3 sterile spikelets (bristles) in a cluster, the fertile spikelets subtended by an involucre of persistent bristles, the bristles 3 mm 

long; glumes about 1 mm long, equal, awned, the awns 1.8–2 mm 

long; fertile florets 1.5–2.6 mm long, lanceolate, laterally compressed, disarticulating below without rachilla extension; lemmas 1.5–2.6 mm long, ovate, keeled, 3-veined, lateral veins close 

to margins, scabrous, apex acuminate, awned, the awns 20–30 

mm long, callus hairy, the hairs 0.3–1 mm long; palea similar to 

lemma; anthers 3, 0.5–0.7 mm long, yellow. Caryopsis 0.8 mm 

long, ellipsoid, with adherent pericarp. 2n = 20. 
NUMBER 107 • 253

Distribution and Habitat. Muhlenbergia 

pereilema grows in tropical and oak–pine forests at elevations 

of 1,240–2,450 m. It ranges from throughout Mexico to Central 

and South America.

Specimens Examined. MEXICO. Chihuahua.

Chinipas: Sierra Saguarivo, 1.3 mi W of Curahui, 9 Sep 2008, 

tropical deciduous forest, 1001 m, P.M. Peterson & J.M. Saarela 

22147 (US). Guachochi: 39.2 km S of Creel on road to Batopilas 

at the Barranca El Cobre, 10 Sep 1989, oak forest, 1930 m, P.M. 

Peterson, Annable & Y. Herrera 8016 (ENCB, US); 24.6 km S of 

Mex 127 and 11.1 km NE of La Bufa, 11 Sep 1989, oak forest, 

2000 m, P.M. Peterson, Annable & Y. Herrera 8048 (ENCB, US); 

Parque Nacional Barranca del Cobre, 11.3 km NE of La Bufa and 

2.1 km S of Kirare, 1950 m, P.M. Peterson, Annable & ValdésReyna 10818 (US). Temosachi: Nobogame, 12 Oct 1988, 1800 m,

Laferr. 2038 (MEXU). Urique: km 1 al S de Kirare, Urique, 10 Sep 

1999, 1800 m, T. Lebgue, G. Quintana, E. Estrada 2454 (NMC). 

247. Muhlenbergia peruviana (P. Beauv.) Steud., Nomencl. Bot. 

(ed. 2) 1: 41. 1840.

FIGURE 156E–H

Caespitose annual. Culms 5–30 cm tall, erect, very branched 

at the base. Sheaths veined with hyaline margins; ligules 

1.5–3 mm long, membranous, apex acute, entire to erose; blades 

1–5 cm long, 0.6–1.5 mm wide, flat or involute, short-pubescent 

to glabrous. Panicles 2–8 cm long, 0.3–3.4 cm wide, exsert or 

included in the superior sheath, contracted or open; branches 

ascending, flowered from the base; pedicels 0.5–5 mm long, 

ascending, erect. Spikelets 1.4–4.2 mm long; glumes glabrous 

or scabrous along veins, narrow or widely lanceolate, greenwithish, occasionally with spots purplish, apex acute-awned; 

lower glumes 0.8–2.5 mm long, 1-veined; upper glumes 1–3 mm 

long, 2- to 3-veined, wider, acute, 2- to 3-toothed, the teeth 

0.3–0.8 mm long; lemmas 1.4–4.2 mm long, narrow-lanceolate, 

pilose in the proximal 1⁄2, scabrous above, apex bifid, the teeth 

0.5–0.8 mm long, awn 18–22 mm long, arising between slender 

teeth, flexuous, purple, callus short-pilose; paleas 1.3–3.8 mm 

long, narrowly lanceolate; anthers 0.5–1 mm long, purplish to 

yellowish. Caryopsis 1–1.6 mm long, fusiform, brown. n = 15. 

Distribution and Habitat. Muhlenbergia 

peruviana grows in pine–oak–juniper forests at elevations of 

2,000–2,600 m. It ranges from United States and Mexico in 

Aguascalientes, Chiapas, Chihuahua, Distrito Federal, Durango, 

Guanajuato, Guerrero, Hidalgo, Jalisco, México, Michoacán, 

Morelos, Oaxaca, Puebla, Querétaro, San Luis Potosí, Tlaxcala, 

and Veracruz to Central and South America.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 12.4 mi NE of El Vergel on Hwy 24, SW of Parral, 

2200 m, P.M. Peterson & Annable 4577 (ENCB, US); 12.1 mi 

NE of El Vergel on Hwy 24, SW of Parral, 2000 m, P.M. Peterson & Annable 4065 (TAES, US); 7.2 mi SW of El Vergel on 

Mex. Hwy 24, SW of Parral, 2200 m, P.M. Peterson & Annable 

4073, 4574 (TAES, US); 16 mi SW of El Vergel on Hwy 24, m, 

6 Sep 1985, P.M. Peterson & Annable 4076 (US); 0.5 mi SW 

of El Vergel, m, P.M. Peterson & Annable 4078 (US); 34 mi W 

of Balleza on road towards Guachochi, 2500 m, P.M. Peterson, 

M.B. Knowles, C.H. Dietrich & S.M. Braxton 13543 (US); 45 mi 

W of Balleza on road towards Guachochi, 2560 m, P.M. Peterson, M.B. Knowles, C.H. Dietrich & S.M. Braxton 13549 (US); 

43.5 km W of Balleza and 51.6 km E of Guachochi, 2320 m, P.M. 

Peterson, Annable & Valdés-Reyna 10760 (US); 56.4 km W of 

Balleza and 38.7 km E of Guachochi, 2480 m, P.M. Peterson, Annable & Valdés-Reyna 10767 (US). Bocoyna: Cabecera de la cañada de Recogoata, 2400 m, B.Tah V. 35, 41 (MEXU). Carichi: 

Sánchez, along railroad, 12 Oct 1910, Hitchcock 1354, 7663, 

7722 (US). Chihuahua: 38 km W of Hwy 45 on road towards 

Benito Juárez, 2230 m, P.M. Peterson & Annable 12560 (US). 

Guachochi: 16 mi E of Guachochi on Mex 127 towards Balleza, 

2600 m, Y. Herrera, P.M. Peterson & Annable 976 (CIIDIR); 

38.4 mi W of Guachochi on Mexico 127 towards Creel, 2440 m, 

Y. Herrera, P.M. Peterson & Annable 975 (CIIDIR); 29 km E of 

Guachochi on Mex 127 towards Balleza, 2600 m, P.M. Peterson 

& R.M. King 8082 (US); 19.3 km E of Guachochi, 2300 m, P.M. 

Peterson & Annable 5926 (US); Just N of Guachochi (1 km), 

2500 m, P.M. Peterson & Annable 5918 (US); 38.4 mi NW of 

Guachochi on Mex 127 towards Creel, 2440 m, P.M. Peterson 

& R.M. King 8078 (US); Parque Nacional Barranca del Cobre, 

20 mi NW of Aborreachi on road towards Creel, 2390 m, P.M. 

Peterson, M.B. Knowles, C.H. Dietrich & S.M. Braxton 13559 

(US); 12.4 km S of Cusarare on road to Guachochi, 2400 m, P.M. 

Peterson & Annable 5890 (US); 2.3 mi W of San Juanito on road 

towards Baquiriachic, 2590 m, P.M. Peterson & J. Cayouette 

15360 (US); 3.7 km N of San Juanito on road to Creel, near km 

53 marker, 5860 m, P.M. Peterson & Annable 5860 (US); 1.1 km 

N of San Juanito near large lumber mill, 2200 m, P.M. Peterson 

& Annable 5871 (US); 24.6 km W of Guachochi and 0.6 km S 

of Rocheachi, 2340 m, P.M. Peterson, Annable & Valdés-Reyna 

10789 (US). Guadalupe y Calvo: Rio Verde Crossing, 21 mi SW 

of El Vergel on hwy 24, 14 Sep 2006, 2330–2360 m, P.M. Peterson 20068, F. Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, 

US). Guerrero: Sierra Madre, porphyry ledges near Guerrero, 27 

Aug 1887, 2200 m, C.G. Pringle 1416 (US), Isotype; 35.4 km SW 

of La Junta and approx.74 km N of Creel, 2200 m, P.M. Peterson 

& Annable 5840 (US); 33.6 mi W of Hwy Junction at La Junta on 

road to Tomochic, 18 mi E of Tomochic., 2200 m, P.M. Peterson 

& Annable 4535 (US). Ocampo: Approx. 10 mi E of Basaseachic 

on Hwy towards La Junta, 2110 m, P.M. Peterson & Annable 

12539 (US). Riva Palacio: Cumbres de Majalca, 21.5 mi W of 

Hwy 45, 2200 m, P.M. Peterson & Annable 4526, 4527 (ENCB, 

US); Col. Cumbres de Majalca, approx. 32.2 km W of Hwy 4, 

2200 m, P.M. Peterson & Annable 5792 (US).

248. Muhlenbergia phalaroides (Kunth) P. M. Peterson, Caldasia 31(2): 294–296, f. 7A,B. 2009. Lycurus phalaroides

Kunth, Nov. Gen. Sp. (quarto ed.) 1: 142. 1815 [1816]. 

Caespitose perennial. Culms 10–40 cm tall, erect or decumbent, nodes and internodes scabrous. Sheaths sparsely 
254 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

puberulent near margins, compressed-keeled near the base; ligules 0.5–1 mm long, apex truncate; blades 1–6 cm long, 0.3–0.7 

mm wide, glabrous to sparsely puberulent, apically navicular to 

short-acute, margins and midvein not whitish-thickened. Panicles 1–6.5 cm long, 3–5 mm wide, narrow, contracted, spikelike, 

densely flowered; branches tightly appressed. Spikelets 3–4 mm 

long, 1-flowered, often paired, the upper perfect, the lower staminate or sterile; lower glumes 0.8–2 mm long, usually 2-veined, 

rarely 1-veined, usually 2-awned, rarely 1-awned, the awns 0.7–

2.5 mm long; upper glumes 1–2 mm long, awn 1–3 mm long; 

lemmas 3–4 mm long, awned, the awn 1–2.9 mm long, scabrous; 

anthers 1.5–2.1 mm long. Caryopsis 1.8–2 mm long.

Distribution and Habitat. Muhlenbergia 

phalaroides grows in grasslands, xerophilous scrublands, and 

pine–oak forests at elevations of 2,218–2,535 m. It ranges from 

the United States and Mexico in Aguascalientes, Baja California 

Sur, Chiapas, Chihuahua, Coahuila, Colima, Distrito Federal, 

Durango, Guanajuato, Hidalgo, Jalisco, México, Michoacán, 

Morelos, Nayarit, Nuevo León, Oaxaca, Puebla, Querétaro, San 

Luis Potosí, Tamaulipas, Tlaxcala, Veracruz, and Zacatecas to 

Central and South America.

Specimens Examined. MEXICO. Chihuahua. 

Casas Grandes: Rancho la Morita en praderas irrigadas [irrigated meadows], 6 Jul 1995, suelos arcillosos arenosos [sandy 

loam soils], 2000 m, J.C. Gamez, (MEXU). Chihuahua: 38 km 

W of hwy 45 on road towards Benito Juárez, 17 Oct 1992, 

pinyon–juniper woodlands, 2230 m, P.M. Peterson & Annable 

12557 (US). Guachochi: Barranca de Basihuare, 28 Aug 2003, 

bosque de encino [oak forest], 1700 m, P.M. Peterson & P. Catalán 17589 (US). Guerrero: km 19 carr. [hwy] la Junta San Juanito, 22 Sept 1997, 2300 m, B. Tah V. 23 (MEXU). Hidalgo del 

Parral: 10 mi W of Parral on road to El Vergel, 7 Oct 1966, 

Reeder & C. Reeder 4619 (ARIZ-4620).

249. Muhlenbergia phleoides (Kunth) Columbus, Aliso 28: 66. 

2010. Lycurus phleoides Kunth, Nov. Gen. Sp. (quarto ed.) 

1: 142, pl. 45. 1815 [1816]. 

FIGURE 172

Loosely caespitose perennial. Culms 20–60 cm tall, erect 

to decumbent at the base, scabrous to puberulent just above or 

below the nodes. Sheaths usually 0.5–3 cm long, glabrous to pubescent, compressed-keeled near the base; ligules 2–3 mm long, 

acuminate and erose, usually auriculate with triangular lateral 

lobes 0.5–2.5 mm long, decurrent below; blades 2–8 cm long, 

1–1.5 mm wide, flat or folded, glabrous to puberulent adaxially and puberulent to hirsute abaxially, margins and midvein 

whitish-thickened, apex acute or sometimes with a narrow bristle 0.5–3 mm on the upper blades. Panicles (2)4–10 cm long, 

4–8 mm wide, narrow, contracted, densely flowered, and spikelike; primary branches 0.1–0.3 cm long, tightly appressed. Spikelets 3–4 mm long, 1-flowered, often paired, the upper perfect, 

the lower staminate or sterile; glumes 1–2 mm long, scaberulous near apex, awned, the awns 1–5 mm long; lower glumes 

usually 2(3)-veined and 2-awned; upper glumes 1(2)-veined, the 

FIGURE 172. Muhlenbergia phleoides. A. Habit. B. Ligule. 

C. Glumes. D. Floret. Drawn by Linda Ann Vorobik and Karen 

Klitz; copyright Utah State University.
NUMBER 107 • 255

awns 2–5 mm long; lemmas 3–4 mm long, puberulent along the 

margins, awned, the awns 1–3 mm long; paleas 3–4 mm long, 

puberulent between the veins; anthers 1.5–2 mm long, yellow. 

Caryopsis 1.8–2.2 mm long, brownish. 2n = 40.

Distribution and Habitat. Muhlenbergia 

phleoides grows on rocky slopes, in canyons, and on flats, often 

occurring in calcareous soils and oak–pinyon–juniper woodlands associated with Quercus gregii and Larrea tridentata at 

elevations of 1,200–2,500 m. It extends from the southwestern United States in Texas and New Mexico to northern and 

central Mexico in Aguascalientes, Chihuahua, Distrito Federal, 

Durango, Guanajuato, Hidalgo, Jalisco, México, Michoacán, 

Morelos, Nayarit, Oaxaca, Puebla, Querétaro, San Luis Potosí, 

Sonora, Tlaxcala, and Zacatecas.

Specimens Examined. MEXICO. Chihuahua. Aldama: Rancho el eden de Aldama hacia [toward] Ojinaga (km 

desviar a la izquierda por terraceria [divert to left by dirt road] 

6 km, 27 Oct 2000, matorral [scrub],G. Gómez 708 (MEXU). 

Balleza: 7.4 km W of Balleza on road to Guachochi, 18 Sep 1991, 

huizachal, 1660 m, P.M. Peterson, Annable & Valdés 10729

(CIIDIR); 56.4 km W of Parral on road to Balleza and 35.5 km 

S of Balleza, 18 Sep 1991, pine forest–encino [oak], 2210 m, 

P.M. Peterson, Annable & Valdés 10723 (CIIDIR). Batopilas: 

SW Chihuahua, Aug 1885, E. Palmer 2 (US). Bocoyna: 24.7 mi 

N of San Juanito on road towards Cuauhtemoc, 5 Sep 2008, 

2233 m, P.M. Peterson & J.M. Saarela 22036 (US); cabecera 

de la Cañada de Recogoata, 22 Sep 1997, pine forest–encino 

en cañada, 1900 m, B. Tah V. 32 (MEXU). Bocoyna: Sánchez,

12 Oct 1910, Hitchcock 7684, 7698 (US). Buenaventura: km 

11 San Buenaventura–El Carmen 19 Sep 1955, Hern.-Xol. & 

Mathus N-1944 (US). Carichi: Mojarachic, 5 Sep 1938, I.W. 

Knobloch 5650 (US). Casas Grandes: Between Casas Grandes 

and Sabinal, 4–5 Sep 1899, E.W. Nelson 6356 (US); El Alamito, 

Col. Cuahutémoc, 12 Aug 1996, P. Olivas, R. Reyes, I. Enríquez 

& A. Márquez POS836 (UACJ); Rancho Palanganas, mesa del 

cuervo, 12 Sep 1996, pastizal [pastureland], 2020 m, R. Fierros

129 (MEXU); W of Casas Grandes, 4 Sep 1958, Pine–oak, 1890 

m, Reeder & C. Reeder3229 (MEXU); W of Casas Grandes 9 mi 

NE of Cuesta Blanca, 18 Sep 1960, pine–oak, 7500 ft, Reeder, 

C. Reeder & Soderstrom 3554 (MEXU). Chihuahua: near Chihuahua, 28 May 1885, C.G. Pringle 426 (ENCB, MEXU, US); 

10 Oct 1935, LeSueur Mex-076 (MEXU, US); 8 Oct 1935, 

LeSueur (MEXU); 14 Oct 1910, Hitchcock 7793 (US); Rancho 

Experimental La Campana, 23 Oct 1980, pastizal, Valdés-Reyna

(MEXU, US); 5 mi SW of Chihuahua on rd to Cuauhtémoc, 

6 Oct 1959, Soderstrom 906 (US); A. Melgoza 633 (CIIDIR, 

ENCB); Ca 30 mi N Cd Chihuahua W Mex Hwy 45 W Boca 

del Potrero in Mts (opposite jct to El Sauz on Hwy 45) 7.5 road 

mi W Bella, 16 Jul 1981, 2000 m, D. Ward & R. Worthington 

81-375 (NMC); La Campana; 4 km Poninte carr. [hwy] Panamericana, 31 Aug 1973, pastizal con encinos, 1700 m, ValdésReyna VR-45, VR-46 (RELC). Cuauhtémoc: Cuauhtémoc, 

Hotel rancho La Estancia, 20 Oct 1981, encinar, R. Guzmán, 

4916, (MEXU). Gómez Farías: Laguna de Babicora, 15 km al 

SO [SW] de San Jose de Babicora, 26 Aug 1994, 2250 m, C. Yen 

& E. Estrada 3371 (NMC). Guachochi: 48.6 mi S of Creel on 

road towards Rocheachic, 5 Oct 2000, pine forest, 2630 m, P.M. 

Peterson & J. Cayouette 15379 (US); Cusarare along arroyo just 

NW of cusarare church, 14 Oct 1977, 2200 m, Bye & W.A. 

Weber8121 (MEXU). Guerrero: Miñaca, 13 Oct 1910, Hitchcock 7740 (US); al lado [side] de la carr. a Creel, Tonochic, pine 

forest, 17 Sep 1975, J. Passini & M.F. Robert 6902 (ENCB); 

carr. la Junta–San Juanito 17 km, 22 Nov 1997, 2290 m, B. Tah 

V. 10 (MEXU); Tomochi 2 km alrededor del poblado [around 

the village], 24 Sep 1997, pine forest, 2100 m, B. Tah V. 145

(MEXU). Guadalupe y Calvo: Rio Verde Crossing, 21 mi SW of 

El Vergel on hwy 24, 14 Sep 2006, 2330–2360 m, P.M. Peterson 20078, F. Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, 

US). Hidalgo del Parral: 14 mi E of Parral, 6 Sep 1967, 5300 ft, 

Reeder & C. Reeder 4877 (ENCB); about 5 mi S of Parral, 7 Oct 

1966, 6000 ft, Reeder & C. Reeder 4615 (ENCB). Janos: Chihuahua–Sonora border, Rancho Carretas, 26 Aug 1939, 1460 

m, L. H. Harvey 1610 (US). Juárez: 1 km al S de Carr. Fed. No. 

2 en el km 25, matorral de dunas arenosas [sandy dune scrub] 

(Izotal con mesquite), 29 Aug 1997, 1150 m, A. Aquino AA78a

(UACJ). Madera: Laguna de Babicora, Ejido Año de Hidalgo,15 

Sep 1994, 2300 m, T. Lebgue, G. Quintana & E. Estrada 3782

(NMC); Laguna de Babicora, Camino Las Varas–El Alamillo, 

18 Aug 1994, 2250 m, Quintana, Lebgue & Estrada 3245

(NMC); Llanura de Babicora, 19 Sep 1934, Pennell 19011 (US). 

Matamoros: 12 mi S of Villa matamoros, 8 Oct 1966, Reeder 

& C. Reeder 4826 (ARIZ). Riva Palacio: Majalca, 18–20 Aug 

1935, LeSueur Mex-016, Mex-023 (US); Col. Cumbres de Majalca, 33.8 km W of Mex 45, N of Chihuahua City, 7 Sep 1989, 

pine forest, 2190 m, P.M. Peterson, Annable & Y. Herrera 7962, 

7964 (ENCB, US); 40 km W of Chihuahua, 20 Aug 1939, L. H. 

Harvey 1548 (US); Rancho las Carretas, de Chih.–Namiquipa 

desviar [divert] en Campo 73 a la izquierda terraceria [to left 

dirt road] 12 km, 10 Oct 2000, bosque de encino & pino [oak 

and pine forest], G. Gómez 228, 240 (MEXU). San Francisco del 

Oro: about 10 mi W of Parral on El Vergel, 7 Oct 1966, 6200 ft, 

Reeder & C. Reeder 4611 (ARIZ, ENCB).

250. Muhlenbergia polycaulis Scribn., Bull. Torrey Bot. Club 

38: 327. 1911.

FIGURE 166E–I

Loosely caespitose perennial; from a firm, knotty, short rhizomatous base. Culms 15–40(50) cm tall, erect, decumbent at 

the base, often geniculate, strigulose below the nodes; internodes 

strigulose to glabrous. Sheaths 1–8 cm long, mostly shorter than 

the internodes, glabrous to scaberulous, not becoming spirally 

coiled when old; ligules 0.5–2.5 mm long, erose or lacerate, apex 

obtuse to acute, margins hyaline, firmer than the central portion; 

blades 3–10 mm long, 0.5–2 mm wide, flat or involute, occasionally folded, hirsute or scaberulous adaxially and scaberulous or 

smooth abaxially. Panicles 2–12 cm long, (0.6)1–2 cm wide, narrow, contracted and interrupted below; branches 0.5–4 cm long, 

ascending and appressed occasionally spreading to 30° from 

the rachises, spikelet bearing to the base; pedicels 0.1–1.5 mm 
256 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

long, scabrous. Spikelets 2–3.5 mm long, plump near the middle; glumes (1)1.5–2.6 mm long, more than 1⁄2 as long as the 

lemma, subequal, 1-veined, mucronate, awned or awnless, scabrous along midvein near the apex, apex acute sometimes acuminate, the awn to 1.4 mm long; lemmas 2–3.5 mm long, elliptic, 

widest near the middle, appressed-pubescent along the midvein 

and margins on the proximal 1⁄2 to 2⁄3, the hairs up to 0.5 mm 

long, apex acuminate, scaberulous, awned, the awn 10–20(25) 

mm long, flexuous; paleas 2–3.5 mm long, elliptic, appressedpubescent between the veins on the proximal 1⁄2, apex acuminate; 

anthers 1.5–2 mm long, orange. Caryopsis 1.5–2 mm long, fusiform, brownish. 2n = 20, 40.

Distribution and Habitat. Muhlenbergia 

polycaulis grows on steep rocky slopes, canyon walls, cliffs, table 

rocks, and volcanic rock outcrops in open vegetation associated 

with Quercus spp. and Pinus spp. at 1,200–2,410 m. It occurs 

in southeastern Arizona, southern New Mexico, southwestern 

Texas, and Mexico in Aguascalientes, Baja California, Baja California Sur, Chihuahua, Durango, Guanajuato, Hidalgo, Jalisco, 

México, Nayarit, Querétaro, San Luis Potosí, Sinaloa, Sonora, 

and Zacatecas.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 19.3 km SE of Balleza towards Parral, 1800 m, P.M. 

Peterson & Annable 5947 (US); 34 mi W of Balleza towards 

Guachochi, 2500, P.M. Peterson, M.B. Knowles, C.H. Dietrich, 

S.M. Braxton 13536 (US); 11 mi SE of Balleza on road to Parral, 

1800, P.M. Peterson, M.B. Knowles, C.H. Dietrich, S.M. Braxton 13532 (US); 56.4 km W of Balleza and 38.7 km E of Guachochi, 2280 m, P.M. Peterson, Annable & Valdés-Reyna 10764

(US); 16 mi E of Balleza on road towards Parral, 1950 m, P.M. 

Peterson & J. Cayouette 15386 (US); 34 mi W of Balleza on road 

towards Guachochi, 2500 m, P.M. Peterson, M.B. Knowles, C.H. 

Dietrich & S.M. Braxton 13541 (US); 7.4 km W of Balleza on 

road to Guachochi, 1660 m, P.M. Peterson, Annable & ValdésReyna 10733 (US); 10 mi SW of El Ojito, 12 Sep 2006, 1902 m, 

P.M. Peterson 20032, F. Sánchez Alvarado & E.P. Gómez Ruíz

(CIIDIR, US). Bocoyna: Napahuiche, 2380 m, R.N.F. & J.L.D. 

s.n. (CHAPA). Buenaventura, 6 mi E of Buenaventura, 1768 m, 

Reeder & C. Reeder 3200 (ENCB, US). Carichi: Sánchez, 12 Oct 

1910, Hitchcock 7685 (US). Casas Grandes: 22.5 mi SW of Col. 

Juarez on road to Hernandez Javales, 2 Sep 1985, 2100 m, P.M. 

Peterson & Annable 4034, 4035 (US); 20 km al SE de Nuevo 

Casas Grandes, 2100 m, Hern.-Xol. & A.J. Sharp X–10428

(TAES). 20 km al SE de Nuevo Casas Grandes, 27 Aug 1887, 

2200 m, C.G. Pringle 1414 (MEXU, US), type. Chihuahua: Base 

de la Sierra de La Campana, 80 km al N de Chihuahua, 1700 

m, Rzedowski 32343-A (ENCB); Rocky hills near Chihuahua, 

2190 m, C.G. Pringle 394 (TAES, US). Mts NW of Chihuahua, 

H. LeSueuer 146 (US); 38 km W of Hwy 45 on road towards 

Benito Juárez, 2230 m, P.M. Peterson & Annable 12565 (US); 

9.1 mi W of Hwy 45 on dirt road towards Santa Clara, 1690 m, 

P.M. Peterson & Annable 12585 (US); 14.5 mi W of Hwy 45 on 

road up Los Prietos Canyon, 1910 m, P.M. Peterson & Annable 12601 (US); Sierra Madre Occidental, slopes with Quercus, 

Cupressus, Pinus, Arbutus and Juniperus, 1840–1900 m, P.M. 

Peterson & P. Catalán 17597 (US). Cuauhtémoc: 12 mi W of 

Cuauhtémoc, 2128 m, Reeder & C. Reeder 3185, 4856 (ENCB);

3189 (ENCB, US); 16 mi W of Cuauhtémoc, 2400 m, Reeder & 

C. Reeder 3474 (ENCB, US); 12 mi W of Cuauhtémoc, 2128 m, 

F.W. Gould 8929 (TAES, US). Guachochi: approx. 22.5 mi NE of 

Cieneguita de Barranca on road towards Creel, 2160 m, P.M. Peterson, P. Catalán, C. López, & G. Villegar 17694 (US); Yamuco 

at 1 km E of Hwy towards Basihuare and Creel, N of Rio Urique 

crossing, 1891 m, P.M. Peterson & P. Catalán 17551 (US); along 

Río Corareáchi, slopes with Quercus, Cupressus, Pinus, Arbutus and Juniperus, 1840–1900 m, P.M. Peterson & P. Catalán 

17597 (CIIDIR, US); 20.3 km NE of La Bufa and 3.2 km S of 

Basigochi, 2180 m, P.M. Peterson, Annable & Valdés-Reyna 

10811 (US); Parque Nacional Barranca del Cobre, 13.6 mi NE 

of La Bufa on road towards Samachique, 2240 m, P.M. Peterson, M.B. Knowles, C.H. Dietrich & S.M. Braxton 13568 (US); 

Cusarare, along arroyo just NW of Cusarare church, Bye 8096 

(US); 41.3 km S of Creel on road to Batopilas, 10 Sep 1989, 

2075 m, P.M. Peterson, Annable & Y. Herrera 8031 (US); 29 

km E of Guachochi on Mex 127 towards Balleza, 13 Sep 1989, 

2600 m, P.M. Peterson, Annable & Y. Herrera 8084 (US); Barranca de Basihuare, 1700 m, P.M. Peterson & P. Catalán 17591 

(US). Guadalupe y Calvo: Rio Verde Crossing, 21 mi SW of El 

Vergel on hwy 24, 14 Sep 2006, 2330–2360 m, P.M. Peterson 

20076, F. Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, US). 

Guerrero: 38.6 km SW of La Junta and approximately 70.8 km 

N of Creel at P. Arroyo Ancho crossing, 21 km marker, 24 Sep 

1988, 2200 m, P.M. Peterson & Annable 5842 (US); 46.7 km 

W of La Junta on road to Parque Nacional Cascada de Basaseachic, 30 Sep 1989, 2260 m, P.M. Peterson & R.M. King 8201 

(US); 54.3 km W of La Junta on road to Parque Nacional Cascada de Basaseachic, 30 Sep 1989, 2260 m, P.M. Peterson & 

R.M. King 8218 (US). Hidalgo del Parral: NE edge of Parral, 

2200 m, Correll 22684 (ENCB, US). Ignacio Zaraza: 20.3 km 

NE of Ignacio Zaragoza on Mex 23, 28 Sep 1989, 2400 m, P.M. 

Peterson & R.M. King 8161 (US); 72.5 km S of Ignacio Zaragoza on Mex 23, 28 Sep 1989, 2300 m, P.M. Peterson & R.M. 

King 8174 (US). Namiquipa: Rancho Teseachic, 2000 m, A.A. 

Beetle M-3267 (MEXU). Nuevo Casas Grandes: E de la sierra 

La Escondida, en el Cañón de La Madera, 1840 m, M.A. López 

s.n. (INEGI). Ocampo: 122.5 km W of La Junta and 56.7 km W 

of Tomochic in Parque Nacional Cascada de Basaseachic, 1 Oct 

1989, 2100 m, P.M. Peterson & R.M. King 8236, 8247 (US); 

Along trail just above Cascada de Basaseachic, 1880 m, P.M. 

Peterson & Annable 12532 (US). Riva Palacio: Col. Cumbres 

de Majalca, approx. 32.2 km W of Hwy 45 N of Chihuahua, 22 

Sep 1988, P.M. Peterson & Annable 5801 (ENCB, US); 21 mi W 

of Mexico 45, N of Chihuahua city, Col. Cumbres de Majalca, 

2120 m, Y. Herrera, P.M. Peterson & Annable 948 (CIIDIR, US); 

Nuevo Majalca. Approx. 14.5 km W of Hwy 45, N of Chihuahua, 22 Sep 1988, 1700 m, P.M. Peterson & Annable 5770 (US); 

11.3 km W of Nuevo Majalca, 25.7 km W of Hwy 45, N of 

Chihuahua, 22 Sep 1988, 1800 m, P.M. Peterson & Annable 

5781 (US); 17.7 km W of Nuevo Majalca on road to Cumbres de 

Majalea, Parque Nacional., 22 Sep 1988, 2000 m, P.M. Peterson 
NUMBER 107 • 257

& Annable 5785 (US); Col. Cumbres de Majalca, 33.8 km W of 

Mex 45, N of Chihuahua City, 2190 m, P.M. Peterson & Annable 7938, 7942A (US). 

251. Muhlenbergia porteri Scribn. ex Beal, Grass. N. Amer. 2: 

259. 1896.

FIGURE 173

Loosely caespitose perennial; with a wiry and knotty base, 

rhizomes absent, distinctly bushy in appearance. Culms 25–100 

cm tall, 0.5–1.5 mm thick near base, erect, geniculate and widely 

spreading near base, freely branched, branching at the lower and 

middle nodes; scaberulous below the nodes; internodes mostly 

scaberulous. Sheaths 0.7–4 cm long, shorter than the internodes, 

glabrous; ligules 1–2.5(4) mm long, toothed or lacerate, apex 

truncate, margins hyaline, decurrent, sometimes extended to 

form short auricles; blades 2–8 cm long, 0.5–2 mm wide, flat 

or folded, scaberulous adaxially and smooth to scaberulous 

abaxially. Panicles 4–14 cm long, 6–15 cm wide, open, loosely 

flowered, usually purple; branches 1–7.5 cm long, widely divergent and stiffly spreading 30°–90° from the rachises, not floriferous basally; pedicels 2–13(20) mm long, scabrous. Spikelets 

3–4.5 mm long, often purple; glumes 2–3 mm long, subequal, 

1-veined, occasionally mucronate, scabrous along the vein, 

apex acuminate, occasionally mucronate, the mucro to 0.4 mm 

long; lemmas 3–4.5 mm long, lanceolate, purplish, appressedpubescent on the margins and midvein on the proximal 1⁄2 to 3⁄4, 

apex acuminate, awned, the awn 5–13 mm long, straight; paleas 3–4.5 mm long, lanceolate, glabrous or appressed-pubescent 

between the veins on the proximal 4⁄5, apex acuminate; anthers 

1.5–2.3 mm long, purple to yellow. Caryopsis 2–2.4 mm long, 

ellipsoid, compressed, yellowish-brown. 2n = 20, 23, 24, 40.

Distribution and Habitat. Muhlenbergia 

porteri grows on rocky slopes among dry streams, desert flats, 

grasslands, and scrublands, frequently in the protection of 

shrubs associated with Prosopis spp. and Larrea tridentata at 

600–1,700 m. It occurs in southeastern California, southern Nevada, southern Utah, Arizona, southern New Mexico, and western Texas to Mexico in Baja California, Chihuahua, Durango, 

San Luis Potosí, Sonora, and Zacatecas.

Specimens Examined. MEXICO. Chihuahua. Allende: Rancho La Reforma, 1600 m, J.S. Sierra s.n. (CIIDIR); 

km 38 carr. [hwy] Chihuahua–Ojinaga, 1210 m, A. Baray 44, 

59 (MEXU). Aquiles Serdán: Km 2 camino [road] a San Diego 

de Alcalá, ,1260 m, A. González 103 (MEXU). Ascensión: 8 km 

al W de Guzmán, 1230 m, V.M. López V12-2 (INEGI); 7 km al 

E de Los Chontes, 1250 m, S. Aguirre 29 (INEGI). Buenaventura: 15 mi W of Flores Magón, 1829 m, Reeder, C. Reeder & 

Soderstrom 3497 (ENCB, US). Camargo: 6 mi SE of Camargo, 

1400 m, Reeder & C. Reeder 4605 (US). Casas Grandes: 17 mi 

S of Nuevo Casas Grandes on Mex 2, 1585 m, P.M. Peterson & 

R.M. King 8144 (US); Between Casas Grandes and Sabinal, 31 

Aug 1899, E.W. Nelson 6349 (US). Chihuahua: Hills near Chihuahua, 12 Sep 1885, 1800 m, C.G. Pringle 478 (US); Base de la 

Sierra de La Campana, 80 km al N de Chihuahua, 1700 m, M.A. 

FIGURE 173. Muhlenbergia porteri. A. Habit. B. Glumes. C. Floret. 

Drawn by Linda Ann Vorobik and Annaliese Miller; copyright Utah 

State University.
258 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

López s.n. (INEGI); F. Cárdenas s.n. (US). Galeana: 1.5 km al E 

de Horcasitas, 1530 m, C. Yen & E. Estrada 8993 (CIIDIR); 4 mi 

NW of Galeana, 1524 m, Reeder & C. Reeder 3202 (ENCB). 

Hidalgo del Parral: 14.5 km al NE de Parral, 2.5 km al W de San 

Gregorio, 1700 m, E. Aldrete s.n. (INEGI); Parral–Chihuahua 

road, 10 km al N of Rio San Pedro, 1375 m, L. H. Harvey 1430 

(US). Jiménez: In arroyo 50 km N of Jiménez, 1 Aug 1939, 1280 

m, L. H. Harvey 1369 (US); W slopes Sierra Sta. Eulalia, 1400 

m, L. H. Harvey 1527 (US). La Cruz: Km 18 carr. Camargo–

Chihuahua, 1220 m, A. Rodríguez 108 (MEXU). Saucillo: Mancomún El Pajarito Domingueño, 18 km de Las Varas, 1280 m, 

R. Fierros 103 (MEXU).

252. Muhlenbergia pubescens (Kunth) Hitchc., N. Amer. Fl. 

17(6): 460. 1935. 

Densely caspitose perennial. Culms 1–1.5 m tall, erect, 

sparsely to densely pilose, especially near base. Sheaths basal, 

compressed-keeled and flattened, villous, lacking auricles; ligules 2–4 mm long, membranous, lacerate; blades 25–50 cm 

long, 2.5–6 mm wide, flat, villous. Panicles 20–40(50) cm long, 

2–7 cm wide, erect, columnar, densely flowered, gray to graypurplish. Spikelets 2.5–3 mm long; glumes 2.5–3 mm long, longer than florets, sparsely to densely villous, widely acute in the 

apex, subequal or lower glume 1–2 mm shorter than the upper 

glume; lemmas 2.2–2.6 mm long, villous, awned, the awn 5–10 

mm long; anthers 0.8–1.2 mm long, yellow to purplish. Caryopsis 1.2–1.5 mm long, ellipsoid to ovoid, light brown. 

Distribution and Habitat. Muhlenbergia pubescens occurs in grasslands, pine–oak–juniper forests at elevations of 1,700–2,000 m. In Mexico it occurs in Aguascalientes, 

Chihuahua, Distrito Federal, Durango, Guanajuato, Hidalgo, 

Jalisco, México, Michoacán, Nayarit, Oaxaca, Puebla, San Luis 

Potosí, Tlaxcala, and Zacatecas.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 34 mi W of Balleza on road towards Guachochi, 2500 

m, P.M. Peterson, M.B. Knowles, C.H. Dietrich & S.M. Braxton 

13537 (US); 16.1 km W of Balleza and 77.9 km E of Guachochi, 

1990 m, P.M. Peterson, Annable & Valdés-Reyna 10748 (US); 

56.4 km W of Balleza and 38.7 km E of Guachochi, 2480 m, 

P.M. Peterson, Annable & Valdés-Reyna 10772 (US). Chihuahua: Rocky hills near Chihuahua, 1800 m, C.G. Pringle 391 

(US); Base de la Sierra de La Campana, 80 km al N de Chihuahua, 1700 m, Rzedowski 32311 (CHAPA). Guachochi: 12.4 

km S of Cusarare on road to Guachochi, 25 Sep 1988, 2400 m, 

P.M. Peterson & Annable 5895 (US); 9 mi S of Guachochi at 

edge of Barranca Río Green, 2470 m, P.M. Peterson & J. Cayouette 15375 (US); White-tuff volcanic outcrops surrounding 

Napuchis, 2140 m, P.M. Peterson & P. Catalán 17677 (CIIDIR, 

US); 43 km S of Creel on road to Batopilas, 11 Sep 1989, P.M. 

Peterson, Annable & Y. Herrera 8036 (US). Guerrero: overlook 

of Casada de Basaseachic, approx. 37 mi W of Tomochic, 22 Sep 

1986, 2200 m, P.M. Peterson & Annable 4549 (US); 46.7 km W 

of La Junta on road to Parque Nacional Cascada de Basaseachic, 

2260 m, P.M. Peterson & R.M. King 8200 (US); 54.3 km W of 

La Junta on road to Parque Nacional Cascada de Basaseachic, 

30 Sep 1989, 2260 m, P.M. Peterson & R.M. King 8205 (US). 

Hidalgo del Parral: 5 km al E de Parral, 1800 m, S. Ojeda s.n.

(INEGI); 5 km al S de Parral, 2000 m, E. Aldrete s.n. (INEGI); 

5 mi S of Parral, 1900 m, Reeder & C. Reeder 4616 (US). Matamoros: 19.3 km S of Villa Matamoros on Hwy 45 to Durango, 

1800 m, P.M. Peterson & Annable 5982 (US); 19.3 km S of Villa 

Matamoros on Mex 45 to Durango, 3 Oct 1989, 1910 m, P.M. 

Peterson & R.M. King 8258 (US). Moris: Approx. 17.6 mi E 

of Maycoba on Hwy 16 towards Yepachic and 2 mi E of Sonora–Chihuahua boundary, 1540 m, P.M. Peterson & Annable 

12516 (US). Riva Palacio: 38 km W of Hwy 45 on road towards 

Benito Juárez, 2230 m, P.M. Peterson & Annable 12563 (US); 

Col. Cumbres de Majalca, approx. 32.2 km W of Hwy 45 N of 

Chihuahua, 2100 m, P.M. Peterson & Annable 5802 (US); Col. 

Cumbres de Majalca, 33.8 km W of Mex 45, N of Chihuahua 

City, 2190 m, P.M. Peterson, Annable & Y. Herrera 7945 (US).

253. Muhlenbergia pubigluma Swallen, Proc. Biol. Soc. Wash. 

56: 78. 1943.

Densely caespitose perennial. Culms (50)65–125 cm tall, 

stout, erect, puberulent below the nodes, 2 or 3 nodes per culm; 

internodes glabrous. Sheaths 10–32 cm long, usually longer than 

the internodes, scaberulous, basal sheaths compressed-keeled, 

glabrous, dark brown with the age; ligules 5–13 mm long, membranous above and firm and brown below, decurrent; blades 

10–35 cm long, 1.5–3 mm wide, folded to involute, attenuate, 

firm, scabrous with whitish pubescence, the short hairs about 

0.1 mm long, these slightly longer on the upper surface and 

near the collar. Panicles (15)20–34 cm long, 1–3 cm wide, narrow, loosely contracted; primary branches 1–6 cm long, mostly 

ascending and appressed, rarely spreading to 20° from the rachises, grayish-green; pedicels 0.3–2.5 mm long, usually shorter 

than the spikelets, scabrous. Spikelets 2.5–3.5 mm long; glumes 

2–3.3 mm long, usually shorter than the floret, 1-veined, lightly 

pubescent especially near the base, apex obtuse to acute, awnless; lemmas 2.8–3.5 mm long, lanceolate, grayish-green to purplish, the lateral veins indistinct, appressed villous on the lower 

1⁄2, basal margins densely villous, the hairs less than 0.5 mm long, 

apex acute, usually short-awned, the awns 0.5–3.5 mm long; paleas 2.7–3 mm long, pubescent between the veins on the proximal 1⁄3, apex obtuse; anthers 1.4–1.6 mm long, yellowish. 

Distribution and Habitat. Muhlenbergia pubigluma is endemic to Mexico and has been reported in Chihuahua, Coahuila, Nuevo León, and Tamaulipas (Valdés Reyna, 

2015). Muhlenbergia pubigluma primarily occurs on calcareous 

slopes and flats within oak–pinyon–juniper woodlands at 1,800–

3,400 m.

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000) and Herrera Arrieta and 

Cortés Ortiz (2010).

254. Muhlenbergia purpusii Mez, Repert. Spec. Nov. Regni Veg. 

17(13–18): 214. 1921.

Caespitose perennial. Culms 25–60 cm tall, erect, pubescent below the nodes, the nodes all basal, terete, usually 1 node 
NUMBER 107 • 259

per culm; internodes scabrous and pubescent. Sheaths 1–20 cm 

long, shorter than the internodes, pubescent to hirsute, sheaths 

rounded, brownish with age below; ligules 4–10 mm long, membranous above and firm and brownish below, decurrent, margins puberulent and wider than 1⁄2 the adjacent blade width, 

apex acuminate; blades 5–13 cm long, 0.7–1.8 mm wide, flat 

or folded, falcate, puberulent to hirsute above and below, the 

hairs about 0.1 mm long, margins scabrous. Panicles 7–25(30) 

cm long, 1–10 cm wide, loosely contracted to open, ovate to 

pyramidal, purplish; primary branches 2–8.5 cm long, capillary, 

ascending, appressed or spreading to 50° from the rachises; pedicels (2)4–14 mm long, mostly longer than the spikelets, flexuous, glabrous and smooth. Spikelets 2.4–3.2 mm long, purplish; 

glumes 0.7–1.1 mm long, less than 1⁄2 as long as the lemma, obscurely 1-veined, puberulent on upper 2⁄3, apex obtuse to acute 

often erose; lemmas 2.3–3.1 mm long, lanceolate, purplish, short 

pilose, the hairs 0.1–0.2 mm long, callus short pilose, apex acute, 

entire to minutely bifid, awned, the awn 10–20 mm long, flexuous; paleas 2.4–3.2 mm long, slightly longer than the lemma, 

short pilose between the veins, apex acute; anthers 1.6–2 mm 

long, purplish. Caryopsis 1–1.2 mm long, fusiform to ovoid, 

brownish. 2n = 20.

Distribution and Habitat. Muhlenbergia purpusii occurs on calcareous-derived soils primarily on gypsum flats, 

usually on the sides of sink holes, rock outcrops, roadsides, and 

slopes with pinyon–juniper woodlands at 1,240–1,900 m. This 

species is reported in Chihuahua, Coahuila, and San Luis Potosí.

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000).

255. Muhlenbergia quadridentata (Kunth) Trin., Gram. Unifl. 

Sesquifl. 194, t. 5b, f. 14. 1824.

Densely tufted perennial. Culms 20–70 cm tall, erect, mostly 

glabrous below the basal nodes, flattened, 1 node per culm; internodes mostly scabrous. Sheaths 10–30 cm long, shorter than the 

internodes, scabrous to smooth; basal sheaths densely pubescent 

to glabrous abaxially, smooth and shiny adaxially, becoming flat 

and usually not spirally twisted with the age; ligules 2–8 mm 

long, membranous to hyaline above, firm and often brownish 

with evident veins near the margins below, decurrent, apex acuminate often lacerate; blades 5–15 cm long, 0.6–2 mm wide, flat 

or usually tightly involute, scaberulous below, short-spiculate 

and often villous above, the hairs 0.2–0.5 mm long, usually appressed, the spicules shiny to whitish. Panicles 5–20 cm long, 

0.5–2 cm wide, narrow, loosely contracted, interrupted below, 

mostly plumbeous; primary branches 0.5–5(6) cm long, appressed and ascending to spreading to 30° from the rachises; 

central axis flattened with 2 ribs, scabrous; pedicels 0.5–2 mm 

long, shorter than the spikelets, scabrous. Spikelets 3.4–4.7 mm 

long, mostly plumbeous; glumes 1.8–4 mm long, shorter to almost as long as the floret, unequal, mostly greenish-plumbeous, 

scabrous, usually with few short hairs below; lower glumes 

1.5–2.5(3) mm long, 1-veined, apex obtuse to acute, often with 

2 small teeth; upper glumes (3)3.2–4 mm long, 3-veined, apex 

truncate, obtuse or acute, often with 3 or 4 small teeth, the teeth 

less than 1⁄6 the length of the glumes; lemmas 3–4.7 mm long, lanceolate, terete, usually awned, greenish-plumbeous to mottledplumbeous, sparsely pilose near base and margins on lower 1⁄2, 

apex acuminate, scabrous, unawned, mucronate or with an awn 

1–20 mm long, flexuous, scabrous, greenish-plumbeous; paleas 

2.8–4.3 mm long, shorter than the lemma, pilose on the proximal 1⁄2; anthers 1–2.5 mm long, purple. Caryopsis 1.8–2 mm 

long, fusiform, brownish. 2n = 20.

Distribution and Habitat. Muhlenbergia quadridentata occurs on open to forested slopes derived from calcareous and volcanic rocks and is associated with Pinus spp., and 

Quercus spp. at (1,900)2,500–4,100 m; it occurs throughout 

Mexico in the higher mountains and also found in Guatemala.

Specimens Examined. MEXICO. Chihuahua. 

Guadalupe y Calvo: near Cumbre Mohinora, 13 Sep 2006, 3300 

m, P.M. Peterson 20038, F. Sánchez Alvarado & E.P. Gómez 

Ruíz (CIIDIR, US). 

256. Muhlenbergia ramulosa (Kunth) Swallen, Contr. U.S. Natl. 

Herb. 29(4): 205. 1947.

FIGURE 174

Annual; delicate, slender, often purplish. Culms (3)5–25 cm 

tall, erect or geniculate, branched at the base, glabrous. Sheaths 

glabrous or scabrous; ligules 0.2–0.5 mm long, hyaline, truncate, 

ciliate, without lateral lobes (auricles); blades 5–30 cm long, 

0.8–1.2 mm wide, flat or involute, glabrous to puberulent. Panicles (1)2–9 cm long, 0.6–2.5 cm wide, ovoid, sparsely flowered; 

branches (0.5)1–3.2 cm long, ascending to spreading (open) or 

closely appressed; pedicels 1–3 mm long, glabrous or scabrous, 

rigid. Spikelets 0.8–1.3 mm long, erect; glumes 0.4–0.7 mm long, 

equal, 1-veined, glabrous, whitish, obtuse or subacute, awnless; 

lemmas 0.8–1.3 mm long, oval, with green spots, inflated at 

maturity, glabrous or appressed-pubescent on margins and midvein, apex acute, awnless; palea 0.7–1.3 mm long, oval; anthers 

0.2–0.3 mm long, purplish; Caryopsis 0.5–1 mm long, ellipsoid, 

brownish to purplish. n = 10. 

Distribution and Habitat. Muhlenbergia ramulosa occurs in open pine-oak and tropical forests at elevations 

of 1,620–2,680 m. It ranges from the United States to throughout Mexico, Central America, and Argentina. 

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 12.1 mi NE of El Vergel on Hwy 24, SW of Parral, 2000 

m, P.M. Peterson & Annable 4064 (ENCB, US); 18.7 mi N of 

San Juanito on road to Creel, 2335 m, Y. Herrera, P.M. Peterson 

& Annable 958 (CIIDIR, US); 16 mi SW of El Vergel on Hwy 24, 

Río Green, 2200 m, P.M. Peterson & Annable 4074 (US); Río 

Green, on road from El Vergel to Cienega Prieta, Correll 22902 

(US); 45 mi W of Balleza on road towards Guachochi, 2560 m, 

P.M. Peterson, M.B. Knowles, C.H. Dietrich & S.M. Braxton 

13550 (US); 43.5 km W of Balleza and 51.6 km E of Guachochi, 

2320 m, P.M. Peterson, Annable & Valdés-Reyna 10763 (US). 

Batopilas: N of Quirare, 2350 m, Bye 6960 (TAES). Bocoyna: 

Cabecera de la cañada de Recogoata, 2400 m, B. Tah V. 28-A, 

45 (MEXU); 18.7 mi S of San Juanito on road to Creel, 2200 
260 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

m, P.M. Peterson, Annable & Y. Herrera 8000 (US). Carichi: 

Sánchez, 12 Oct 1910, Hitchcock 1315 (TAES); Sánchez, Oct 

1910, Hitchcock 7661 (US). Casas Grandes: 3 mi W of Cuesta 

Blanca, W of Casas Grandes, 2073 m, Reeder & C. Reeder 3219

(US). 3 mi S of Cuesta Blanca, W of Casas Grandes, Reeder 

& C. Reeder 3538 (US). Chihuahua: 38 km W of Hwy 45 on 

road towards Benito Juárez, 2230 m, P.M. Peterson & Annable 

12562 (US). Guadalupe y Calvo: near Cumbre Mohinora, 13 

Sep 2006, 3300 m, P.M. Peterson 20040, F. Sánchez Alvarado & 

E.P. Gómez Ruíz (CIIDIR, US); west slope of Sierra Mohinora, 

13 Sep 2006, 3008 m, P.M. Peterson 20053, F. Sánchez Alvarado 

& E.P. Gómez Ruíz (CIIDIR; US). Guachochi: Km 85 carr. [hwy] 

Balleza–Guachochi, 2300 m, M.E. Siqueiros 1606 (MEXU); Cusarare, S of Creel, 2200 m, Bye 7063 (TAES); 6.3 mi S of Cusarare on rd to Guachochi, 2420 m, P.M. Peterson & Annable 

5887 (US); 38.4 mi W of Guachochi on Mexico 127 towards 

Creel, 2440 m, P.M. Peterson, Annable & Y. Herrera 8077 (US); 

18 mi E of Guachochi on Mex 127 towards Balleza, 2680 m, 

P.M. Peterson, Annable & Y. Herrera 8081 (US); 19.3 km E of 

Guachochi, 26 Sep 1988, 2300 m, P.M. Peterson & Annable 

5928 (US); Norogachic, 2320 m, E. Palmer 404b (US); 1885, 

E. Palmer 4b (US), holotype; 24.6 km W of Guachochi and 0.6 

km S of Rocheachi, 2340 m, P.M. Peterson, Annable & ValdésReyna 10790 (US). Guerrero: 4.5 mi W of Tomochic on Hwy 16, 

2200 m, P.M. Peterson & Annable 4543 (TAES, US); 22 mi SW 

of La Junta on rd to Creel, 2200 m, P.M. Peterson & Annable 

5836 (US); 24 mi SW of La Junta on road to Creel, 2000 m, P.M. 

Peterson & Annable 5854 (US); 33.7 mi W of La Junta on road 

to Parque Nacional Cascada Basaseachic, 2200 m, P.M. Peterson & R.M. King 8213 (US). Madera: 12 mi NW of Madera, 

2285 m, Reeder & C. Reeder 2649 (SLPM, US); 11 mi N of 

Long, 2500 m, Reeder & C. Reeder 2686 (US). Namiquipa: 45 

mi S of Ignacio Zaragoza, 2200 m, P.M. Peterson & R.M. King 

8169 (US). Ocampo: Parque Nacional Cascada de Basaseachic, 

1620 m, R. Fierros 1694 (MEXU); Parque Nacional Cascada 

de Basaseachic, 1700 m, M.E. Siqueiros 201 (MEXU); Parque 

Nacional Cascada de Basaseachic, 2100 m, Tenorio & R. Torres 

3777c (MEXU); Approx. 10 mi E of Basaseachic on Hwy towards La Junta, 2110 m, P.M. Peterson & Annable 12542 (US). 

Riva Palacio: Cumbres de Majalca, 21.5 mi W of Hwy 45, 2000 

m, P.M. Peterson & Annable 4522 (TAES, US); Cumbres de Majalca, 21.5 mi W of Hwy 45, 2200 m, P.M. Peterson & Annable 

5793 (US).

257. Muhlenbergia repens (J. Presl) Hitchc., Fl. Calif. 1: 111. 1912

FIGURE 175A–D

Perennial; with shining, creeping, scaly rhizomes. Culms 

5–42 cm tall, decumbent near base, forming dense mats, freely 

branching above, glabrous below the nodes; internodes mostly 

glabrous below, lightly nodulose roughened just below the inflorescence. Sheaths 0.6–3.4 cm long, shorter or longer than the 

internodes, glabrous, margins hyaline; ligules 0.1–1(1.8) mm 

long, membranous, decurrent, apex truncate, occasionally 

FIGURE 174. Muhlenbergia ramulosa. A. Habit. B. Spikelet. C. Floret. Drawn by Linda Ann Vorobik and Annaliese Miller; copyright 

Utah State University.
NUMBER 107 • 261

lacerate; blades 0.4–6 cm long, 0.5–1.4 mm wide, involute, 

somewhat arcuate-spreading, mostly glabrous below and scaberulous above. Panicles 1–9 cm long, 0.1–0.6 cm wide, narrow, 

contracted, loosely flowered, usually included at the base in the 

uppermost leaf sheath; primary branches 0.2–3 cm long, usually closely appressed, rarely diverging to 40° from the rachises; 

pedicels 0.2–3.6 mm long, minutely setose. Spikelets 2.6–4.2 mm 

long, occasionally 2-flowered; glumes 1.1–3.6 mm long, 1⁄2 to as 

long as the lemma, subequal, usually 1-veined, occasionally 2- to 

3-veined, light green, apex acute; lemmas 2.6–3.2(4.2)mm long, 

lanceolate, unawned or mucronate, dark greenish or mottled, 

glabrous or with minute appressed pubescence along the margin 

FIGURE 175. Muhlenbergia repens. A. Habit. B. Ligule. C. Glumes. D. Floret. Muhlenbergia utilis. E. Habit. F. Rhizome. G. Ligule. H. Glumes. I. Floret. Drawn by Cathy 

Pasquale for Smithsonian Institution, Department of Botany.
262 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

and base, the hairs less than 0.1 mm long, apex acute to attenuate and tapering, scaberulous, the mucro 0.1–0.8 mm long; paleas 2.1–3.3 mm long, lanceolate, glabrous to scaberulous, apex 

acute; anthers 0.7–1.4 mm long, yellow to purplish. Caryopsis 

1.1–1.5 mm long, ellipsoid to ovoid, brownish. 2n = 60, 70–72.

Distribution and Habitat. Muhlenbergia 

repens occurs in sandy meadows, canyon bottoms, calcareous 

rocky flats, gypsum flats, rolling slopes, and roadsides associated with oak–pinyon–juniper woodlands at 100–3,120 m; it occurs in southern Utah, southern Colorado, eastern Arizona, New 

Mexico, and west Texas and throughout México.

Specimens Examined. MEXICO. Buenaventura: 

15 mi W of Flores Magón, 1829 m, R. Guzmán 4933 (MEXU). 

Camargo: Col. Encinillas de la Laguna, 1500 m, Valdés-Reyna 

VR-407 (ENCB). Carichi: Sánchez, 12 Oct 1910, Hitchcock 

7710 (US). Casas Grandes: 18 mi W of Col. Juárez, 2073 m, 

Reeder & C. Reeder 1219 (ENCB). Cuauhtémoc: 16 km W of 

Cuauhtémoc on Hwy 16, 2100 m, P.M. Peterson & Annable 

4056 (US); 10 mi W of Cuauhtemoc on Hwy 16, P.M. Peterson 

& Annable 4057 (US); 5 mi N of LAug at the edge of small 

lake, 2375 m, Reeder & C. Reeder 2683 (MEXU); 5.5 mi W 

of Cuauhtémoc, 23 Sep 1988, 2100 m, P.M. Peterson & Annable 5822 (US); 11 mi W of Cuauhtemoc, Reeder & C. Reeder 

4598 (US). About 12 mi W of Cuauhtémoc, 2285 m, Reeder & 

C. Reeder 2619 (US). Chihuahua: La Campana, 10 km W carr. 

[hwy] Panama, 1700 m, Valdés-Reyna VR-243 (TAES); Chihuahua, 1700 m, LeSueur 050 (US). Guachochi: 3.7 km N of San 

Juanito on road to Creel, near km 53 marker, 24 Sep 1988, 2200 

m, P.M. Peterson & Annable 5863 (US). Guerrero: Basuchil, 

NW de La Junta, 2000 m, I.W. Knbloch 660 (TAES); 17.3 mi W 

of La Junta on road to Tomochic, 4 Sep 1985, P.M. Peterson & 

Annable 4052A (US). Janos: San Pedro River, Mexican boundary line, E.A. Mearns 1128 (US). Madera: 2 mi N of Madera, 

2165 m, Reeder & C. Reeder 2644 (SLPM). Riva Palacio: 11.3 

km W of Nuevo Majalca, 25.7 km W on Hwy 45, 1800 m, P.M. 

Peterson & Annable 5795 (US). 

258. Muhlenbergia richardsonis (Trin.) Rydb., Bull. Torrey Bot. 

Club 32(11): 600. 1905.

Perennial; rhizomatous, not caespitose, often mat-forming. 

Culms 5–30 cm tall, decumbent, geniculate, or erect; internodes 

usually nodulose (occasionally smooth) for most of their length, 

puberulent or nodulose below the nodes. Sheaths shorter or 

longer than the internodes, glabrous; ligules 0.8–3 mm long, 

membranous, acute to truncate, erose; blades 0.4–6.5 cm long, 

0.5–4.2 mm wide, flat or involute, straight or arcuate-spreading, 

glabrous abaxially, hirtellous adaxially. Panicles 1–15 cm long, 

0.1–1.7 cm wide, exserted, narrow or spikelike, rachises usually concealed by the branches; primary branches 0.4–5 cm 

long, usually closely appressed at maturity, rarely diverging 

up to 20° from the rachises; pedicels 0.2–2 mm long, setulose. 

Spikelets 1.7–3.1 mm long, occasionally with 2 florets. Glumes 

subequal, 0.6–2 mm long, 1⁄3–1⁄2 as long as the lemmas, green, 

1(2)-veined, acute, sometimes mucronate, mucros less than 

0.2 mm long; lemmas 1.7–2.6(3.1) mm long, lanceolate, dark 

greenish, plumbeous, or mottled, glabrous, apex scaberulous, 

acute to acuminate, sometimes mucronate, mucros to 0.5 mm 

long; paleas 1.2–2.4(2.9) mm long, lanceolate, acute; anthers 

0.9–1.6 mm long, yellow to purplish. Caryopses 0.9–1.6 mm 

long, narrowly ellipsoid, brown. 2n = 40.

Distribution and Habitat. Muhlenbergia richardsonis grows in open sites in alkaline meadows, prairies, sandy 

arroyo bottoms, talus slopes, rocky flats, and the shores of rivers. 

It occurs from the Yukon Territory to Quebec south to northern 

Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Cuauhtémoc: 10 mi W of Cuauhtemoc on Hwy 16, 5 Sep 1985, 

2100 m, P.M. Peterson & Annable 4056, 4057 (US).

259. Muhlenbergia rigens (Benth.) Hitchc., J. Wash. Acad. Sci. 

23: 453. 1933.

FIGURE 176

Densely caespitose perennial. Culms (35)50–150 cm tall, 

erect, rounded and up to 5 mm thick near base, mostly glabrous 

below the nodes; internodes glabrous. Sheaths 3–45 cm long, 

longer than the internodes, glabrous to scaberulous, rounded 

to keeled and chartaceous near base; ligules 0.5–2(3) mm long, 

somewhat firm, decurrent, apex truncate, usually minutely ciliolate; blades 10–50 cm long, 1.5–6 mm wide, flat or involute, 

stiff, glabrous abaxially and scabrous between the prominent 

ridges adaxially. Panicles 15–60 cm long, 0.5–1.2 cm wide, narrow, elongate, contracted and spikelike, densely flowered, often 

interrupted below, grayish-green; primary branches 0.2–4 cm 

long, ascending and tightly appressed; pedicels 0.2–3 mm long, 

mostly shorter than the spikelets, hirsute. Spikelets 2.4–4 mm 

long, erect, grayish-green; glumes 1.8–3.2 mm long, subequal, 

shorter than the lemma, scabrous to scaberulous, 1-veined, apex 

acute or obtuse, occasionally acuminate or notched, mucronate 

or short-awned, the awn to 1.7 mm long; lemmas 2.4–4 mm 

long, lanceolate, unawned, rarely mucronate, glabrous below 

and scabrous above, short appressed pubescence on the callus, midvein, and margins on the proximal 1⁄6, the hairs up to 

0.4 mm long, apex acute or obtuse, the mucro to 0.9 mm long; 

paleas 2.3–3.8 mm long, lanceolate, glabrous below and scabrous above, apex mostly acute; anthers 1.3–1.8 mm long, yellow to purple. Caryopsis 1.8–2.2 mm long, fusiform, brownish. 

2n = 40.

Distribution and Habitat. Muhlenbergia rigens occurs in sandy washes, gravelly canyon bottoms, rocky 

drainages, and moist, sandy slopes often along small streams 

associated with pinyon–juniper woodlands at 90–2,500 m. It 

ranges from California, Arizona, New Mexico, and Texas to 

northcentral Mexico in Aguascalientes, Baja California, Baja 

California Sur, Chihuahua, Durango, Jalisco, Michoacán, 

Puebla, Sonora, and Zacatecas.
NUMBER 107 • 263

Specimens Examined. MEXICO. Chihuahua. 

Carichi: Sánchez, 12 Oct 1910, Hitchcock 7686 (US). Casas 

Grandes: W of Casas Grandes, 5 mi S of Hernández, 2200 m, 

Reeder & C. Reeder 3511 (ENCB, US); Rancho Palanganas, 

2200 m, A. González 110 (MEXU); Valle de las Cuevas S Ejido 

Ignacio Zaragoza, 1760 m, Tenorio & Romero 1707 (CHAPA). 

W of Casas Grandes, 5 mi S of Hernández, 2200 m, Reeder & 

C. Reeder 3508 (CHAPA, US). Cuauhtémoc: 16 mi W of Cuauhtémoc, 2400 m, Reeder & C. Reeder 3479 (CHAPA, US); 18 

mi W of Cuauhtémoc, 2400 m, Reeder & C. Reeder 4589 (US); 

25 mi W of Cuauhtémoc, Reeder & C. Reeder 4231 (US); 5.6 

mi N of Cuahutémoc on Mex 23, 14 Sep 1989, 2120 m, P.M. 

Peterson & R.M. King 8110 (US); 18.5 km W of Cuauhtémoc on 

Hwy 16, 23 Sep 1988, 2000 m, P.M. Peterson & Annable 5818 

(US). Chihuahua: 38 km W of Hwy 45 on road towards Benito 

Juárez, 2230 m, P.M. Peterson & Annable 12569 (US); Base de la 

Sierra de La Campana, 80 km al N de Chihuahua, 1700 m, M.E. 

Siqueiros 339 (MEXU); Streams near Chihuahua, 1950 m, C.G. 

Pringle 417 (US), Isotype; Along aqueduct, 1700 m, Hitchcock 

7770, 7773 (US); W of Chihuahua, 1800 m, LeSueur 073 (US); 

Canyon de St. Diego, Chih. 1900 m, C.V. Hartman 803 (US); 12 

mi N of Chihuahua on road to Cd. Juarez, 1700 m, Reeder & 

C. Reeder3486 (US); Soderstrom 927, 928, 929 (US); 38 km W of 

Hwy 45 on road towards Benito Juárez, 2230 m, P.M. Peterson 

& Annable 12567 (US); 17.5 mi W of Hwy 45 on road up Los 

Prietos Canyon, 2120 m, P.M. Peterson & Annable 12599 (US). 

Gómez Farías: Near Gómez Farías, 1900 m, A.A. Beetle M-7944

(MEXU). Guachochi: Just N of Guachochi (1 km), 26 Sep 1988, 

2500 m, P.M. Peterson & Annable 5915 (US); Yamuco at 1 km 

E of Hwy towards Basihuare and Creel, N of Rio Urique crossing, 1891 m, P.M. Peterson & P. Catalán 17546 (US). Guerrero: 

About 5 mi SE Guerrero, 2130 m, Reeder & C. Reeder 2623

(ENCB); Miñaca, 13 Oct 1910, Hitchcock 7748, 7749 (US). Hidalgo del Parral: 1 mi S of Parral on road to Mexico city, Soderstrom 830 (US); 21 km W of Parral and approx. 8 km N on dirt 

road to Torrenocillo, 1900 m, P.M. Peterson & Annable 5970 

(US). Madera: Sierra Madre Mts, Marsh Lake, Sep 1903, M.E. 

Jones s.n. (US) type fragm.; near Col. Garcia in the Sierra Madre, 

21 Sep 1899, C.H.T. Townsend & C.M. Barber 341 (US), holotype; Arroyo de La Quinta, ejido El Long, 2100 m, O. Bravo 

1868-a (CIIDIR). Matamoros: 84.6 km SE of Villa Matamoros 

and 1.6 km N of Ejido Revolución on Mex 45, 1900 m, P.M. 

Peterson, Annable & Valdés-Reyna 10870 (US). Moris: SW Chihuahua, 1900 m, E. Palmer 1, 21 (US). Ocampo: Along trail just 

above Cascada de Basaseachic, 1880 m, P.M. Peterson & Annable 12530 (US); Parque Nacional de Cascada Basaseachic, 1 km 

airline S of Cascada, 2100 m, Tenorio & R. Torres 4488 (MEXU, 

US); 122.5 km W of La Junta on road to Parque Nacional Cascada de Basaseachic and 56.7 km W of Tomochic, 1 Oct 1989, 

2100 m, P.M. Peterson & R.M. King 8238 (US). Riva Palacio: 

Canyon de Majalca, 1850 m, Pennell 19264 (US); 32.3 km W 

of Mex 45, and ca. 0.8 km E of Col. Cumbres de Majalca, 7 Sep 

1989, 2180 m, P.M. Peterson, Annable & Y. Herrera 7975 (US). 

FIGURE 176. Muhlenbergia rigens. A. Habit. B. Inflorescence. 

C. Glumes. D. Floret. Drawn by Linda Ann Vorobik and Annaliese 

Miller; copyright Utah State University.
264 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Uruáchi: 16 mi W of Maycoba on Hwy 16 towards Yécora, 1520 

m, P.M. Peterson & J. Cayouette 15348 (US). 

260. Muhlenbergia rigida (Kunth) Kunth, Révis. Gramin. 1:63. 

1829.

FIGURE 170A–G

Densely caespitose perennial. Culms 40–100 cm tall, stiffly 

erect, glabrous to scaberulous below the basal, terete nodes; 

usually 1 node per culm; internodes mostly glabrous. Sheaths 

2–30 cm long, longer than the internodes, glabrous to scaberulous, rounded near base; ligules (1)3–12(15) mm long, often 

lacerate, firmer below, strongly decurrent; apex obtuse to acute; 

blades 12–35 cm long, 1–3 mm wide, flat or involute, not falcate, glabrous to scaberulous below and scaberulous to hirsutulous above. Panicles (4)10–35cm long, (2)3–5(15) cm wide, 

loosely contracted to open and lax, purplish; primary branches 

0.4–10 cm long, sometimes capillary, ascending and spreading 

to 80° from the rachises; pedicels 1–10 mm long, mostly longer 

than the spikelets. Spikelets 3.5–5 mm long, purplish; glumes 

1–1.7(2) mm long, about equal, 1-veined, unawned, apex obtuse 

to subacute, sometimes hirsutulous, rarely mucronate; lemmas 

3.5–5 mm long, narrow lanceolate, scaberulous to scabrous, 

purple, awned, callus with hairs to 0.5 mm long, apex acuminate, the awn (5)10–22 mm long, flexuous; paleas 3.5–5 mm 

long, narrow lanceolate, purple, scaberulous, apex acuminate; 

anthers 1.7–2.3 mm long, purplish. Caryopsis 2–3.5 mm long, 

fusiform, brownish. 2n = 40, 44.

Distribution and Habitat. Muhlenbergia 

rigida occurs on rocky slopes, ravines, and sandy, gravelly slopes 

derived from granitic and calcareous substrates associated with 

oak–pinyon–juniper woodlands at 1,200–2,500 m. It ranges 

from southeastern Arizona and southwestern New Mexico to 

southwestern Texas and throughout Mexico to South America 

in Andean Ecuador, Peru, Bolivia, and Argentina.

Specimens Examined. MEXICO. Chihuahua. 

Aldama: Entre [between] Jumiles & Felipe Angeles, 1360 m, 

S. González & J.M. Peña 398 (TAES). Balleza: 69.2 km E of 

Guachochi and 25.7 km W of Balleza, 26 Sep 1988, 2100 m, P.M. 

Peterson & Annable 5941 (US); 7.2 mi SW of El Vergel on Mex. 

Hwy 24, SW of Parral, 2200 m, M.E. Siqueiros 1568 (MEXU); 

14.8 mi NE of El Vergel, 2100 m, M.E. Siqueiros 1569 (MEXU); 

11 mi SE of Balleza on road to Parral, 1800 m, P.M. Peterson, 

M.B. Knowles, C.H. Dietrich & S.M. Braxton 13530 (US); 24.9 

km SE of Balleza and 22.5 km N of Hwy 24, W of Parral, 26 

Sep 1988, 1900 m, P.M. Peterson & Annable 5949 (US); 16.1 

km W of Balleza and 77.9 km E of Guachochi, 1990 m, P.M. 

Peterson, Annable & Valdés-Reyna 10742 (US); 24.2 km W of 

Balleza on Mex 127 towards Guachochi, 13 Sep 1989, 2380 m, 

P.M. Peterson, Annable & Y. Herrera 8089 (US); 10 mi SW of 

El Ojito, 12 Sep 2006, 1902 m, P.M. Peterson 20030, F. Sánchez 

Alvarado & E.P. Gómez Ruíz (CIIDIR, US). Batopilas: Hacienda San Miguel, near Batopilas, 2100 m, E. Palmer 13 (TAES, 

US); N of Quirare, 2350 m, Bye 2798 (TAES). Bocoyna: 24.7 

mi N of San Juanito on road towards Cuauhtemoc, 5 Sep 2008, 

2233 m, P.M. Peterson & J.M. Saarela 22027 (US); Cabecera 

de la cañada de Recogoata, 2400 m, B. Tah V. 27 (MEXU). 

Buenaventura: 15 mi W of Flores Magón, 1829 m, R. Guzmán, 

4934, 4937, 4939 (MEXU). Casas Grandes: Rancho Palanganas, 2200 m, R. Fierros 126 (MEXU). Cuauhtémoc: 10.6 km 

W of Cuauhtémoc on Hwy 16, 2000 m, P.M. Peterson & Annable 5817 (US); 5.5 mi W of Cuauhtémoc, 2100 m, Reeder & 

C. Reeder 2617 (TAES); 20.9 km W of Cuauhtémoc on Hwy 

16, 23 Sep 1988, 2000 m, P.M. Peterson & Annable 5824 (US). 

Cusihuiriáchi: 1 km al NE del rancho de Santiago, 2550 m, V.M. 

López 5 (INEGI). Chihuahua: Base de la Sierra de La Campana, 

80 km al N de Chihuahua, 1700 m, Rzedowski 32307 (SLPM); 

Km 43 [hwy] carr. Chihuahua–Cd. Cuauhtémoc, 1600 m, R.G. 

Reeves & J. Morrow G-452 (TAES); Hills near Chihuahua, 1800 

m, C.G. Pringle 926 (US); W of Chihuahua, 1700 m, LeSueur 

046 (US); 13 mi SW of Chihuahua on road to Cuauhtémoc, Soderstrom 919 (US); 33–35 km W of Hwy 45 on road towards 

Benito Juárez, 2200 m, P.M. Peterson & Annable 12555 (US); 

38 km W of Hwy 45 on road towards Benito Juárez, 2230 m, 

P.M. Peterson & Annable 12570, 12571 (US); 6.1 mi W of Hwy 

45 on dirt road towards Santa Clara, 1640 m, P.M. Peterson 

& Annable 12579 (US); 16.7 mi W of Hwy 45 on road up Los 

Prietos Canyon, 2120 m, P.M. Peterson & Annable 12591 (US). 

Guachochi: Just N of Guachochi (1 km), 26 Sep 1988, 2500 

m, P.M. Peterson & Annable 5923 (US); entering Barranca El 

Cobre, 28.3 km S of Cusarare on road to Guachochi, 25 Sep 

1988, 1900 m, P.M. Peterson & Annable 5902, 5906 (US); 9 mi 

S of Guachochi at edge of Barranca Río Green, 2470 m, P.M. 

Peterson & J. Cayouette 15380, 15373 (US); White-tuff volcanic outcrops surrounding Napuchis, 2140 m, P.M. Peterson 

& P. Catalán 17683 (CIIDIR, US); Arroyo Baqueachi, at 5 km 

E of small village, 2004 m, P.M. Peterson & P. Catalán 17569 

(CIIDIR, US); Parque Nacional Barranca del Cobre, 13.6 mi NE 

of La Bufa on road towards Samachique, 2240 m, P.M. Peterson, M.B. Knowles, C.H. Dietrich & S.M. Braxton 13566 (US); 

Yamuco, 1 mi E of hwy N of Rio Urique crossing towards Basihuare and Creel, 6 Sep 2008, 1880−1900 m, P.M. Peterson & 

J.M. Saarela 22061 (US). Guerrero: 35.4 km SW of La Junta and 

approx. 74 km N of Creel, 2200 m, P.M. Peterson & Annable 

5838 (US); 35.4 km SW of La Junta on road to Creel, 23 Sep 

1988, 2200 m, P.M. Peterson & Annable 5826 (US); km 25 carr. 

La Junta–Tomochi, 2380 m, Valdés-Reyna VR-711 (ENCB); Tomochi, 2 km alrededor del poblado [around the village], 2100 

m, M. Vergara 148 (MEXU); Carr. San Juanito–La Junta, 17 km, 

2000 m, B. Tah V. 14 (MEXU); Tomochi, 2 km alrededor del 

poblado, 2100 m, M. Vergara 151 (MEXU); 10 km al S de Guerrero, 2000 m, Valdés-Reyna VR-672 (TAES); Miñaca, 13 Oct 

1910, Hitchcock 7747 (US); 40.3 km W of La Junta on road to 

Parque Nacional Cascada de Basaseachic, 29 Sep 1989, 2390 m, 

P.M. Peterson & R.M. King 8190 (US); 54.3 km W of La Junta 

on road to Parque Nacional Cascada de Basaseachic, 30 Sep 

1989, 2260 m, P.M. Peterson & R.M. King 8211 (US); 16 km 

SW of La Junta on road to Creel, 2270 m, P.M. Peterson 9616
NUMBER 107 • 265

(US). Hidalgo del Parral: 5 km al E de Parral, 1800 m, S. Ojeda 

s.n. (INEGI); Cerro Borregos, 1930 m, S. Ojeda s.n. (INEGI); 5 

km al S de Parral, 2000 m, E. Aldrete s.n. (INEGI); 21 km W of 

Parral and approx. 3.2 km N on dirt road to Torrenocillo, 26 

Sep 1988, 2000 m, P.M. Peterson & Annable 5963, 5971 (US); 

33.8 km W of Parral on Hwy 24 towards El Vergel, 26 Sep 1988, 

2000 m, P.M. Peterson & Annable 5956 (US); Minas Nuevas, 

about 8 mi NW of Parral, Correll 22742 (US); 2 mi E of Parral 

on road to Juárez, 3 Oct 1959, Soderstrom 855 (US). Ignacio 

Zaragoza: 20.3 km NE of Ignacio Zaragoza on Mex 23, 28 Sep 

1989, 2400 m, P.M. Peterson & R.M. King 8159 (US). Jiménez: 

Sta. Eulalia Mts, C.G. Pringle 401 (US). Madera: 10 km al N 

de Madera, 2100 m, Valdés-Reyna VR–675 (ENCB). Matachi: 

23.3 km SE of Madera on Mex 16 to La Junta, 2190 m, P.M. 

Peterson & R.M. King 8177 (US); 71.7 km SE of Madera on 

Mex 16 and 1.6 km S of Temosachici, 29 Sep 1989, 2090 m, 

P.M. Peterson & R.M. King 8187, 8188 (US). Matamoros: 19.3 

km S of Villa Matamoros on Hwy 45 to Durango, 27 Sep 1988, 

1800 m, P.M. Peterson & Annable 5985 (US); 12 mi S of Villa 

Matamoros on Hwy 45 towards Parral, 1900 m, V. Jaramillo, 

G. Villegas & A. Miranda 2/10 (MEXU); 19.3 km S of Villa 

Matamoros on Mex 45 to Durango, 1910 m, P.M. Peterson & 

R.M. King 8261 (US); 84.6 km SE of Villa Matamoros and 1.6 

km N of Ejido Revolución on Mex 45, 1900 m, P.M. Peterson, 

Annable & Valdés-Reyna 10876 (US). Moris: Approx. 17.6 mi E 

of Maycoba on Hwy 16 towards Yepachic and 2 mi E of Sonora/

Chihuahua boundary, 1540 m, P.M. Peterson & Annable 12518, 

12519 (US). Riva Palacio: Col. Cumbres de Majalca, approx. 

32.2 km W of Hwy 45 N of Chihuahua, 2100 m, P.M. Peterson 

& Annable 5805 (US); 2.7 km W of Nuevo Majalca, 17.2 km 

W of Hwy 45, N of Chihuahua, 22 Sep 1988, 1700 m, P.M. Peterson & Annable 5776 (US); Cumbres de Majalca, 21.5 mi W 

of Hwy 45, 7 Sep 1989, 2190 m, P.M. Peterson, Annable & Y. 

Herrera 7970 (US); Cumbres de Majalca, 21.5 mi W of Hwy 45, 

2200 m, C. Yen & E. Estrada 8612 (ENCB); Lookout approximately 1.6 km E of Col. Cumbres de Majalca and 30.6 km W of 

Hwy 45, N of Chihuahua, 23 Sep 1988, 2150 m, P.M. Peterson 

& Annable 5816, 5817 (US); 17.7 km W of Nuevo Majalca on 

road to Cumbres de Majalea, Parque Nacional, 22 Sep 1988, 

2000 m, P.M. Peterson & Annable 5782, 5783 (US); 32.3 km W 

of Mex 45, and ca. 0.8 km E of Col. Cumbres de Majalca, 7 Sep 

1989, 2180 m, P.M. Peterson, Annable & Y. Herrera 7977 (US). 

San Francisco del Oro: 56.4 km W of Parral on road to Balleza 

and 35.5 km S of Balleza on Mex 432, near Corral de Duarte, 

2210 m, P.M. Peterson, Annable & Valdés-Reyna 10711 (US); 

10 km al E del retén de policia [police checkpoint], carr. Parral–

El Vergel, 2450 m, M. Sequeiros 1545 (MEXU). Santa Bárbara: 

Ejido Buenavista, 1950 m, S. Aguirre 2055 (MEXU). Temósachi: 

2.5 km al W de San Juan, 1800 m, S. Aguirre 25 (INEGI). 

261. Muhlenbergia robusta (E. Fourn.) Hitchc., N. Amer. Fl. 

17(6): 462. 1935.

Caespitose perennial. Culms 100–230(300) cm tall, erect, 

compressed-keeled near base, glabrous to sometimes pubescent 

below the nodes; internodes glabrous. Sheaths 15–70 cm long, 

longer than the internodes, glabrous, becoming brownish below, 

sometimes shredded; sheath auricles present, (1)2–4(10) cm 

long, linear subulate to broadly triangular, longer above, straight 

or twisted, firm below; ligules 2–10(12) mm long, membranous, 

lacerate throughout; blades 40–100 cm long, 4–7 mm wide, 

folded sometimes involute toward tip, scaberulous above and 

below, the margins and keel saw-toothed. Panicles 30–80 cm 

long, (2)3–8 cm wide, narrow to loosely contracted, greenishgray to silvery gray or purplish; primary branches 1–15(17) cm 

long, naked on the lower 1⁄4, ascending and closely appressed to 

spreading up to 40° from the rachises; pedicels 0.3–1.1 mm long, 

shorter than the spikelets, erect, scaberulous; central axis prominently ribbed, scabrous. Spikelets (1.8)2–3(3.2) mm long, erect, 

greenish-gray or purplish; glumes 1.8–3.2 mm long, usually longer than the floret, subequal, narrowly oblong to elliptic, veinless to indistinctly 1-veined, hyaline to greenish-gray, glabrous 

to scaberulous, apex acute to obtuse occasionally erose; lemmas 

1.7–2.6 mm long, linear-oblong, unawned or rarely mucronate, 

greenish to yellowish-brown, glabrous or pubescent with scattered hairs on lower 1⁄2, the hairs up to 0.3 mm long, callus glabrous or with few hairs, apex acute, the mucro when present up 

to 1 mm long; paleas 1.7–2.6 mm long, glabrous to sparingly 

pilose between the veins on the lower 1⁄2, apex acute; anthers 

1.1–2 mm long, purplish. Caryopsis 1.2–1.7 mm long, fusiform, 

brownish. 2n = 40.

Distribution and Habitat. Muhlenbergia robusta occurs in mountainous areas from Sinaloa and Chihuahua 

south to Chiapas and Central America; found on rocky slopes, 

along barrancas (canyons), in pine and pine–oak forests, and in 

tropical deciduous forests at 850–3,000 m.

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000) and Herrera Arrieta and 

Cortés Ortiz (2010).

262. Muhlenbergia schmitzii Hack., Ann. K. K. Naturhist. Hofmus. 17: 255. 1902.

FIGURE 163E–H

Caespitose annual; stout, appearing perennial. Culms 

30–80 cm tall, scabrous below nodes, erect, little branched. 

Sheaths scabrous to apex, margins membranous, light brownish; 

ligules 2–3 mm long, membranous, apex obtuse to truncate, erose 

to deeply incised or toothed, margins entire; blades 5–20 cm long, 

1.6–5 mm wide, flat, scabrous to glabrous. Panicles 12–36 cm 

long, 3.2–14 cm wide, spreading, elongated; branches 1.2–8 cm 

long, 1 occasionaly 2 per node, ascending or open; pedicels 

1–1.5 mm long, strong, erect. Spikelets 2.5–3.4 mm long, wide, 

dorsally flattened, ascending, appressed along branches; glumes 

1.3–2 mm long, subequal, scabrous, sometimes short-pubescent 

near apex and margins, 1-veined, awned, the awns 0.5–0.8 mm 

long; lower glumes ovate-lanceolate, acuminate; upper glumes oblong, abruptly acuminate, apex 2- to 3-lobed to tridentate; lemmas 

2.5–3.2 mm long, oblong-ellipsoid, brown-yellowish with age, 
266 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

veins prominent, sometimes dorsally flattened, silky-pubescent, 

appressed on midvein, hairs 0.3 mm long, apex entire to toothed, 

mucronate, the mucro 0.3–0.5 mm long; paleas 2.6–3.4 mm long, 

oblong-ellipsoid, a little longer than lemma, glabrous, apex bilobate, the lobes 0.3 mm long, acute; anthers 0.9–1.6 mm long, purplish changing to brown-yellowish with age. Caryopsis 1–2 mm 

long, oblong, compressed, straw-colored. n = 20.

Distribution and Habitat. Muhlenbergia 

schmitzii occurs in humid areas in pine–oak forests at elevations 

of 1,500–2,460 m. It is endemic to Mexico and found in Chihuahua, Hidalgo, México, and Michoacán.

Muhlenbergia schmitzii is easily confused with M. flavida 

and M. strictior, and can be distinguished in having tall culms 

(30–80 cm tall), blades longer and wider (5–20 cm long and 

1.6–5 mm wide), mucronate lemmas (mucro 0.3–0.5 mm long) 

rather than short-awned, and longer anthers (0.9–1.6 mm).

Specimens Examined. MEXICO. Chihuahua. 

Guadalupe y Calvo: Sierra Mohinora, about 3 mi S of La Rocha, 

2250 m, Correll & Gentry 23228 (ENCB, US). Madera: Guayanopa Canyon, Sierra Madre, Sep 1903, 2000 m, M.E. Jones 

7316 (US), isotype.

263. Muhlenbergia scoparia Vasey, Contr. U.S. Natl. Herb. 1(8): 

283. 1893.

FIGURE 165A–E

Densely caespitose perennial. Culms 55–90 cm tall, glabrous to scaberulous, nodes and internodes glabrous. Sheaths 

basal, compressed-keeled, glabrous and scaberulous near the 

collar, undulate when mature, brown-reddish, fibrose; ligules 

8–16 mm long, membranous, auricles absent; blades 25–50 cm 

long, 1–4.5 mm wide, flat or folded, toothed at the apex, scabrous. Panicles 20–30 long, 1.5–5 cm wide, somewhat open, the 

ascending to arching branches narrow, interrupted into groups 

along the rachis, light green to brown-reddish, rachis scabrous, 

with prominent ribs; primary branches 3.5–10 cm long, naked 

at base; secondary branches 1–5.5 cm long; pedicels of lateral 

spikelets 0.6–1.2 mm long, up to 3 mm long in terminal spikelets, scabrous. Spikelets 1.5–2.2 mm long; glumes shorter than 

the florets, subequal, mucronate, hyaline, veinless to 1-veined, 

glabrous to scaberulous apex acute; lower glumes 0.8–1 mm 

long; upper glume 1–1.5 mm long, the mucro to 1 mm long; lemmas 1.5–2 mm long, acuminate, awned, glabrous to scaberulous 

dorsally, the hairs 0.5–0.7 mm long, rigid, on proximal margins, 

the awn 8–15 mm long, emerging a little below of apex; paleas 

1.5–2 mm long, glabrous; anthers 0.5–0.7 mm long. 

Distribution and Habitat. Muhlenbergia 

scoparia occurs in oak forests at elevations of 1,540–2,000 m. 

It is endemic to Mexico and is found in Chihuahua, Durango, 

Jalisco, Michoacán, Nayarit, Sinaloa, and Sonora.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: Batopilas, 2000 m, C.G. Pringle 2350 (ENCB, 

MEXU); Batopilas, 2000 m, E. Palmer 766 (TAES); Potrero La 

Sierra, 4 km Pte Carr. [hwy] Panamericana, 7 Sep 73, bosque de 

encino [oak forest], 1700 m, J. Valdés-Reyn VR-144 (RELC). 

Chinipas: Saguarivo, 53 mi N of Alamos, 9 Sep 2008, slopes with 

oaks and pines, 1540 m, P.M. Peterson & J.M. Saarela 22115, 

22131 (US); Sierra Saguarivo, 1.3 mi W of Curahui, 9 Sep 2008, 

tropical deciduous forest, 1001 m, P.M. Peterson & J.M. Saarela 

22151 (US). Moris: Approx. 17.6 mi E of Maycoba on Hwy 16 

towards Yepachic and 2 mi E of Sonora/Chihuahua boundary, 

1540 m, P.M. Peterson & Annable 12520 (US).

264. Muhlenbergia setifolia Vasey, Bot. Gaz. 7(8–9): 92. 1882.

Caespitose perennial. Culms 30–85 cm tall, erect, slender, 

slightly decumbent near base, hirsutulous below the terete nodes, 

2–4 nodes per culm; internodes glabrous to hirsutulous. Sheaths 

2–13 cm long, shorter than the internodes, glabrous to puberulent, basal sheaths rounded, margins whitish; ligules 4–7(10) mm 

long, membranous, firm below, decurrent, margins glabrous to 

puberulent and wider than 1⁄2 the adjacent blade width, apex 

acuminate, lacerate; blades 5–20(25) cm long, 1–2.5 mm wide, 

tightly involute to falcate, scaberulous below and scaberulous 

to hirsutulous above, the hairs less than 0.1 mm long. Panicles 

8–20(25) cm long, (2)3–5 cm wide, loosely contracted, ovate; 

primary branches 0.5–7 cm long, capillary, ascending, appressed 

or spreading up to 70° from the rachises; pedicels 3–20 mm long, 

mostly longer than the spikelets, delicate, flexuous, glabrous and 

smooth. Spikelets 3.5–5.1 mm long; glumes 1.5–2.5 mm long, 

subequal, thin and hyaline, stramineous to reddish; lower glumes 

veinless, apex truncate or obtuse, often toothed or notched; 

upper glumes 1-veined or veinless, apex obtuse to acute often 

mucronate, the mucro less than 0.7 mm long; lemmas 3.5–

5.1 mm long, narrow lanceolate, glabrous, smooth and shining, 

stramineous to reddish, awned, callus with hairs up to 0.6 mm 

long, apex acuminate, demarcation of lemma body and awn not 

evident, the awn 2–7(10) mm long, flexuous; paleas 3.5–5.1 mm 

long, as long as the lemma, narrow lanceolate, glabrous, apex 

acuminate; anthers 2–2.6 mm long, greenish. Caryopsis 2.4–

3.2 mm long, fusiform, brownish. 2n = 40.

Distribution and Habitat. Muhlenbergia setifolia grows on calcareous rocky slopes, on rock outcrops, and 

in desert grasslands associated with oak–pinyon–juniper woodlands at 1,000–2,250 m. It is found in western Texas, New Mexico, and northern Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua. Chihuahua: Sierra de la Campana, 10 km al W de 

la [hwy] Carr. Panamericana, 19 Sep 1973, pastizal [pastureland], 1700 m, J. Valdés-Reyna VR-325 (RELC). Juárez: Santo 

Domingo, north of Chihuahua, Sierra del Presidio, Desierto Chihuahuense, I.M. Johnston s.n. (US). Temósachi: Between Yécora 

and Naicova, 2250 m, Correll & I.M. Johnston 21630 (US). 

Mpio.?: Sierra de los Pinos, Dec 1937, LeSueur 0215 (US).

265. Muhlenbergia shepherdii (Vasey) Swallen, Contr. U.S. 

Natl. Herb. 29(4): 204. 1947. Sporobolus shepherdii Vasey, 
NUMBER 107 • 267

Bull. Torrey Bot. Club 14: 8. 1887. Blepharoneuron shepherdii (Vasey) P. M. Peterson & Annable, Syst. Bot. 15(4): 

519. 1990.

Caespitose annual. Culms 16–40 cm tall, scaberulous to 

strigoses below nodes, slender to quite thick, erect to geniculatespreading, with many branches near base; internodes 2.2–5 cm 

long. Sheaths 3.2–9 cm long, usually longer than internodes, 

glabrous, margins hyaline; ligules 1.4–2.8 mm long, membranous hyaline, apex irregularly toothed to lacerate, occasionally entire, truncate to obtuse, margins entire, decurrent; blades 

4–8.5 cm long, 0.8–2 mm wide, flat to slightly involute, shortpubescent above and glabrous to scaberulous below. Panicles 

8–18 cm long, 2.7–7 cm wide, open, branches 3–6 cm long, ascending to spreading 20°–70° from the culm axis, often capillary, 1 or 2 per node; pedicels 7–12 mm long, capillary, nodding 

and reflexed, minutely granular at the swollen apex. Spikelets 

1.3–1.7(1.9) mm long; glumes subequal, green-grayish, glabrous, ovate to oblong, occasionally lanceolate, apex frequently 

acute; lower glumes 0.7–1.6 mm long; upper glumes 1–1.7 mm 

long; lemmas 1.3–1.7(1.9) mm long, green-grayish, lanceolate, 

appressed-pubescent to open, silky hairs on midvein and margins, these hairs often appearing as ridges on the surface of the 

lemma at 20× magnification, apex often obtuse; paleas 1.2–

1.7 mm long, almost as long as lemma, villous between veins; 

anthers 0.8–1.4 mm long, brown. Caryopsis 1–1.7 mm long, 

dorsally compressed, flattened, yellow. n = 8.

Distribution and Habitat. Muhlenbergia 

shepherdii occurs on wet seepage banks, washes, disturbed 

gravelly roadcuts, and slopes in pine–oak–madrone forests and 

pinyon–juniper woodlands with Arctostaphylos. It is endemic to 

Mexico and found in Chihuahua, Durango, Sonora, and Zacatecas at elevations of 1,900–2,900 m.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 15 mi W of Flores Magón, 16 Sep 1960, Reeder, 

C. Reeder & Soderstrom 3500-B (ARIZ). Balleza: 0.5 mi NE 

El Vergel, 6 Sep 1985, 2100 m, P.M. Peterson & Annable 4069

(US); 16 mi SW of El Vergel on hwy 24, Río Verde, 6 Sep 1985, 

P.M. Peterson & Annable 4072, 4077 (ENCB, MEXU, US); 

19.6 km W of Balleza and 74.2 km E of Guachochi, 18 Sep 

1991, bosque de encino [oak forest], 2120 m, P.M. Peterson, 

Annable & Valdés 10751 (CIIDIR, US). Batopilas: SW Chihuahua, Aug–Nov 1885, E. Palmer 9 (US), lectotype. Bocoyna: 

10.8 km N of Creel on Mex 127 and 20 km S of San Juanito, 

10 Sep 1989, pine forest, 2235 m, P.M. Peterson, Annable & 

Y. Herrera 8005 (ENCB, MEXU, US); 1.1 km N of San Juanito near large lumber mill, 24 Sep 1988, 2200 m, P.M. Peterson & Annable 5872 (ENCB, MEXU, US). Casas Grandes: W 

of Casas Grandes, 3 mi NE of Cuesta Blanca, 18 Sep 1960, 

Reeder, C. Reeder &Soderstrom 3546 (ARIZ); 2 mi NE of 

Cuesta Blanca, W of Casas Grandes, 18 Sep 1960, Reeder, 

C. Reeder & Soderstrom 3539-Bi (ARIZ). Chihuahua: 32 km 

W of hwy 45 towards Benito Juárez, 17 Oct 1992, pinyon–juniper woodlands, 2110 m, P.M. Peterson & Annable 12545 (US). 

Cuauhtémoc: 12 mi w of Cuauhtemoc, 28 Oct 1959, Gould 

8925 (US); 11 mi W of Cuauhtémoc, 5 Oct 1966, Reeder & 

C. Reeder 4594 (ARIZ, ENCB, MEXU); Hotel Rancho la Estancia, 20 Oct 1981, laderas pedregosas con vegetación de 

encinar [rocky slopes with oak vegetation], R. Guzmán 4912 

(MEXU). Cusihuiriachic: Cusihuiriachic, on la Bufa, 12 Sep 

1986, Spellenberg & J. Zimmerman 8587 (US). Guachochi: 2.3 

mi W of San Juanito on road towards Baquiriachic, 5 Oct 2000, 

bosque de pino [pine forest], 2590 m, P.M. Peterson & J. Cayouette 15362 (US). Guadalupe y Calvo: 15.2 mi E of Ocote on 

hwy 24 towards El Vergel, 14 Sep 2006, 2580 m, P.M. Peterson 

20065, F. Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, US). 

Guerrero: km 25 carr. [hwy] La Junta–Tomochi, Cd. Cuauhtémoc, 6 Oct 1974, Valdés-Reyna VR-705 (ENCB); 35.4 mi W 

of La Junta on road to Parque Nacional Cascada de Basaseachic and 4.4 mi E of Tomochic, 30 Sep 1989, 2350 m, P.M. 

Peterson & R.M. King 8222 (ENCB, MEXU, NMC, US); 38.6 

km SW of La Junta and approx. 70.8 km N of Creel at p. Arroyo Ancho crossing, 21 km marker, 24 Sep 1988, pine woods, 

2200 m, P.M. Peterson & Annable 5857 (ENCB, MEXU, US); 

37 km SW of La Junta on road to Creel at the puente [bridge] 

Arroyo Ancho, 10 Sep 1989, pine forest, 2230 m, P.M. Peterson, Annable & Y. Herrera 7992 (ENCB, MEXU, US); 10 km 

S de la Junta, carr. La Junta–Temochi, 6 Oct 74, Bosque de 

pino–encino, 1900 m, Valdés-Reyna VR-700 (RELC). Madera: 

near Col. Garcia in the Sierra Madre, 14 Sep 1899, C.H.T. 

Townsend & C.M. Barber 330 (US); 10 km al Sur de Madera, 5 

Oct 74, Bosque de pino–encino, 2000 m, Valdés-Reyna VR-666

(RELC); Zona Arqueológica “40 casas” 20 km al NW de las 

varas, 28 Sep 1982, bosque de pino–encinar, 2140 m, Tenorio 

& Romero1836 (MEXU). Ocampo: 20 mi W of Tomochic on 

road towards Cascada de Basaseachic, 22 Sep 1986, 2100 m, 

P.M. Peterson & Annable 4552 (ENCB, MEXU, US).

266. Muhlenbergia sinuosa Swallen, Contr. U.S. Natl. Herb. 

29(4): 204. 1947. 

FIGURE 177

Caespitose delicate annual. Culms 12–50 cm tall, erect, slender, very branched near base, sometimes geniculate-ascending, 

glabrous, scabrous below nodes. Sheaths glabrous or scabrous; 

ligule 1.5–3 mm long, hyaline, truncate to obtuse, toothed to 

lacerate; blades 2–8.5 cm long, 0.8–2 mm wide, flat to involute, short-pubescent to scabrous, midvein prominent. Panicle 

10–26 cm long, 2.8–8 cm wide, branches 2.5–7 cm long, often 

capillary, 1 or 2 per node, ascending or something divergent, 

pedicels 4–7 mm long, slender, capillary, curved or reflexed. 

Spikelets 1.4–2 mm long, reflexed; glumes 0.7–1.2 mm long, 

equal, conspicuously pilose near apex and margins, hairs 0.3 mm 

long, 1-veined, apex acute to obtuse, awnless; lemma 1.4–2 mm 

long, oblong-elliptic, green, sometimes with purple spots, silkypubescenct, short-appressed along midvein and margins, apex 

acute to obtuse, awnless; palea 1.3–1.8 mm long, oblong-elliptic, 
268 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

glabrous; anthers 0.6–1.2 mm long, olive-green. Caryopsis 0.8–

1.2 mm long, fusiform, brown. n = 10, 12. 

Distribution and Habitat. Muhlenbergia 

sinuosa grows in pine forests at elevations of 1,650–2,300 m. 

It ranges from the United States to Mexico in Chihuahua and 

Sonora.

Specimens Examined. MEXICO. Chihuahua. 

Bocoyna: Cabecera de la cañada de Recogoata, 2100 m, B. Tah 

V. 28 (MEXU). Casas Grandes: 21 mi SW of Col. Juárez on road 

to Hernández Javales, 2200 m, P.M. Peterson & Annable 4031

(US); 25.0 mi SW of Col. Juárez on road to Hernández Javales, 

2000 m, P.M. Peterson & Annable 4037 (US); About 43 mi SW 

of Casas Grandes, 2100 m, Reeder & C. Reeder 2694 (SLPM, 

US); 22.5 mi SW of Col. Juárez on rd to Hernández Javales, 

2100 m, P.M. Peterson & Annable 4033 (US). 3 mi S of Hernández Javales, 32 mi SW of Col. Juárez, 2200 m, P.M. Peterson 

& Annable 4044 (US); 3 mi NE of Cuesta Blanca, W of Casas 

Grandes, Reeder & C. Reeder 3545 (US); 5 mi S of Hernández, 

W of Casas Grandes, Reeder & C. Reeder 3514 (US); 2 mi S of 

Hernández, W of Casas Grandes, Reeder & C. Reeder 3504 (US); 

3 mi E of Cuesta Blanca, W of Casas Grandes, 2012 m, Reeder 

& C. Reeder 3220, 3236 (US); 21 mi W of Col. Juárez, 2100 m,

Reeder & C. Reeder 3209 (US); 25 mi SW of Col. Juárez on road 

to Hernández Javales, 2000 m, Reeder & C. Reeder 4037 (US). 

Chihuahua: 32.5 km de la carr. [hwy] Panamericana rumbo 

[course] a Namiquimpa, 2340 m, M. Vergara 186 (MEXU); 32 

km W of Hwy 45 towards Benito Juárez, 2110 m, P.M. Peterson 

& Annable 12546 (US). Guerrero: 4.5 mi W of Tomochic on 

Hwy 16, 2200 m, P.M. Peterson & Annable 4540 (US). Madera: 

About 15 mi S of Madera, 2165 m, Reeder & C. Reeder 2632

(CIIDIR, ENCB, US); 17 mi S of Madera, 2100 m, Reeder & 

C. Reeder 2629 (SLPM, US); 14.5 mi SE of Madera on Mex 

16 to La Junta, 2200 m, P.M. Peterson & Annable 8179 (US); 

Chuichupa, LeSueur 155 (US); About 17 mi NW of Madera, 

2285 m, Reeder & C. Reeder 2657 (US). Namiquipa: Sierra El 

Nido, 16.7 mi W of Hwy 45 on road up to Los Prietos Canyon, 

2400 m, P.M. Peterson 12590 (US). Riva Palacio: 21.1 mi W of 

Hwy 45, 0.4 mi E of Cumbres de Majalca, 2200 m, P.M. Peterson & Annable 4523 (US); Parque Cumbres de Majalca, 2120 

m, P.M. Peterson & Annable 5813 (US); 20 mi W of México 45 

and about 1⁄2 mi E of Cumbres de Majalaca, 7 Sep 1989, 2180 m, 

P.M. Peterson & Annable 7976 (US).

267. Muhlenbergia speciosa Vasey, Bull. Torrey Bot. Club 

13(12): 231. 1886. 

Densely caespitose perennial. Culms 1–1.5 m tall, strong, 

forming large mats, pilose below, hairs 1–1.5 mm long. Sheaths 

35–60 cm long, compressed-keeled, pilose, auricles missing; ligules 0.5–1 mm long; blades 30–50 cm long, 2.5–4 mm wide, 

folded, pilose, pilose to somewhat glabrous. Panicles 40–60 long, 

5–10 cm wide, straight or pendulous; branches 7–10(13) cm 

long, ascending or appressed, the upper divaricate, densely flowered, purplish to reddish; pedicels 0.5–2 mm long. Spikelets 1.2–

2.2 mm long; glumes 1.4–2.3 mm long, longer than the lemma, 

FIGURE 177. Muhlenbergia sinuosa. A. Habit. B. Spikelet. Drawn 

by Linda Ann Vorobik and Annaliese Miller; copyright Utah State 

University.
NUMBER 107 • 269

equal to subequal, apex obtuse, rarely awned, pilose, occasionally glabrous, hairs 0.5–0.7 mm long; lemma 1.2–2.2 mm long, 

pilose to sometimes glabrous, awned, the awn 8–12(17) mm 

long, flexuous, scabrous; paleas 1.2–2 mm long, pilose, obtuse; 

anthers 0.4–0.6 mm long, purplish.

Distribution and Habitat. Muhlenbergia speciosa grows in oak and pine forests at elevations of 2,200–2,650 

m. It occurs in Mexico in Chihuahua, Durango, Jalisco, Michoacán, Nayarit, and Sinaloa.

Specimens Examined. MEXICO. Chihuahua. 

Guachochi: 38.4 mi W of Guachochi on Mexico 127 towards 

Creel, 2440 m, M.E. Siqueiros 1628 (MEXU). Moris: Southwestern Chihuahua, 1900 m, E. Palmer 30 (MEXU, US) isotype.

268. Muhlenbergia strictior Scribn. ex Beal, Grass. N. Amer. 2: 

263. 1896. 

Caespitose annual; often decumbent. Culms 5–32 cm tall, 

strigulous below nodes, slender, branched. Sheaths with hyaline 

margins to green-yellowish, sparingly scabrous to apex; ligules 

1.5–3.2 mm long, membranous, apex obtuse to truncate, erose 

or toothed, decurrent; blades 2–6.5 cm long, 1.2–2.5 mm wide, 

strigulose to minute-villous above, glabrous below. Panicles 

(3)5.2–11 cm long, 0.4–2(3.5) cm wide, contracted; branches 

0.9–2.4 cm long, capillary, ascending, flowered to base, the florets overlapping, 1 or 2 per node. Spikelets 3–4.2 mm long, wide 

and dorsally flattened, straw color, short-pedicelled, appressed; 

glumes 1.2–2 mm long, subequal, glabrous to scaberulous near 

apex, 1-veined, narrow, acuminate, often mucronate, the mucros 

up 0.8 mm long; lower glumes ovate-lanceolate, apex acuminate; 

upper glumes oblong, apex abruptly acuminate, sometimes 2- to 

3-lobed to 3-toothed; lemmas 3–4.2 mm long, oblong-ellipsoid, 

lanceolate, with prominent veins, yellowish when mature, with 

silky pubescence over the keels and margins, the hairs 0.3 

mm long, apex entire or minute 2-toothed, the teeth 0.2 mm 

long, awned, the awns 1–3 mm long, delicate, straight; paleas 

3–4.2 mm long, oblong-ellipsoid, glabrous, apex 2-toothed, the 

teeth 0.3 mm long; anthers 0.5–0.7 mm long, olive-green to light 

brown. Caryopsis 2–2.5 mm long, oblong, compressed, brown 

to yellowish. n = 10. 

Distribution and Habitat. Muhlenbergia 

strictior grows in tropical and oak–pine forests at elevations of 

1,500–2,650 m. It occurs in Mexico in Chihuahua, Distrito Federal, Durango, México, and Sonora.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 12.1 mi NE of El Vergel on Hwy 24, SW of Parral, 

2000 m, P.M. Peterson & Annable 4066 (US); 56.4 km W of 

Parral on road to Balleza and 35.5 km S of Balleza on Mex 

432, near Corral de Duarte, 2210 m, P.M. Peterson, Annable 

& Valdés-Reyna 10709 (US). Bocoyna: Cabecera de la cañada 

de Recogoata, 2400 m, B. Tah V. 38 (MEXU). Casas Grandes: 

21 mi SW of Col. Juárez on road to Hernández Javales, 2200 m, 

Correll & Gentry 23226 (ENCB, US); P.M. Peterson & Annable 4039, 4043 (TAES, US); 5 mi S of Hernández, W of Casas 

Grandes, Reeder & C. Reeder 3512 (US). Chihuahua: Hills near 

Chihuahua, 1800 m, C.G. Prigle 3034 (TAES, US). Guachochi: 

Cusarare, S of Creel, 2200 m, Bye 5191 (MEXU); 20.3 mi S of 

Creel on road towards Rocheachic, 2510 m, P.M. Peterson & 

J. Cayouette 15369 (US); 24.6 km W of Guachochi and 0.6 km S 

of Rocheachi, 2340 m, P.M. Peterson, Annable & Valdés-Reyna 

10787 (US); 0.6 mi N of Guachochi, 2400 m, P.M. Peterson & 

Annable 5919 (US); 10.6 mi NE of La Bufa on road to Creel, 

2235 m, P.M. Peterson, Annable & Y. Herrera 8071 (US); Flat 

rock outcrops at Napuchis, 2140 m, P.M. Peterson & P. Catalán 

17673 (CIIDIR, US). Guadalupe y Calvo: 15.2 mi E of Ocote 

on hwy 24 towards El Vergel, 14 Sep 2006, 2580 m, P.M. Peterson 20063, F. Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, 

US). Guerrero: 24 mi SW of La Junta on road to Creel, 2200 m, 

Y. Herrera, P.M. Peterson & Annable 954 (CIIDIR); 20 mi W of 

Tomóchic on road towards Cascada Basaseachic, 2200 m, P.M. 

Peterson & Annable 4553 (US); Miñaca, 13 Oct 1910, Hitchcock 7765 (US); Wet ledges by streams 2 ó 3 mi S of Guerrero, 

2200 m, C.G. Pringle 1418 (MEXU, US); 4.5 mi W of Tomóchic 

on Hwy 16, 2200 m, P.M. Peterson & Annable 4539 (TAES, 

US); 13 mi SW of La Junta on rd to Creel, 2200 m, P.M. Peterson & Annable 5825 (US); 22 mi SW of La Junta on rd to Creel, 

2200 m, P.M. Peterson & Annable 5831 (US); 24 mi SW of La 

Junta on road to Creel, 2200 m, P.M. Peterson & Annable 5852

(US); 15.5 mi W of La Junta on road to Tomóchic, 15 km mark 

on Hwy 16, 2100 m, P.M. Peterson & Annable 4054 (TAES, 

US); 25 mi W of La Junta on rd to Parque Nacional Cascada 

Basaseachic, 2200 m, P.M. Peterson & R.M. King 8194 (US); 

33.7 mi W of La Junta on road to Parque Nacional Cascada 

Basaseachic, 30 Sep 1989, 2260 m, P.M. Peterson & R.M. King 

8219 (US); 20 mi SW of La Junta on road to Creel, P.M. Peterson & Annable 7894 (US); 122.5 km W of La Junta on road to 

Parque Nacional Cascada de Basaseachic and 56.7 km W of Tomochic, 1 Oct 1989, 2100 m, P.M. Peterson & R.M. King 8239 

(US). Madera: Round Valley, Sierra Madre, Sep 1903, 1950 m, 

M.E. Jones 7315 (MEXU, US), Isotype. Ocampo: Parque Nacional de Cascada Basaseachic, 1 km airline S of Cascada, 2100 m, 

Tenorio & R. Torres 3777, 4511 (MEXU, SLPM); Parque Nacional de Cascada Basaseachic, 1 km airline S of Cascada, 2100 

m, R. Fierros 1684 (MEXU); Along trail just above Cascada de 

Basaseachic, 1880 m, P.M. Peterson & Annable 12537 (US); Approx. 10 mi E of Basaseachic on Hwy towards La Junta, 2110 

m, P.M. Peterson & Annable 12543 (US). Riva Palacio: 21 mi W 

of México 45, N of Chihuahua city, Col. Cumbres de Majalca, 

2120 m, P.M. Peterson & Annable 4520 (TAES, US).

269. Muhlenbergia tarahumara P. M. Peterson & Columbus, 

J. Bot. Res. Inst. Texas 3(2): 528–531, f. 1–2. 2009.

FIGURE 178

Caespitose perennial. Culms 18−35 cm tall, erect, terete 

near the base, glabrous below the nodes, usually 3 nodes per 

culm; internodes glabrous and shiny. Sheaths 0.8−8 cm long, 

shorter than the internodes above, pubescent or glabrous; ligules 

1−1.8 mm long, membranous, abaxially pubescent or glabrous, 
270 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

FIGURE 178. Muhlenbergia tarahumara. A. Habit. B. Ligule. C. Two paired spikelets. D. Branch with two spikelets (only one seen from this perspective). E. Glumes. F. Floret on branch axis (glumes, other spikelet removed). 

G. Lemma. H. Paleas. I. Stamens and pistil. J. Lodicules. Drawn by Alice R. Tangerini for Smithsonian Institution, 

Department of Botany.
NUMBER 107 • 271

apex acute, often erose, minutely ciliolate; blades (2)3.5−13 cm 

long, 0.2−1.3 mm wide, flat to tightly involute, apically acuminate, somewhat sinuous, antrosely hirsute on both surfaces, 

the hairs 0.1−0.4 mm long. Panicles 3−6 cm long, 0.7−1.6 cm 

wide, narrow, with 5−13 racemosely arranged primary branches, 

1 branch per node; branches 0.5−1.4 cm long, with 2 terminal 

spikelets, deciduous, disarticulation near the base, branches first 

ascending then spreading (bending sharply or curling near the 

base) from the culm axis, antrorsely hirsute, the hairs 0.2−0.4 mm 

long; inflorescence axis flattened, ending in terminal branch, 

margins hirsute; pedicels fused or 0.2−0.6 mm long, 1 slightly 

longer than the other, tightly appressed. Spikelets 4.5−7.8 mm 

long, appressed to one another, 1-flowered; glumes 3−5.8 mm 

long, narrowly lanceolate, usually equal in length, shorter than 

the lemma, membranous to chartaceous, 1-veined, pubescent, 

apex acuminate, awned, the awns 1.4−3.2 mm long; lemmas 

3.6−7.3 mm long, lanceolate, awned, distinctly 3-veined, membranous to chartaceous, appressed-pubescent, apex acute to acuminate, bifid, the central awn 2−3.7 mm long, straight or slightly 

recurved, the lateral veins excurrent into awns 0.6−1.3 mm long; 

paleas 3−4.6 mm long, shorter than the lemma, membranous, 

glabrous below and appressed-pubescent near apex, 2-veined, 

apex acuminate, each vein excurrent as a mucro, the mucro 

0.2−0.9 mm long; anthers 2.2−2.8 mm long, yellowish-orange. 

Distribution and Habitat. Muhlenbergia tarahumara is known only from three locations in the Sierra Madre 

Occidental in Chihuahua, and a single location in Durango (Peterson & Herrera Arrieta 25508 [CIIDIR, US], Mpio. Santiago 

Papasquiaro near jtn of hwy 36 and turnoff to San Diego trout 

farm), and it occurs on rocky slopes, ridgetops, and white-tuff 

rock outcrops with Pinus spp., Pinus lumholtzii B. L. Rob. & 

Fernald, Arctostaphylos pungens Kunth, Quercus, Cupressus, 

Ceanothus, Muhlenbergia lucida, M. montana, and M. rigida at 

1,880−2,407 m (Peterson and Columbus, 2009).

Specimens Examined. MEXICO. Chihuahua. Guachochi: 2 km W of Rio Coraréachi and E of Osichi, 

1960–2040 m, 30 Aug 2003, P.M. Peterson & P. Catalán 17621

(CIIDIR, RSA, US); 41.3 km S of Creel on road to Batopilas, 

2075 m, 10 Sep 1989, P.M. Peterson, Annable & Y. Herrera 

8032 (ENCB, RSA, US); Yamuco, 1 mi E of hwy N of Rio Urique 

crossing towards Basihuare and Creel, 1880–1900 m; 26 Aug 

2003, P.M. Peterson & P. Catalán 17542 (CIIDIR, RSA, US); 

P.M. Peterson & J.M. Saarela 22053, 22079 (US).

270. Muhlenbergia tenuifolia (Kunth) Kunth, Révis.Gramin. 

1(4): 63. 1829.

FIGURE 179

Loosely caespitose to densely tufted, annual to short-lived 

perennial with delicate base, flowering the first year. Culms 20–70 

cm tall, erect or decumbent at the base, branching at the lower 

and middle nodes, wiry, scaberulous below the terete nodes; internodes generally 2.0–9.5 cm long. Sheaths 4.0–7.5 cm long, 

commonly shorter than the internodes, glabrous or scaberulous; 

FIGURE 179. Muhlenbergia tenuifolia. A. Habit. B. Spikelet. 

C. Glumes. D. Floret. Drawn by Linda Ann Vorobik and Annaliese 

Miller; copyright Utah State University.
272 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

ligules 1.2–3.0(5.0) mm long, membranous, apex acute, often 

lacerate with age; blades 2–13 cm long, 1.2–2.5 mm wide, flat 

or loosely involute, scaberulous to glabrous below and scabrous 

above. Panicles 7–20 cm long, 1.0–6.5 cm wide, narrow and 

contracted to loosely spreading, interrupted below, terminal and 

axillary, 15–23 nodes per panicle; primary branches 3.5–7.5 cm 

long, usually 1 per node, when immature the branches mostly 

appressed and ascending, when mature the branches sometimes 

widely spreading to 70° from the rachises; pedicels 1–3 mm long, 

usually shorter than the spikelets, antrorsely scabrous, stout, appressed or spreading. Spikelets 2–4 mm long, erect, often purplish; glumes 1.2–2.8 mm long, unequal, 1-veined, scabrous 

along the veins, apex acute to acuminate, often mucronate or 

erose, the mucro to 0.5 mm long; lower glumes 1.2–2.0 mm 

long; upper glumes 1.5–2.8 mm long, more than 1⁄2 as long as the 

lemma; lemmas 2.0–3.5(4.0) mm long, lanceolate, widest near 

the base, awned, scaberulous above and villous on proximal 1⁄2

along the margins and the midvein, the hairs 0.5–1.5 mm long, 

callus short-pubescent, the awn 10–30(40) mm long, scabrous, 

flexuous; paleas 1.8–3.4(3.8) mm long, lanceolate, sparsely 

appressed-pubescent between the veins on the proximal 1⁄2; anthers 0.9–1.5 mm long, yellowish. Caryopsis 1.0–2.2 mm long, 

narrowly fusiform, terete, brownish. 2n = 20, 40.

Distribution and Habitat. Muhlenbergia tenuifolia grows on rocky slopes, limestone rock outcrops, gravelly 

roadsides, and sandy drainages in grama grasslands and oak–

pinyon–juniper woodlands at 1,200–2,500 m. It ranges from southern Arizona, New Mexico, and Texas south throughout Mexico in 

the mountains to Venezuela, Bolivia, Peru, and Argentina.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 15.6 mi NE of El Vergel on Hwy 24, 2000 m, P.M. 

Peterson & Annable 4062 (TAES, US); 11 mi SE of Balleza on 

road to Parral, 1800, P.M. Peterson, M.B. Knowles, C.H. Dietrich & S.M. Braxton 13524 (US); 56.4 km W of Parral on road 

to Balleza and 35.5 km S of Balleza on Mex 432, near Corral 

de Duarte, 2210 m, P.M. Peterson, Annable & Valdés-Reyna 

10712 (US); 7.4 km W of Balleza on road to Guachochi, 1660 

m, P.M. Peterson, Annable & Valdés-Reyna 10735 (US); 10 mi 

SW of El Ojito, 12 Sep 2006, 1902 m, P.M. Peterson 20017, 

F. Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, US). Batopilas: 7.4 km SW of La Bufa and 15 km NE of Batopilas, 920 

m, thorn scrub vegetation, 20 Sep 1991, P.M. Peterson, Annable & Valdés-Reyna 10848 (US); 33 mi S of Creel on road 

to Batopilas, 1810 m, P.M. Peterson & R.M. King 8038 (US). 

Bocoyna: 20 km S of San Juanito on road to Creel and 3 km S 

of Bocoyna, 2330 m, Y. Herrera, P.M. Peterson & Annable 962 

(ENCB). Buenaventura: 15 mi W of Flores Magón, Reeder & C. 

Reeder 3498 (US). Casas Grandes: 20 km al SE de Nuevo Casas 

Grandes, 2100 m, Hern.-Xol–10428 (US); About 43 mi SW of 

Casas Grandes, 2100 m, Spellenberg, N. Zucker, Bye & R. Corral 12256 (CIIDIR). Cuauhtémoc: Rancho La Estancia, 2300 m, 

M.E. Siqueiros 1722 (MEXU). Chihuahua: 39 km Carr. [hwy] 

Chihuahua–Namiquipa, 2300 m, M. Vergara 192 (MEXU); Río 

Bonito, 2000 m, LeSueur 091 (US); Rocky hills near Chihuahua, 

1800 m, C.G. Pringle 428 (US); Chihuahua, 1800 m, Hitchcock 

7779, 7787 (US); Hills near Chihuahua, 1800 m, C.G. Pringle 

397, 929 (ENCB); 9.1 mi W of Hwy 45 on dirt road towards 

Santa Clara, 1690 m, P.M. Peterson & Annable 12586 (US). 

Guachochi: 38.4 mi W of Guachochi on Mexico 127 towards 

Creel, 2440 m, M.E. Siqueiros 1634 (MEXU); 8.8 km NE of 

La Bufa and 4.8 km S of Kirare, 1730 m, P.M. Peterson, Annable & Valdés-Reyna 10822 (US); Parque Nacional Barranca 

del Cobre, 1.6 km E of La Bufa, 1950 m, P.M. Peterson & M.B. 

Knowles 13581 (US); 15.4 mi S of Mex 127 and 5.5 mi N of La 

Bufa, 1845 m, P.M. Peterson & R.M. King 8056 (US); Yamuco 

at 1 km E of Hwy towards Basihuare and Creel, N of Rio Urique 

crossing, 1891 m, P.M. Peterson & P. Catalán 17552 (US); West 

of Munérachi along route (trail) to Sorichique, 1701 m, P.M. Peterson & P. Catalán 17706 (US). Hidalgo del Parral: 13.5 mi W 

of Parral on Hwy 24 towards El Vergel, 2000 m, P.M. Peterson 

& Annable 4555 (ENCB, US); 26 mi NE of Parral, 2100 m, F.W. 

Gould & J. Morrow 7945 (TAES); NE edge of Parral, Correll 

22682, 22686 (US); 3 mi NE of Parral on Hwy 45 towards Chihuahua, 2000 m, P.M. Peterson & Annable 4059 (TAES, US); 3 

mi E of Parral, Reeder & C. Reeder 3454 (US); 1.5 mi NE of Parral on Hwy 45 towards Chihuahua, 2000 m, P.M. Peterson & 

Annable 4060 (TAES, US); 12 km al NE de Hidalgo del Parral, 2 

km al N de La Estancia, 1740 m, E. Aldrete s.n. (INEGI); 13 km 

al NE de Hidalgo del Parral, 1740 m, E. Aldrete s.n. (INEGI); 36 

mi N of Parral on MEX 24 towards Chihuahua, 2000 m, P.M. 

Peterson & R.M. King 8102 (US). Ignacio Zaragoza: 12.6 mi NE 

of Ignacio Zaragoza, 2400 m, P.M. Peterson & R.M. King 8163, 

8164 (US). Jiménez: Sta Eulalia Mts, C.G. Pringle 396 (US); E. 

Wilkinson 40, 48 (US); 2 km N of San Antonio, Sierra de Sta 

Eulalia, L. H. Harvey 1513 (US); 24 mi NW of Chihuahua–Durango State line, 1580 m, Reeder & C. Reeder 4838 (ENCB, US); 

Vicinity of Sta Eulalia, 1300 m, E. Palmer 133 (US). Matamoros: 

12 mi S of Villa Matamoros on Hwy 45 towards Parral, 1900 

m, P.M. Peterson & Annable 4085 (TAES, US); P.M. Peterson & 

R.M. King 8253 (US); 19.3 km S of Villa Matamoros on Hwy 45 

to Durango, 1800 m, P.M. Peterson & Annable 5975 (US). Riva 

Palacio: 0.7 mi W of Nuevo Majalca, 8.5 mi W of Hwy 45, 1700 

m, P.M. Peterson & Annable 4513 (US); 38 km W of Hwy 45 on 

road towards Benito Juárez, 2230 m, P.M. Peterson 12554 (US). 

San Francisco del Oro: Ejido Corral de Duarte, 1950 m, E.S. 

Blanco 1553 (MEXU); 23 km al NW de San Francisco, 2100 m, 

Dávila, Tenorio & J. Sánchez-Ken 130 (MEXU). Valle de Zaragoza: 54.4 mi N of Parral on Mex 24 to Chihuahua, 2100 m, 

P.M. Peterson, Annable & Y. Herrera 8103, 8104 (US).

271. Muhlenbergia texana Buckley, Proc. Acad. Nat. Sci. Philadelphia 14: 91. 1862.

FIGURE 180

Caespitose, delicate annual. Culms 10–40 cm tall, erect, 

strigulose below the nodes; internodes 9–35 mm long. Sheaths 

2.5–4 cm long, shorter or longer than internodes, strigulose; 

ligules 1–2.5 mm long, hyaline, apex lacerate, acute to obtuse; 
NUMBER 107 • 273

blades 2–8 cm long, 0.8–2 mm wide, flat or involute, scabrous to 

sparsely strigulose. Panicles 9–20 cm long, 2–6 cm wide; branches 

1–6 cm long, ascending or open, occasionally capillary, spreading 

up to 70° from the culm axis; pedicels 2–7 mm long, longer than 

florets, usually spreading. Spikelets 1.4–2.2 mm long, ascending, 

straight; glumes 0.8–1.5 mm long, subequal, sparsely hirsute 

to pilose near apex and along margins, 1-veined, apex acute or 

acuminate; lower glumes 0.8–1.2 mm long; upper glumes 0.9–

1.5 mm long, slightly wider near base than lower glume; lemmas 1.4–2.2 mm long, lanceolate, awned, short-pubescent along 

the raised midvein and margins on proximal 1⁄2 , apex acute or 

acuminate, mucronate or with awn up to 2 mm long; paleas 1.4–

2.2 mm long, oblong-elliptic, minutely appressed-pubescent at 

the base, apex acute; anthers 0.4–0.5 mm long, purplish. Caryopsis 0.8–1 mm long, fusiform, brown. n = 20. 

Distribution and Habitat. Muhlenbergia 

texana grows in oak–pine–cedar forests at elevations of 1,420–

2,650 m. It ranges from United States to Mexico in Baja California, Baja California Sur, Chihuahua, Durango, Nayarit, Sinaloa, 

and Sonora.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 64.5 km W of Balleza and 30.6 km E of Guachochi, 2650 

m, P.M. Peterson & Annable 5937, 10777 (US); 56.4 km W of 

Parral on road to Balleza and 35.5 km S of Balleza, 2210 m, P.M. 

Peterson, Annable & Valdés-Reyna 10720 (US). Batopilas: 22 

km al S de Humira, 21.8 km al SW de la dev. a La Bufa, 2070 m, 

Tenorio & R. Torres 3690, 3691 (MEXU). Bocoyna: Cabecera 

de la cañada de Recogoata, 2400 m, B. Tah V. 44-A (MEXU). 

Casas Grandes: 3 mi S of Hernández Javales, 32 mi SW of Col. 

Juárez, 2200 m, P.M. Peterson & Annable 4045 (US); 21 mi SW 

of Col. Juárez on road to Hernández Javales, 2200 m, P.M. Peterson & Annable 4028 (US); 3 mi W of Cuesta Blanca, W of Casas 

Grandes, Reeder & C. Reeder 3216, 3217 (US). Chinipas: Sierra 

Milpillas 28.1 mi E of Los Tanques on road to Chínipas, 1.6 mi N 

of Los Chinicas, 2100 m, P.M. Peterson & Annable 4175 (TAES, 

US); 3.4 mi W of Saguarivo on road to Chinacas, 10 Sep 2008, 

rocky slopes with Acacia, Opuntia, Quercus, 1617 m, P.M. Peterson & J.M. Saarela 22169 (US); Sierra Milpillas, 24.1 mi E of Los 

Tanques on road to Milpillas, 2100 m, A.A. Beetle, R. Alcaráz & 

R. Cuadra M-9085, 9203, 9206, M-9251 (MEXU); Saguarivo, 

53 mi N of Alamos, 9 Sep 2008, slopes with oaks and pines, 

1540 m, P.M. Peterson & J.M. Saarela 22136 (US). Guachochi: 

Parque Nacional Barranca del Cobre, 24.8 km NE of La Bufa on 

road to Samachic, 2440 m, P.M. Peterson, Annable & ValdésReyna 10802 (US); 28.3 km S of Cusarare on road to Guachochi, 

entering Barranca del Cobre, 1900 m, P.M. Peterson & Annable 

5907 (US); 25.6 mi S of Creel on road to Batopilas, 2100 m, P.M. 

Peterson & Annable 8037 (US); 24.3 mi S of Creel on road to 

Batopilas at Barranca del Cobre, 1930 m, P.M. Peterson, Annable 

& Y. Herrera 8015 (US); Flat rock outcrops at Napuchis, 2140 

m, P.M. Peterson & P. Catalán 17674 (CIIDIR, US); 10.6 mi NE 

of La Bufa on road to Creel, 2235 m, P.M. Peterson, Annable 

& Y. Herrera 8070 (US); Parque Nacional Barranca del Cobre, 

13.6 mi NE of La Bufa on road towards Samachique, 2240 m, 

FIGURE 180. Muhlenbergia texana. A. Habit. B. Glumes. C. Two 

florets. Drawn by Linda Ann Vorobik and Annaliese Miller; copyright Utah State University.
274 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

P.M. Peterson, M.B. Knowles, C.H. Dietrich & S.M. Braxton 

13569 (US); 5.5 mi S of Cieneguita de Barranca on road towards 

Sorichique, 2125 m, P.M. Peterson, P. Catalán, C. López, & 

G.Villegar 17704 (US). Guerrero: 16 km SW of La Junta on road 

to Creel, 2270 m, P.M. Peterson & Annable 9613 (US); 4.5 mi 

W of Tomóchic on Hwy 16, 2200 m, P.M. Peterson & Annable 

4542 (TAES, US); 35.4 km SW of La Junta and 74 km N of Creel, 

2200 m, P.M. Peterson & Annable 5827, 5829 (US); 54.3 km W 

of La Junta on road to Parque Nacional Cascada Basaseachic, 

30 Sep 1989, 2260 m, P.M. Peterson & R.M. King 8215 (US). 

Madera: 12 mi SW of Madera of Hwy 16 towards Cuauhtémoc, 

2100 m, P.M. Peterson & Annable 4049 (TAES, US); 15 mi S of 

Madera, 2165 m, Reeder & C. Reeder 2636 (US). Matamoros: 

18.2 km SE of Villa Matamoros on Mex 45 to Durango, 1780 m, 

P.M. Peterson, Annable & Valdés-Reyna 10862 (US). Moris: 9.6 

mi E of Maycoba on Hwy 16 towards Yepachic, 1420 m, P.M. 

Peterson & Annable 12508 (US); Approx. 17.6 mi E of Maycoba 

on Hwy 16 towards Yepachic and 2 mi E of Sonora/Chihuahua 

boundary, 1540 m, P.M. Peterson & Annable 12512 (US). Ocampo: Cascada de Basaseachic, 37 mi W Tomóchic, 2200 m, P.M. 

Peterson & Annable 4545 (US); Along trail just above Cascada 

Basaseachic, 1880 m, P.M. Peterson & Annable 12524, 12525, 

12538 (US). 76 mi W of La Junta and 35.2 mi W of Tomochic in 

Parque Nacional Cascada de Basaseachic, 2100 m, P.M. Peterson 

& R.M. King 8227, 8245 (US). Uruáchi: 1.8 mi W of Yécora on 

Hwy 16 towards Maycoba, 1860 m, P.M. Peterson & J. Cayouette 15316 (US); 9 mi E of Yécora on Hwy 16 towards Maycoba 

and 10.7 mi S on a dirt road toward Talayote, 1800 m, P.M. 

Peterson & Annable 12483 (US).

272. Muhlenbergia torreyi (Kunth) Hitchc. ex Bush, Amer. Midl. 

Naturalist 6: 84. 1919.

FIGURE 181

Caespitose perennial. Culms 10–40(50) cm tall, decumbent at base, hirsute below the nodes, usually no culm nodes 

exposed above the tightly clustered leafy base, the leafy portion 

not reaching more than 1⁄5 the plant height; internodes mostly 

scabrous to glabrous. Sheaths 0.1–2.5(3.2) cm long, shorter than 

the internodes, scaberulous to glabrous, margins hyaline; ligules 

2–5(7) mm long, hyaline, often splitting down the middle and 

appearing as auricles, apex acuminate, lacerate, margins entire; 

blades 1–3(5) cm long, 0.3–0.9 mm wide, tightly involute or 

folded, arcuate, somewhat sharp pointed, scaberulous. Panicles 

7–21 cm long, 3–15 cm wide, open, diffuse; primary branches 

1–8 cm long, ascending to stiffly spreading at maturity 30°–90° 

from the rachises; pedicels 1–8 mm long, erect, sometimes appressed to the branches. Spikelets 2–3.5 mm long, erect; glumes 

1.3–2.5 mm long, about equal in length, 1-veined, awnless, 

mucronate or awned, scaberulous toward apex, apex acute to 

acuminate, minutely erose, the mucro or awn to 1.1 mm long; 

lemmas 2–3.2(3.5) mm long, narrow elliptic to lanceolate, mucronate or awned, appressed-pubescent on the margins and midvein on the proximal 1⁄2 to 3⁄4, scabrous above, apex acuminate, 

the mucro or awn 0.5–4 mm long; paleas 2–3.2(3.5) mm long, 

narrow elliptic, sparsely pubescent between the veins, apex acuminate, sometimes with 2 mucros, the mucros 0.2 mm long; anthers 1.2–2.1 mm long, greenish. Caryopsis 1.7–2.0 mm long, 

fusiform, brownish. 2n = 20, 21.

Distribution and Habitat. Muhlenbergia torreyi grows in desert grasslands, sandy mesas, calcareous rock 

outcrops, rocky slopes, and open woodlands at 1,000–2,450 m; 

it ranges from the south central United States to northern Mexico in Chihuahua and Sonora and is disjunct in northwestern 

Argentina and Bolivia.

Specimens Examined. MEXICO. Chihuahua. 

Janos: Chihuahua–Sonora border, Rancho Carretas, 1780 m, 

A.A. Beetle M-7975 (MEXU).

273. Muhlenbergia tricholepis (Torr.) Columbus, Aliso 28: 66. 

2010. Blepharoneuron tricholepis (Torr.) Nash, Bull. Torrey 

Bot. Club 25(2): 88. 1898. Muhlenbergia tricholepis (Torr.) 

P. M. Peterson, Amer. J. Bot. 97(9): 1546. 2010.

Densely tufted, caespitose perennial. Culms 10–70 cm tall, 

0.3–0.7 mm diameter just below the inflorescence, glabrous to 

scabrous just above and below nodes, slender, erect; internodes 

1.2–10 cm long. Sheaths 1.8–9.5 cm long, shorter or longer than 

internodes, usually glabrous, crowded near the base, the margins 

glabrous, occasionally scabrous, whitish; ligules (0.3)0.7–2(2.7) 

mm long, hyaline to opaque, truncate to obtuse, margins entire, 

decurrent, apex erose-toothed to finely ciliate and irregularly 

toothed; blades 1–15 cm long, 0.6–2.5 mm wide, filiform, involute, arcuate, scabrous in both surfaces, the midvein evident, 

raised abaxially. Panicles 3–25 cm long, 1–10 cm wide, narrow 

or open; primary branches 1–6 cm long, ascending, spreading up 

to 50° from the rachises, 1–3 per node; pedicels 2–9 mm long, 

slender, capillary, minutely granular just below the spikelet, 

flexuous nodding to reflexed; 5–25 nodes per panicle. Spikelets 

2.3–3.4(3.8) mm long, grayish-green; glumes (1.5)1.8–3.2(3.7) 

mm long, nearly equal to subequal in length, grayish-green 

(olivaceous) and occasionally purplish tinged, glabrous, ovate 

to oblong-elliptical, the apex obtuse to acute often irregularly 

toothed; lower glumes (1.5)1.8–2.6(3) mm long; upper glumes 

(1.7)2–3.2(3.7) mm long, broader and often appearing 3-veined 

by its characteristic folding, however, only the midvein contains 

a vascular trace; lemmas (2)2.3–3.4(3.8) mm long, lanceolate, 

grayish-green (olivaceous), often purplish tinged, apex acute to 

obtuse with a thick covering of appressed to spreading tawny to 

shining silky hairs on the midvein and margins, the hairs to 1.2 

mm long; paleas (2)2.2–3.5(3.9) mm long, densely villous between the veins; anthers 1.2–2.1 mm long, brownish. Caryopsis 

1.2–1.4 mm long, fusiform to elliptic, the embryo with a dorsal 

ridge extending 2⁄3 of the grain, light brownish. 2n = 16.

Distribution and Habitat. Muhlenbergia 

tricholepis occurs in dry rocky to sandy slopes, canyon walls, rock 

outcrops, dry meadows, and open woods in pine–oak–madrone 

forests with Arctostaphylos spp., pinyon–juniper woodlands, 

spruce–fir forests, and pine woodlands at 700–3,660 m. It occurs 
NUMBER 107 • 275

in central Mexico north throughout the Sierra Madre Occidental 

and Sierra Madre Oriental.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 19.3 km E of Guachochi, 26 Sep 1988, pine forest, 

2300 m, P.M. Peterson & Annable 5924 (ENCB, MEXU, US); 

29 km E of Guachochi on Mex 127 towards Balleza, 13 Sep 

1989, 2600 m, P.M. Peterson, Annable & Y. Herrera 8086

(ENCB, MEXU, US). Batopilas: SW Chihuahua, Aug 1885, 

E. Palmer 6 (MEXU, US); Between Quirire and basigochic, 

4 Jun 1974, pine–oak, 7000 ft, Bye 6126 (MEXU). Bocoyna: 

Sánchez, 12 Oct 1910, Hitchcock 7670 (MEXU, US); cabecera 

de la cañada de Bocogoata, 22 Sep 1997, pine forest–encino en 

cañada [oak glen], 2400 m, B. Tah V. 40 (MEXU); SW of Creel 

around small mesas S of old Sánchez road, 30 Oct 1972, Bye 

FIGURE 181. Muhlenbergia torreyi. A. Habit. B. Inflorescence. C. Glumes. D. Floret. 

Drawn by Linda Ann Vorobik and Annaliese Miller; copyright Utah State University.
276 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

3049 (MEXU); NW of Cusarare near boundary with san Ignacio 

Arareco, 15 Oct 1973, pine–oak, 7200 ft, Bye 5451 (MEXU). 

Casas Grandes: W of Casas Grandes, 3 mi E of Cuesta Blanca, 

4 Sep 1958, 2073 m, Reeder & C. Reeder 3221 (ARIZ, ENCB, 

US); W of Casas Grandes, 5 mi S of Hernández, 18 Sep 1960, 

7000 ft, Reeder, C. Reeder &Soderstrom 3520 (ARIZ, ENCB, 

MEXU). Chihuahua: Summits Mapula Mts, 26 Oct 1886, C.G. 

Pringle 822 (ENCB, MEXU, US); 32 km W of hwy 45 towards 

Benito Juárez, 17 Oct 1992, pinyon woodlands, 2110 m, P.M. 

Peterson & Annable 12551 (US); 38 km W of hwy 45 on road 

towards Benito Juárez, 17 Oct 1992, pinyon woodlands, 2230 

m, P.M. Peterson & Annable 12577 (US); 17.5 mi W of hwy 45 

on road up Los Prietos Canyon, 18 Oct 1992, pinyon woodlands, 2120 m, P.M. Peterson & Annable 12598 (US). Cuauhtémoc: 11 mi W of Cuauhtemoc, 5 Oct 1966, Reeder & C. Reeder 

4594-Bis (ARIZ). Guachochi: 8.5 km S of Cusarare on road to 

Guachochi, 25 Sep 1988, pine forest, 2400 m, P.M. Peterson & 

Annable 5881 (ENCB, MEXU, US); 24.6 km W of Guachochi 

and 0.6 km S of Rocheachi, 2340 m, P.M. Peterson, Annable 

& Valdés-Reyna 10782 (US); Cusarare along arroyo just NW 

of cusarare church, 14 Oct 1977, 2200 m, Bye & W.A. Weber 

8122 (MEXU); East of Yahuiriachic east of Cusarare, 16 Oct 

1973, pine–oak, 2100 m, Bye 5457 (MEXU). Guerrero: 10 km 

S La Junta; carr. [hwy] La Junta–Temochi, 5 Oct 74, pine forest–encino, 1900 m, Valdés-Reyna VR-710 RELC); km 193 carr. 

Chihuahua–Hermosillo tramo [section] San Pedro Temochic, 24 

Sep 1997, 2200 m, M.A. Vergara 172 (MEXU); 24 Sep 1997, 

pine forest, 2200 m, M.A. Vergara167 (MEXU); 46.7 km W of 

La Junta on road to Parque Nacional Cascada de Basaseachic, 

30 Sep 1989, 2260 m, P.M. Peterson & R.M. King 8198 (US). 

Madera: near Col. Garcia in the Sierra Madre, 15 Sep 1899, 

2300 m, C.H.T. Townsend & C.M. Barber 333 (US). About 7 

mi NW of Madera on a rocky slope with scattered pines, oaks, 

and junipers, 10 Oct 1953, 2195 m, Reeder & C. Reeder 2661

(ENCB, MEXU). Ocampo: Parque Nacional “Cascada de Basaseachic,” at overlook ca. 1 km airline S of Cascada, 5 Oct 

1986, 2100 m, Spellenberg, Soreng, R. Corral & T. Lebgue 8869 

(NMC). Riva Palacio: Parque Nacional, 0.4 mi E of Cumbres de 

Majalca, 21.1 mi W of hwy, 20 Sep 1986, bosque de pino [pine 

forest], 2200 m, P.M. Peterson & Annable 4521 (ENCB, US). 

Tomachic: al lado [side] de la carr. a Creel, Tomachic, 17 Sep 

1975, J. Passini & M.F. Robert 6908 (ENCB). Zaragoza: 5.3 km 

al sur [S] de Lalolandia, 27 Oct 77, pine forest–encino, 2200 m, 

S. González & J.M. Peña 792 (RELC).

274. Muhlenbergia uniseta (Lag.) Columbus, Aliso 28: 66. 

2010. Hymenothecium unisetum Lag., Gen. Sp. Pl. 4. 1816.

Aegopogon tenellus (DC.) Trin.

FIGURE 149A,B

Slender often sprawling, caespitose annual. Culms (2) 6–30 

cm tall, glabrous below the nodes; internodes 0.6–6 cm long, 

glabrous to pilose. Sheaths mostly 0.5–4.8 cm long, shorter 

than the internodes, glabrous to sparsely pilose; ligules 0.6–1.5 

mm long, apex mostly truncate, lacerate; blades 1.5–6 cm long, 

0.5–1.5(1.7) mm wide, flat, scaberulent and pubescent above, 

smooth beneath. Panicles 2–6 cm long, 0.5–1.2 cm wide, open, 

loosely flowered; racemose primary branches 3–5 mm long, excluding the awns, 1 per node. Spikelets 1.5–3.2 mm long, often 

greenish or purplish, the clusters with 1 short-pedicelled spikelet 

(perfect), the pedicels 0.2–0.6 mm long, and the other 2 spikelets 

(staminate or sterile) short-pedicelled, the pedicels about 0.7–1.5 

mm long; glumes (1)1.3–2 mm long, oblong and wider distally, 

apex deeply notched, entire or mucronate, the mucro 0.2–1 mm 

long, lobes obtuse or rounded; lemmas 2.5–3.2 mm long, 3-

awned, the central awns 3–8(11) mm long, lateral awns usually 

mucronate or awned up to 2 mm long or missing; paleas 2.2–3 

mm long, puberulent, apex 2-mucronate, the mucros less than 

0.8 mm long; anthers 0.5–0.8 mm long, yellowish. Caryopsis 

1.1–1.3 mm long, obovoid, light brownish. 2n = 20, 60.

Distribution and Habitat. Muhlenbergia uniseta grows on moist slopes, cliffs, canyons, roadsides and along 

or near springs, usually in shaded areas associated with Pinus 

and Quercus, at 1,300–2,860 m. It ranges from southern Arizona to most of Mexico and Central America.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 56.4 km W of Parral on road to Balleza and 35.5 km 

S of Balleza, 18 Sep 1991, pine forest–encino [oak], 2210 m, 

P.M. Peterson, Annable & Valdés-Reyna 10700 (CIIDIR). Casas 

Grandes: W of Casas Grandes, 2 mi NE of Cuesta Blanca, 18 

Sep 1960, Reeder, C. Reeder & Soderstrom 3540 (ARIZ). Chinipas: Saguarivo, 53 mi N of Alamos, 9 Sep 2008, slopes with 

oaks and pines, 1540 m, P.M. Peterson & J.M. Saarela 22110 

(US); Sierra Saguarivo, 1.3 mi W of Curahui, 9 Sep 2008, tropical deciduous forest, 1001 m, P.M. Peterson & J.M. Saarela 

22149 (US). Chihuahua: Chihuahua, 27 Apr 1908, E. Palmer 

28 (US). Gómez Farías: Laguna de Babicora, Cerro Canoas, 3 

Sep 1994, 2400 m, T. Lebgue, G. Quintana & E. Estrada 2921

(NMC). Guachochi: Yamuco, 1 mi E of hwy N of Rio Urique 

crossing towards Basihuare and Creel, 5 Sep 2008, 1890 m, P.M. 

Peterson & J.M. Saarela 22044 (US); 5.5 mi S of Cienegulta 

de Barranca on road towards Sorichique, 5 Sep 2003, pine forest–encino, 2125 m, P.M. Peterson & P. Catalán 17701 (US); 

Steep slopes above Barranca Basihuare, 28 Aug 2003, pine forest–encino, 1815 m, P.M. Peterson & P. Catalán 17575 (US). 

Guerrero: Tomochi, 2 km alrededor del poblado [around the 

village], 24 Sep 1987, pine forest, 2100 m, M.A. Vergara 150

(CIIDIR, ENCB); Arroyo ancho, 15 Oct 1887, C.G. Pringle 

1408 (US); Ignacio Zaragoza: 20.3 km NE of Ignacio Zaragoza 

on Mex 23, 28 Sep 1989, pine woods, 2400 m, P.M. Peterson 

& R.M. King 8152 (ENCB). Madera: La Tinaja, ejido El Long, 

29 Aug 1990, bosque de encino-pino [oak–pine forest], 1840 m, 

O. Bravo 1334 (CIIDIR, ENCB); 3 km al Noreste de Madera, 5 

Oct 74, bosque de pino–encino, 2000 m. Valdés-Reyna VR–689, 

VR–646 (RELC). Ocampo: Parque Nacional “Cascada de Basaseachic,” in camp ground area, 22 Sep 1994, 2000 m, Spellenberg, Corral, Estrada & Mahrt 12072 (NMC); Parque Nacional 

“Cascada de Basaseachic,” at overlook ca. 1 km airline S of Cascada, 3 Oct 1986, 2100 m, Spellenberg, Soreng, R. Corral & 

T. Lebgue 8649 (NMC); Near Mirador of Cascada Basaseachic, 
NUMBER 107 • 277

2022 m, slopes with Pinus, 7 Sep 2008, P.M. Peterson & J.M. 

Saarela 22098 (US). San Francisco del Oro: San Francisco del 

Oro mines, 20 mi from Parral, Soderstrom 876 (US).

275. Muhlenbergia utilis (Torr.) Hitchc., J. Wash. Acad. Sci. 

23(10): 453. 1933.

FIGURE 175E–I

Perennial; with slender, scaly rhizomes. Culms 7–30 cm tall, 

erect to decumbent, older plants trailing, up to 1 m long, minutely pubescent to glabrous below the nodes; internodes mostly 

smooth to lightly nodulose roughened. Sheaths 0.3–2.4 cm long, 

shorter or longer than the internodes, glabrous, margins hyaline; 

ligules 0.2–0.8 mm long, membranous, decurrent, apex truncate; 

blades 0.5–4.7 cm long, 0.2–1.8 mm wide, involute, sometimes 

flat, straight or arcuate-spreading, blades often at right angles 

to culms, mostly glabrous abaxially and hirsutulous adaxially. 

Panicles 1–5 cm long, 0.1–0.4 cm wide, narrow, contracted, interrupted between each branch, partially included in the upper 

sheaths; primary branches 0.2–1.2 cm long, appressed, rarely ascending to 30° from the rachises; rachises usually visible between 

the branches; pedicels 0.1–1.1 mm long, glabrous. Spikelets 1.4–

2.4 mm long, erect; glumes 0.5–1.4 mm long, 1⁄3 to 1⁄2 as long 

as the lemma, subequal, unawned, glabrous, usually 1-veined, 

occasionally 2- to 3-veined, yellowish to light green, apex acute; 

lemmas 1.3–2.4 mm long, lanceolate, unawned, glabrous or with 

minute appressed pubescence along the margins and the base, the 

hairs about 0.1 mm long, green or purplish, apex acute; paleas 

1–2 mm long, lanceolate, glabrous, apex acute; anthers 0.7–1.4 

mm long, yellow to purplish. Caryopsis 0.7–1.2 mm long, ellipsoid to ovoid, brown. 2n = 20.

Distribution and Habitat. Muhlenbergia utilis occurs in wet soils along streams, ponds, depressions in grasslands, and alkaline or gypsiferous plains associated with Quercus 

spp. at 200–2,500 m. It ranges from the southern United States 

to Mexico in Chiapas, Chihuahua, Durango, Guanajuato, Hidalgo, Jalisco, México, Distrito Federal , Michoacán, Puebla, 

Querétaro, Sonora, Veracruz, and Zacatecas, and to Costa Rica.

Specimens Examined. MEXICO. Chihuahua. 

Casas Grandes: 5 km al NE de Cuesta Blanca, 1980 m, M.A. 

Martínez s.n. (ENCB). Cuauhtémoc: 12 mi W of Cuauhtemoc, 

2128 m, Reeder & C. Reeder 2622 (ENCB, US). Chihuahua: 

Hills near Chihuahua, 1800 m, C.G. Pringle 418 (US); La Campana, 10 km W carr. [hwy] Panamericana, 1700 m, F.W. Gould 

8911 (TAES). Madera: Mesa de El Poleo, ejido El Long, 2400 m, 

Blanco 08/77 (IBUG).

276. Muhlenbergia vaginata Swallen, Contr. U.S. Natl. Herb. 

29(9): 406. 1950. 

Annual or short-lived perennial. Culms 16–40 cm tall, 

lax, slender, glabrous, decumbent, rooting at the lower nodes. 

Sheaths 0.7–1.6 cm long, shorter than the internodes, glabrous; 

ligules 1.3–3 mm long, hyaline, apex acute to obtuse, decurrent; 

blades 0.5–3.5(4) cm long, 0.6–1.8(2) mm wide, mostly cauline, 

flat or folded, with navicular apex, glabrous to scabrous. Panicles 

0.5–3 cm long, 3–7 mm wide, frequently partially included in the 

upper sheath; branches 3–10 mm long, ascending or appressed; 

pedicels 0.5–3 mm long, appressed, scabrous. Spikelets 1.6–2.5 

mm long; glumes 0.6–1 mm long, subequal, glabrous, 1-veined, 

oblong to ovate, light green to green-grayish, apex obtuse, 

rounded to subacute, occasionally erose; lower glumes 0.6–0.8 

mm long; upper glumes 0.6–1 mm long; lemmas 1.6–2.5 mm 

long, lanceolate, sparsely pubescent below and along the midvein and margins, mottled with olive-green spots, often purplish, 

apex scabrous, acuminate, sometimes mucronate, the mucro 0.2 

mm long; palea 1.5–2.5 mm long, lanceolate, glabrous or with a 

few hairs between the veins; anthers 0.5–0.8 mm long, purplish. 

Caryopsis 1–1.2 mm long, ellipsoid to fusiform, brown. n = 9. 

Distribution and Habitat. Muhlenbergia 

vaginata occurs in pine–oak forests at elevations of 1,880–2,400 

m and ranges from Mexico to Central America. In Mexico it is 

found in Chiapas, Chihuahua, Distrito Federal, Durango, Hidalgo, Jalisco, México, Michoacán, Morelos, Puebla, Querétaro, 

Sinaloa, Tlaxcala, and Veracruz.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 0.5 mi NE El Vergel, 6 Sep 1985, 2100 m, P.M. Peterson 

& Annable 4070 (US). Batopilas: Hacienda San Miguel, near 

Batopilas, 2100 m, E. Palmer 17 (TAES, US); 308 (TAES). Bocoyna: 18.7 mi S of San Juanito on road to Creel, 2200 m, P.M. 

Peterson & Annable 5862 (US); 33.7 mi W of La Junta on road 

to Parque Nacional Cascada Basaseachic, 30 Sep 1989, 2260 m, 

P.M. Peterson & R.M. King 8220 (US). Carichi: Sánchez, 12 Oct 

1910, 2400 m, Hitchcock 7723 (US). Guachochi: 20.3 km NE 

of La Bufa and 3.2 km S of Basigochi, 2180 m, P.M. Peterson 

& Annable 10816 (US); Flat rock outcrops at Napuchis, 2140 

m, P.M. Peterson & P. Catalán 17668 (CIIDIR, US); 0.6 mi N 

of Guachochi, 2400 m, P.M. Peterson & Annable 5917 (US); 

20.3 mi S of Creel on road towards Rocheachic, 2510 m, P.M. 

Peterson & J. Cayouette 15370 (US). Guadalupe y Calvo: near 

Cumbre Mohinora, 13 Sep 2006, 3300 m, P.M. Peterson 20037, 

F. Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, US). Guerrero: 16 km SW of La Junta on road to Creel, 2270 m, P.M. 

Peterson & Annable 5866 (US); 23.6 mi W of Hwy jct at La 

Junta on road to Tomóchic, 18 mi E of Tomóchic, 2200 m, P.M. 

Peterson & Annable 4538 (ENCB, US); 15.5 mi W of La Junta 

on road to Tomóchic, 15 km mark on Hwy 16, 4 Sep 1985, 2100 

m, P.M. Peterson & Annable 4052 (ENCB, TAES, US). Ocampo: 

Along trail just above Cascada Basaseachic, 1880 m, P.M. Peterson & Annable 12523 (US); Approx. 10 mi E of Basaseachic 

on Hwy towards La Junta, 2110 m, P.M. Peterson & Annable 

12541 (US). Riva Palacio: Cumbres de Majalca, 21.5 mi W of 

Hwy 45, 2200 m, P.M. Peterson & Annable 4575 (ENCB, US). 

277. Muhlenbergia villiflora Hitchc., N. Amer. Fl. 17(6): 470. 

1935.

Perennial; with scaly rhizomes. Culms 4–20(27) cm tall, to 

2 mm thick, erect, wiry, smooth to nodulose roughened below 

the nodes; internodes smooth or nodulose. Sheaths 5–15 cm 

long, shorter than the internodes, about 1⁄2 the length of the 

internodes, glabrous to nodulose roughened, margins hyaline; 
278 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

ligules 0.4–1.5 mm long, membranous, decurrent, apex acute, 

erose and toothed; blades 0.7–2 cm long, 0.2–1.2 mm wide, 

involute, arcuate-spreading, glabrous below and hirsutulous 

above. Panicles 1–5 cm long, 0.1–0.5 cm wide, narrow, contracted, loosely flowered, usually on an exserted peduncle; 

primary branches 0.2–1.1 cm long, appressed, ascending; 

pedicels 0.1–0.8(1.2) mm long, shorter than the spikelets, minutely setose. Spikelets 1.4–2.4 mm long; glumes 0.6–1.8 mm 

long, equal, unawned, glabrous, usually 1-veined, occasionally 

2- to 3-veined, 1⁄2 to 2⁄3 the length of the floret, green or purple, 

apex acute; lemmas 1.4–2.4 mm long, lanceolate, indistinctly 

3-veined, mucronate or not, green or purplish, densely villous 

along the midvein and margins on the proximal 4⁄5, the hairs 

0.4–1 mm long, apex acute, the mucro 0.1–0.6 mm long; paleas 

1.2–2.1 mm long, lanceolate, densely villous between the veins 

on the proximal 2⁄3, apex acute; anthers 0.8–1.5 mm long, yellow, dark green, or purple. Caryopsis 1–1.4 mm long, ellipsoid 

to fusiform, dark brown. 2n = 20, 22.

Distribution and Habitat. Muhlenbergia villiflora occurs in openings primarily on alkaline soils derived from 

gypsum, rocky flats, and desert grasslands, usually in small, isolated populations at 1,500–2,100 m. In Mexico, Muhlenbergia 

villiflora var. villiflora also occurs in Durango, San Luis Potosí, 

and Zacatecas.

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000) and Herrera Arrieta and 

Cortés Ortiz (2010).

278. Muhlenbergia virescens (Kunth) Trin., Gram. Unifl. Sesquifl. 193, t. 5a, f. 7. 1824.

Muhlenbergia straminea Hitchc., Muhlenbergia curvula Swallen.

FIGURE 182

Plants perennial; caespitose. Culms 25–70(100) cm tall, 

erect, rounded near the base; internodes glabrous. Sheaths 

10–30 cm long, glabrous, stiff, becoming flat, ribbonlike or papery, and conspicuously spirally coiled when old; ligules (6)10–

20 mm long, hyaline, acuminate, lacerate; blades 10–30 cm long, 

(0.5)1–4 mm wide, flat to involute, scabrous abaxially, spiculate 

adaxially. Panicles 10–25 cm long, 1–8 cm wide, loosely flowered, stramineous; primary branches 0.6–8 cm long, appressed 

or diverging up to 30° from the rachises; pedicels 0.2–5 mm long, 

scabrous. Spikelets 4–7 mm long, light grayish-green to white; 

glumes 3.5–6(7) mm long, scaberulous, unawned, rarely mucronate; lower glumes shorter than the upper glumes, 1-veined; 

upper glumes equaling or exceeding the florets, 3-veined, apex 

FIGURE 182. Muhlenbergia virescens. A. Habit. B. Inflorescence. 

C. Glumes. D. Floret. Drawn by Linda Ann Vorobik and Annaliese 

Miller; copyright Utah State University.
NUMBER 107 • 279

acuminate to acute; lemmas 3.5–5.5(6) mm long, lanceolate, pubescent on the lower 1⁄2 along the midveins and margins, hairs 

to 1 mm long, apex scabrous, acuminate, awned, the awns 

12–27 mm long, flexuous; paleas 3.5–5.5 mm long, lanceolate, 

pilose between the veins, apex scaberulous, acuminate; anthers 

2–3.5 mm long, purple. Caryopses 1.9–2 mm long, fusiform, 

light brown.

Distribution and Habitat. Muhlenbergia virescens grows on rocky slopes, volcanic tuffs, canyon bottoms, and 

ridges, usually in open pine forests, at elevations of 1,800–2,600 

m. It is known from the southwestern United States and north 

central Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 34 mi W of Balleza on road towards Guachochi, 2500 

m, P.M. Peterson, M.B. Knowles, C.H. Dietrich & S.M. Braxton 

13547 (US); 45 mi W of Balleza on road towards Guachochi, 

2560 m, P.M. Peterson, M.B. Knowles, C.H. Dietrich & S.M. 

Braxton 13552 (US). Batopilas: Rancho Byarly, Sierra Charuco, 

17–25 Apr 1948, 1700 m, Gentry 8143 (US); 10 mi E of jct 

to Batopilas, on road to Guachochi, 2500 m, Y. Herrera, P.M. 

Peteson & Annable 973 (CIIDIR, US); Brecha Samachique–

Batopilas, 1800 m, A. Rodríguez & J. Enrique 1606 (CHAPA). 

Bocoyna: 20 km S of San Juanito on road to Creel and 3 km S 

of Bocoyna, 2330 m, Y. Herrera, P.M. Peteson & Annable 963

(CIIDIR, US); NE of San Ignacio Arreco, in old road to Panalachic, 2466 m, Bye 3054 (MEXU); 20 km S of San Juanito on 

road to Creel and 3 km S of Bocoyna, 10 Sep 1989, 2330 m, P.M. 

Peterson, Annable & Y. Herrera 8006 (US). Buenaventura: Hills 

near Buenaventura, 1950 m, A.A. Beetle M-7878 (MEXU). Guachochi: Ca 3.5 mi SE of Tónachic, 2200 m, R. McVaugh 11507

(US); 11 km al SW de Cuasarare, 2420 m, M.E. Siqueiros 790

(MEXU); Camino Guachochi–Creel, 5 km antes del entronque 

[before junction] a la Bufa, 2440 m, E. Blanco 1621 (MEXU); 

M.E. Siqueiros 1621 (MEXU); 8.5 km S of Cusarare on road 

to Guachochi, 24 Sep 1988, 2400 m, P.M. Peterson & Annable 

5876, 5877 (US); 28.3 km S of Cusarare on road to Guachochi, 

entering Barranca del Cobre, 26 Sep 1988, 1900 m, P.M. Peterson & Annable 5913 (US); 19.3 km E of Guachochi, 26 Sep 

1988, 2300 m, P.M. Peterson & Annable 5929 (US); 18 mi E of 

Guachochi on Mex 127 towards Balleza, 13 Sep 1989, 2680 m, 

P.M. Peterson, Annable & Y. Herrera 8073 (US); 5.8 mi N of 

Creel on road (Hwy 25) towards San Juanito, 2480 m, P.M. Peterson & J. Cayouette 15364 (US); 11.5 mi NW of Aboreachi on 

road towards Creel, 2500 m, P.M. Peterson, M.B. Knowles, C.H. 

Dietrich & S.M. Braxton 13554, 13556 (US); Parque Nacional 

Barranca del Cobre, 20 mi NW of Aborreachi on road towards 

Creel, 2390 m, P.M. Peterson, M.B. Knowles, C.H. Dietrich & 

S.M. Braxton 13562 (US); Parque Nacional Barranca del Cobre, 

65.3 km W of Guachochi on road towards Batopilas, 2410 m, 

P.M. Peterson, Annable & Valdés-Reyna 10861 (US). Guadalupe 

y Calvo: San Juan, Sierra Chinatú, 2700 m, Correll & Gentry 

22922 (US). Guerrero: Waldungen der Sierra Madre Occidental, 

umgebrung [surroundings] von Sierra Colorada, 4 Apr 1906, 

R. Endlich 1210 (US); 1226 (US); About 5 mi SE Guerrero, 2130 

m, A.A. Beetle M-3280 (MEXU). Ignacio Zaragoza: 20.3 km 

NE of Ignacio Zaragoza on Mex 23, 28 Sep 1989, 2400 m, P.M. 

Peterson & R.M. King 8150 (US). Madera: 12 mi SW of Chuhichupa, 2260 m, Spellenberg & J. Zimmerman 8952 (CIIDIR). 

Nuevo Casas Grandes: Al NE del campo Menonita, 1900 m, 

M.A. López s.n. (INEGI). Ocampo: 122.5 km W of La Junta 

and 56.7 km W of Tomochic in Parque Nacional Cascada de 

Basaseachic, 1 Oct 1989, 2100 m, P.M. Peterson & R.M. King 

8234 (US). Temósachi: Between Yeporema and Baviacora, 2250 

m, Correll & M.I. Johnston 21634 (US). 

279. Muhlenbergia wrightii Vasey ex J. M. Coult., Man. Bot. 

Rocky Mt. 409. 1885.

FIGURE 183

Caespitose perennial. Culms 15–60 cm tall, erect with 

knotty, thickened bases, flattened, strigose to hirsute below the 

nodes; internodes hirsute to almost glabrous. Sheaths 1.2–7.5 cm 

long, mostly shorter than the internodes, glabrous to scaberulous, compressed-keeled near the base; ligules 1–3(5) mm long, 

membranous, apex truncate; blades 1.4–12 cm long, 1–3 mm 

wide, flat to folded, slightly keeled, strigose adaxially glabrous to 

scaberulous abaxially. Panicles 5–16 cm long, 0.2–1.2 cm wide, 

narrow, densely flowered, contracted and spikelike; branches 

0.3–2 cm long, ascending and tightly appressed; pedicels 0.1–

1.4 mm long, shorter than the spikelets. Spikelets 2–3 mm long, 

dark green or plumbeous; glumes 0.5–1.6 mm long, about equal, 

1-veined, mucronate, scaberulous along midvein, apex abruptly 

narrowed, acute or obtuse, the mucros 0.5–1 mm long; lemmas 2–3 mm long, lanceolate, mucronate, plumbeous, sometimes mottled with greenish-black areas and lighter areas, with 

short appressed pubescence along the margins and midvein on 

the proximal 1⁄2 to 3⁄4, the hairs about 0.5 mm long, apex acute 

to acuminate, scaberulous, the mucro 0.3–1 mm long; paleas 

1.9–3 mm long, lanceolate, short appressed pubescence between 

the veins on the proximal 3⁄4, apex acute to acuminate, the veins 

sometimes mucronate, the mucros to 0.3 mm long; anthers 

1.3–1.8 mm long, greenish. Caryopsis 1.2–2 mm long, fusiform, 

brownish.

Distribution and Habitat. Muhlenbergia 

wrightii is found growing in gravelly prairies, grassy flats, rocky 

slopes, and open wet and dry meadows on granitic, sandstone, 

or limestone derived soils and is associated with Pinus spp., Juniperus spp., and Quercus spp. at 1,100–3,000 m. This species 

occurs in southwestern Utah, eastern Arizona, New Mexico, and 

western Colorado to northern Mexico in Baja California, Chihuahua, Durango, and Sonora.

Specimens Examined. MEXICO. Chihuahua. 

Carichi: Sánchez, 12 Oct 1910, Hitchcock 7693.5 (US). Cuahutémoc: 21 km W of Cuauhtemoc, on Hwy 16, 23 Aug 1990, 

2000 m, P.M. Peterson & Annable 9586 (US). Gómez Farías: 

Laguna Bavícora, 2400 m, A. Saucedo s.n. (INEGI). Guerrero: 

Santo Tomas, on railroad NW of San Isidro, 2000 m, Pennell 

18989 (US); Miñaca, 13 Oct 1910, Hitchcock 7759 (US).
280 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Munroa Torr.

Annual; stoloniferous, mat-forming; stolons 2–8 cm long, 

terminating in involucres of leaves from which new culms arise. 

Culms 3–15(30) cm. Leaves mostly basal, sometimes with a 

purple tint; sheaths with a tuft of hairs at the throat; auricles 

absent; ligules of hairs; blades linear, usually involute, sometimes flat or folded, with white, thickened margins, apex sharply 

pointed. Inflorescences terminal, capitate panicles of spikelike 

branches; branches almost completely hidden in a subtending 

leafy bract, with 2–4 subsessile or pedicellate spikelets. Spikelets 

laterally compressed, with 2–10 florets; lower florets bisexual 

or pistillate; terminal florets sterile; disarticulation above the 

glumes or beneath the leaves subtending the branches. Glumes 

shorter than the spikelets, keeled, 1-veined, unawned; lower 

glumes usually present on all spikelets (absent from all spikelets 

in M. mendocina); upper glumes absent or reduced on the terminal spikelet; lemmas with a pilose tuft of hairs along the margins 

at midlength, membranous or coriaceous, 3-veined, lateral veins 

occasionally shortly excurrent, apex emarginate or 2-lobed; paleas glabrous, smooth; lodicules present or absent, truncate; anthers 2 or 3, yellow; style branches elongate, 2(3), barbellate. 

Caryopsis dorsally compressed. x = 7 or 8.

Munroa, a genus of five species, is endemic to the Western 

Hemisphere. One species occurs in Chihuahua.

280. Munroa squarrosa (Nutt.) Torr., Pacif. Railr. Rep. 4(5): 

158. 1857.

FIGURE 184

Stolons slender. Culms 3–15(30) cm long, highly branched, 

scabrous, often minutely puberulent. Sheaths shorter than the 

internodes, membranous; ligules 0.5–1 mm long; blades 1–5 cm 

long, 1–2.5 mm wide. Spikelets 6–8(10) mm long, with 3–5 florets; glumes 2.5–4.2 mm long, first 1–2 spikelets subequal, narrow, 1-veined, acute; glumes of upper spikelets unequal; lower 

glumes reduced or even absent in the terminal spikelets; lemmas 

in lower spikelets scaberulous, lanceolate, midvein excurrent, 

forming a stout, scabrous awn, the awn 0.5–2 mm long, lateral 

veins with a tuft of hairs on the margins near midlength, excurrent; anthers 1–1.5 mm long. 2n = 16.

Distribution and Habitat. Munroa squarrosa grows in dry, open areas, usually in sandy soil or disturbed 

sites, from Saskatchewan and Alberta south to Chihuahua, 

Mexico.

FIGURE 183. Muhlenbergia wrightii. A. Habit. B. Sheath and blades. C. Ligule. D. Inflorescence. E. Glumes. F. Floret. Drawn by Linda Ann Vorobik and Annaliese Miller; 

copyright Utah State University.
NUMBER 107 • 281

Specimens Examined. MEXICO. Chihuahua. 

Juárez: aprox. 6 km al S del poblado [village] Samalayuca, 9 Sep 

1995, en arenas profundas [deep sands], 1200 m, R. Corral & 

P. Olivas RCD6325 (UACJ); carr. [hwy] No. 2 Juárez–Janos, km 

42, 11 Aug 1996, matorral de médanos [dune scrub], 1250 m, 

P. Olivas, R. Rivas & I. Enríquez POS793 (UACJ); near Ciudad 

Juárez, 28 Sep 1902, Sandy soil, C.G. Pringle 11236 (MEXU); 

km 320 carr. Chihuahua–Cd. Juárez, 14 Oct 1990, zona de médanos [dune area], 1280 m, A. González s/n (MEXU); 2.3 (rd) 

mi E of Samalayuca, 13 Sep 1972, in sandy flats and small dunes, 

4200 ft, J. Henrickson 7490 (MEXU); 4.1 (rd.) mi N of Samalayuca along Hwy 45, 13 sep 1972, sand dune area, 4700 ft, 

J. Henrickson 7434 (MEXU). 

Nassella Desv.

Plants usually perennial, rarely annual; caespitose, occasionally rhizomatous. Culms branched at the upper nodes, branches 

flexible; prophylls not evident, shorter than the sheaths. Leaves

mostly basal, not overwintering; sheaths open; cleistogenes sometimes present; auricles absent; ligules membranous, sometimes pubescent or ciliate; blades basal, apex narrowly acute to acute, not 

sharp, flag leaf blades present, bases about as wide as the top of the 

sheaths. Inflorescences terminal panicles, sometimes partially included at maturity. Spikelets with 1 floret; rachillas not prolonged 

beyond the base of the floret; disarticulation above the glumes, beneath the floret. Glumes longer than the floret, narrowly lanceolate 

or ovate, basal portion usually purplish at anthesis, color fading 

with age, (1)3- to 5-veined, sometimes awned; florets usually terete, 

sometimes slightly laterally compressed; calluses blunt or sharp, 

glabrous or antrorsely strigose; lemmas usually papillose or tuberculate, at least distally, sometimes smooth throughout, glabrous 

or variously hairy, strongly convolute, wrapping 1.2–1.5 times 

around the caryopsis, apex not lobed, fused distally into crowns,

these often evident by their pale color and constricted bases; crowns

mostly glabrous, rims often bearing hairs with bulbous bases; 

awns terminal, centric or eccentric, deciduous or persistent, usually 

twice-geniculate, second geniculation often obscure; paleas up to 1⁄2

as long as the lemmas, glabrous, without veins, flat; lodicules 2 or 

3, if 3, the third somewhat shorter than the other 2; anthers 1 or 3, 

if 3, often of 2 lengths, penicillate; ovaries glabrous; styles 2, bases 

free. Caryopsis glabrous, not ribbed. x = 7, 8.

Nassella used to be interpreted as a genus of approximately 14 

species but now has about 125 species primarily in South America.

FIGURE 184. Munroa squarrosa. A. Habit. B. Inflorescence branch. C. Lower spikelet. D. Floret, ventral view. Drawn by Linda Ann 

Vorobik and Karen Klitz; copyright Utah State University.
282 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

281. Nassella mucronata (Kunth) R. W. Pohl, Taxon 39(4): 611. 

1990.

Perennial. Culms 60–100 cm tall, erect or geniculate, ascending, nodes pubescent. Sheaths glabrous, margins hairy; 

ligules 0.5–1 mm long, membranous; blades 10–20 cm long, 

1–3 mm wide, flat or involute, pubescent, sparsely hairy on 

both sides. Panicles 10–30 cm long, open, linear, dense, nodding, branches appressed or ascending. Spikelets 8–10 mm long, 

solitary, pedicelled, lanceolate, subterete, disarticulating below 

each fertile floret, callus about 2 mm long, elongated, pubescent (tawny), acute; glumes 25–40 mm long, persistent, equal, 

exceeding apex of florets, thinner than fertile lemma, oblong, 

membranous, purple; lower glumes 3-veined, primary vein scabrous, apex acuminate; upper glumes 5-veined, apex acuminate; 

lemmas 5–6 mm long, 1 mm wide, 5-veined, oblong, subterete, 

coriaceous, dark brown, papillose, rough above, pubescent, 

hairy below, margins convolute and covering most of palea, 

apex with a short cylindrical neck, surmounted by a ring of 

hairs, the hairs 0.5 mm long, awned, the awn 35–50 mm long, 

2-geniculate, with a twisted column, the column 9–10 mm long, 

middle segment of awn 8–9 mm long; paleas 2-veined; anthers 

3, 4–4.5 mm long.

Distribution and Habitat. Nassella mucronata is known from Mexico and South America.

Specimens Examined. MEXICO. Chihuahua. 

Reported in Espejo Serna et al. (2000). 

Oplismenus P. Beauv.

Annual or perennial. Culms weak, trailing on the ground, 

branching. Leaves cauline; ligules membranous and ciliate, or 

of hairs; blades lanceolate. Inflorescences terminal, panicles of 

unilateral branches, spikelets paired (but the first spikelet sometimes reduced), rachises and branches terminating in a spikelet; 

branches persistent; disarticulation below the glumes. Spikelets 

dorsally compressed, not sunken into the rachis, lacking subtending bristles, with 2 florets. Lower glumes awned; upper glumes 

not ciliate on the margins, unawned or with awns shorter than 

those of the lower glumes, awns of both glumes often becoming 

viscid; lower florets sterile or staminate, lower lemmas acute to 

short-awned, lower paleas present or absent; upper florets bisexual; upper lemmas papery to leathery, glabrous, smooth, unawned, white or yellow at maturity; upper paleas similar to the 

upper lemmas. x = 9. 

Oplismenus is a genus of 11 closely related species that 

grow in shady, mesic forests of tropical and subtropical regions.

282. Oplismenus burmannii (Retz.) P. Beauv., Ess. Agrostogr. 

54: 169. 1812. Panicum burmannii Retz., Observ. Bot. 3: 

10. 1783.

Annual; usually slender. Culms (15)25–45(65) cm tall; nodes

hairy; internodes grooved, usually hairy in the grooves, less so on 

the nodes. Leaves light green; sheaths glabrous or sparsely hairy, 

the edges ciliate; ligules 0.6–1.2(1.8) mm long, ciliate; blades

(2)3–7(8) cm long, 6–13 (16) mm wide, ovate-oblong to oblonglanceolate, usually hairy, midvein weak, with 2–3 lateral veins 

on each side, cross venation usually visible. Panicles (3)4–8(10) 

cm long, sometimes hairy, with 3–10 primary branches; lower 

primary branches (0.2)0.5–1.5(3) cm long, with (3)10–20(25) 

spikelets, spikelets borne in pairs, usually encircled at the base 

with hairs almost as long as the spikelets. Spikelets (2)2.8–4.5 

mm long, usually densely hairy, sometimes glabrous, flattened 

to rounded on the back; lower glumes (1.3)1.9–2.4 mm long, 

0.7–0.9(1.2) mm wide, oblong-oval, densely hairy, with 3–5(7) 

veins, awned, the awns (3)6–11(15) mm long, frail, whitish, and 

scabrous; upper glumes (1.5)2–2.3 mm long, (0.7)–1.2(1.5) mm 

wide, similar to the lower glumes in shape, fairly densely hairy, 

with 5–7 veins, awned, the awns (0.4)3–6(9) mm long, frail, whitish, and scabrous; lower lemmas (2)2.6–3.5 mm long, (1)1.7–2.4 

mm wide, oblong, with (5)7–9(11) veins, mucronate or shortawned; lower paleas absent. Caryopsis oblong-lanceolate. 

Oplismenus burmannii is a pantropical species that is most 

abundant in Africa. In Mexico it has two varieties: O. burmanii var. burmanii and O. burmannii var. nudicaulis (McVaugh, 

1983), and only the former variety is known from Chihuahua. 

However, we include a key to both varieties since O. burmanii

var. nudicaulis is known from eastern Sonora near the boundary 

of Chihuahua (P.M. Peterson & Saarela 22107).

KEY TO VARIETIES OF OPLISMENUS BURMANNII

1. Spikelets (2)2.5–3.5 mm long, the sterile lemma narrowed to an acute point, mostly with weak converging veins; caryopsis 

essentially filling and distending the lemma; uplands, mostly above 1,500 m . . . . . . . . . . . . O. burmannii var. burmannii

1. Spikelets (3)3.5–4.5 mm long, the sterile lemma prolonged into a cylindric and often arcuate tip with 9 strong, raised, parallel 

veins; caryopsis not extending into the tip of the lemma; mostly lowlands and foothills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . O. burmannii var. nudicaulis (Vasey) McVaugh

Oplismenus burmannii var. burmannii

Distribution and Habitat. Oplismenus burmannii var. burmannii is known from Mexico to South America.

Specimens Examined. MEXICO. Chihuahua. 

Chinipas: Saguarivo, 53 mi N of Alamos, 9 Sep 2008, slopes 

with oaks and pines, 1540 m, P.M. Peterson & J.M. Saarela 

22122 (US). Ocampo: Parque Nacional “Cascada de Basaseachic,” in the barranca [canyon] to W of falls, 4 Oct 1986, 

1800 m, Spellenberg, Soreng, R. Corral & T. Lebgue 8826 

(NMC).
NUMBER 107 • 283

Otatea (McClure & E. W. Sm.) 

C. E. Calderón & Soderstr.

Perennial bamboos of medium size, clump-forming with 

pachymorph rhizomes. Culms woody, erect, internodes cylindrical, solid becoming partially fistulose, glabrous, branches 

3 per node at the middle of the culm. Sheaths persistent on 

the lower nodes, tardily deciduous on the upper nodes; ligules 

membranous, auriculate; blades lanceolate, flat, the blades of 

branches with pseudopetioles. Inflorescence a panicle; spikelets 

with several florets; glumes 1 or 2, short-awned; florets bisexual; upper florets reduced; rachilla internodes scabrous, ciliolate; lemma awned; palea with a dentate apex. Fruit a small, 

dry caryopsis. 

Otatea has 11 species known from tropical areas, 10 are 

endemic to Mexico, and 1, O. fimbriata Soderstr., is wide ranging from Mexico and Central America to Columbia (Juziewicz 

et al., 1999; Ruiz Sanchez et al., 2011, 2015; Ruiz Sanchez and 

Castro Castro 2016).

283. Otatea acuminata (Munro) C. E. Calderón & Soderstr., 

Smithsonian Contr. Bot. 44: 21. 1980. Arundinaria acuminata Munro, Trans. Linn. Soc. London 26(1): 25. 1868. 

Rhizomatous perennial. Culms 2–10 m tall, 1–2.5 cm thick, 

erect, solid on young plants and fistulose on mature individuals; internodes green-yellowish or purple. Leaves cauline; sheaths 

appressed-hirsute on the upper 1⁄2, setose on the shoulders, the 

hairs about 3 mm long; ligules 0.3–0.6 mm long, truncate; blades 

6–15 cm long, 0.5–1.1 cm wide, linear to narrowly lanceolate, 

glabrous adaxially, abaxially pilose near the base, deciduous at 

the ligule. Panicles 5–10 cm long; pedicels glabrous. Spikelets 

3–4 cm long, 3- to 7-flowered; rachilla internodes 4–7 mm long, 

zigzag, visible between the lemmas and disarticulating at maturity, pubescent; glumes unequal, awned, the awns 1–3 mm long; 

lower glumes 2.5–4.5 mm long excluding the awn; upper glumes 

3.5–6 mm long; lemmas 11–15 mm long, 9- to 11-veined, pilose 

on margins, lanceolate, keeled with a terminal awn, the awn 3–6 

mm long; paleas 9–11 mm long, oblong, pubescent on the keels 

and between, apex truncate and narrow; anthers 5–6.5 mm long. 

Caryopsis 6–8.5 mm long, linear. 

There are two subspecies; only Otatea acuminata subsp. 

aztecorum (McClure & E. W. Sm.) R. Guzmán, Anaya & Santana is present in Chihuahua.

Distribution and Habitat. Otatea acuminata 

subsp. aztecorum grows in wet places in tropical forests and 

is endemic to the Mexican Pacific slopes, the Trans-Mexican 

Volcanic Belt, Oaxaca, Puebla, Querétaro, and Veracruz at 

150–2,000 m.

Specimens Examined. MEXICO. Chihuahua.

Batopilas: 37.3 km al NE de Batopilas, rumbo [course] a Quirare, 

26 Oct 2002, 1860 m, P. Tenorio & J. Rodríguez 22429 (US). 

Guachochi: 1–2 km S of Río Osichi and Río Basihuare jct, 1 Sep 

2003, bosque [forest] de Quercus–Pinus, 1600 m, P.M. Peterson & P. Catalán 17638 (CIIDIR). Urique: Guapalayna, 19 Apr 

2002, R. Bye, M. Mendoza, D. Castro, J. Rodriguez, P. Tenorio 

& R. Alvarado 28690 (US).

Panicum L.

Annual or perennial. Culms herbaceous, sometimes hard and 

almost woody, or woody, simple or branched, bases not cormlike; 

internodes solid, spongy, or hollow. Leaves cauline, basal, or both, 

basal leaves not forming a winter rosette; ligules membranous, 

usually ciliate; blades filiform to ovate, flat to involute, glabrous or 

hairy. Inflorescence terminal on the culms and branches, sometime 

axillary, terminal panicles typically appearing after midsummer; 

sterile branches and bristles absent; disarticulation usually below 

the glumes, sometimes at the base of the upper florets, if at the 

base of the upper florets, then the florets not very plump at maturity. Spikelets dorsally compressed, sometimes subterete or laterally compressed, awnless. Glumes usually unequal, herbaceous, 

glabrous or hairy, rarely tuberculate or glandular, apex not or only 

slightly gaping at maturity; lower glumes minute to almost equaling the spikelets, 1- to 9-veined, truncate, acute, or acuminate; 

upper glumes slightly shorter to much longer than the spikelets, 

3- to 13(15)-veined, bases rarely slightly sulcate, apex rounded to 

attenuate; lower florets sterile or staminate; lower lemmas similar 

to the upper glumes; lower paleas absent or shorter than the lower 

lemmas and hyaline; upper floret bisexual, 2⁄3 to as long or exceeding the upper glume, sessile or stipitate, apex acute, glabrous or 

hairy; upper lemmas usually more or less rigid and chartaceousindurate, usually shiny, glabrous, and smooth, sometimes pubescent, sometimes verrucose or faintly transversely rugose, margins 

involute, usually clasping the paleas, rarely with basal wings or 

lunate scars, apex obtuse, acute, apiculate, or occasionally with 

small green crests; upper paleas striate, rarely transversely rugose; 

lodicules 2; anthers usually 3. Caryopsis smooth; pericarp thin; 

endosperm hard, without lipid, starch grains simple or compound, 

or both; hila round or oval. x = 9 (usually), sometimes 10, with 

polyploid and dysploid derivatives. 

Panicum has approximately 330 species of cosmopolitan 

distribution.

KEY TO SPECIES OF PANICUM

1. Plants robust, greater than 1 m tall; plants perennial and generally rhizomatous; cultivated in pastures.

2. Culms with bases strongly knotty; the diameter of the nodes frequently twice the diameter of the internodes; spikelets 

2.5–3 mm long, arranged in pairs, or terminal spikelets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. antidotale

2. Culms with bases not knotty; nodes and internodes of similar diameter; spikelets 3–4 mm long, not in pairs.
284 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

3. Upper florets rugulose, elliptical, minutely puberulent at the apex; lower glume less than 1⁄2 as long as the spikelet, 

subacute, 3-veined; spikelets 3–3.4 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. plenum

3. Upper florets smooth, ovate, glabrous; lower glume more than 1⁄2 as long as the spikelet, acuminate, 3- to 5-veined; 

spikelets 3–5(6) mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. virgatum

1. Plants not robust, less than 1 m tall; annual or perennial but never rhizomatous; never cultivated in pastures.

4. Spikelets 1.1–1.3 mm long; plants clearly annual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. trichoides

4. Spikelets 2 mm long or more; perennial or appearing annual.

5. Spikelets 3.7–5.8(6) mm long; upper glume and lemma 11–15-veined; culms erect, not geniculate.

6. Spikelets 3.7–4.2 mm long; panicle branches spreading and flexuous, naked near base with 1 to 3 spikelets near the 

tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. lepidulum

6. Spikelets 4.5–6 mm long; panicle branches ascending or spreading, never flexuous, branches few-flowered or 

floriferous to base.

7. Lower glumes 2–2.7 mm long, acute or obtuse; rachilla between the glumes inconspicuous; panicle branches 

floriferous to base, ascending and appressed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. decolorans

7. Lower glumes 2.8–4.2 mm long, acuminate; rachilla between the glumes elongate; panicle branches fewflowered, naked near lower 1⁄2, spreading and ascending . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. parcum

5. Spikelets 2–3.5(4) mm long (4 mm in P. pampinosum); upper glume and lemma 7- to (9)-veined (lemma 9-veined in 

P. pampinosum); culms decumbent and geniculate.

8. Lower glume 1⁄4 to 1⁄3 as long as the spikelet, apex obtuse to acute.

9. Upper floret 0.2–0.5 mm shorter than lemma of the lower floret . . . . . . . . . . . . . . . . . . . . . . . . P. vaseyanum

9. Upper floret 1–1.3 mm shorter than lemma of the lower floret . . . . . . . . . . . . . . . . . . . . . P. dichotomiflorum

8. Lower glume 1⁄2 or more as long as the spikelet, apex acute or acuminate.

10. Perennial, culms hardened at the base; blades generally glaucous and glabrous . . . . . . . . . . . . . . . . . P. hallii

10. Annual, culms usually not hardened at the base; blades papillose-hirsute to pilose at least on the base and 

margins.

 11. Panicle spiciform to subspiciform, the primary branches appressed to ascending . . . . . . . P. pampinosum

 11. Panicle lax, diffuse to contracted, the primary branches divergent.

12. Upper floret short stipitate with 2 cartilaginous extensions at the base of the lemma; blades glabrous 

to sparsely papillose-hirsute, the base rounded to subcordate . . . . . . . . . . . . . . . . . . . . . . P. alatum

12. Upper floret neither stipitate nor with cartilaginous extensions; blades densely papillose-hirsute, the 

base rounded to cordate-clasping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. hirticaule

284. Panicum alatum Zuloaga & Morrone, Ann. Missouri Bot. 

Gard. 83(2): 224–226, f. 15. 1996.

Caespitose annual. Culms 25–95 cm tall, erect to geniculate, 

branched at base, generally glabrous. Leaf sheaths pappilose-hirsute 

with deciduous hairs; ligules 0.7–1.8 mm long, membranous, ciliate, the cilia 0.5–1.5 mm long; blades 5–18 cm long, 3–17 mm 

wide, flat, linear-lanceolate, glabrous to sparsely papillose-hirsute, 

the base rounded to subcordate. Panicles 5–25 cm long, terminal 

and axillary, diffuse; branches 4.5–12 cm long, lax, ascending to 

divergent; rachis scabrous. Spikelets 2.4–3.5 mm long, 0.7–1.5 mm 

wide, elliptic, glabrous, acute to acuminate; lower glume 1.5–

1.8(2.5) mm long, 3⁄4 as long as the spikelet, 5- to 7-veined, ovateacuminate, separated from the upper glume by an internode of 0.3 

mm long; upper glume 2.2–2.7(3.3) mm long, 7- to 9(11)-veined; 

lower floret neuter; inferior lemma similar to the upper glume; 

inferior palea lacking, or if present 0.2–0.9 mm long, lanceolate, 

bilobed; upper floret perfect, short stipitate with 2 cartilaginous 

extensions at the lemma base, whitish, opaque, markedly papillose 

over the entire surface or only at apex; palea oblong-ovate, apex 

abruptly acute; anthers 0.9–1.1 mm long. n = 9.

Distribution and Habitat. Panicum alatum 

occurs in open areas, sometimes at lake margins. This taxon has 

three varieties; Panicum alatum var. minus (Anderson) Zuloaga 

& Morrone is reported from Chihuahua (Espejo Serna et al., 

2000) and ranges from the United States to South America. It 

was described from Baja California but is uncommon in Mexico. 

285. Panicum antidotale* Retz., Observ. Bot. 4: 17. 1786.

Caespitose perennial; rhizomatous, the rhizomes about 

1 cm thick, knotted, pubescent, with large, scalelike leaves. 

Culms 50–300 cm tall, 2–4 mm in diameter, often compressed, 

erect or ascending, hard, becoming almost woody; nodes swollen, glabrous or pubescent; internodes glabrous and glaucous. 

Sheaths shorter than or equal to the internodes, not keeled, 

glabrous or the lower sheaths at least partially pubescent, the 

hairs papillose-based; ligules 0.3–1.5 mm long; blades 10–60 

cm long, 3–20 mm wide, elongate, flat, scabrous below and 

along margins, occasionally pubescent above near the base with 

prominent, white midveins, bases rounded to narrowed. Panicles 10–45 cm long, 1⁄2 as wide as long, open or somewhat contracted with many spikelets; branches 4–12 cm long, ascending 

to spreading, inserted opposite or alternately along the rachis; 

pedicels 0.3–2.5 mm long, scaberulous to scabrous, appressed 

to diverging less than 45° from the branch axes. Spikelets 
NUMBER 107 • 285

2.4–3.4 mm long, 1–1.3 mm wide, ellipsoid-lanceoloid to narrowly ovoid, often purplish, glabrous, acute; lower glumes 

1.4–2.2 mm long, 1⁄3–1⁄2 as long as the spikelets, 3- to 5-veined, 

obtuse; upper glumes and lower lemmas subequal, glabrous, 

5- to 9-veined, margins scarious, acute; lower florets staminate; 

upper florets 1.8–2.8 mm long, 0.9–1.1 mm wide, smooth, lustrous, acute. 2n = 18, 36.

Distribution and Habitat. Panicum antidotale is found on grassy flats and is cultivated at Rancho La Campana. This species is native to India and has been introduced to 

the Western Hemisphere.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: Rancho Experimental La Campana, 82 km al N de 

la ciudad de Chihuahua, 26 Aug 1978, 1550 m, C.A. Fernández 

s.n. (ENCB); La Campana, 24 Sep 1976, Jardín de observación 

forrajera [forage observation garden], 1500 m, S. González 769

(RELC).

286. Panicum decolorans Kunth, Nov. Gen. Sp. (quarto ed.) 1: 

100. 1815.

Caespitose annual. Culms 30–60 cm tall, internodes distally pilose. Sheaths hirsute with tubercle-based hairs; ligules 1 mm long, a ciliolate membrane; blades 8–15 cm long, 

7–10 mm wide. Panicles 10–18 cm long with branches floriferous throughout, ascending and appressed, somewhat narrow. 

Spikelets 4.5–6 mm long, ovate, dorsally compressed, acute, 

falling entire, pedicelled; glumes as long as the florets, unequal, 

ovate, membranous, thinner than fertile lemma, apex acute; 

lower glumes 2–2.7 mm long, 5- to 7-veined, acute to obtuse; 

upper glume 4.5–6 mm similar to lemma of the sterile floret; 

lemma of sterile floret as long as the spikelet, ovate, membranous, acute; sterile floret palea 1⁄4 as long as the lemma; fertile 

lemma 2.3–3.5 mm long, 1.5 mm wide, elliptic, dorsally compressed, indurate, pallid, shiny, margins involute; fertile palea 

involute, indurate; anthers 2.1 mm long, dark brown. Caryopsis 

2–2.5 mm long. n = 16, 18.

Distribution and Habitat. Panicum decolorans grows in grasslands. It is endemic to Mexico, from Chihuahua, Durango, Guanajuato, Hidalgo, Jalisco, México, 

Michoacán, Oaxaca, Puebla, Querétaro, Sinaloa, and San Luis 

Potosí (Espejo Serna et al., 2000; Herrera Arrieta and Cortés 

Ortiz , 2010).

287. Panicum dichotomiflorum* Michx., Fl. Bor.-Amer. 1: 48. 

1803.

Annual or short-lived perennial; usually terrestrial, sometimes 

aquatic but not floating. Culms 5–200 cm tall, 0.4–3 mm thick, 

decumbent to erect, commonly geniculate to ascending, rooting 

at the lower nodes when in water, simple to divergently branched 

from the lower and middle nodes, usually succulent, slightly compressed, glabrous; nodes usually swollen, sometimes constricted 

on robust plants, glabrous; internodes glabrous, shiny, pale green 

to purplish. Sheaths compressed, inflated, sparsely pubescent near 

the base, elsewhere mostly glabrous, sparsely pilose, or hispid, 

hairs sometimes papillose-based, margins or throat ciliate with 

papillose-based hairs; ligules 0.5–2 mm long; blades 10–65 cm 

long, 3–25 mm wide, glabrous or sparsely pilose, often scabrous 

near the margins, midribs stout, whitish. Panicles 4–40 cm long, 

diffuse, lax, with a few spikelets; branches to 15 cm long, ascending to spreading, stiff, scabrous, alternate or opposite, occasionally verticillate; pedicels 1–6 mm long, sharply 3-angled, scabrous, 

apex expanded to cuplike, appressed mostly to the abaxial side 

of the branches. Spikelets 1.8–3.8 mm long, 0.7–1.2 mm wide, 

ellipsoid to narrowly ovoid, light green to red-purple, glabrous, 

acute to acuminate; lower glumes 0.6–1.2 mm long, 1⁄4–1⁄3 as long 

as the spikelets, 0- to 3-veined, obtuse to acute; upper glumes and 

lower lemmas similar, exceeding the upper florets by 0.3–0.6 mm 

long, 7- to 9-veined; lower paleas vestigial to almost as long as the 

lower lemmas; lower florets sterile; upper florets 1.4–2.5 mm long, 

0.7–1.1 mm wide, narrowly ellipsoid, smooth, shiny, stramineous 

to nigrescent, with pale veins. 2n = 36, 54.

Distribution and Habitat. Panicum dichotomiflorum grows in open, often wet, disturbed areas such as cultivated and fallow fields, roadsides, ditches, open stream banks, 

receeding shores, clearings in flood plain woods, and sometimes 

in shallow water. It is probably native throughout the eastern 

United States and adjacent Canada but introduced elsewhere. 

This species is reported for Chihuahua in Espejo Serna et al. 

(2000) and Herrera Arrieta and Cortés Ortiz (2010).

288. Panicum hallii Vasey, Bull. Torrey Bot. Club 11(6): 61. 

1884.

FIGURE 185

Caespitose perennial. Culms 10–100 cm tall, 2–10 mm 

thick, erect, simple or sparingly branched basally; nodes sericeous, pilose or glabrous; internodes usually glaucous. Leaves 

often crowded basally; sheaths rounded, glabrous or hirsute, 

hairs fragile, papillose-based, margins sometimes ciliate distally; ligules 0.6–2 mm long; blades 4–23 cm long, 1–10 mm 

wide, erect to spreading, flat or sometimes involute (on sterile 

branches), often curling at maturity, glaucous, abaxial surfaces 

sometimes with prominent papillae along the midribs, bases 

rounded or narrowing to the sheaths, margins cartilaginous, 

ciliate basally, scaberulous elsewhere, apex acute. Terminal 

panicles 7–31 cm long, 3–15 cm wide; rachises glabrous, tending to break at maturity; branches usually alternate, slender, 

stiff, ascending to divergent; pedicels 1–15 mm long, appressed. 

Spikelets 2.1–4.2 mm long, 0.8–1 mm wide, usually ovoid, glabrous; lower glumes 1.2–2.4 mm long, 1⁄2–3⁄4 as long as the spikelets, attenuate; upper glumes and lower lemmas similar, 7- to 

11-veined, acuminate, extending 0.3–1.2 mm beyond the upper 

florets; lower florets sterile; lower paleas 0.8–2 mm long; upper 

florets 1.5–2.4 mm long, 0.7–1.2 mm wide, ovoid to ellipsoid, 

smooth, nigrescent. 2n = 18.

Distribution and Habitat. Panicum hallii

grows on sandy, gravelly, or rocky land, including roadsides, pastures, rangeland, oak and pine savannahs, chaparral, and moist 
286 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

areas in deserts and on mesas. Its range extends from the southwestern United States to Guatemala.

Specimens Examined. MEXICO. Chihuahua.

Ahumada: 10 km al S de Moctezuma, 30 Jul 1994, 1200 m, 

R. Corral, E. Pérez, A. Domínguez & F. Félix RCD5337 (UACJ). 

Buenaventura: 10 km al SE de Buenaventura, 23 Oct 74, matorral [scrub], Valdés-Reyna VR-743 (RELC). Chihuahua: La Campana; 1 km Pte. carr. [hwy] Panamericana, 5 sep 73, Pastizal 

[pastureland], 1570 m, Valdés-Reyna VR-68 (RELC). Janos:10 

km antes [before] de Janos, 23 Oct 74, matorral, Valdés-Reyna 

VR-754 (RELC). Jiménez: Reserva de la Biosfera de Mapimí, 

dunas de arena [sand dunes] La Soledad, 9 Jul 1997, matorral 

xerófilo [xerophilous scrub], 1140 m, A. García 2702 (CIIDIR); 

20 sep 1999, A. García 3682 (CIIDIR); 13 km S of Jimenez, 

30 Jul 1939, L. H. Harvey 1342 (US); Sta. Eulalia Mts, 1885, 

C.G. Pringle 376 (ENCB, US); 2 km N of San Antonio, 16 Aug 

1939, L. H. Harvey 1516 (US). Manuel Benavides: 1 mi E of 

Pozo de Villa along road from Ojinaga to Castillon, via La Mula, 

Trincheras, Piramide and San Salvador, 10–12 Aug 1941, I.M. 

Johnston 817 (US).

289. Panicum hirticaule J. Presl, Reliq. Haenk. 1(4–5): 308. 

1830.

FIGURE 186

Annual. Culms 11–110 cm long, erect to decumbent; nodes 

short hirsute or glabrous. Sheaths shorter than the internodes, 

greenish to purplish, glabrous or with papillose-based hairs, 

ciliate on 1 margin, glabrous on the other; collars hirsute; ligules 1.5–3.5 mm long, of hairs; blades 3–30 cm long, 3–30 mm 

wide, flat, usually densely to sparsely hirsute, hairs papillosebased, sometimes glabrous, bases rounded to cordate-clasping, 

margins ciliate, cilia papillose-based, apex acute. Panicles 9–30 

cm long, 5–8 cm wide, erect or nodding, partially included to 

well-exserted, rachises glabrous or sparsely hirsute basally; 

primary branches usually alternate to opposite, divergent, secondary branches and pedicels confined to the distal 2⁄3; pulvini 

inconspicuous; secondary branches appressed; pedicels 9–27 

mm long, appressed. Spikelets 1.9–4 mm long, 0.8–1 mm wide, 

ovoid to almost spherical, often reddish-brown, glabrous, veins 

prominent, scaberulous, apex abruptly acuminate; lower glumes 

1.3–2.4 mm long, 1⁄2–3⁄4 as long as the spikelets, 3- to 5-veined; 

upper glumes 1.8–3.3 mm long, 7- to 11-veined; lower florets 

sterile; lower lemmas similar to the upper glumes, 9-veined; 

lower paleas 0.4–0.9 mm long; upper florets 1.5–2.4 mm long, 

0.4–0.8 mm wide, ellipsoid, smooth or conspicuously papillate, 

shiny, stramineous, often with a lunate scar at the base. 

Distribution and Habitat. Panicum hirticaule

grows in rocky or sandy soils in waste places, roadsides, ravines, 

and wet meadows along streams. Its range extends from southeastern California and southwestern Texas southward through 

Mexico, Central America, Cuba, and Hispaniola to western 

South America and Argentina. Two varieties are known from 

Chihuahua (Zuloaga and Morrone 1996).

FIGURE 185. Panicum hallii. A. Culm and inflorescence. B. Spikelet. Drawn by Linda Ann Vorobik and Cindy Roché; copyright Utah 

State University.
NUMBER 107 • 287

KEY TO VARIETIES OF PANICUM HIRTICAULE

1. Spikelets 1.9–2.8 (3.3) mm long; upper floret stramineous, shiny, smooth with simple papillae on the apex of the lemma 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. hirticaule var. hirticaule

1. Spikelets 2.4–3.5 mm long; upper floret grayish, opaque with simple papillae on the entire surface of the lemma . . . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. hirticaule var. verrucosum

Panicum hirticaule var. hirticaule

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 12 km al N de Flores Magón, 7 Oct 1995, matorral desértico [desert scrub], 1180 m, R. Corral, P. Olivas & 

J.O. Torres RCD6490 (UACJ). Ascención: SW of Cd. Juarez, 

6.8 (rd) mi N of Guzman, 14 Sep 1974, J. Henrickson 14098 

(US). Buenaventura: km 40 San Buenaventura–El Carmen 25 

Oct 1954, Hern.-Xol. & C. Tapia N-231 (US). Camargo: rd 

from Mesteñas NE to Ojinaga, 26 Sep 1938, I.M. Johnston 

7992 (US); 20 km S of Cd. Camargo, 2 Aug 1939, 1220 m, 

L. H. Harvey 1378 (US). Casas Grandes: E.W. Nelson 6355 

(US); Casas Grandes, 25 Aug 1899, E.W. Nelson 6297 (US). 

Chihuahua: Rancho La Presa, 21 Oct 1954, 1100 m, Hern.-

Xol. & C.Tapia N-67 (US); km 1773 carr. [hwy] a Cd. Juárez, 

15 Sep 1955, Hern.-Xol. & V. Mathus N-1791 (US); Hacienda 

Sta Gertrudis, criadero [hatchery] número 2 caballería Ejercito 

Nacional [national army cavalry], 21 sep 55, 1650 m, Hern.-

Xol. & V. Mathus N-1991 (US). 5 mi SW of Chihuahua on rd 

to Cuauhtémoc, 6 Oct 1959, 1463 m, Soderstrom 896 (US); La 

Campana Experimental Station & Rancho El Arco Iris, 81–84 

km along Pan American Hwy to Chihuahua City, Oct 1977, 

J.K. Meents & W.H. Moir 72 (NMC). Jiménez: W slope Sierra 

de Sta Eulalia, 18 Aug 1939, L. H. Harvey 1533 (US); Reserva 

de la Biosfera Mapimí, 30 Aug 1983, pastizal [pastureland], 

E. Ruiz de Esparza RRE-51 (RELC); 33 mi SE of Jiménez, 

27 Sep 1963, Reeder & C. Reeder 3613 (ARIZ); El Hugo, 

Torreoncitos, 13 Aug 2010, matorral de Prosopis sp., 1355 

m, D. Ramírez & M.L. Juárez 3394 (CIIDIR). Julimes: entre 

[between] Felipe Ángeles & Trincheras, 31 Jul 1976, pequeño 

bajío [small shallows] de Hilaria mutica, 1240 m, S. González 

& J.M. Peña 405 (ENCB); El Hugo, Torreoncitos, 13 Aug 

2010, terrenos de cultivo [farmland], 1355 m, D. Ramírez 

& M.L. Juárez 3376 (CIIDIR). Madera: Chuichupa, 24 Aug 

1937, LeSueur 0172 (US); Laguna de Babicora, Ejido Año 

de Hidalgo, 15 Sep 1994, 2300 m, T. Lebgue, G. Quintana 

& E. Estrada 3783 (NMC). Meoqui: Meoqui, 24 Aug 1935, 

LeSueur Mex-032 (US). Uruachi: Guazaremos, Río Mayo, 20 

Sep 1935, Gentry 1841 (US).

Panicum hirticaule var. verrucosum Zuloaga & Morrone, Annals Missouri Bot. Gard. 83: 253–254. 1996.

Specimens Examined. MEXICO. Chihuahua. 

Casas Grandes: W of Casas Grandes, 5 mi S of Hernández, 18 

Sep 1960, 2200 m, Reeder & C. Reeder 3517 (US); between 

Casas Grandes and Sabinal, 4–5 Sep 1899, E.W. Nelson 6355 

(US), holotype. Janos: Chihuahua–Sonora border, Rancho Carretas, 26 Aug 1939, 1460 m, L. H. Harvey 1600 (ENCB, US).

290. Panicum lepidulum Hitchc. & Chase, Contr. U.S. Natl. 

Herb. 15: 75, f. 64. 1910.

Perennial; solitary or caespitose. Culms 25–70(100) cm tall, 

erect, with 1 or 2 per plant, sparsely papillose-pilose to scabrous 

toward the apex. Leaf sheaths papillose-hirsute with ascending 

hairs; ligules 1.8–2 mm long, membranous; blades 7–20(30) cm 

long, 5–10 mm wide, flat or conduplicate, sparsely pilose. Panicles 

10–20(30) cm long, terminal, largely exserted, ovoid, the branches 

ascending and flexuous with 1–3 spikelets near the tips, naked 

below. Spikelets 3.7–4.2 mm long, 1.3–1.5 mm wide, narrowly 

ovate, turgid, apex acuminate; lower glumes 1.7–2.7 mm long, 

ovate, 5-veined, the midvein scabrous to the apex, acute or acuminate; upper glumes 3.7–4.2 mm long, apiculate; lower floret sterile, lower lemma similar to the upper glume, lower palea 1.5 mm 

long; upper floret perfect. Caryopsis 3.2–3.8 mm long, 1.2–1.4 

mm wide, oval, turgid and obtuse, pale, glabrous, smooth, bright. 

Distribution and Habitat. Panicum lepidulum

grows in grasslands, xerophilous scrub, and pine–oak forests. It 

ranges from Mexico in Chihuahua, Distrito Federal, Durango, 

Guanajuato, Jalisco, Michoacán, Morelos, and Oaxaca to Central America.

Specimens Examined. MEXICO. Chihuahua.

near Chihuahua, Aug 1885, C.G. Pringle 497 (US).

291. Panicum pampinosum Hitchc. & Chase, Contr. U.S. Natl. 

Herb. 15: 66, f. 48. 1910.

Caespitose annual. Culms 12–30 cm long, erect, decumbent, 

glabrous, with branches on central and inferior nodes; nodes 

hairy, the hairs white and silky about 1 mm long. Leaf sheaths 

papillose-pilose, collar glabrous; ligules 1 mm long, membranous; 

blades 3–12 cm long, 3–10 mm wide, flat, linear-lanceolate, with 

short hairs or hispid, margins pilose toward base, base rounded 

to subcordate. Terminal panicles 5–6 cm long, axillary panicles 

2–3 cm long, contracted, spiciform to subspiciform, generally 

exserted, few-flowered, often the spikelets clustered near the 

end of the branches; primary branches 4–8 cm long, appressed 

and ascending, alternate; pulvinus glabrous; rachis glabrous 

ot scabrous. Spikelets 3.6–4 mm long, 1.4 mm wide, globose, 

glabrous, acute; lower glumes 2.4–3.1 mm long, 3- to 5-veined, 

acuminate; upper glumes 3.6–4 mm long, 7-veined; lower lemma 

sterile, similar to the upper glume, 9–veined; lower paleas 1.2–

1.4 mm long, glabrous; upper floret 2–2.4 mm long, 1.2 mm 

wide, obovate to globose, smooth, lustrous, with 2 basal scars, 

the scars 0.3 mm long. n = 9, 18. 

Distribution and Habitat. Panicum pampinosum grows in grasslands and open areas; it ranges from the 

United States to Mexico.
288 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Specimens Examined. MEXICO. Chihuahua. 

Gómez Farías: Laguna de Babicora, San Jose Babicora, 18 Aug 

1994, 2200 m, G. Quintana & E. Estrada 3087 (NMC).

292. Panicum parcum Hitchc. & Chase, Contr. U.S. Natl. Herb. 

15: 68, f. 53. 1910.

Caespitose annual. Culms 30–90 cm tall, erect to geniculate, 

simple or branched on lower and middle nodes, glabrous. Leaf 

sheaths papillose-hispid; ligules 0.6–1.5 mm long, membranous, 

ciliate, the cilia 0.5–1 mm long; blades 10–25 cm long, 3–10 

mm wide, linear, flat, papillose-pilose, ciliate, rounded on base. 

Panicles 7–35 cm long, open, lax, few-flowered, terminal and 

axillary; primary branches 9–18 cm long, scabrous, spreading; 

spikelets divergent, solitary at the end of the branches. Spikelets 4.8–5.8 mm long, ovoid, glabrous, acuminate; lower glumes 

2.8–4.2 mm long, clasping near base, 5- to 7-veined, acuminate, 

glumes internode elongated; upper glumes 4.8–5.8 mm long, 9-

to 11-veined, acuminate; lower palea 1.5–2.5 mm long; upper 

floret perfect; upper lemma 2.8–3.4 mm long, 1.5–2 mm wide, 

smooth, bright, glabrous, obtuse, sessile; anthers 1.4–2 mm long. 

Caryopsis 2.3–2.5 mm long, whitish. 2n = 36.

Distribution and Habitat. Panicum parcum

grows in grasslands, it occurs in Mexico and Central America. 

This species is reported in Espejo Serna et al. (2000) and Herrera 

Arrieta and Cortés Ortiz (2010).

293. Panicum plenum Hitchc. & Chase, Contr. U.S. Natl. Herb. 

15: 80. 1910.

FIGURE 187

Rhizomatous perennial. Culms 70–150 cm tall, decumbent, 

simple, glaucous; internodes flattened, glabrous. Leaf sheaths glabrous to appresed-pilose; ligules 0.5–1.2 mm long, membranous, 

ciliate, the cilia 0.2–0.7 mm long; blades 10–30 cm long, 4–8 mm 

wide, linear, flat, broadened to subcordate neare base, glabrous 

or scaberulous. Panicles 10–30 cm long, about 2⁄3 as wide, open, 

all terminal; branches 4–10 cm long, ascending to spreading, 

solitary. Spikelets 3–3.4 mm long, 1.2–1.4 mm wide, ellipsoid or 

lanceolate, glaucous, some purplish, solitary, acute to subacute; 

lower glumes 1–1.2 mm long, less than 1⁄2 as long as the spikelet, 

subacute, 3-veined; upper glumes 3–3.4 mm long, 5- to 7-veined, 

obtuse; lower floret sterile or staminate; lower lemma 3–3.4 mm 

long, 5- to 7-veined, subacute; lower palea shorter than the lower 

lemma; anthers 2–2.7 mm long; upper floret perfect, rugulose, 

elliptic, minutely puberulent near the apex, acute; upper lemma 

3–3.2 mm long, 1.1–1.3 mm wide; anthers 2.1–2.8 mm long.

Distribution and Habitat. Panicum plenum

grows in oak forests and occurs in the United States and Mexico in Chihuahua, Durango, Guerrero, Morelos, Sonora, and 

Veracruz.

Specimens Examined. MEXICO. Chihuahua.

Chihuahua: 14 Oct 1910, Hitchcock 7772 (US); 6 mi N of Chihuahua, 8 Oct 1959, Soderstrom 923 (US). Jiménez: Sta. Eulalia 

plains, 8 Sep 1885, E. Wilkinson 51, 60 (US).

FIGURE 186. Panicum hirticaule var. hirticaule. A. Habit. B. Spikelet showing lover glume. C. Spikelet showing upper glume. Drawn 

by Linda Ann Vorobik and Cindy Roché; copyright Utah State 

University.
NUMBER 107 • 289

294. Panicum trichoides Sw., Prodr. 24. 1788.

FIGURE 188

Annual. Culms 15–100 cm tall, 0.5–1(2) mm thick, sprawling to erect, without cormlike bases, freely branching and 

rooting from the lower nodes; nodes prominent, glabrous or pubescent; internodes not succulent, pilose. Sheaths shorter than 

the internodes, rounded, with papillose-based hairs; collars pilose; ligules 0.2–0.5 mm long; blades 2–7 cm long, 5–20 mm 

wide, 4–6 times longer than wide, lanceolate, thin, flat, sparsely 

to densely pilose, the hairs papillose-based; bases asymmetrical, 

cordate to subcordate; lower margins ciliate, papillose. Panicles 

4–24 cm long, almost as wide as long, diffuse, partially included 

or exserted; primary branches to 10 cm long, ascending to reflexed, branching in the distal 2⁄3, alternate; pedicels 9–20 mm 

long, threadlike. Spikelets 1–1.4 mm long, 0.5–0.6 mm wide, 

not secund, lanceolate to narrowly ovoid, plano-convex in side 

view, sparsely pubescent; lower glumes 0.4–0.8 mm long, 1⁄3–1⁄2

as long as the spikelets, 1- to 3-veined, subacute; upper glumes 

0.8–1.2 mm long, arising 0.2 mm above the lower glumes, 3- to 

5-veined; lower florets sterile; lower lemmas 0.1–0.2 mm longer 

than the upper glumes, 3- to 5-veined; lower paleas 0.5–0.8 mm 

long, hyaline; upper florets 0.8–1.2 mm long, 0.4–0.6 mm wide, 

finely rugose; lemmas strongly convex. 2n = 18.

Distribution and Habitat. Panicum trichoides

grows in moist, often weedy fields, woodlands, and savannahs in 

Mexico, Central America, and the Caribbean

Specimens Examined. MEXICO. Chihuahua.

Batopilas: 225 air km SW of Cd. Chihuahua on the Río Baropilas, 5 km downstream from the bridge at La Bufa, 19 Oct 1986, 

1160 m, Spellenberg 8929 (NMC); 7 km por la brecha [gap] a la 

Cumbre en dirección a Rodeo, 17 Sep 2003, 1400 m, Tenorio, J. 

Rodríguez, M. Hilerio & E. Zárate 23597, 23629 (US). Chinipas: Saguarivo, 53 mi N of Alamos, 9 Sep 2008, slopes with oaks 

and pines, 1540 m, P.M. Peterson & J.M. Saarela 22139, 22140 

(US); Curahui, 926 m, tropical deciduous forest, 9 Sep 2008, 

P.M. Peterson & J.M. Saarela 22142 (US). Ocampo: 122.5 km 

W of La Junta on road to Parque Nacional Cascada de Basaseachic and 56.7 km W of Tomochic, 1 Oct 1989, 2100 m, P.M. 

Peterson & R.M. King 8230 (US).

295. Panicum vaseyanum Scribn. ex Beal, Grass. N. Amer. 2: 

140. 1896.

Caespitose annual. Culms 30–70 cm tall, ascending or 

suberect from a decumbent base, rooting at the lower nodes. 

Leaf sheaths shorter than the internodes, inflated below, glabrous, often exposing the culms with age; ligule 0.5–1.5 mm 

long, membranous, white, pilose, the hairs 0.4–1.4 mm long; 

blades 5–20 cm long, 3–7 mm wide, flat, conduplicate on base, 

glabrous. Panicles 4–7 cm long, narrow, terminal and axillary; 

FIGURE 187. Panicum plenum. A. Spikelet showing upper below. 

B. Spikelet showing upper glume above. C. Upper floret, ventral 

view. Drawn by Linda Ann Vorobik and Cindy Roché; copyright 

Utah State University.

FIGURE 188. Panicum trichoides. A. Inflorescence. B. Spikelet 

showing lower glume below. C. Spikelet showing upper glume 

below. D. Upper floret, ventral view. Drawn by Linda Ann Vorobik 

and Cindy Roché; copyright Utah State University.
290 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

branches 1–4 cm long, 3–5 per rachis, the lower reflexed at maturity, the upper appressed. Spikelets 2.2–3.2 mm long, solitary, 

appressed, ellipsoid, subacute; lower glumes 0.9–1.2 mm long, 

almost 1⁄3 as long as the spikelet, obtuse to acute, clasping below; 

upper glumes slightly shorter than the lower lemma, 7-veined, 

acute; lower floret sterile; lower lemma 2.2–3.2 mm long; lower 

palea absent; upper floret perfect; anthers 1.1–1.9 mm long. 

Caryopsis 2–2.7 mm long, 1–1.2 mm wide, smooth, bright, glabrous, olive-green to brown, acute.

Distribution and Habitat. Panicum vaseyanum grows in grasslands and oak forests. It occurs in Mexico 

in Aguascalientes, Chiapas, Chihuahua, Distrito Federal, Guanajuato, Guerrero, Jalisco, México, Michoacán, and Querétaro.

Specimens Examined. MEXICO. Chihuahua. Bocoyna: Arroyo Rituchi con Rancho & Cueva, 12 Sep 2003, 2205 

m, Bye & col. 32287 (US). Casas Grandes: 5 mi S of Hernández, 

W of Casas Grandes, 18 Sep 1960, Reeder, C. Reeder & Soderstrom 3526 (ARIZ-3527, US). Chihuahua: Base of Sierra Madre, 

30 Sep 1887, C.G. Pringle 1415 (US), holotype; km 15 V. Guerrero–Sto. Tomás, 29 Oct 1954, Hern.-Xol. & C. Tapia N-382

(US). Cuauhtémoc: 11 mi W of Cuauhtémoc, 4 Sep 1967, low 

area between hwy and R. R. tracks, surrounded by Oak and Juniper covered hills, 7000 ft, Reeder, C. Reeder & Gooding 4849 

(ENCB, US). Guachochi: 24.6 km S of Mex 127 and 11.1 km NE 

of La Bufa, 11 Sep 1989, oak forest, 2000 m, P.M. Peterson, Annable & Y. Herrera 8054 (ENCB, US). Guerro: Miñaca, 13 Oct 

1910, 7000 ft, Hitchcock 7757 (US).

296. Panicum virgatum L., Sp. Pl. 1: 59. 1753.

Panicum havardii Vasey.

FIGURE 189

Rhizomatous perennial; the rhizomes often loosely interwoven, hard, with closely overlapping scales, sometimes short 

or forming a knotty crown. Culms 40–300 cm tall, 3–5 mm 

thick, solitary or forming dense clumps, erect or decumbent, 

usually simple; nodes glabrous; internodes hard, glabrous or 

glaucous, green or purplish. Sheaths longer than the lower internodes, shorter than internodes above, glabrous or pilose, especially on the throat, margins usually ciliate; ligules 2–6 mm 

long; blades 10–60 cm long, 2–15 mm wide, flat, erect, ascending or spreading, glabrous or pubescent, adaxial surfaces sometimes densely pubescent, particularly basally, bases rounded to 

slightly narrowed, margins scabrous. Panicles 10–55 cm long, 

4–20 cm wide, exserted, open; primary branches ascending to 

spreading, scabrous, usually rebranching once, thin, straight, 

solitary to whorled or fascicled; pedicels 0.5–20 mm long, appressed to spreading. Spikelets 2.5–8 mm long, 1.2–2.5 mm 

wide, narrowly lanceoloid, turgid to slightly laterally compressed, glabrous, acuminate; lower glumes 1.8–3.2 mm long, 

1⁄2–4⁄5 as long as the spikelets, glabrous, 5- to 9-veined, acuminate; upper glumes and lower lemmas extending 0.4–3 mm 

beyond the upper florets, 7- to 11-veined, strongly gaping at 

the apex; lower florets staminate; lower paleas 3–3.5 mm long, 

FIGURE 189. Panicum virgatum. A. Habit. B. Spikelet showing lower glume below. C. Spikelet showing upper glume. Drawn 

by Linda Ann Vorobik and Cindy Roché; copyright Utah State 

University.
NUMBER 107 • 291

ovate-hastate, lateral lobes folded over the anthers before anthesis; upper florets 2.3–3 mm long, 0.8–1.1 mm wide, narrowly ovoid, smooth, glabrous, shiny; upper lemmas clasping 

the paleas only at the base. 2n = 18, 21, 25, 30, 32, 35, 36, 

54–60, 67–72, 74, 77, 90, 108.

Distribution and Habitat. Panicum virgatum

grows in tall grass prairies on dry slopes and sandy sites in open 

oak or pine woodlands and along shores, river banks, and brackish marshes. Its range extends from southern Canada throughout 

the United States to Mexico, Cuba, Bermuda, and Costa Rica; 

possibly introduced in Argentina.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: El Plan RELAC, 26 Mar 83, pastizal [pastureland], 

1300 m, G. Melgoza 130 (RELC). La Campana, 24 Sep 76, 

Jardín de observación [observation garden], 1500 m, S. González 

763 (RELC). Juárez: 38 mi S of Juárez along hwy to Ciudad 

Chihuahua, 8 Sep 1948, 1300 m, Gentry 8212 (US); near Paso 

del Norte, 23 Sep 1886, C.G. Pringle 1124 (US) ); Sand Dunes, 

10–20 Oct 1935, LeSueur Mex-082 (US).

Pappophorum Schreb.

Perennial; caespitose, essentially glabrous throughout. 

Culms 30–130 cm tall. Sheaths open; ligules of hairs; micro hairs 

of the blades with an inflated terminal cell similar in length to the 

basal cell. Inflorescence terminal, narrow, spikelike or somewhat 

open panicle; disarticulation above the glumes but not between 

the florets, these falling together. Spikelets with 3–5 florets, only 

the lower 1–3 bisexual; glumes subequal, thin, membranous, 

1-veined, acute; lemmas rounded on the back, hairy at least basally, obscurely (5)7(9)-veined, veins extending into scaberulous 

awns of unequal length, several additional narrow awn-like lobes 

usually also present, awns and lobes together forming a pappuslike crown; paleas textured like the lemmas, 2-veined, 2-keeled, 

keels scabrous or hairy; anthers 3; styles 2. Caryopsis elliptical, 

plump, slightly dorsally flattened or nearly terete; embryos about 

1⁄2 as long as the caryopsis. x = 10.

Pappophorum is an American genus with nine species. It 

grows in warm regions of North and South America.

KEY TO SPECIES OF PAPPOPHORUM

1. Panicles purple-tinged, narrow, but usually with some slightly spreading branches; lemma bodies 3–4 mm long, the awns 

mostly not more than 1.5 times as long, these rarely spreading at right angles . . . . . . . . . . . . . . . . . . . . . . . . . . P. bicolor

1. Panicles white or tawny, rarely slightly purplish, tightly contracted; lemma bodies 3–3.2 mm long, the awns about twice as 

long, commonly spreading at right angles when mature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. vaginatum

297. Pappophorum bicolor E. Fourn., Mexic. Pl. 2: 133. 1886.

Perennial. Culms 30–80(100) cm tall. Sheaths mostly glabrous, apex with a tuft of hairs on either side; ligules about 1 mm 

long; blades 10–20(30) cm long, 2–5 mm wide, flat to involute. 

Panicles 12–20 cm long, narrow but usually with some slightly 

spreading branches, pink or purple-tinged. Spikelets with the 

lower 2 or 3 florets bisexual, distal 1 or 2 florets sterile; glumes 

3–4 mm long, thin, glabrous, apex acute or minutely notched 

and mucronate; lemmas somewhat firm, usually faintly 7-veined, 

with 11–15 awns; lowest lemma bodies 3–4 mm long, midveins 

and margins pubescent from the base to about midlength, awns 

about 1.5 times as long as the lemma bodies; paleas subequal to 

the lemma bodies or slightly longer. Caryopsis about 2 mm long. 

2n = 100.

Distribution and Habitat. Pappophorum 

bicolor grows in open valleys, road rights-of-way, and grassy 

plains in Texas and northern Mexico.

Specimens Examined. MEXICO. Chihuahua.

Aldama: Santo Domingo, 50 km SW of Coyame of Mex 16 between Presidio, Texas and Chihuahua, 22 Sep 1988, 1400 m, 

P.M. Peterson & Annable 5753 (US); km 38 carr. [hwy] Aldama–

Ojinaga, 15 Oct 1980, pastizal [pastureland], 1275 m, Loya 

1711 (MEXU); km 60 de la carr. Chihuahua–Ojinaga, 28 Aug 

1978, matorral [scrub], 1270 m, Molinar, Rodríguez & Baray 39

(MEXU). Camargo: en llano [flat] entre [between] Los Ángeles 

& Jaco, 3 Aug 76, matorral, 1265 m, S. González & J.M. Peña 

498 (RELC). Chihuahua: Rancho experimental la campana, 

82 km al N de la ciudad de Chihuahua, 26Aug 1978, jardines de 

observación de zacates [grass observation garden], 1550 m, C.A. 

Fernández s.n. (ENCB). Jiménez: El Hugo, Torreoncitos, 13Aug 

2010, matorral de Prosopis sp., 1355 m, D. Ramírez & M.L. 

Juárez 3396, 3400 (CIIDIR).

298. Pappophorum vaginatum Buckley, Prelim. Rep. Surv. Texas 

App. 1. 1866.

Perennial. Culms (40)50–100 cm tall. Sheaths mostly glabrous, with a tuft of hairs at the throat; blades 10–25 cm long, 

2–5 mm wide, flat to involute, adaxial surfaces scaberulous. Panicles 10–25 cm long, tightly contracted, usually white or tawny, 

rarely slightly purple-tinged. Spikelets with 1(2) bisexual florets 

and 2 reduced florets; glumes (3)4–4.5 mm long, glabrous, acute; 

lowest lemma bodies 3–3.2 mm long, midveins and margins pubescent from the base to about midlength, awns about twice as 

long as the lemma bodies, tending to spread at right angles when 

mature; paleas longer than the lemma bodies. 2n = 60.

Distribution and Habitat. Pappophorum 

vaginatum grows in similar habitats to P. bicolor, the two species sometimes growing together. Its range extends from southern Arizona to Texas and northern Mexico and from Uruguay 

to Argentina.

Specimens Examined. MEXICO. Chihuahua. Aldama: Santo Domingo, 50 km SW of Coyame of Mex 16 between 

Presidio, Texas and Chihuahua, 22 Sep 1988, 1400 m, P.M. Peterson & Annable 5752 (US); 26 (rd) mi NE of Aldama along Hwy 
292 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

16 near El Morrion, 15 Sep 1972, 1400 m, J. Henrickson 7563

(MEXU, NMC); 60 km Chih–Ojinaga, matorral [scrub], 1270 m, 

Molinar, Rodríguez & Baray 150 (MEXU). Chihuahua: Rancho 

La Campana, 24 Sep 76, Jardines de observación [observation gardens], 1500 m, S. González 822 (RELC); Rancho Experimental La 

Campana, 82 km al N de Chihuahua, 26 Aug 1978, pastizal [pastureland], 1500 m, M.A. Bernal s/n (MEXU). Delicias: 14 km N 

of Delicias road from Chihuahua to Delicias, 29 Jun 1974, weedy 

vegetation in irrigated area, S.D. Koch 74156 (ENCB, MEXU). 

Jiménez: 39 mi N of Ceballos on Mex 49, 31 Mar 1971, mesquite 

along hwy, 3950 ft, W.E. Harmon 5431 (ENCB).

Paspalum L.

Annual or perennial; caespitose, rhizomatous or stoloniferous. Culms erect, spreading or prostrate, sometimes trailing. 

Sheaths open; auricles sometimes present; ligules membranous. 

Inflorescences terminal, sometimes also axillary, panicles of 

1 to many spikelike branches, these digitate or racemose on 

the rachis, spreading to erect, 1 or more branches completely 

or partially hidden in the sheaths in some species; branch axes 

flattened, usually narrowly to broadly winged, usually terminating in a spikelet, sometimes extending beyond the distal spikelet 

but never forming a distinct bristle; disarticulation below the 

glumes. Spikelets subsessile to shortly pedicellate, plano-convex, 

rounded to acuminate, dorsally compressed, not subtended 

by bristles or a ring-like callus, solitary or paired (1 spikelet 

of the pair reduced in some species), in 2 rows along 1 side of 

the branch, with 2 florets, first rachilla segment not swollen, 

upper glumes and upper lemmas adjacent to the branch axes; 

lower florets sterile; upper florets sessile or stipitate, bisexual, 

acute or rounded; lower glumes absent or present only on some 

spikelets of each branch, without veins or 1-veined, unawned; 

upper glumes and lower lemmas subequal, membranous, apex 

rounded, unawned; lower paleas absent or rudimentary; upper 

lemmas convex, indurate, smooth to slightly rugose, stramineous 

to dark brown, margins scarious, involute, clasping the paleas; 

upper paleas indurate, smooth to slightly rugose, stramineous to 

dark brown. Caryopsis orbicular to elliptical, plano-convex or 

flattened, white, yellow, or brown. x = 10, 12.

Paspalum includes about 310 species, most of which are native to the Western Hemisphere (Soreng et al., 2017b).

KEY TO SPECIES OF PASPALUM

1. Upper florets dark brown. 

2. Plants perennial; sterile lemma with corrugated or rippled margins; panicle branch rachis 0.5–1 mm wide, not winged 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. plicatulum

2. Plants annual; sterile lemma without corrugated or rippled margins; panicle branch rachis 1–2 mm wide, winged . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. convexum

1. Upper florets white-yellowish or straw-colored. 

3. Racemes 2, conjugate or paired at the apex of culms, rarely a third raceme present below the apex; spikelets solitary, 

rarely paired . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. distichum

3. Racemes numerous, generally more than 2, racemose or fasciculate on the axes and not conjugate or paired; spikelets 

paired.

4. Spikelets 1.4–2.6 mm long. 

5. Racemes 0.7–2 cm long, 2.2–2.5 mm wide, winged; culms 2–8(15) cm tall; plants annual, caespitose . . . . . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. prostratum var. pygmaeum

5. Racemes 2–12(17) cm long, 0.2–1.2 mm wide, not winged; culms 40–110 cm tall; plants perennial, caespitose or 

short rhizomatous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. setaceum

4. Spikelets 2.1–3.6 mm long.

6. Lower glumes absent; plants decumbent, stoloniferous, never rhizomatous; upper glumes 2.8–3.6 mm long, 

3-veined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. pubiflorum

6. Lower glumes present at least in the subsessile spikelets; plants erect, caespitose, never stoloniferous; upper glumes 

2.2–2.5 mm long, 3- to 5-veined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. botterii

299. Paspalum botterii (E. Fourn.) Chase, J. Wash. Acad. Sci. 

13(20): 436. 1923.

Caespitose perennial. Culms 23–125 cm tall, erect; nodes glabrous or pubescent. Sheaths hirsute with tubercled-based hairs; 

ligules 0.6–1.9 mm long, an eciliate membrane; blades 17–44 cm 

long, 12–24 mm wide, flat, pilose, hairy with tubercle-based hairs. 

Panicles 5–25 cm long, terminal, with 3–7 racemose branches along 

a central axis, unilateral; racemes 5–20 cm long, erect to divergent, terminating in a spikelet; rachis narrowly winged 0.5–1 mm 

wide, glabrous or ciliare on margins. Spikelets 2.2–2.5 mm long, 

1.3–1.6 mm wide, paired, obovate, dorsally compressed, obtuse, 

stramineous to brown, falling entire, densely packed, irregular, 

4-rowed; lower glumes 0.4–1.2(1.8) mm long, 1-veined, present 

in some spikelets (on the subsessile), thinner than fertile lemma; 

upper glumes 2.0–2.4 mm long, puberulous, 3- to 5-veined, membranous; lemmas 2.1–2.5 mm long, striate, puberulous, 3- to 

5-veined, indurate, pallid; paleas involute, indurate. Caryopsis 

1.3–1.5 mm long, light to dark brown. 2n = 40, 60.
NUMBER 107 • 293

Distribution and Habitat. Paspalum botterii

is native to North America and extends from Mexico to Venezuela. It grows at the edges of moist woods and in disturbed areas.

Specimens Examined. MEXICO. Chihuahua.

Batopilas: 14.5 km N of Batopilas on road to La Bufa, 12 Sep 

1989, 850 m, P.M. Peterson, Annable & Y. Herrera 8065 (US). 

Chinipas: Sierra Saguarivo, 1.3 mi W of Curahui, 9 Sep 2008, 

tropical deciduous forest, 1001 m, P.M. Peterson & J.M. Saarela 

22145 (US). Ocampo: 1 km W of W boundary of Parque Nacional “Cascada de Basaseachi”, 21 km from the cahuisori Ocampo 

road on the road to Candameña, 10.5 km below Cruz Verde, 24 

Sep 1994, 965 m, Spellenberg, R. Corral & E. Estrada 12207 

(CIIDIR, MEXU, NMC). 

300. Paspalum convexum Humb. & Bonpl. ex Flüggé, Gram. 

Monogr., Paspalum 175. 1810.

FIGURE 190

Annual. Culms 10–53 cm long, erect; nodes glabrous. 

Sheaths pubescent or glabrous; ligules 2–4.1 mm long; blades 

5–25(80) cm long, 2.9–10.2(12) mm wide, flat. Panicles terminal, 

with 1–5 racemosely arranged branches; the branches 1.1–5.4(7) 

cm long, divergent; branch axes 0.8–1.3 mm wide, not or narrowly winged, glabrous, terminating in a spikelet. Spikelets 2.1–

2.6 mm long, 1.7–2.4 mm wide, paired, appressed to the branch 

axes, broadly obovate to suborbicular, shortly pubescent, light 

to dark brown; lower glumes absent; upper glumes and lower 

lemmas short-pubescent, 5- to 7-veined, margins entire, not corrugated; lower paleas rarely present; upper florets dark glossy 

brown. Caryopsis 1.3–1.5 mm long, white. 2n = 30, 32, 40, 60.

Distribution and Habitat. Paspalum convexum grows in disturbed areas in the southeastern United 

States. It is native in Mexico, Central America, northern South 

America, and the Caribbean Islands (Zuloaga et al., 2003).

Specimens Examined. MEXICO. Chihuahua. 

Bachiniva: about 4 mi SE of Bachiniva, 20 Oct 1968, pine and 

oak woodland, 1800 m, Spellenberg & M. Spellenberg 2000

(ENCB, NMC). Balleza: 10 mi SW of El Ojito, 12 Sep 2006, 

1902 m, P.M. Peterson 20023, F. Sánchez Alvarado & E.P. 

Gómez Ruíz (CIIDIR, US). Batopilas: Yamuco, 1 mi E of hwy 

N of Rio Urique crossing towards Basihuare and Creel, 6 Sep 

2008, P.M. Peterson & J.M. Saarela 22070 (US). Carichi: Mojarachic, 5 Sep 1938, I.W. Knobloch 5515 (US). Chihuahua: Sierra 

Madre, 14 Oct 1887, C.G. Pringle 1175 (US); 4 Oct 1888, C.G. 

Pringle 1875 (US). Guachochi: 37.4 km S of Creel on road to 

Batopilas, 10 Sep 1989, pine forest, 2045 m, P.M. Peterson, Annable & Y. Herrera 8011 (US); Barranca de Basihuare, 28 Aug 

2003, bosque de encino [oak forest], 1700 m, P.M. Peterson & 

P. Catalán 17585 (CIIDIR, US). Guerrero: Tomochi, 2 km alrededor del poblado [around the village], 24 sep 1997, bosque 

de pino [pine forest], 2100 m, M.A. Vergara156 (CIIDIR). Ocampo: Parque Nacional “Cascada de Basaseachic,” a los lados 

[sides] del arroyo Basaseachic, aprox. a 500 m al N del area 

de campamentos [camp area], 21 Sep 1990, 1980 m, R. Corral 

FIGURE 190. Paspalum convexum. A. Habit. B. Inflorescence. 

C. Spikelet, showing upper glume. D. Spikelet showing lower 

lemma. Drawn by Linda Ann Vorobik and Cindy Roché; copyright 

Utah State University.
294 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

RCD-3811(NMC); Parque Nacional “Cascada de Basaseachic,” 

at overlook ca. 1 km airline S of Cascada, 3 Oct 1986, 2100 

m, Spellenberg, Soreng, R. Corral & T. Lebgue 8665 (NMC); 

Parque Nacional Cascada Basaseachic, a los lados del arroyo, 21 

Sep 1990, bosque de pino–encino, 1980 m, R. Corral RCD3811

(UACJ). Riva Palacio: Col. Cumbres de Majalca, 33.8 km W of 

Mex 45, N of Chihuahua City, 7 Sep 1989, pine forest, 2190 

m, P.M. Peterson, Annable & Y. Herrera 7966 (US). Temosachi: 

Nabogame, 5 Aug 1987, 1800 m, Laferr. 676 (NMC).

301. Paspalum distichum L., Syst. Nat. 2: 855. 1759.

Paspalum paucispicatum Vasey.

FIGURE 191

Perennial; hardened near the base; rhizomatous sometimes 

caespitose. Culms 5–65 cm tall, erect; nodes glabrous. Sheaths 

glabrous, sparsely long-pubescent distally; ligules 1–2 mm long; 

blades to 14 cm long, 1.8–11.5 mm wide, flat or conduplicate, 

glabrous or pubescent, apex involute. Panicles terminal, usually 

composed of a digitate pair of branches, a third branch sometimes present below; branches 1.4–7 cm long, diverging, often 

arcuate; branch axes 1.2–2.2 mm wide, winged, glabrous, margins scabrous, terminating in a spikelet. Spikelets 2.4–3.2 mm 

long, 1.1–1.6 mm wide, solitary (rarely paired), appressed to the 

branch axes, broadly elliptic, stramineous, sometimes partially 

purple; lower glumes absent or, if present, up to 1 mm long and 

triangular; upper glumes sparsely and shortly pubescent on the 

back, 3-veined; lower lemmas glabrous, 3-veined; upper florets 

stramineous. Caryopsis 1.9–2.1 mm long, yellow. 2n = 20, 30, 

40, 48, 60, 61.

Distribution and Habitat. Paspalum distichum grows on the edges of lakes, ponds, rice fields, and wet 

roadside ditches. It is native to warm regions throughout the 

world, being most abundant in humid areas. In the Western 

Hemisphere it occurs in the United States and ranges south to 

Argentina and Chile.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 32 km SW of Villa Ahumada, 22 Oct 1954, Hern.-

Xol.. & C.Tapia N-98 (US). Batopilas: Yamuco, 1 mi E of hwy N 

of Rio Urique crossing towards Basihuare and Creel, 6 Sep 2008, 

P.M. Peterson & J.M. Saarela 22072 (US). Camargo: 5 km W of 

cd. Camargo, 5 Aug 1939, 1220 m, L. H. Harvey 1407 (ENCB). 

Chihuahua: La Campana, Potrero el plan, 4 km Ote [W] carr 

[hwy] panamericana, 6 sep 1973, lugares humedos [humid 

places], 1500 m, Valdés-Reyna VR-118 (CIIDIR, ENCB); VR181 (RELC). Cuahtémoc: km 5 to the W of Cd. Cuauhtémoc, 27 

Oct 1954, Hern.-Xol. & C. Tapia N-348 (US); about 13 mi SE of 

Bachimba along hwy 7, along roadside, 11 Jul 1950, Alkali soil, 

Reeder, C. Reeder & Goodding 1252 (ENCB). Delicias: km 76 

Cd. Chihuahua–Cd. Delicias, 1 Nov 1954, 950 m, Hern.-Xol. & 

C. Tapia N-531 (US). Guachochi: small spring below Napuchis, 

2 Sep 2003, 1950 m, P.M. Peterson & P. Catalán 17658 (US).

Guerrero: Miñaca, 13 Oct 1910, Hitchcock 7735, 7762 (US). 

Madera: Laguna de Babicora, Ejido Año de Hidalgo, 15 Sep 

FIGURE 191. Paspalum distichum. A. Habit. B. Ligule. C. Portion of the inflorescence branch. D. Spikelet showing upper glume. 

E. Spikelet showing lower lemma. Drawn by Linda Ann Vorobik 

and Cindy Roché; copyright Utah State University.
NUMBER 107 • 295

1994, 2300 m, Quintana, Lebgue & Estrada 3770 (NMC). Matamoros: about 12 mi S of Villa Matamoros, 8 Oct 1966, Reeder 

& C. Reeder 4624 (ARIZ, ENCB, US). Riva Palacio: Nuevo Majalca, approx. 14.5 km W of hwy 45, N of Chihuahua, 22 Sep 

1988, grassland, 1700 m, P.M. Peterson & Annable 5773 (US). 

Saucillo: along Isla de Perla road about 4 mi E of Cd. Delicias, 

11 Jul 1950, in cultivated and irrigated valley, Reeder, C. Reeder 

& Goodding 1260 (ENCB).

302. Paspalum plicatulum Michx., Fl. Bor.-Amer. 1: 45. 1803.

FIGURE 192

Caespitose perennial; rhizomes short, often indistinct. 

Culms 30–120 cm tall, erect, or geniculately ascending. Ligules 2–3 mm long, an eciliate membrane; blades 15–30 cm 

long, 2–7 mm wide, flat or folded, surface glabrous or pilose, 

apex acuminate. Inflorescence composed of 2–7 racemes, the 

racemes 2–15 cm long, borne along a central axis, unilateral, 

the central axis 3–15 cm long; rachis 0.5–1 mm wide, wingless, 

angular. Spikelets 2.3–3.2 mm long, 1.5–2.2 mm wide, in pairs, 

with 1 basal sterile floret; 1 fertile floret, 2- to 4-rowed; fertile 

spikelets pedicelled, without rhachilla extension, elliptic or obovate, dorsally compressed, plano-convex, obtuse, falling entire; lower glume absent; upper glume reaching apex of floret, 

thinner than fertile lemma, ovate, membranous, without keels, 

5-veined, surface glabrous or puberulous; lemma of lower sterile floret similar to upper glume, ovate, as long as the spikelet, 

membranous, corrugated or rippled near margins, 5-veined, 

obtuse; fertile lemma 2–3 mm long, ovate, gibbous, indurate, 

dark brown, surface granulose, margins involute; palea involute, indurate. 2n = 10, 20.

Distribution and Habitat. Paspalum plicatulum grows on the edges of forests and disturbed areas. It is native 

to the Americas: south central and southeastern United States to 

Mexico, South America, and the Caribbean Islands. It has been 

reported from Chihuahua (Herrera Arrieta 2001). 

303. Paspalum prostratum var. pygmaeum Scribn. & Merr.,

Bull. Div. Agrostol., U.S.D.A. 24: 9. 1901.

Caespitose annual. Culms 2–8(15) cm tall, erect to geniculate near base. Sheaths with scattered papillose-based hairs, 

these often appressed; ligules 0.4–0.6 mm long, a ciliate membrane; blades 1.5–7.5 cm long, 2–7 mm wide, lanceolate, flat, 

pilose, the hairs papillose-based. Panciles terminal with 1–4 racemes; the racemes 0.7–2 cm long, 2.2–2.5 mm wide, winged, 

exserted or partially enclosed in the sheath, reflexed and 

spreading at 80°–100° from the culm axis; rachis nodes hairy. 

Spikelets 2–2.2 mm long, glabrous, light yellowish, solitary in 

2 rows; lower glume absent; upper glumes 2 mm long, elliptic, 

hyaline, 3-veined; lemmas 2 mm long, elliptic, 3-veined, chartaceous, shiny.

Distribution and Habitat. Paspalum prostratum var. pygmaeum can be found growing on rocky slopes with 

Pinus, Juniperus, and Holodiscus in wet clayish soils between 

FIGURE 192. Paspalum plicatulum. A. Habit. B. Culm and Inflorescence. C. Inflorescence branch. D. Spikelet showing upper glume. 

E. Spikelet showing lower lemma. Drawn by Linda Ann Vorobik 

and Cindy Roché; copyright Utah State University.
296 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

1,700 and 3,300 m. It is known from the states of Durango, 

Jalisco, México, Distrito Federal, Michoacán, Morelos, and Veracruz (Herrera Arrieta, 2001; Dávila et al., 2006). Paspalum 

prostratum var. pygmaeum can be separated from Paspalum 

prostratrum Scribn. & Merr. var prostratum in having undifferentiated leaf blade bases (rounded in the latter variety), narrower leaf blades (2–7 versus 8–20 mm wide), and shorter culms 

(2–8[15] versus 30–75 cm tall) (Clayton et al., 2006). 

Specimens Examined. MEXICO. Chihuahua.

Guadalupe y Calvo: near Cumbres Mohinora, 13 Sep 2006, 

3250–3300 m, P.M. Peterson 20035, F. Sánchez Alvarado, E.P. 

Gómez Ruíz (CIIDIR, US).

304. Paspalum pubiflorum Rupr. ex E. Fourn., Mexic. Pl. 2: 11. 

1886.

FIGURE 193

Perennial; usually decumbent, rooting at the nodes, stoloniferous. Culms 30–130 cm long, decumbent; nodes glabrous 

or pubescent. Sheaths glabrous or pubescent; ligules 1–3.2 mm 

long; blades to 31 cm long, 4–18 mm wide, flat, glabrous, with 

a few hairs behind the ligules. Panicles terminal, with 2–7 racemosely arranged branches; branches 2.2–7.9 cm long, divergent 

to spreading, terminating in a spikelet; branch axes 1.1–2.3 mm 

wide, narrowly winged, glabrous, margins scabrous. Spikelets 

2.8–3.6 mm long, 1.5–2 mm wide, paired, imbricate, appressed 

to divergent from the branch axes, elliptic to obovate, pubescent 

or glabrous, light brown to stramineous; lower glumes absent; 

upper glumes and lower lemmas 2.8–3.6 mm long, glabrous or 

sparsely pubescent, the hairs shorter than 0.1 mm long, 3-veined, 

margins entire; lower lemmas lacking ribs over the veins; upper 

florets stramineous. Caryopsis 1.8–2 mm long, golden brown or 

white. 2n = 60, ca. 64.

Distribution and Habitat. Paspalum pubiflorum grows on the edges of forests and in disturbed areas. It is 

native to the southeastern United States, Mexico, and Cuba.

Specimens Examined. MEXICO. Chihuahua. 

Aldama: km 38 Cd. Chihuahua Hormigas, N of V. Aldama, 

31 Oct 1954, 1100 m, Hern. Xol. & C. Tapia N-517 (US). Camargo: 5 km W of Cd. Camargo, 5 Aug 1939, 1220 m, L. H. 

Harvey 1405a (ENCB); 10 mi N of cd. Camargo, 4 Oct 1953, 

scattered plants along the ditch, 1280 m, Reeder & C. Reeder 

2611 (ENCB). Chinipas: Sierra Saguarivo, 1.3 mi W of Curahui, 9 Sep 2008, tropical deciduous forest, 1001 m, P.M. Peterson & J.M. Saarela 22156 (US). Chihuahua: near Chihuahua, 

Sep 1885, C.G. Pringle 374 (US); 12 mi N of Chihuahua on 

rd to Cd. Juárez, 8 Oct 1959, 1494 m, Soderstrom 932 (US). 

Madera: Paraje Agua Caliente, predio particular [private property] El Chorrito, 17 Oct 1990, bosque de encino [oak forest], 

2350 m, O. Bravo 1946 (CIIDIR); Paraje Sirupa, ejido Cebadilla 

de Dolores, 24 Aug 1990, vegetación riparia [riparian vegetation], 1220 m, O. Bravo 1254 (CIIDIR). Saucillo: along Isla de 

Perla road about 4 mi E of cd. Delicias, 11 Jul 1950, in cultivated 

and irrigated valley, 1250 m, Reeder & C. Reeder 1253 (ENCB).

FIGURE 193. Paspalum pubiflorum. A. Culm base. B. Culm and 

inflorescence. C. Inflorescence branch. D. Spikelet showing upper 

glume. E. Spikelet showing lower lemma. Drawn by Linda Ann 

Vorobik and Cindy Roché; copyright Utah State University.
NUMBER 107 • 297

305. Paspalum setaceum Michx., Fl. Bor.-Amer. 1: 43. 1803.

FIGURE 194

Perennial; caespitose or short rhizomatous. Culms 40–

110 cm tall, erect, spreading, or prostrate; nodes glabrous or pubescent. Sheaths glabrous or pubescent; ligules 0.2–0.5 mm long; 

blades flat, glabrous or pubescent. Panicles terminal and axillary, with 1–6 racemosely arranged branches, axillary panicles 

partially or completely enclosed by the subtending leaf sheath; 

branches 2–12(17) cm long, ascending to spreading, often arcuate, terminating in a spikelet; branch axes 0.2–1.2 mm wide, glabrous, sometimes scabrous. Spikelets 1.4–2.6 mm long, paired, 

imbricate, appressed to the branch axes, elliptic to obovate to 

ovate to orbicular, stramineous or brown; lower glumes absent; 

upper glumes and lower lemmas glabrous or with short capitatepubescent (glandular tipped), 3-veined, margins entire; lower 

lemmas lacking ribs over the veins; upper florets stramineous. 

Caryopsis elliptic to suborbicular, white. 2n = 20.

Distribution and Habitat. Paspalum setaceum

is a variable species that grows east of the Rocky Mountains in 

the contiguous United States and Mexico. Paspalum setaceum

has nine varieties in North America; P. setaceum var. ciliatifolium and P. setaceum var. setaceum are known from Mexico, and 

both occur in Chihuahua.

Specimens Examined. MEXICO. Chihuahua. Chihuahua, 10–20 Oct 1935, LeSueur Mex-062 (US); 1 km al E del 

Rancho El 45, 28 Sep 73, 1450 m, J. Valdés-Reyna VR-369 (RELC). 

Juárez: near Paso del Norte, 23 Sep 1886, C.G. Pringle 1123 (US).

KEY TO VARIETIES OF PASPALUM SETACEUM

1. Lower lemmas with evident midveins; leaf blades dark green to purplish, glabrous or with a few hairs along the midrib 

(rarely short pilose) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. setaceum var. ciliatifolium (Michx.) Vasey

1. Lower lemmas without evident midveins; leaf blades grayish-green, conpiscuously hirsute, usually with long stiff hairs and 

short soft hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. setaceum var. setaceum

Peyritschia E. Fourn.

Perennial; caespitose. Culms erect or decumbent, slender or 

weak. Ligules an eciliate membrane; blades flat or involute. Inflorescence a panicle, open or contracted, sometimes spiciform. 

Spikelets solitary, comprising 2 fertile florets, without rachilla 

extension or with a barren rachilla extension, sometimes with 

reduced florets at the apex; spikelets oblong or cuneate, disarticulating below each floret. Glumes linear, lanceolate or elliptic, 

persistent, hyaline or membranous, shorter than spikelets, same 

size or exceeding the apex of the floret, lower glumes 1-veined, 

upper glumes 1- to 3-veined, as long as fertile lemma; fertile lemmas lanceolate, elliptic or oblong, subterete, membranous or 

cartilaginous, 5-veined, lemma surface snooth or scaberulous, 

the margins flat or involute, the apex entire, toothed or 2- to 

4-lobed, 1-awned, dorsally emerging, straight or geniculate; 

palea embraced by lemma or gaping, same size or a little less 

than the lemma, hyaline or membranous; apical sterile florets 

resembling fertile but underdeveloped. Caryopsis with adherent 

pericarp, fusiform, soft; endosperm liquid. x = 7.

Peyritschia is a genus with seven species native to temperate 

regions of the New World (Finot et al., 2004, 2006).

FIGURE 194. Paspalum setaceum. A. Habit. B. Inflorescence. C. Spikelet showing upper 

glume. D. Spikelet showing lower lemma. Drawn by Linda Ann Vorobik and Cindy Roché; 

copyright Utah State University.
298 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

KEY TO SPECIES OF PEYRITSCHIA

1. Lemma awn emerging 1 mm above the base; rachilla hairs short, inconspicuos; panicle densely cylindrical, the axis hidden 

by the spikelets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. pringlei

1. Lemma awn emerging 2–3 mm above the base; rachilla hairs 1.5–2.5 mm long in the superior part of each internode; 

panicles lax, the axis at least partially visible . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. deyeuxioides

306. Peyritschia deyeuxioides (Kunth) Finot, Contr. U.S. Natl. 

Herb. 48: 478. 2003. Avena deyeuxioides Kunth, Nov. 

Gen. Sp. (quarto ed.) 1: 147. 1816. Trisetum deyeuxioides 

(Kunth) Kunth, Révis. Gramin. 1: 102. 1829.

Caespitose perennial. Culms 50–120 cm tall, slender, erect

or ascending, glabrous, simple, sometimes branched on the lower 

nodes. Sheaths glabrous, scabrous or pilose; ligules (0.5)1–4 mm 

long; blades 8–25 cm long, (1.5)2–6 mm wide, flat, glabrous or pilose. Panicles 10–35 cm long, 1–4 cm wide, narrow, lax, somewhat 

open and nodding, axis visible at least partially, scabrous, often 

pilose; branches 6–11 cm long, appressed or ascending, fasciculate, the longest naked on the lower 1⁄3–1⁄2. Spikelets 4.5–6(8) mm 

long, 2- or 3-flowered, disarticulation above glumes and between 

florets; rachilla hairy, the hairs 1.5–2.5 mm long near the summit 

of each internode; internodes 1–1.7 mm long; glumes 3.5–5.5(8) 

mm long, subequal, 1-veined, scabrous on the back; lemma of fertile florets 3.5–4.5(6) mm long, subcylindrical, glabrous, the margins involute, apex 2-lobed, the lobes rounded, truncate or acute, 

awned, the awns 5–9(12) mm long, emerging 2–3 mm above the 

base of the lemma, geniculate and flexuous or twisted below, scabrous and pilose, the hairs 2.5–3 mm long; stamens 2, the anthers 

1–1.5(2.5) mm long. Caryopsis 1.8–2.5 mm long. 2n = 14, 28.

Distribution and Habitat. Peyritschia deyeuxioides grows in moist meadows and grasslands, thorny scrub, 

and oak–pine forests. It is native in Mexico, Central America, 

and South America.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: Camino Balleza–Guachochic, km 45, 24 Sep 1981, pastizal [pastureland], R. Fierros & M.A. Siqueiros 1590 (MEXU); 

36 km al SE de Baquiriachi, camino [road] Balleza, 24 Sep 1985, 

bosque de pino–encino [pine–oak forest], 2225 m, P. Dávila, 

Tenorio e I. Solis 133 (MEXU). Batopilas: Yamuco at 1 km E of 

Hwy towards Basihuare and Creel, N of Rio Urique crossing, 26 

Aug 2003, bosque de pino, 1891 m, P.M. Peterson & P. Catalán 

17549 (US); SW Chihuahua, Aug 1885, E. Palmer 14 (US). Bocoyna: Sánchez, 12 Oct 1910, Hitchcock 7676 (US); 3.7 km N of 

San Juanito on road to Creel, near km 53 marker, 24 Sep 1988, 

pine woods, 2200 m, P.M. Peterson & Annable 5861 (ENCB, 

US); Cabecera de la cabaña de Recognata, 22 sep 1997, bosque de 

pino–encino en cañada, 2400 m, B. Tah V. 30 (MEXU). Chinipas: 

Saguarivo, 53 mi N of Alamos, 9 Sep 2008, slopes with oaks and 

pines, 1540 m, P.M. Peterson & J.M. Saarela 22111 (US). Chihuahua: Mapula Mts, 30 Oct 1886, C.G. Pringle 821 (US); Base 

of the Sierra Madre, 21 Sep 1887, pine plains, C.G. Pringle 1428

(MEXU, US); Canyons of the Sierra Madre, 13 Sep 1887, springy 

banks, C.G. Pringle 1432 (MEXU, US). Cuisihuiriachic: Rancho 

El Coronel, 2 Sep 1981, bosque esclero-aciculifolio [narrowleaved sclerophyllous forest], 2500 m, Loya & Méndez 1521

(MEXU). Guachochi: Yamuco, 1 mi E of hwy N of Rio Urique 

crossing towards Basihuare and Creel, 6 Sep 2008, P.M. Peterson 

& J.M. Saarela 22058 (US); approx. 22.5 mi NE of Cieneguita 

de Barranca on road towards Creel, 5 Sep 2003, bosque de pino, 

2160 m, P.M. Peterson & P. Catalán 17695 (US); proximidad a 

la Col. Chuichupa, 1 Nov 1990, pastizal & bosquete [grove] de 

Juniperus deppeana, 2240 m, A. Benítez 2182 (CIIDIR, MEXU); 

Ciénega Ojo de la Vibora, ejido El Largo, 14 Oct 1990, bosque 

de pino, 2300 m, O. Bravo 1903 (MEXU, CIIDIR). Guerrero: 

km 193 carr. [hwy] Chihuahua–Hermosillo, tramo [section] 

San Pedro–Temochic, 24 Sep 1997, 2200 m, M.A. Vergara 

174 (MEXU); carr. la Junta–San Juanito, 17 km, 22 Sep 1997, 

2290 m, B. Tah V. 1 (MEXU). Madera: Laguna de Babicora, Ejido 

Año de Hidalgo,15 Sep 1994, 2300 m, T. Lebgue, G. Quintana & 

E. Estrada 3765 (NMC); Laguna de Babicora, Arroyo Las Varas, 

10 Sep 1994, 2300 m, G. Quintana & E. Estrada 3559 (NMC); 

10 km al sureste [southeast] de Madera, 5 Oct 74, bosque de 

pino–encino, 2000 m, Valdés-Reyna VR-665 (RELC); Chuhuichupa, Aug–Sep 1936, LeSueur Mex-0114 (MEXU); Madera, 8 Sep 

1977, 2400 m, Blanco 10/77 (MEXU). Ocampo: Parque Nacional 

“Cascada de Basaseachic,” in a canyon along Rio Basaseachi leading to falls, 4 Oct 1986, 1950 m, Spellenberg, Soreng, R. Corral & 

T. Lebgue 8805 (NMC). Namiquipa: Aprox. km 39 carr. Chihuahua–Namiquipa, 24 Sep 1997, bosque de encino, 2300 m, M.A. 

Vergara 180-A (MEXU). Tomochi: Tomochi, 2 km alrededor del 

poblado [near the village], 24 Sep 1997, bosque de pino, 2100 m, 

M.A. Vergara 145 (MEXU).

307. Peyritschia pringlei (Scribn.) S. D. Koch, Taxon 28(13): 

233. 1979. Deschampsia pringlei Scribn., Proc. Acad. Nat. 

Sci. Philadelphia 43(2): 300–301, t. 13, f. 1, 1a. 1891.

Caespitose perennial. Culms 30–100 cm tall, glabrous, 

simple. Sheaths glabrous, sometimes pubescent below; ligules 

1.5–4 mm long, membranous, truncate or rounded; blades 

5–15 cm long, 1–3(4) mm wide, flat, occasionaly involute, glabrous to pilose. Panicles 7–15(20) cm long, 0.5–1.5 cm wide, 

compact, narrow to somewhat open and interrupted below, 

axis hidden between the spikelets, scabrous; rachilla hairy, the 

hairs inconspicuous; branches ascending and appressed. Spikelets (3.5)4–5 mm long, 2- or 3-flowered, disarticulation above 

glumes and between florets; rachilla sparsely pilose, the hairs 

0.7–1 mm long; glumes 4.1–5.3 mm long, equal to subequal, 

1-veined; lemma of lower floret 3–4.3 mm long, the upper 

shorter, apex 2-lobed, the lobes rounded, awns (4.5)5–7 mm 
NUMBER 107 • 299

long, emerging 1 mm above the base of the lemma, geniculate 

and twisted near the base; stamens 2, anthers 0.8–1 mm long. 

Caryopsis 1.5–2 mm long. 2n =28. 

Distribution and Habitat. Peyritschia pringlei 

grows in grasslands and oak–pine forests. It is native in Mexico, 

Central America, and South America.

Specimens Examined. MEXICO. Chihuahua. 

Bocoyna: 1.1 km N of San Juanito near large lumber mill, 24 

Sep 1988, 2200 m, P.M. Peterson & Annable 5865 (ENCB, US). 

Chihuahua: Chihuahua, 9 Oct 1887, C.G. Pringle 1429 (US), 

holotype. Cuauhtémoc: 20.9 km W of Cuauhtémoc on hwy 16, 

23 Sep 1988, pine woods, 2000 m, P.M. Peterson & Annable 

5821 (ENCB, US). Guadalupe y Calvo: 9.5 mi E of Guadalupe y 

Calvo on hwy 24, 14 Sep 2006, 2570 m, P.M. Peterson 20056, 

F. Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, US). Guerrero: 35.4 km SW of La Junta and approx. 74 km N of Creel, 24 

Sep 1988, pine woods, 2200 m, P.M. Peterson & Annable 5830

(ENCB, US); 37 km SW of La Junta on road to Creel at the puente [bridge] Arroyo Ancho, 10 Sep 1989, pine forest, 2230 m, 

P.M. Peterson, Annable & Y. Herrera 7994 (ENCB, US); entre 

La Junta & Namiquipa: Aprox. km 39 carr. [hwy] Chihuahua–

Namiquipa, 24 Sep 1997, bosque de encino [oak forest], 2300 

m, M.A. Vergara 180 (MEXU); Miñaca, 13 Oct 1910, 7000 ft, 

Hitchcock 7762 (MEXU); Carr. la Junta–San Juanito, 17 km, 

22 Sep 1997, 2290 m, B. Tah V. 13 (MEXU). Gómez Farías: 

near Gomez Farías, between Cuahutémoc and Buenaventura, 26 

Oct 1881, A.A. Beetle M-7939 (MEXU). Temochic: Temochi, 13 

Aug 1976, bosque de pino–encino [pine–oak forest], 2195 m, S. 

González & J.M. Peña 606 (RELC).

Phalaris L.

Annual or perennial; caespitose or not, sometimes rhizomatous. Culms sometimes swollen at the base, not branching above 

the base. Leaves more or less evenly distributed, glabrous; sheaths 

open for most of their length, uppermost sheaths often somewhat inflated; auricles absent; ligules hyaline, truncate to acuminate, entire or lacerate, glabrous; blades usually flat, sometimes 

revolute. Inflorescence a terminal panicle, sometimes spikelike, 

ovoid to cylindrical, dense, sometimes interrupted, with 10–200 

spikelets borne singly or in clusters, the spikelets homogamous 

in species with single spikelets, heterogamous in species with 

the spikelets in clusters, the lower spikelets in the clusters staminate (rarely sterile), the terminal spikelets bisexual or pistillate. 

Spikelets pedicellate, homomorphic, laterally compressed, 1- to 

3(4)-flowered, only the terminal (or only) floret reproductively 

functional, the lower floret(s), if present, sterile; disarticulation 

in species with single spikelets above the glumes, the florets falling together or, in species with clustered spikelets, usually at the 

base of the spikelet clusters, sometimes beneath the bisexual or 

pistillate spikelets; glumes equal or almost so, exceeding the florets, 1- to 5-veined, keeled, keels often conspicuously winged; 

lower (sterile) florets reduced, varying from knoblike projections 

on the calluses of the terminal florets to linear or lanceolate lemmas less than 3⁄4 as long as the terminal florets; terminal florets 

usually bisexual, pistillate, or staminate, rarely sterile, in the 

lower spikelets of a spikelet cluster; lemmas of terminal florets 

coriaceous to indurate, shiny, glabrous or pubescent, inconspicuously 5-veined, acute to acuminate or beaked, unawned; paleas 

similar to the lemmas in length and texture, enclosed by the lemmas at maturity, 1-veined, mostly glabrous, veins shortly hairy; 

lodicules absent or 2 and reduced; anthers 3; ovaries glabrous; 

styles 2, plumose. Caryopsis with a reticulate pericarp, falling 

free of the lemma and palea; hila long-linear. x = 6, 7.

Phalaris has 17 species, most of which grow in temperate 

regions (Baldini, 1995; Clayton et al., 2006). It is found in a wide 

range of habitats, although most species prefer somewhat mesic, 

disturbed sites.

KEY TO SPECIES OF PHALARIS

1. Spikelets in clusters, heterogamous, the lower 4–7 spikelets in each cluster with a staminate (rarely sterile) terminal floret, 

only the terminal spikelet in the clusters with a pistillate or bisexual floret; disarticulation usually at the base of the spikelet 

clusters, sometimes beneath the bisexual or pistillate spikelets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. paradoxa

1. Spikelets borne singly, homogamous, all spikelets with a bisexual floret; disarticulation above the glumes, below the sterile 

florets.

2. Glume keels not winged or with wings no more than 0.2 mm wide.

3. Perennial; bisexual florets with acute to somewhat acuminate apex . . . . . . . . . . . . . . . . . . . . . . . . . P. arundinacea

3. Annual; bisexual florets with beaked or strongly acuminate apex . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. caroliniana

2. Glume keels broadly winged, the wings 0.2–1 mm wide.

4. Sterile florets usually 1, or if 2, then the lower floret up to 0.7 mm long and the upper floret 1–3 mm long . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. aquatica

4. Sterile florets 2, equal to subequal, 0.5–4.5 mm long.

5. Panicles cylindrical, discontinuous, sometimes lobed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. angusta

5. Panicles usually ovoid to ellipsoid, occasionally cylindrical, continuous, not lobed.

6. Glumes 0.8–1.5 mm wide, with acute to acuminate apices . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. caroliniana

6. Glumes 2–2.5 mm wide, with rounded, mucronate apices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. canariensis
300 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

308. Phalaris angusta Nees ex Trin., Sp. Gram. 1: t. 78. 1827.

FIGURE 195

Annual; not rhizomatous. Culms 10–170 cm tall. Ligules 4–7 mm long, truncate to rounded or obtuse, lacerate; 

blades 3–15 cm long, 2–12 mm wide. Panicles 2–20 cm long, 

0.6–1.5 cm wide, cylindrical, discontinuous, sometimes lobed; 

branches sometimes evident, the spikelets borne singly, not 

clustered. Spikelets homogamous, all spikelets with a bisexual 

floret; florets 3; disarticulation above the glumes, beneath the 

sterile florets; glumes 2–5.5 mm long, 0.6–1.1 mm wide, rectangular, often purplish, keels winged, scabrous, wings about 

0.4 mm wide, smooth, lateral veins conspicuous, scabrous, 

apex mucronate; sterile florets 2, 0.5–1.5 mm long, equal, linear, sparsely and inconspicuously hairy; bisexual florets 2–3.8 

mm long, 0.9–1.5 mm wide, laterally compressed, pubescent, 

particularly distally, shiny, apex tapering; anthers 0.5–1.3 mm 

long. 2n = 14.

Distribution and Habitat. Phalaris angusta

grows in the contiguous United States and Mexico and in South 

America from Ecuador south to Chile and Argentina. This species occurs in open grasslands and prairies. Reported from Chihuahua by Espejo Serna et al. (2000).

309. Phalaris aquatica* L., Cent. Pl. I. 4. 1755.

FIGURE 196

Caespitose perennial; short rhizomatous. Culms 60–200 

cm tall, often swollen at the base, rooting at the lower nodes. 

Ligules 2–12 mm long, truncate, lacerate; blades 5–15(20) cm 

long, 0.5–10 mm wide. Panicles 1.5–15 cm long, 1–2.5 cm 

wide, usually cylindric, sometimes ovoid, occasionally lobed 

at the base, the spikelets borne individually, not clustered; 

branches not evident. Spikelets homogamous, all spikelets with 

a bisexual floret; florets 2–3(4), occasionally with 2 bisexual 

florets, occasionally the terminal floret viviparous; disarticulation above the glumes, beneath the sterile florets; glumes 4.4–

7.5 mm long, 1.2–1.5 mm wide, keels winged distally, wings 

0.2–0.4 mm wide, usually entire, lateral veins conspicuous, 

smooth; sterile florets usually 1, if 2, the lowest floret much 

shorter, to 0.7 mm long, the upper or only sterile floret 1–3 mm 

long, pubescent; bisexual florets 3.1–4.6 mm long, 1.2–1.5 mm 

wide, pubescent, stramineous, acute; anthers 3–3.6 mm long. 

2n = 28.

Distribution and Habitat. Phalaris aquatica

is native to the Mediterranean region and was introduced into 

South America because of its forage value. It is also reported as 

introduced to Chihuahua, Mexico.

Specimens Examined. MEXICO. Chihuahua. Chihuahua: Rancho La Campana, 4 km al E de la carr. 

Panamericana, 17 May 1975, jardín de adaptación de zacates 

[grass adaptation garden], 1500 m, J. Valdés-Reyna VR-903

(RELC).

FIGURE 195. Phalaris angusta. A. Culm and inflorescence. B. Spikelet. C. Florets. Drawn by Linda Ann Vorobik and Hana Pazdírková; 

copyright Utah State University.
NUMBER 107 • 301

310. Phalaris arundinacea L., Sp. Pl. 1: 55. 1753.

FIGURE 197

Perennial; not caespitose, rhizomatous, rhizomes scaly. 

Culms 40–250 cm tall. Ligules 4–10(11) mm long, truncate, 

lacerate; blades 10–30 cm long, 5–20 mm wide, surfaces scabrous, margins serrate. Panicles 5–40 cm long, 1–2 cm wide, 

elongate, often dense, always evidently branched at least near 

the base; branches to 9 cm long, normally appressed but spreading during anthesis, the spikelets borne singly, not clustered. 

Spikelets homogamous, all spikelets with a bisexual floret; florets 3; disarticulation above the glumes and beneath the sterile 

florets; glumes 4–8.1 mm long, 0.8–1 mm wide, subequal, keels 

smoothly curved, usually scabrous, not or narrowly winged distally, wings to 0.2 mm wide, lateral veins inconspicuous, apex 

acute; sterile florets 2, 1.5–2 mm long, less than 1⁄2 as long as the 

bisexual spikelets, subequal to equal, pubescent; bisexual florets 

2.5–4.2 mm long; lemmas glabrous below, pubescent distally and 

on the margins, dull yellow when immature, shiny gray-brown 

FIGURE 196. Phalaris aquatica. A. Inflorescence. B. Spikelet. C. Florets. Drawn by Linda Ann Vorobik and Hana Pazdírková; copyright 

Utah State University.

FIGURE 197. Phalaris arundinacea. A. Habit. B. Glumes. C. Spikelet. D. Florets. Drawn by Linda Ann Vorobik and Hana Pazdírková; 

copyright Utah State University.
302 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

to brown at maturity, apex acute; anthers 2.5–3 mm long. 2n = 

27, 28, 29, 30, 31, 35.

Distribution and Habitat. Phalaris arundinacea is a circumboreal species, native to north temperate regions; 

it is introduced in the Southern Hemisphere. It grows in wet 

areas such as the edges of lakes, ponds, ditches, and creeks, often 

forming dense stands; in some areas it is a problematic weed.

Specimens Examined. MEXICO. Chihuahua. 

Práxedis G. Guerrero: Rancho Escuela, km 65, 16 Aug 1997, 

cultivo de alfalfa, I. Enriquez, S. Ordoñez, L. Sushii, S. Carrasco, 

A. Perales & N. Loya IEA14 (UACJ).

311. Phalaris canariensis* L., Sp. Pl. 1: 54–55. 1753.

FIGURE 198

Annual. Culms 30–100 cm tall. Ligules 3–6 mm long, 

rounded to obtuse, lacerate; blades 3–25 cm long, 2–10 mm 

wide. Panicles 1.5–5 cm long, 1.5–2 cm wide, ovoid to oblongovoid, continuous, not lobed, truncate at the base; branches not 

evident, the spikelets borne singly, not clustered. Spikelets homogamous, all spikelets with a bisexual floret; florets 3; disarticulation above the glumes, beneath the sterile florets; glumes 

7–10 mm long, 2–2.5 mm wide, smooth, mostly glabrous, sometimes sparsely pilose between the veins, keels winged, the wings 

to 0.6 mm long, widening distally, lateral veins inconspicuous, 

smooth, apex rounded, mucronate; sterile florets 2, 2–4.5 mm 

long, 1⁄3 or more the length of the bisexual florets, equal or subequal, lanceolate, sparsely pubescent, acute; bisexual florets 4.5–

6.8 mm long, ovate, densely pubescent, shiny, stramineous to 

gray-brown; anthers 2–4 mm long. 2n = 12.

Distribution and Habitat. Phalaris canariensis is native to southern Europe and the Canary Islands but is 

now widespread and is mostly grown for birdseed. This species 

has been reported from Chihuahua (Espejo Serna et al., 2000; 

Dávila et al., 2006).

312. Phalaris caroliniana Walter, Fl. Carol. 74. 1788.

FIGURE 199

Annual; not rhizomatous. Culms to 150 cm tall. Ligules 

1.5–7 mm long, truncate to broadly acute; blades 1.5–15 cm long, 

2–11 mm wide, smooth, shiny green, apex acuminate. Panicles 0.5–

8(8.5) cm long, 0.8–2 cm wide, ovoid to subcylindrical; branches 

not evident, the spikelets borne singly, not clustered. Spikelets homogamous, all spikelets with a bisexual floret; florets 3; disarticulation above the glumes, below the sterile florets; glumes 3.8–6(8) 

mm long, 0.8–1.5 mm wide, keels smooth or scaberulous, narrowly to broadly winged distally, the wings 0.1–0.5 mm wide, entire, smooth, lateral veins prominent, usually smooth, sometimes 

scaberulous, apex acute or acuminate; sterile florets 2, 1.5–2.5 mm 

long, 1⁄2 or more the length of the bisexual florets, pubescent; bisexual florets 2.9–4.7 mm long, 0.9–1.8 mm wide, pubescent, shiny, 

stramineous when immature, brown when mature, apex acuminate to beaked; anthers 1.5–2 mm long. 2n = 14.

FIGURE 198. Phalaris canariensis. A. Habit. B. Culm and inflorescence. C. Spikelet. D. Florets. Drawn by Linda Ann Vorobik and 

Hana Pazdírková; copyright Utah State University.
NUMBER 107 • 303

Distribution and Habitat. Phalaris caroliniana grows in wet, marshy, and swampy ground. It is a common 

species in much of southern United States and northern Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Ascensión: alrededores del cruce [around the crossing] del río 

Casas Grandes con la carr. [hwy] Juárez–Ascensión, 11 Jun 

2005, 1180 m, R. Corral, M. Vargas & H. Gutiérrez RCD 7155

(UACJ). Chihuahua: Vicinity of Chihuahua, 27 Apr 1908, 1300 

m, E. Palmer 32 (US). Práxedis G. Guerrero (San Ignacio): a 

2 km al S del poblado del mismo nombre [village of the same 

name], Rancho Escuela de la Univ. Autónoma de Cd. Juárez, 18 

Mar 1995, 1090 m, R. Corral, P. Olivas & E. Pérez RCD6031

(UACJ); a 2 km del poblado Práxedis G. Guerrero (San Ignacio), 

Rancho Escuela de la Univ. Autónoma de Ciudad Juárez, 5 May 

1995, maleza de acequia [ditch weed], 1090 m, R. Corral, Bye, 

A. Domínguez, K. Chico & A. Soutyrine RCD6083 (UACJ).

313. Phalaris paradoxa* L., Sp. Pl. (ed. 2) 2: 1665. 1763.

FIGURE 200

Caespitose annual. Culms 20–100 cm tall, not swollen at the 

base. Ligules 3–5 mm long, truncate to acute; blades 5–10(15) 

cm long, 2–5 mm wide. Panicles 3–9 cm long, about 2 cm wide, 

dense, obovoid to clavate, tapering at the base, rounded to truncate at the top; branches with groups of 5–6 usually staminate, 

rarely sterile spikelets clustered around a terminal pistillate or bisexual spikelet, the spikelets homomorphic; pedicels hispid; disarticulation beneath the spikelet cluster. Spikelets heterogamous, 

some staminate or sterile, others bisexual or pistillate; florets 3, 

the lower 2 florets sterile, highly reduced, the terminal floret staminate, pistillate, or bisexual (rarely sterile); glumes of staminate 

or sterile spikelets to 9 mm long, usually narrowly winged and 

clavate, those of the spikelets at the base of the panicles reduced 

to knobs of tissue terminating the pedicels; glumes of pistillate or 

bisexual spikelets 5–8 mm long, about 1 mm wide, keeled, keels 

winged, the wings 0.2–0.4 mm wide, terminating below the apex 

and forming a single, prominent tooth, lateral veins conspicuous, 

apex acuminate to awned, awns about 0.5 mm; sterile florets of 

all spikelets 0.2–0.4 mm long, knoblike projections on the calluses of the terminal florets, often with 1–2 hairs; terminal florets 

of all spikelets 2.5–3.5 mm long, 0.8–1.5 mm wide, indurate, 

shiny, glabrous or with a few short hairs near the tip; anthers 

1.5–2.5 mm long. 2n = 14.

Distribution and Habitat. Phalaris paradoxa

is native to the Mediterranean region; it is now found throughout the world, primarily in waste areas and near old dumps. 

This species has been reported in Chihuahua (Espejo Serna et al., 

2000; Dávila et al., 2006).

Phragmites Adans.

Perennial; rhizomatous or stoloniferous, often forming dense 

stands. Culms leafy; internodes hollow. Leaves cauline, mostly 

glabrous; sheaths open; ligules membranous, ciliate; blades flat 

FIGURE 199. Phalaris caroliniana. A. Habit. B. Spikelet. C. Florets. Drawn by Linda Ann Vorobik and Hana Pazdírková; copyright 

Utah State University.
304 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

or folded. Inflorescence terminal, a plumose panicle. Spikelets 

with 2–8 florets, weakly laterally compressed, lower 1–2 florets 

staminate, distal 1–2 florets rudimentary, remaining florets bisexual; rachilla internodes sericeous; disarticulation above the 

glumes and below the florets; glumes unequal, shorter than the 

florets, 1- to 3-veined, glabrous; lower glumes much shorter than 

the upper glumes; calluses pilose; lemmas 3-veined, glabrous, unawned; anthers 1–3. Caryopsis rarely maturing. x = 12. 

The genus is treated as having four species worldwide. Phragmites australis has been divided into three subspecies in North America and a key is included below even though no specimens have been 

seen by us (Saltonstall et al., 2004; Saltonstall and Hauber, 2007). 

314. Phragmites australis (Cav.) Steud., Nomencl. Bot. (ed. 2) 

1: 143. 1840. Arundo australis Cav., Anales Hist. Nat. 1(2): 

100–101. 1799.

FIGURE 201

Culms 1–4 m tall, 0.5–1.5 cm thick, erect. Ligules 0.4–1.7 mm 

long; blades 15–40 cm long, 2–4 cm wide, long-acuminate, disarticulating from the sheath at maturity. Panicles 15–35 cm long, 

8–20 cm wide, ovoid to lanceoloid, often purplish when young, 

straw-colored at maturity. Spikelets with 3–10 florets; rachilla 

hairs (4)6–10 mm long; lower glumes 2.5–6.5 mm long; upper 

glumes 4.5–11 mm long; lemmas 7.5–13.5 mm long, glabrous, 

linear, margins somewhat inrolled, apex long-acuminate; paleas 

3–4 mm long, membranous; anthers 1.5–2 mm long, purplish; 

styles persistent. Caryopsis 2–3 mm long, rarely maturing. 2n = 

36, 42, 44, 46, 48, 49-54, 72, 84, 96, 120.

Distribution and Habitat. Phragmites australis grows in wet or muddy ground along waterways, in saline or 

freshwater marshes, and in sloughs throughout North America. 

Its tall, leafy, often persistent culms and plumose panicles make 

it one of our easier species to recognize. This species is reported 

from Chihuahua in Espejo Serna et al. (2000), Dávila et al. 

(2006), and Herrera Arrieta and Cortés Ortiz (2010).

KEY TO SUBSPECIES OF PHRAGMITES AUSTRALIS

1. Ligules 1.0–1.7 mm long; lower glumes 3.0–6.5 mm long; upper glumes 5.5–11.0 mm long; lemmas 8.0–13.5 mm long; leaf 

sheaths caducous with age; culms exposed in the winter, smooth and shiny; rarely occurs in a monoculture . . . . . P. australis

subsp. americanus Saltonstall, P. M. Peterson & Soreng (native lineage)

1. Ligules 0.4–0.9 mm long; lower glumes 2.5–5.0 mm long; upper glumes 4.5–7.5 mm long; lemmas 7.5–12.0 mm long; leaf 

sheaths not caducous with age; culms not exposed in the winter, smooth and shiny or ridged and not shiny; usually occurs 

as a monoculture.

2. Culms smooth and shiny; throughout Mexico and Central America . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. australis subsp. berlandieri Saltonstall & Hauber (Gulf Coast lineage)

2. Culms ridged and not shiny . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. australis subsp. australis (introduced lineage)

Piptochaetium J. Presl

Perennial; caespitose, not rhizomatous. Culms usually 

erect, sometimes decumbent, glabrous, not branched above the 

base; basal branching intravaginal; prophylls shorter than the 

sheaths, mostly glabrous, keels usually with hairs, apex bifid, 

teeth; cleistogenes not developed. Sheaths open to the base, margins glabrous; ligules membranous, decurrent, truncate to acute, 

sometimes highest at the sides, sometimes ciliate; blades convolute to flat, translucent between the veins, often sinuous distally. 

FIGURE 200. Phalaris paradoxa. A. Inflorescence. B. Inflorescence 

branch. C. Sterile spikelet. D. Fertile Spikelet. Drawn by Linda Ann 

Vorobik and Hana Pazdírková; copyright Utah State University.
NUMBER 107 • 305

Inflorescence a terminal panicle, open or contracted, spikelets 

usually confined to the distal 1⁄2 of each branch. Spikelets with 

1 floret; rachillas not prolonged beyond the base of the floret; 

disarticulation above the glumes, beneath the floret; glumes subequal, longer than the floret, lanceolate, 3- to 7(8)-veined; florets globose to fusiform, terete to laterally compressed; calluses

well-developed, sharp or blunt, glabrous or antrorsely strigose, 

hairs yellow to golden brown; lemmas coriaceous to indurate, glabrous or pubescent, striate, particularly near the base, 

smooth, papillose, or tuberculate, often smooth on the lower 

portion and papillate to tuberculate distally, margins involute, 

fitting into the grooved palea, apex fused into a crown, awned, 

lemmas often narrowed below the crown, crowns usually ciliate; awns caducous to persistent, usually twice-geniculate, first 

2 segments usually twisted and hispid, terminal segment straight 

and scaberulous; paleas longer than the lemmas, similar in texture, glabrous, sulcate between the veins, apex prow-tipped; 

lodicules 2 or 3, membranous, glabrous, blunt or acute; anthers

3; ovaries glabrous; styles 2. Caryopsis terete to globose or lensshaped. x = 11. 

Piptochaetium is primarily South American, being particularly abundant in Argentina (Ciadella et al., 2007). There are 

eight species of Piptochaetium in Mexico, three of which are 

known to occur in Chihuahua (Espejo Serna et al., 2000).

KEY TO SPECIES OF PIPTOCHAETIUM

1. Florets 2.3–5 mm long; culms 35–95 cm tall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. fimbriatum

1. Florets 5–10 mm long; culms 50–125 cm tall. 

2. Florets 6.5–10 mm long; leaf blades 1–3.5 mm wide, flat to loosely folded . . . . . . . . . . . . . . . . . . . . . . . . . . P. pringlei

2. Florets 5–6.5 mm long; leaf blades about 1 mm wide, tightly involute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. virescens

315. Piptochaetium fimbriatum (Kunth) Hitchc., J. Wash. Acad. 

Sci. 23(10): 453. 1933. Stipa fimbriata Kunth, Nov. Gen. 

Sp. (quarto ed.) 1: 126. 1815.

FIGURE 202

Culms 35–95 cm tall, usually glabrous, sometimes pubescent 

below the nodes; nodes 2–3, often dark, glabrous. Sheaths glabrous, smooth; ligules of basal leaves 0.4–1.8 mm long, of upper 

leaves 1.5–2 mm long, truncate to rounded; blades 6–26 cm 

long, 0.3–0.5 mm in diameter, usually involute, sometimes flat 

and 0.5–1(1.5) mm wide, 3-veined, glabrous, veins often scaberulous, margins scabrous. Panicles 6.5–25 cm long, open, 

often partially enclosed in the upper leaf sheath, with 20–60 

spikelets; branches flexuous; pedicels 4–12 mm long, flattened, 

hispid; glumes 4–6.2 mm long, 1.8–3.1 mm wide, subequal, 5-

to 7-veined, often partly purplish; florets 2.3–5 mm long, 0.6–

1.9 mm thick, somewhat laterally compressed, obovate in side 

view, asymmetrical; callus 0.2–0.7 mm long, blunt, strigose; lemmas awned, tan to light chocolate brown, shiny, smooth, evenly 

pubescent when immature, hairs easily rubbed off; crowns about 

0.8 mm wide, inconspicuous, glabrous or glabrate; awns 11–20 

mm long, persistent, twice-geniculate; paleas about 3.5 mm long; 

lodicules about 1 mm long, 2; anthers 0.3–0.5 mm long, not 

penicillate. Caryopsis 2.5–3 mm long, 0.6 mm thick, fusiform. 

2n = 42.

Distribution and Habitat. Piptochaetium 

fimbriatum is an attractive species that grows in oak and pinyon woods in the southwestern United States and adjacent 

Mexico. 

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 56.4 km W of Parral on road to Balleza and 35.5 km 

S of Balleza on Mex 432, near Corral de Duarte, 18 Sep 1991, 

bosque de pino–encino [pine–oak forest], 2210 m, P.M. Peterson, Annable & Valdés-Reyna 10713 (CIIDIR, US). Bocoyna: 

24.7 mi N of San Juanito on road towards Cuauhtemoc, 5 Sep 

2008, 2233 m, P.M. Peterson & J.M. Saarela 22029 (US); Cabecera de la cañada de Recogoata, 22 Sep 1997, bosque de 

pino–encino en cañada, 2400 m, B. Tah V. 36 (MEXU); along 

old railroad bed and old road between Creel and Bacoyna near 

tunnel, 13 Jul 1973, Bye 4214 (MEXU). Chihuahua: 32 km W 

of hwy 45 towards Benito Juárez, 17 Oct 1992, pinyon woodlands, 2110 m, P.M. Peterson & Annable 12548 (US); Sta. Clara 

Canyon, 10 Oct 1935, LeSueur Mex-075 (US); 16.7 mi W of 

hwy 45 on road up Los Prietos Canyon, 18 Oct 1992, 2120 m, 

bosque de pino, 2120 m, P.M. Peterson & Annable 12596 (US); 

rancho Tepehuanes de chihuahua hacia [toward] Namiquipa 

desviar [divert] en “Ocampo 73” a la izq terrac [to left dirt 

road] 6 km, 13 Oct 2000, pastizal mediano abierto [mostly open 

grassland], G. Gómez 330 (MEXU). Cuauhtémoc: 21 km W of 

Cuauhtemoc, on Hwy 16, 23 Aug 1990, 2000 m, P.M. Peterson 

& Annable 9594 (US). Cusihuiriachic: Rancho el Coronel, 2 Sep 

1981, bosque esclero-aciculifolio [narrow-leaved sclerophyllous 

forest], Loya & Méndez 1508 (MEXU). Guachochi: Parque Nacional Barranca del Cobre, 24.8 km NE of La Bufa on road 

to Samachic, 2440 m, P.M. Peterson, Annable & Valdés-Reyna 

10801 (US). Guadalupe y Calvo: 9.5 mi E of Guadalupe y Calvo 

on hwy 24 and 5 mi W of El Ocote, 14 Sep 2006, P.M. Peterson 

20057, F. Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, US). 

Guazapares: Above waterfalls at Wasachic, SW of Rokoroibo, 

25 Jul 1974, 1875 m, Bye 6494 (NMC). Guerrero: Barranca 

Colorada, Sierra Gazachic, 35 km S of Miñaca, 2500 m, Pennell 18940 (US): Miñaca, Hitchcock 7741 (US) 32.3 km SW of 

La Junta on road to Creel, 10 Sep 1989, pine forest, 2310 m, 

P.M. Peterson, Annable & Y. Herrera 7985 (ENCB, US); 37 km 

SW of La Junta on road to Creel at the puente [bridge] Arroyo 

Ancho, 10 Sep 1989, pine forest, 2230 m, P.M. Peterson, Annable & Y. Herrera 7997 (ENCB, US); 10 km S de La Junta, carr. 

[hwy] La Junta–Tomochi, 6 Oct 74, bosque de pino–encino, 
306 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

FIGURE 201. Phragmites australis. A. Rhizome. B. Culm and inflorescence. C. Spikelet. D. Floret. Drawn by Linda Ann Vorobik and 

Hana Pazdírková; copyright Utah State University.

FIGURE 202. Piptochaetium fimbriatum. A. Habit. B. Ligule. 

C. Glumes. D. Floret. E. Palea. F. Apex of lemma. Drawn by Cindy 

Roché; copyright Utah State University.
NUMBER 107 • 307

1900 m, Valdés-Reyna VR-709 (RELC); Entre [between] La 

Junta & Tomochi, 13 Aug 1976, bosque de pino–encino, 2195 

m, S. González & J.M. Peña 594 (RELC); Tomochi 2 km alrededor del poblado [around the village], 24 de Sep 1997, bosque 

de pino, 2100 m, M.A. Vergara 162 (MEXU); 4 km al poblado 

de Tomochic km 210 sobre carr. Chihuahua Basaseachi, 24 Sep 

1997, bosque de pino, 2200 m, B. Tah V. 165 (MEXU); carr. 

La Junta–San Ignacio 17 km, 22 Sep 1997, 2290 m, B. Tah 

V. 7 (MEXU); ca. 0.5 mi N of El Alamito on road between San 

Juanito and San Pedro, 2 Aug 1977, pine–oak, 2125 m, Bye 

7860 (MEXU). Madera: Proximidad a la Col. Chuichupa, 1 sep 

1990, bosquete de junipero [juniper grove], 2240 m, A. Benítez 

2175 (CIIDIR). Namiquipa: 72.5 km S of Ignacio Zaragoza on 

Mex 23, 28 Sep 1989, pine woods, 28 Sep 1989, 2300 m, P.M. 

Peterson & R.M. King 8170 (ENCB). Ocampo: Parque Nacional “Cascada de Basaseachic”, 5 Aug 1994, 1900 m, C. Yen & 

E. Estrada 2853 (NMC); Rio Basaseachic river canyon, 1.9 mi 

by road along the river canyon northward from Mexico Hwy 

16 between villages of Baquiriachic and Basaseachic ca. 5 km N 

of Cascada de Basaseachic, 5 Jul 1994, pine–oak, 2060 m, R.S. 

Felger, M. Wilson, G. Ferguson, M. Fishbein & S. MacMahon 

94-260A (MEXU); beside the road near Ocampo, Rio Mayo 

Region, 26 Jul 1990, pine–oak woodland, 2000 m, P. Jenkins 

90-292 (ARIZ). Riva Palacio: Majalca, 11 Oct 1939, L. H. Harvey 1458 (US); Col. Cumbres de Majalca, approx. 32.2 km W 

of hwy 45 N of Chihuahua, 23 Sep 1988, pine woods, 1800 m, 

P.M. Peterson & Annable 5807 (ENCB, US); Col. Cumbres de 

Majalca, approx. 32.2 km W of hwy 45 N of Chihuahua, 22 Sep 

1988, pine woods, 1800 m, P.M. Peterson & Annable 5811b

(ENCB, US); Col. Cumbres de Majalca, 33.8 km W of Mex 45, 

N of Chihuahua City, 7 Sep 1989, pine forest, 2190 m, P.M. 

Peterson, Annable & Y. Herrera 7950 (ENCB, US); Rancho las 

carr.s de Chihuahua hacia Namiquipa desviar en “Ocampo 73” 

a la izq terrac 12 km, 7 Oct 2000, bosque abierto con encino 

& pino, G. Gómez 215 (MEXU). Temosachi: Temosachi, 5 Sep 

1988, 1800 m, Laferr. 1923 (MEXU). 

316. Piptochaetium pringlei (Beal) Parodi, Revista Mus. La 

Plata, Secc. Bot. 6(25): 230, f. 1D. 1944. Oryzopsis pringlei

Beal, Bot. Gaz. 15(5): 112. 1890.

FIGURE 203

Culms 50–125 cm long, mostly glabrous, pubescent below 

the nodes; nodes 2–3, dark, glabrous or slightly pubescent. 

Sheaths smooth to scaberulous; ligules of basal leaves 0.5–

2.8 mm long, truncate to rounded; of upper leaves 1–3.5 mm 

long, rounded to acute; leaf blades 10–30 cm long, 1–3.5 mm 

wide, flat to loosely folded, prominently 3- to 5-veined, abaxially 

glabrous, smooth, adaxially smooth or scabrous over the veins, 

margins smooth or scabrous. Panicles 6–20 cm long, open, with 

10–25 spikelets, branches ascending, spreading, flexuous; pedicels to 1 mm long, flattened, hispid; glumes subequal, 9–12 mm 

long, 2.5–3.5 mm wide; lower glumes 5- to 7-veined; upper 

FIGURE 203. Piptochaetium pringlei. A. Ligule. B. Inflorescence. 

C. Glumes. D. Floret. E. Floret, magnified. F. Palea. G. Apex of 

lemma. Drawn by Cindy Roché; copyright Utah State University.
308 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

glumes 7-veined; florets 6.5–10 mm long, 1.5–2.1 mm thick, 

symmetrically oblong, terete to somewhat laterally compressed; 

calluses 0.6–1.9 mm long, blunt to acute, strigose; lemmas 6.5–

10 mm long, golden brown to dark brown at maturity, shiny 

or not, smooth to spiny-tuberculate distally or for almost their 

entire length, densely pubescent, hairs tawny to golden brown, 

evenly distributed or somewhat more abundant on the basal 1⁄2, 

apex tapering to the crown; crowns 0.5–0.6 mm long, inconspicuous, straight, hairy, the hairs 0.5–1 mm long; awns 19–27(35) 

mm long, persistent, twice-geniculate, sometimes inconspicuous; 

paleas 6.3–9.5 mm long; lodicules 2, 1–1.5 mm long, acute; anthers 3.5–5.5 mm long, sometimes penicillate. Caryopsis about 

7 mm long, fusiform. 2n = 42.

Distribution and Habitat. Piptochaetium 

pringlei grows in oak woodlands, often on rocky soils, in the 

southwestern United States and northwestern Mexico. It is often 

confused with P. fimbriatum but differs from that species in having longer florets and sharper calluses.

Specimens Examined. MEXICO. Chihuahua. 

Bocoyna: Sánchez, 12 Oct 1910, Hitchcock 7681 (US); 7677 

(US); Cabecera de la cañada de Recogoata, 22 Sep 1997, bosque 

de pino–encino [pine–oak forest], 2400 m, B. Tah V. 53 (MEXU); 

Moist llano [flat] Sw de Creel near San Ignacio, 17 Oct 1977, pine 

forest, Bye & A.W. Weber 8272 (MEXU). Guerrero: Barranca 

Colorada, Sierra Gazachic, 35 km S of Miñaca, 2500 m, Pennell 18929 (US). Guachochi: 24.6 km W of Guachochi and 0.6 

km S of Rocheachi, 2340 m, P.M. Peterson, Annable & ValdésReyna 10781 (US); km 85 carr. [hwy] Balleza–Guachochic, 24 

Sep 1981, bosque esclérofilo caducifolio [deciduous sclerophyllous forest], 2300 m, M.E. Siqueiros 1600 (MEXU). Guerrero: 

37 km SW of La Junta on road to Creel at the puente [bridge] 

Arroyo Ancho, 10 Sep 1989, pine forest, 2230 m, P.M. Peterson, 

Annable & Y. Herrera 7996 (ENCB, US); along río Corareachi, 

30 Aug 2003, 1840–1900 m, P.M. Peterson & P. Catalán 17596

(US); carr. La Junta–San Juanito, 17 km, 22 Sep 1997, 2290 m, 

B. Tah V. 18-A (MEXU). Juárez: 5 km de Lalolandia, 27 Oct 

1977, bosque de pino–encino, 2100 m, J.M. Peña 778 (RELC). 

Sierra Madre, 5 Oct 1887, C.G. Pringle 1410 (US), Isotype.

317. Piptochaetium virescens (Kunth) Parodi, Revista Mus. La 

Plata, Secc. Bot. 6(25): 230. 1944.

Caespitose perennial; densely clumped. Culms 100–120 cm 

tall, wiry. Leaf blades 15–30 cm long, 1 mm wide, involute, filiform. Panicles 10–25 cm long, narrow, lanceolate; primary 

branches 5–10 cm long, appressed. Spikelets 6–8.5 mm long, oblong, laterally compressed, breaking up at maturity, disarticulating below each floret; florets 5–6.5 mm long; callus 1 mm long, 

evident, pubescent, acute; glumes 6–8.5 mm long, exceeding 

apex of florets, elliptic, 3-veined, membranous, equal, purple, 

persistent, thinner than fertile lemma, apices acute; fertile lemmas 5–6.5 mm long, symmetrically oblong, subterete, indurate, 

awned, surface papillose, pubescent, margins involute, interlocking with palea keels, the hairs tawny, apex truncate; crown a 

ring of hairs of 0.5 mm long; lemma awn 15–20 mm long overall, twice-geniculate with twisted column; palea as long as the 

lemma, 2-veined, keels contiguous above a sulcus. 

Distribution and Habitat. Piptochaetium virescens grows in Mexico, Central America, and South America; 

the species is uncommon in Chihuahua. 

Specimens Examined. MEXICO. Chihuahua. 

Bocoyna: Cuesta Prieta, 10 km después de la estación [after station] San Juanito, rumbo [course] a Creel, 11 Aug 1997, bosque 

de pino-encino [pine–oak forest], 2520 m, A. Espejo 5771, 

A.R. López Ferrari, J. Ceja, A. Mendoza & B. Pérez (CIIDIR, 

UAMIZ).

Poa L.

Annual or perennial; usually synoecious, sometimes monoecious, gynodioecious, dioecious, and/or asexual; with or 

without rhizomes or stolons, densely to loosely tufted or the 

culms solitary. Basal branching intravaginal, pseudointravaginal, or extravaginal; prophylls of intravaginal shoots 2-keeled 

and open, of pseudointravaginal shoots not keeled and tubular, of extravaginal shoots scalelike. Culms hollow, usually unbranched above the base. Sheaths from almost completely open 

to almost completely closed, terete or weakly to strongly compressed; auricles absent; ligules membranous, truncate to acuminate; blades flat, folded, or involute, adaxial surfaces with a 

groove on each side of the midvein, other intercostal depressions 

shallow, indistinct, apex often prow-shaped. Inflorescences usually terminal panicles, rarely reduced and raceme-like. Spikelets

usually laterally compressed, infrequently terete to subterete, 

usually lanceolate, sometimes ovate; florets (1)2–6(13), usually 

sexual, sometimes bulb-forming; rachillas usually terete, sometimes prolonged beyond the base of the distal floret; disarticulation above the glumes and beneath the florets; glumes usually 

shorter than the lowest lemma in the spikelet, usually keeled, 

1- to 3(5)-veined, unawned; calluses blunt, usually terete or 

slightly laterally compressed, sometimes slightly dorsally compressed, glabrous or hairy, hairs often concentrated in 1(3) tufts 

or webs, sometimes distributed around the calluses below the 

lemmas as a crown of hairs; lemmas usually keeled, infrequently 

weakly keeled or rounded, similar in texture to the glumes, 

5(7–11)-veined, lateral veins sometimes faint, margins scarioushyaline distally, apex scarious-hyaline, truncate or obtuse to 

acuminate, unawned; paleas from 2⁄3 as long as to subequal to 

the lemmas, distinctly 2-keeled, margins and intercostal regions 

milky white to slightly greenish; lodicules 2, broadly lanceolate, 

glabrous, lobed; functional anthers (1–2)3; ovaries glabrous. 

Caryopsis ellipsoidal, often shallowly ventrally grooved, solid. 

x = 7.

Poa includes about 550 species worldwide and is found principally in temperate and boreal regions (Soreng et al., 2017b). 

There are 23 species of Poa in Mexico, and 6 are known from 

Chihuahua (Soreng and Peterson 2012).
NUMBER 107 • 309

KEY TO SPECIES OF POA

1. Annual; palea keels distinctly pubescent in part, rarely glabrous but then smooth.

2. Floret callus with cobwebby hairs; panicles contracted; palea keels with some apical hooks . . . . . . . . . . . . P. bigelovii

2. Floret callus glabrous; panicles open; palea keels without hooks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. annua

1. Perennial; palea keels glabrous, or sometimes pubescent, but always scabrous in part.

3. Plants without rhizomes or lateral shoots, densely tufted . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. strictiramea

3. Plants with well-developed rhizomes; loosely tufted.

4. Panicles contracted, fairly dense, or slightly open; uppermost culm leaf blades highly reduced or absent; populations 

dioecious or pistillate; callus glabrous; plants of the northern mountains . . . . . . . . . . . . . . . . . . . . . . P. fendleriana

4. Panicles loosely contracted to open; uppermost culm leaf blades usually well-developed; plants all perfect-flowered, or 

if pistillate or staminate, then panicles open; callus, at least of proximal lemmas, with cobwebby hairs, or glabrous.

5. Leaf blades mostly involute, mostly 1−2 mm wide (expanded), both surfaces moderately to densely scabrous; callus 

glabrous (rarely with a few short hairs); lemma keel and marginal veins glabrous or puberulent (hairs to 0.25 mm), 

sometimes puberulent between the veins near the base; plants from uplands of the Chihuahuan Desert . . . . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. strictiramea

5. Leaf blades flat or folded, some or most more than 2 mm wide, or if involute in part, then surfaces smooth or 

nearly so; callus with a dorsal tuft of wooly hairs; lemma glabrous or variously pubescent; plants widespread.

6. Rachilla internodes usually exposed in side view; spikelets 4.5−8 mm long; lemmas glabrous or variously 

pubescent; ligules truncate to obtuse to acute, sometimes irregularly dentate to lacerate, 0.8−6 mm long; 

rhizomes usually short and/or poorly developed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. matri-occidentalis

6. Rachilla internodes mostly hidden from view; spikelets mostly 3−6 mm long; lemmas glabrous between the 

keel and marginal veins; ligules truncate to low rounded, entire, usually 1−2 mm long; plants with an extensive and spreading rhizome system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. pratensis

318. Poa annua* L., Sp. Pl. 1: 68. 1753.

FIGURE 204

Plants usually annual, rarely surviving for a second season; 

not rhizomatous, sometimes stoloniferous, densely tufted; basal 

branching intravaginal, innovations common, similar to the 

culms. Culms 2–20(45) cm tall, prostrate to erect, slender; nodes 

terete, usually 1 exserted. Sheaths closed for about 1⁄3 their length, 

terete or weakly compressed, smooth; ligules 0.5–3(5) mm long, 

smooth, glabrous, decurrent, obtuse to truncate; blades 1–10 cm 

long, 1–3(6) mm wide, flat or weakly folded, thin, soft, smooth, 

margins usually slightly scabrous, apex broadly prow-shaped. 

Panicles 1–7(10) cm long, lengths 1.2–1.6 times widths, erect; 

nodes with 1–2(3) branches; branches ascending to spreading 

or reflexed, straight, terete, smooth, with crowded or loosely arranged spikelets. Spikelets 3–5 mm long, laterally compressed; 

florets 2–6; rachilla internodes smooth, glabrous, concealed or 

exposed, distal internodes less than 1⁄2(3⁄4) the length of the distal lemma; glumes smooth, distinctly keeled, keels smooth; lower 

glumes 1-veined; upper glumes shorter than or subequal to the 

lowest lemma; calluses glabrous; lemmas 2.5–4 mm long, lanceolate, distinctly keeled, smooth throughout, the keels, marginal 

veins, and, usually, lateral veins crisply puberulent to long-villous, 

rarely glabrous throughout, lateral veins prominent, intercostal 

regions glabrous, margins smooth, glabrous, apex obtuse to 

acute; palea keels smooth, usually short- to long-villous, rarely 

glabrous; anthers 0.6–1.1 mm long, oblong prior to dehiscence, 

those of the upper 1–2 florets usually vestigial. 2n = 28.

Distribution and Habitat. Poa annua is one 

of the world’s most widespread weeds. It thrives in anthropomorphic habitats outside the Arctic. A native of Eurasia, it is 

now well established throughout most of Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Bocoyna: S of Creel, S of the arroyo crossing on the old road 

below San Ignacio, 20 May 1973, 2250 m, Bye 3773 (NMC); 

Creel, 20 Sep 2003, Tenorio, J. Rodríguez, M. Hilerio & 

E. Zárate 23768 (US). Chihuahua: Vicinity of Chihuahua, 4–27 

Apr 1908, E. Palmer 28 (US); 11 Abr [Apr] 1886, C.G. Pringle 

s/n (MEXU). Guachochi: 2.3 mi W of San Juanito on road towards Baquiriachic, 5 Oct 2000, P.M. Peterson & J. Cayouette 

15361 (US). Juárez: Universidad Autónoma de Ciudad Juárez, 

Campus ICB, 15 Abr 2005, 1118 m, R. Corral, M. Vargas & 

D. Alvarado RCD7085 (UACJ). Guadalupe y Calvo: near Cumbre Mohinora, 13 Sep 2006, 3300 m, P.M. Peterson 20033, 

F. Sánchez Alvarado & E.P. Gómez Ruíz (CIIDIR, US). Madera: 

Arroyo de las Garrochas, ejido El Largo, 28 Aug 1990, bosque 

mixto de coníferas & latifoliadas [mixed conifer and broadleaf 

forest], 2600 m, O. Bravo 1319 (CIIDIR, MEXU); Ciénega de 

la Víbora, ejido El Largo, 14 Oct 1990, 2300 m, bosque de 

pino–encino [pine–oak forest], O. Bravo 1910 (CIIDIR); Arroyo 

de la Quinta, ejido El Largo, 13 Oct 1990, bosque de Pinus–

Quercus–Pseudotsuga, 2100 m, A. Benítez 2848 (CIIDIR). Ocampo: Parque Nacional “Cascada de Basaseachic,” at base falls, 

26 Apr 1985, 1570 m, Spellenberg, R Soreng & R. Corral 8019 

(NMC). 27 mi W of Tomochic on road to Basaseachic, 25 Apr 

1986, 2100 m, Spellenberg, Soreng, R. Corral, T. Lebgue 8417
310 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

FIGURE 204. Poa annua. A. Habit. B. Inflorescence. C. Glumes. 

D. Florets. E. Floret. Drawn by Sandy Long; copyright Utah State 

University. FIGURE 205. Poa bigelovii. A. Habit. B. Apex of leaf blade. C. Inflorescence. D. Spikelet. E. Floret. Drawn by Sandy Long; copyright 

Utah State University.
NUMBER 107 • 311

(NMC); Parque Nacional Cascada basaseachic, áreas de campamento [camp area], cerca [near] del arroyo, 23 Sep 1990, bosque 

de pino–encino, 1980 m, R. Corral RCD3978 (UACJ).

319. Poa bigelovii Vasey & Scribn., Descr. Cat. Grass. U.S. 81. 

1885. Poa annua var. stricta Vasey ex Scribn., Bull. Torrey 

Bot. Club 10(1): 31. 1883.

FIGURE 205

Plants usually annual, rarely longer-lived; densely tufted, 

tuft bases narrow, usually without sterile shoots, not stoloniferous, not rhizomatous; basal branching intravaginal. Culms 

(2)5–60 (70) cm tall, 0.3–1 mm thick, usually erect, bases rarely 

geniculate; nodes terete, usually 1 exserted. Sheaths closed for 

1⁄4–1⁄2 their length, usually compressed and keeled, smooth or the 

keels scabrous; ligules 2–6 mm long, smooth or scabrous, usually decurrent, obtuse to acute; blades 1.5–5 mm wide, flat, thin, 

soft, finely scabrous, apex broadly prow-shaped, cauline blades 

(1)4–15 cm long, flag leaf blades usually 1–4 cm long. Panicles 

(1)5–15 cm long, erect, cylindrical, contracted, sometimes interrupted, congested, with 2–3(5) branches per node; branches 

erect or steeply ascending, smooth or sparsely to densely scabrous. Spikelets 4–7 mm long, laterally compressed; florets 3–7; 

rachilla internodes to 1 mm long, smooth, glabrous; glumes 

subequal, distinctly keeled, keels and sometimes the lateral 

veins scabrous; lower glumes 1(3)-veined; upper glumes shorter 

than or subequal to the lowest lemmas; calluses webbed; lemmas 2.6–4.2 mm long, lanceolate, distinctly keeled and smooth, 

keels, marginal veins, and sometimes the lateral veins short- to 

long-villous, keels hairy to near the apex, marginal veins to 2⁄3

their length, lateral veins obscure to moderately prominent, intercostal regions glabrous or softly puberulent, upper margins 

white, apex acute; palea keels softly puberulent to short-villous 

at midlength, scabrous near the apex, intercostal regions usually 

softly puberulent; anthers 1–3, 0.2–1 mm long. 2n = 28, 28 + I.

Distribution and Habitat. Poa bigelovii

grows in arid upland regions, particularly on shady, rocky slopes 

in the southwestern United States and northern Mexico. 

Specimens Examined. MEXICO. Chihuahua. Ascensión: Canyon in N face of Sierra Rica, S of Rancho La Consolación, 3 May 1973, matorral [scrub], 1400–2000 m, M.C. Johnston, 

T.L. Wendt & F. Chiang 10776 (MEXU). Chihuahua: cerca [near] 

del Rio Chihuahua, 5 Apr 1886, C.G. Pringle s.n.(MEXU). Juárez: 

Mountains near Paso del Norte, Mar 1881, Vasey s.n. (US). Mpio.: 

Cañón de Tinaja de Corazón, east flank of Sierra de Mulato on Rio 

Grande 29°13′N, 103°45′W [29.21667°N, 103.75000°W], 750 m, 

13 Mar 1986, M.C. Johnston 12898 (TEX).

320. Poa fendleriana (Steud.) Vasey, U.S.D.A. Div. Bot. Bull. 

13(2): t. 74. 1893. Uralepis poaeoides Buckley, Proc. Acad. 

Nat. Sci. Philadelphia 14: 94. 1862.

FIGURE 206

Perennial; densely to loosely tufted, rhizomatous, often 

weakly so, rhizomes usually short and inconspicuous; basal 

branching mainly intravaginal, usually some extravaginal. 

Culms 15–70 cm tall, sometimes stout, erect or the bases decumbent, terete or weakly compressed; nodes terete, 0–1 exserted. Sheaths closed for about 1⁄3 their length, terete, smooth 

or scabrous, glabrous or occasionally retrorsely pubescent, 

bases of basal sheaths glabrous, distal sheath lengths usually 

(5)9+ times blade lengths; collars smooth or scabrous, glabrous 

or hirsute; ligules 0.2–18 mm long, smooth or scabrous, decurrent or not, apex truncate to acuminate, ciliolate or glabrous; 

innovation blades usually moderately to densely scabrous or 

hirsute on and between the veins, infrequently nearly smooth 

and glabrous; cauline blades strongly reduced in length distally, 

(0.5)1–3(4) mm wide, usually involute, moderately thick and 

firm, infrequently moderately thin, abaxial surfaces usually 

smooth, infrequently scabrous, apex narrowly prow-shaped, 

steeply reduced in length distally along the culm, flag leaf 

blades often absent or very reduced, sometimes to 1(3) cm. Panicles 2–12(30) cm long, erect, contracted, narrowly lanceoloid 

to ovoid, congested, frequently with 100+ spikelets; nodes with 

1–2 branches; branches 1–8 cm long, erect, terete to weakly 

angled, smooth or scabrous, with 3–15(25) spikelets. Spikelets 

(3)4–8(12) mm long, lengths to 3 times widths, broadly lanceolate to ovate, laterally compressed, not sexually dimorphic; 

florets 2–7(13); rachilla internodes 0.8–1.3 mm long, smooth, 

glabrous or hairy, hairs to 0.3 mm long; glumes lanceolate, distinctly keeled; lower glumes 1- to 3-veined, distinctly shorter 

than the lowest lemmas; calluses glabrous; lemmas 3–6 mm 

long, lanceolate, distinctly keeled, keels, marginal veins, and 

lateral veins glabrous or short- to long-villous or softly puberulent, lateral veins moderately prominent, intercostal regions 

softly puberulent or glabrous, smooth or sparsely scabrous, 

margins glabrous, apex acute; palea keels scabrous, sometimes 

softly puberulent or long-villous at midlength, hairs to 0.4 mm 

long; anthers vestigial (0.1–0.2 mm) or 2–3 mm long. 2n = 28 

+ II, 56, 56–58, 58–64.

Distribution and Habitat. Poa fendleriana

grows on rocky to rich slopes in sagebrush scrub, interior chaparral, high plains grasslands to forests and from desert hills to 

low alpine habitats. Its range extends from British Columbia to 

Manitoba and south to Mexico.

KEY TO SUBSPECIES OF POA FENDLERIANA

1. Lemmas glabrous; plants from the Sierra Madre Occidental . . . . . . . . . . . . . . . . . . . . . . . . P. fendleriana subsp. albescens

1. Lemmas pubescent on the keel and marginal veins; plants more widespread . . . . . . . . . . P. fendleriana subsp. fendleriana
312 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Poa fendleriana subsp. albescens (Hitchc.) Soreng

Distribution and Habitat. The subspecies is 

endemic to southeastern Arizona and southwestern New Mexico 

in the United States and is known from Chihuahua and Sonora 

in Mexico (Soreng and Peterson, 2012).

Specimens Examined. MEXICO. Chihuahua. Ascensión: Canyon in N face of Sierra Rica, S of Rancho La Consolación, 3 May 1973, Matorral [scrub], 1400–2000 m, M.C. 

Johnston, T.L. Wendt & F. Chiang 729804 (MEXU). Bocoyna: 

San Juanito, ca 18 km W near Headwaters of Rio Oteros origin 

above Arroyo El Ranchito, 27°57.5′N, 107°45′W [27.95833°N, 

107.75000°W], 29 Apr 1985, 2430 m, Soreng & Spellenberg 

2618 (NMC) ; W of Creel, S of Rio Oteros, 6 May 1973, bosque 

[forest] de pine and oak, 7200 ft, Bye 3673 (MEXU); Arroyo del 

Gato, ca 25 air km WSW of San Juanito, 1.5 km W of Talayotes, 27°55′N, 107°49′W [27.91667°N, 107.81667°W], 29 Apr 

1985, 2330 m, Soreng & Spellenberg 2615 (NMC, US); Rancho Blanco, 30 km N of San Juanito towards La Junta, 28.2°N, 

107.6°W, 19 mi N of San Juanito towards La Junta, 29 Apr 

1985, 2090 m, Soreng & Spellenberg 2620, 2623 (NMC); Sierra 

Las Manzanas, 2 km SW of Tosanachic on road to Agua Caliente, ca. 53 km due W of Ciudad Guerrero, 28.30′N, 108°05’W 

[28.5°N, 108.08333°W], 1950 m, 13 Apr 1984, Soreng & 

Spellenberg 2305 (NMC, US). Guachochi: Creel, 5 km S of 

FIGURE 206. Poa fendleriana subsp. fendleriana. A.Habit. B. Inflorescence. C. Ligule D. Spikelet. E. Lemma. Poa fendleriana

subsp. albescens. F. Ligule. G. Lemma. Drawn by Sandy Long; copyright Utah State University.
NUMBER 107 • 313

town, 27°43′N, 107°45′W [27.71667°N, 107.75°W], 15 Apr 

1984, 2380 m, Soreng & Spellenberg 2309 (NMC); S of San 

Ignacio Arareco, south of airstrip, SE of Creel, 27.7°N, 107.7°W, 

20 Jul 1972, 2255 m, Bye 2404 (MEXU); along Rio Oteros, west 

of Creel, Bye 3673 (MEXU); Tomachic, 6.7 mi E and 5 mi W of 

Cieneguita, on road to Cuauhtemoc, 30 km SW of Ciudad Guerrero, 28°20ʹN, 107°43ʹW [28.33333°N, 107.71667°W], 7400 

ft [2255 m], 14 Apr 1984, Soreng & Spellenberg 2307 (NMC, 

US). Guerrero: Waldungen [groves] der Sierra Madre Occidental, umgebrung [surroundings] von Sierra Colorada, 4 Apr 

1906, R. Endlich 1209 (US); Miñaca, 107.35°N, 28.45°W, 1 Apr 

1908, J.N. Rose 11648 (US), holotype. Ocampo: Basaseachic, 

in the barranca [canyon] below the falls, 28°1ʹN, 108°15ʹW 

[28.01667°N, 108.25°W], 27 Apr 1985, 1980 m, Soreng & 

Spellenberg 2606 (NMC); 10 mi SE of Basasiachic on road to 

San Juanito, 8 mi SE of junction with Yecora–Tomochic road, 

2715 m, 28 Apr 1985, Soreng & Spellenberg 2609a (US); 3.3 mi 

S of Chorro de Agua (abandoned sawmill) on road to sawmill 

El Cuervo, 22 Jun 1987, 1900 m, T.R. Van Devender, R.K. Van 

Devender & P.S. Martin s.n. (ARIZ); 9 mi SE of Yoquivo on 

Basasiachic–San Juanito road, 28.0311°N, 107.9234°W, 28 Oct 

1985, 2410 m, Soreng & Spellenberg 2610 (NMC); Temósachi: 

Between Yeporema and Baviacora, 29.2°N, 107.9°W, 2250 m, 

Correll & M.I. Johnston 21626, 21635-A (US).

Poa fendleriana subsp. fendleriana

Distribution and Habitat. The subspecies is 

found throughout the range of the species. In Mexico the subspecies is found in Bajo California, Chihuahua, Coahuila, and 

Sonora (Soreng and Peterson 2012). 

Specimens Examined. MEXICO. Chihuahua. Ascensión: Canyon in N face of Sierra Rica, S of Rancho La Consolación, 3 May 1973, Matorral [scrub], 1400–2000 m, M.C. 

Johnston, T.L. Wendt & F. Chiang 10777 (MEXU). Bocoyna: 

On N-facing slope along Río Oteros, W of Creel, 6 May 1973, 

pine–oak forest, Bye 3675 (MEXU). Guerrero: Barranca del 

Cobre, SE of Creel 28 mi, N of Rio Urique crossing, 2135 m, 

14 Apr 1984, Soreng 2312 & R.W. Spellenberg (US); N of Basuchil, ca. 10 mi NW of Miñaca, arid grassland, 2200 m, 8 May 

1929, Y. Mexia 2511 (CAS, MO). Tomachic, 4.2 mi E on road 

from La Junta to Yecora, 2135 m, 13 Apr 1984, Soreng 2306 & 

Spellenberg (US).

321. Poa matri-occidentalis subsp. mohinorensis Soreng & 

P. M. Peterson, Sida 22(2): 211. 2006.

FIGURE 207

Perennial; tufted, sub-rhizomatous. Culms 45–80 cm tall, 

erect or slightly decumbent, leafy, terete or weakly compressed, 

smooth. Sheaths compressed, distinctly keeled with a short wing 

to 0.5 mm deep, smooth, glabrous, margins fused 66%–80% the 

length; collars smooth or lightly scabrous or ciliate; ligules 3.5–6 

mm long, scarious-white to hyaline, apex obtuse to acute, entire; 

blades mostly 10–30 cm long, 2–6 mm wide, flat, to broad-V 

shaped, thin, lax, abaxial surface and margins lightly scabrous 

along the veins, adaxially smooth, glabrous, apex narrowly 

prow-tipped; mid-cauline blades 20–30 cm long; flag leaf blades 

12–22 cm long. Panicles 12–26 cm long, nodding, open, pyramidal, sparse, with 24–85 spikelets; rachis with (1)2(3) branches 

per node; primary branches ascending to spreading, slender, flexuous, lax, angled, angles sparsely to moderately scabrous; lateral 

pedicels as long as spikelets, scabrous; longest branches 5.5–10 

cm long, with 3–15 spikelets in the distal 1⁄3–1⁄2. Spikelets 4–8 

mm long, 1.8–2.7 mm wide, broadly lanceolate, laterally compressed, not bulbiferous, greenish to stramineous; florets 2–3, 

bisexual; rachilla internodes terete, 1–2 mm long, usually hidden, smooth, glabrous; glumes lanceolate, sub-lustrous, equal to 

subequal, distinctly keeled, keels scabrous distally, edges smooth 

or lightly scabrous, apex narrowly acute; lower glumes 3–5 mm 

long, (1)3-veined, narrowly lanceolate; upper glumes 3.7–5.6 

mm long, distinctly 3-veined, lanceolate to oblanceolate; calluses 

dorsally webbed, the hairs 2–3 mm long, woolly; lemmas 4.6–

6.3 mm long, lanceolate, 5-veined, green, distinctly keeled, keel 

and marginal veins glabrous, sparsely puberulent or scabrous, 

upper margins narrowly scarious-hyaline, apex acute, sometimes 

briefly purple and bronze tinged; paleas 4.4–6 mm long, usually 

distinctly shorter than the lemma, keels long scabrous between 

keels. Flowers chasmogamous; lodicules (0.3)0.6–0.8 mm long, 

broadly lanceolate to ovate, with a lateral lobe; anthers 2–2.2 

mm long, infrequently those of distal flower abortive. Caryopsis 

2.6–3 mm long, fusiform in side view, laterally compressed, light 

brown to olivaceous, grain adherent to the palea. 

Distribution and Habitat. Poa matrioccidentalis P. M. Peterson & Soreng is found on moist rocky 

ledges and cliffs associated with Juniperus, Pinus, Abies, and 

Picea at 2,950–3,300m. It flowers from August to October. 

Poa matri-occidentalis has two subspecies; P. matri-occidentalis

subsp.. mohinorensis is endemic to Chihuahua.

Specimens Examined. MEXICO. Chihuahua. 

Guadalupe y Calvo: Sierra Mohinora, near Cumbre Mohinora, 

3250−3300 m, 13 Sep 2006, P.M. Peterson 20048, 20049, F. 

Sánchez Alvarado & E.P. Gómez Ruíz (US); 16–17 Oct 1959, 

D.S. Correll 23177 & H.S. Gentry (LL); Cerro Mohinora, the 

northern side of the hill, 2 Nov 2007, pine forest, 3090 m, D. 

Stancik & S. Gonzalez 6187 (MEXU); N side of Cerro Mohinora, Ca. 13 mi SW of Guadalupe y Calvo, 20 Aug 1988, 3200 

m, G.L. Nesom & J.A. McDonald s.n. (ARIZ).

322. Poa pratensis L., Sp. Pl. 1: 67–68. 1753.

FIGURE 208

Perennial; green or anthocyanic, sometimes glaucous; extensively rhizomatous, densely to loosely tufted or the shoots solitary. Culms 5–70(100) cm long, erect or the bases decumbent, 

nodes terete or weakly compressed, 1–2(3) exposed. Sheaths 

closed for 1⁄4–1⁄2 their length, terete to slightly compressed, glabrous or sparsely to moderately hairy, glabrous, not swollen; 

collars smooth, glabrous; ligules 0.9–2(3.1) mm long, smooth 
314 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

FIGURE 207. Poa matri-occidentalis. A. Habit. B. Culm and inflorescence. C. Ligule. Poa matri-occidentalis

subsp. mohinorensis. D. Ligule. Drawn by Alice R. Tangerini for Smithsonian Institution, Department of 

Botany.
NUMBER 107 • 315

or scabrous, truncate to rounded, ciliolate or glabrous; blades 

of extravaginal innovations like those of the culms, those of the 

intravaginal shoots sometimes distinctly narrower, 0.4–1 mm 

wide, flat to involute; cauline blades 0.4–4.5 mm wide, flat, 

folded, or involute, soft and lax to moderately firm, smooth, glabrous or sparsely scabrous, frequently sparsely hairy, the hairs 

0.2–0.8 mm long, erect to appressed, slender, curving, sinuous 

or straight, apex usually broadly prow-shaped, blades subequal; 

middle blades longest; flag leaf blades 1.5–10 cm long. Panicles 

2–15(20) cm long, narrowly ovoid to narrowly or broadly pyramidal, loosely contracted to open, sparse to moderately congested, with (25)30–100+ spikelets and (1)2–7(9) branches per 

node; branches (1)2–9 cm long, spreading early or late, terete 

or angled, smooth or sparsely to moderately densely scabrous, 

with 4–30(50) spikelets usually fairly crowded in the distal 1⁄2. 

Spikelets 3.5–6(7) mm long, lengths 3.5 times widths, laterally 

compressed, sometimes bulbiferous; florets 2–5, usually normal, 

sometimes bulb-forming; rachilla internodes usually shorter than 

1 mm long, smooth, glabrous; glumes unequal to subequal, usually distinctly shorter than the adjacent lemmas, narrowly lanceolate to lanceolate, infrequently broadly lanceolate, distinctly 

keeled, keels usually sparsely to densely scabrous, infrequently 

smooth; lower glumes 1.5–4(4.5) mm long, usually narrowly lanceolate to lanceolate, occasionally sickle-shaped, 1- to 3-veined; 

upper glumes 2–4.5(5) mm long, distinctly shorter than to nearly 

equaling the lowest lemmas; calluses dorsally webbed, sometimes with additional webs below the marginal veins, hairs at 

least 1⁄2 as long as the lemmas, crimped; lemmas 2–4.3(6) mm 

long, lanceolate, green or strongly purple-tinged, distinctly 

keeled, keels and marginal veins long-villous, lateral veins usually glabrous, infrequently short-villous to softly puberulent, lateral veins prominent, intercostal regions glabrous, lower portion 

smooth or finely muriculate, upper portion smooth or sparsely 

scabrous, margins narrowly to broadly hyaline, glabrous, apex 

acute; paleas scabrous, keels sometimes softly puberulent, intercostal regions narrow, usually glabrous, rarely sparsely hirsute; 

anthers usually 1.2–2 mm long, infrequently aborted late in development. 2n = 27, 28, 32, 35, 37, 41–46, 48–147.

Distribution and Habitat. Poa pratensis is 

uncommon in our area but widespread and well established in 

North America. Soreng and Peterson (2012) separate it into five 

subspecies, and the only one present in Chihuahua is Poa pratensis subsp. pratensis.

Specimens Examined. MEXICO. Chihuahua.

Balleza: Camino Balleza–Guachochic, km 45, 24 Sep 1981, pastizal amacollado arborescente [grassy pasture], R. Fierro & M.E. 

FIGURE 208. Poa pratensis. A. Habit. B. Inflorescence. C. Ligule. 

D. Leaf blade apex. E. Portion of the inflorescence. F. Spikelet. 

G. Lemma. Drawn by Sandy Long; copyright Utah State University.
316 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Siqueiros 1585 (MEXU). Madera: Rancho de la Ciénega ejido 

el Largo, 24 Jun 1990, bosque de pino [pine forest], 2240 m, 

A. Benítez 1401 (MEXU).

323. Poa strictiramea Hitchc., Contr. U.S. Natl. Herb. 17(3): 

375. 1913.

FIGURE 209

Perennial; densely tufted, not stoloniferous, not rhizomatous; basal branching intravaginal. Culms 30–90 cm tall, slender 

to coarse. Sheaths closed for 1⁄20–1⁄10 their length, terete, scabrous, 

glabrous; collars smooth to scabrous; ligules 0.5–4(6) mm long, 

scabrous, apex truncate to acute, entire or lacerate; innovation blades 15–30 cm; cauline blades 1–4 mm wide, involute or 

rarely flat, moderately thick and firm, both surfaces sparsely to 

densely antrorsely scabrous, apex narrowly prow-shaped; flag 

leaf blades usually longer than their sheaths. Panicles (7)10–

30 cm long, erect, pyramidal, open, with 2–5 branches per node; 

branches 2–8(15) cm long, spreading, straight, angled, moderately to densely scabrous, sometimes densely scabrous all over, 

with 10–30 spikelets. Spikelets 4–7 mm long, lanceolate, laterally compressed; florets 2–5; rachilla internodes 0.8–1.5 mm 

long, smooth or scabrous, sometimes sparsely hirsute; glumes 

sparsely to rarely densely scabrous; lower glumes 1- to 3-veined; 

calluses usually glabrous, rarely sparsely short-webbed; lemmas 2.5–3.5 mm long, lanceolate, distinctly keeled, smooth or 

sparsely to densely scabrous, keels and marginal veins glabrous 

or softly puberulent or short to long villous, lateral veins moderately prominent to prominent, intercostal regions usually glabrous, infrequently sparsely softly puberulent, apex acute; palea 

keels scabrous; anthers 2.2–2.5 mm long or aborted late in development. 2n = 28 + I, 28–29 + II.

Distribution and Habitat. Poa strictiramea

grows on shady, upland mountain slopes, usually below north 

facing cliffs. It ranges from the United States to Mexico in and 

around the Chihuahuan Desert in Chihuahua, Coahuila, Durango, and Nuevo León.

Specimens Examined. MEXICO. Chihuahua. 

Bocoyna: On slopes above Rio Oteros W of Creel, 16 Oct 1977, 

2200 m, Bye & W.A. Weber 8242 (MEXU). Cusihuiriachic: 

Montaña La Bufa, arriba [above] de Cusihuiriachic, 2 Sep 1887, 

C.G. Pringle 1437 (MEXU, US), type. Guachochi: Cusihuiriachic, N-facing slopes below La Buffa, 14 Apr 1984, 2350 m, 

Soreng & Spellenberg 2308 (NMC). Madera: San Jose de Babicora, 3 km W of Pina Blanca on road to Madera, El Diablo Pass, 

13 Apr 1984, 2250 m, Soreng & Spellenberg 2304 (NMC); 1.5 

km al NE de Col. Chihuichupa, 4 May 1992, bosque de pino 

[pine forest], 2240 m, E. Guízar 2663 (CIIDIR, MEXU).

Polypogon Desf.

Annual or perennial; not rhizomatous. Culms 4–120 cm 

tall, erect to decumbent, rooting at the lower nodes, sparingly 

branched near the base. Leaves usually no more than 5 per 

culm, basal and cauline; sheaths open, smooth or scaberulous; 

auricles absent; ligules membranous or hyaline, acute to broadly 

rounded, erose, ciliate; blades flat to convolute. Inflorescence 

a terminal panicle, dense, continuous or interrupted below; 

branches flexible, usually some longer than 1 cm; pedicels absent 

FIGURE 209. Poa strictiramea. A. Habit. B. Inflorescence. C. Ligule. 

D. Spikelet. E. Floret. Drawn by Sandy Long; copyright Utah State 

University.
NUMBER 107 • 317

and the spikelets borne on a stipe, or present and terminating 

in a stipe; stipes scabrous, flaring distally; disarticulation at the 

base of the stipes. Spikelets 1–5 mm long, weakly laterally compressed, with 1 bisexual floret; rachillas not prolonged beyond 

the base of the floret; glumes exceeding the floret, lanceolate, 

bases not fused, apex entire to emarginate or bilobed, usually awned from the sinuses or apex, awns flexuous, glabrous, 

sometimes unawned; lemmas 1- to 3(5)-veined, often awned, 

awns usually terminal or subterminal, sometimes arising from 

just above midlength; paleas from 1⁄3 as long as to equaling the 

lemmas; lodicules 2, oblong-lanceolate to lanceolate; anthers 3; 

ovaries glabrous; styles separate. Caryopsis slightly flattened, 

broadly ellipsoid to oblong-ellipsoid; hila 1⁄6–1⁄4 as long as the 

caryopsis, ovate. x = 7.

Polypogon is a pantropical and warm-temperate genus of 

about 14 species (Soreng et al., 2017b). 

KEY TO SPECIES OF POLYPOGON

1. Inflorescence spiciform, very compact; spikelets awned, annual plants . . . . . . . . . . . . . . . . . . . . . . . . . . . P. monspeliensis

1. Inflorescence a spread panicle, ellipsoid or pyramidal, often interrupted on the base; spikelets awned or awnless; perennial 

plants.

2. Spikelets awnless; panicles 3.5–8.5 cm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. viridis

2. Spikelets prominent awned; panicles 10–30 cm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. elongatus

324. Polypogon elongatus Kunth, Nov. Gen. Sp. (quarto ed.) 1: 

134–135. 1815.

FIGURE 210

Perennial; often flowering the first year. Culms to 100 cm 

tall, erect or decumbent at the base. Sheaths smooth, glabrous; 

ligules 4–8 mm long, scaberulous, lacerate; blades 10–30 cm 

long, 4–15 mm wide. Panicles 10–30 cm long, erect or nodding, 

interrupted, dense; pedicels not developed; stipes 1.5–2.5 mm 

long; glumes 3–5 mm long, hirsute, tapering from about midlength to the acute apex, apex unlobed, awned, the awns 1–3 

mm long; lemmas about 1.5 mm long, awned, the awns 1–2 mm 

long, arising from above midlength; paleas 1⁄2–2⁄3 as long as the 

lemmas; anthers 0.5–0.7 mm long. 2n = 28, 56.

Distribution and Habitat. Polypogon elongatus is native from Mexico to Argentina. It has two varieties: 

Polypogon elongatus var. elongatus, which is widely distributed, 

and P. elongatus var. strictus E. Desv. from southern Chile (Finot 

et al., 2013). 

Specimens Examined. MEXICO. Chihuahua. 

Bocoyna: Cañada de Recogoata, 23 Sep 1997, bosque de pino–

encino [pine–oak forest], 1900 m, B. Tah V. 60-A (MEXU). Camargo: 5 km W of cd. Camargo, 5 Aug 1939, L. H. Harvey 1408

(US). Chihuahua: Presa de Chihuahua, 1 Aug 1936, LeSueur 

0150 (MEXU, US). Guachochi: 1–2 km S of Río Osichi Canyon 

and Río Basihuare jct, 1 Sep 2003, bosque de Quercus–Pinus, 

1600 m, P.M. Peterson & P. Catalán 17633 (CIIDIR, US); Rejogochic, north of Humira, north of Barranca del Cobre, 1 Nov 

1993, grass in sand along arroyo, ca. 6000 ft, Bye 5726 (MEXU). 

Madera: Arroyo La Quinta, ejido El Largo, 13 Oct 1990, bosque 

mixto [mixed forest] de Pinus–Quercus–Pseudotsuga, 2100 m, 

O. Bravo 1880 (CIIDIR, MEXU); Ciénega del Pitorreal ruta 

mesa del huracán [hurricane route] al Hierbanís, 23 Jun 1990, 

bosque de Pinus–Quercus spp con Platanus & Arbutus, 2200 m, 

O. Bravo 820 (MEXU). Ocampo: Parque Nacional “Cascada 

de Basaseachi” in the barranca [canyon] at the base of the falls, 

11 Nov 1989, bosque de encino–Abies, 1570 m, Spellenberg, 

R. Corral D. T. Lebgue & M. Mahrt 10062 (CIIDIR, MEXU); 

Parque Nacional “Cascada de Basaseachic,” in the barranca at 

the base of the falls, 11 Nov 1989, 1700 m, Spellenberg, R. Corral, T. Lebgue & M. Mahrt 10062 (NMC); Parque Nacional 

“Cascada de Basaseachic,” 25 Abr [Apr] 1986, 1700 m, Spellenberg, Soreng, R. Corral & T. Lebgue 8478 (NMC).

325. Polypogon monspeliensis* (L.) Desf., Fl. Atlant. 1: 67. 

1798. Alopecurus monspeliensis L., Sp. Pl. 1: 61. 1753.

FIGURE 211

Annual. Culms 5–65 (100) cm tall, erect to geniculately 

ascending. Sheaths glabrous, the uppermost sheaths sometimes 

inflated; ligules 2.5–16 mm long; blades 1–20 cm long, 1–7 mm 

wide. Panicles 1–17 cm long, narrowly ellipsoid, dense, sometimes lobed, greenish; pedicels absent or to 0.2 mm long; stipes 

0.1–0.2 mm long; glumes 1–2.7 mm long, hirsute throughout, 

the largest prickles restricted to the lower 1⁄2, apex rounded, 

lobed, lobes 0.1–0.2 mm long, 1⁄10 or less the length of the glume 

body, awned from the sinus, the awns 4–10 mm long, yellowish; 

lemmas 0.5–1.5 mm long, glabrous, awned, the awns 0.5–1(4.5) 

mm long; paleas subequal to the lemmas; anthers 0.2–1 mm 

long. 2n = 14, 28, 35, 42.

Distribution and Habitat. Polypogon monspeliensis is native to southern Europe and Turkey. It is now a 

common weed throughout the world, including much of Mexico. It grows in damp to wet, often alkaline soils, particularly in 

disturbed areas.

Specimens Examined. MEXICO. Chihuahua. 

Camargo: 5 km W of cd. Camargo, 5 Aug 1939, L. H. Harvey 

1405 (US). Chihuahua: Rancho Experimental la Campana, 7 Jul 

77, Lotes de producción forrajera [forage-production lots], 1540 

m, S. González 835 (RELC). Jiménez: 2 km W of Cd. Jiménez, 

28 Jul 1939, L. H. Harvey 1317 (US). Juárez: Ciudad Juárez a lo 

largo [along] de la “Asequia Madre” al N del fracc. Rincones de 

San Marcos, 13 Oct 1995, 1140 m, R. Corral, P. Olivas & L.M. 

Barraza RCD6533 (UACJ).
318 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

FIGURE 210. Polypogon elongatus. A. Inflorescence. B. Glumes. 

C. Apex of glume. D. Floret. Drawn by Cindy Roché; copyright 

Utah State University.

FIGURE 211. Polypogon monspeliensis. A. Habit. B. Culm and inflorescence. C. Spikelet. D. Floret. Drawn by Cindy Roché; copyright Utah State University.
NUMBER 107 • 319

326. Polypogon viridis* (Gouan) Breistr., Bull. Soc. Bot. France 

110 (89): 56. 1963. Agrostis viridis Gouan, Hortus Monsp. 

546. 1762.

Agrostis semiverticillata (Forssk.) C. Chr.

FIGURE 212

Perennial; often flowering the first year. Culms 10–90 cm 

long, sometimes decumbent and rooting at the lower nodes. 

Sheaths glabrous, smooth; ligules to 5 mm long; blades 2–13 cm 

long, 1–6 mm wide. Panicles 2–10 cm long, ovate-oblong to 

pyramidal, dense but interrupted, pale green to purplish; pedicels not developed; stipes 0.1–0.6 mm long; glumes 1.5–2 mm 

long, scabrous on the back and keel, apex obtuse or truncate, 

unawned; lemmas about 1 mm long, erose, unawned; paleas subequal to the lemmas; anthers 0.3–0.5 mm long. 2n = 28, 42.

Distribution and Habitat. Polypogon viridis 

grows in mesic habitats associated with rivers, streams, and irrigation ditches. It is native from southern Europe to Pakistan 

but is now established in America, particularly the southwestern 

United States and Mexico. 

Specimens Examined. MEXICO. Chihuahua. 

Bocoyna: Cañada de Recogoata, 23 Sep 1997, bosque de pino–

encino en cañada [pine–oak forest in glen], 1900 m, B. Tah 

V. 60, 67 (MEXU). Chihuahua: Cerca [near] del Río, 28 May 

1888, C.G. Pringle s/n (MEXU); vicinity of Chihuahua, 27 Apr 

1908, E. Palmer 160, 29 (US); El Cima, 29 Jun 1936, LeSueur 

Mex 0104 (US); La Campana: 4 km. Ote. [W] carr. [hwy] Panamericana, 6 Sep 73, Maleza en lotes de producción de semilla 

[meadow in seed-production lots], 1500 m, Valdés-Reyna VR-99

(RELC). Rancho Experimental La Campana, 7 May 77, lugares 

húmedos [humid places], 1540 m, S. González 834 (RELC). Gran 

Morelos: km 21 carr. Chihuhua–Namiquipa (via corta [short]), 

24 Sep 1997, bosque de encino oak forest], 1830 m, M.A. Vergara 189 (MEXU). Guachochic: Along trail to Agua Caliente de 

Cusarare a medicinal hot springs along rio Cusarares, 18 Nov 

1973, 1900 m, Bye 5888 (MEXU). Guadalupe: Sierra San Martin de Borracho, Rancho Carrizozo on the N side, 15 Jun 1973, 

matorral desertico inerme [thornless desert scrub], 1500–2195 

m, M.C. Johnston, T.L. Wendt & F. Chiang 11344 (MEXU). Jiménez: 2 km W of Cd. Jiménez, 28 Jul 1939, L. H. Harvey 1315

(US). Temosachi: Temosachi, 23 May 1987, 1800 m, Laferr. 494

(MEXU).

Schismus P. Beauv.

Annual or short-lived perennials; tufted. Culms sometimes 

decumbent, glabrous. Sheaths open, usually shorter than the internodes, with tufts of hairs on the margins of the collars; auricles 

absent; ligules membranous, ciliate; blades flat or folded, becoming involute on drying. Inflorescence a terminal, dense panicle, 

branches 1 or 2 per node; disarticulation initially above the glumes, 

glumes and pedicels sometimes falling together later. Spikelets 

with (4)5–7(10) florets; glumes subequal, exceeding or exceeded 

by the distal floret, 3- to 7-veined, margins hyaline; lemmas 7- to 

9-veined, margins and intercostal regions usually pubescent, varying to glabrous, margins hyaline, apex bifid or merely notched, 

sinuses sometimes mucronate; paleas spatulate, membranous, 

2-veined, 2-keeled; anthers 3. Caryopsis ovoid. x = 6.

Schismus is a genus of five species that is native to Africa 

and Asia. Two species are established in North America.

FIGURE 212. Polypogon viridis. A. Culm and inflorescence. B. Inflorescence. C. Spikelet. D. Glumes. E. Floret. Drawn by Cindy 

Roché; copyright Utah State University.
320 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

KEY TO SPECIES OF SCHISMUS

1. Lower glumes exceeded by the distal florets; lemmas 1.8–2 mm long, rounded and emarginate; palea rounded, as long as the 

lemma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. barbatus

1. Lower glumes equaling or exceeding the distal florets; lemmas 2.5–3 mm long, the apex with 2 acute and hyaline lobes; palea 

acute, shorter than the lemma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. arabicus

327. Schismus arabicus* Nees, Fl. Afr. Austral. Ill. 422. 1841.

Annual. Culms (2)6–16 cm tall. Ligules 0.5–1.5 mm long, 

of hairs; blades 4–6 cm long, 0.5–2 mm wide, abaxial surfaces 

glabrous or sparsely pubescent, adaxial surfaces sparsely to 

densely pubescent. Panicles (1)2–3.5 cm long. Spikelets 5–7 mm 

long; lower glumes 4.2–6.2 mm long, equaling or exceeding the 

distal florets; upper glumes 4–6 mm long; lemmas 1.8–2.6 mm 

long, with dense, spreading pubescence between the veins, lobes 

longer than wide, acute to acuminate; paleas 1.5–2.2 mm long, 

shorter than the lemmas; anthers 0.2–0.5 mm long. Caryopsis 

0.5–0.8 mm long. 2n = 12.

Distribution and Habitat. Schismus arabicus

is native to southwestern Asia and is established in the southwestern United States to northwestern Mexico (Baja California, 

Chihuahua, and Sonora), growing in open and disturbed sites 

(Dávila et al., 2006).

Specimens Examined. MEXICO. Chihuahua. 

Juárez: por la carr. [hwy] Méx 2, en los alrededores [surroundings] de San Agustín, 29 km al SE de Cd. Juárez, 18 Mar 1995, 

en suelos arenosos [sandy soil], 1120 m, R. Corral, P. Olivas & 

E. Pérez RCD6065 (UACJ).

328. Schismus barbatus* (Loefl. ex L.) Thell., Bull. Herb. Boissier, sér. 2. 7(5): 391. 1907. Festuca barbata Loefl. ex L., 

Demonstr. Pl. 3. 1753.

Annual. Culms 6–27 cm tall. Ligules 0.3–1.1 mm long, of hairs; 

blades 3–15 cm long, 0.3–1.5 mm wide, abaxial surfaces glabrous 

or scabrous, adaxial surfaces scabrous, sparsely long-pubescent 

near the ligules. Panicles 1–6(7.5) cm long. Spikelets 4.5–7 mm 

long; lower glumes 4–5.2 mm long, exceeded by the distal florets; 

upper glumes 4–5.3 mm long; lemmas 1.5–2(2.5) mm long, with 

sparse, appressed pubescence between the veins, or glabrous and 

with spreading hairs on the margins, lobes as wide as or wider than 

long, acute to obtuse; paleas 1.7–2.2(2.6) mm long, those of the 

lower florets in the spikelets as long as or longer than the lemmas; 

anthers 0.2–0.4 mm long. Caryopsis 0.6–0.8 mm long. 2n = 12.

Distribution and Habitat. Schismus barbatus

is native to Eurasia and is established in the southwestern United 

States and northwestern Mexico (Baja California, Baja California Sur, Chihuahua, and Sonora), growing in sandy sites and dry 

riverbeds often along disturbed roadsides and fields (Dávila et 

al., 2006).

Schizachyrium Nees

Annual or perennial; caespitose or rhizomatous, sometimes both caespitose and short rhizomatous. Culms branched 

above the bases, often purplish near the nodes. Leaves not aromatic, sheaths open; auricles usually absent; ligules membranous; blades flat, folded, or involute, those of the uppermost 

leaves often greatly reduced. Inflorescences axillary and terminal, of 1, rarely 2, rames, peduncles subtended by a modified leaf, rames not reflexed, with spikelets in heterogamous 

sessile-pedicellate spikelet pairs; pedicels free of the rame axes, 

usually pubescent; internodes more or less flattened, filiform 

to clavate, without a median groove, apex cupulate or fimbriate; disarticulation in the rame axes, below the sessile spikelets. 

Spikelets somewhat dorsoventrally compressed. Sessile spikelets with 2 florets; glumes exceeding the florets, lanceolate to 

linear, membranous; lower glumes enclosing the upper glumes, 

convex, weakly 2-keeled, with several (sometimes inconspicuous) intercostal veins; lower florets reduced to hyaline lemmas; 

upper florets bisexual, lemmas hyaline, bilobed or bifid to 7⁄8 of 

their length (rarely entire), awned from the sinuses; anthers 3; 

pedicellate spikelets usually shorter than to as long as the sessile 

spikelets, occasionally longer, sterile or staminate, with 1 floret, 

often disarticulating as the rame matures; lemmas present in 

staminate spikelets, hyaline, unawned or with a straight awn. 

x = 10.

Schizachyrium is a genus of about 64 species that are native 

to tropical and subtropical regions of the world; 9 are native to 

North America.

KEY TO SPECIES OF SCHIZACHYRIUM

1. Plants annual: culms 5–40(60) cm tall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. brevifolium

1. Plants perennial; culms 40–150 cm tall.

2. Leaf blades 0.5–2 mm wide, with a longitudinal stripe of white, spongy tissue (formed of bulliform cells) on their adaxial 

surfaces; plants caespitose; pedicellate spikelets about as long as the sessile spikelets . . . . . . . . . . . . . . . . . . S. tenerum

2. Leaf blades (1)1.5–9 mm wide, without a longitudinal stripe of white, spongy tissue on their adaxial surfaces; plants 

caespitose or rhizomatous; pedicellate spikelets equal to or smaller than the sessile spikelets.

3. Pedicellate spikelets 6–8 mm long, about as long as the sessile spikelets, usually staminate, sometimes sterile, unawned 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. cirratum
NUMBER 107 • 321

3. Pedicellate spikelets 0.7–10 mm long, usually shorter than the sessile spikelets, sterile, unawned or awned, the awns 

up to 6 mm long.

4. Upper lemmas cleft for 2⁄3–7⁄8 of their length; lower glumes glabrous or pubescent . . . . . . . . . . . . S. sanguineum

4. Upper lemmas cleft for up to 1⁄2 of their length; lower glumes glabrous . . . . . . . . . . . . . . . . . . . . . . . S. scoparium

329. Schizachyrium brevifolium (Sw.) Nees ex Büse, Pl. Jungh. 

3: 359. 1854. 

Annual. Culms 5–40(60) cm tall, prostrate, slender. Sheaths 

shorter than internodes; ligules a ciliolate membrane; blades 1–6 

cm long, 1–7 mm wide, apex obtuse; inflorescences composed 

of 1 raceme, the raceme 1–2.5 cm long, terminal and axillary, 

subtended by a linear spatheole; rachis fragile at the nodes, 

semiterete, glabrous or ciliate on margins. Spikelets in pairs, 1 

bisexual, sessile, 1 sterile, pedicelled, pedicels glabrous or ciliate; 

sterile spikelets 1–1.5 mm long, rudimentary, lanceolate, dorsally 

compressed, shorter than bisexual spikelet, deciduous with the 

bisexual spikelet, glumes chartaceous, 1 glume awned, the awn 

3–6 mm long; bisexual spikelets 2–4 mm long, with 2 florets, 1 

basal sterile and 1 fertile, lanceolate, laterally compressed, callus 

pilose; glumes 2–4 mm long, equal, exceeding apex of florets, 

firmer than fertile lemma; lower glumes lanceolate, coriaceous, 

2-keeled, keeled above and frontally, glabrous or pilose; upper 

glumes lanceolate, membranous, 1-keeled, apex acuminate; sterile floret lemma oblong, hyaline, 2-veined; fertile lemma oblong, 

hyaline, without keels, apex entire when awnless, or 2-lobed, 

mostly awned to rarely muticous, lemma awn 7–12 mm long, 

from a sinus, geniculate with twisted column, column glabrous; 

palea absent or minute; anthers 3, 0.5–1 mm long. 

Distribution and Habitat. Schizachyrium 

brevifolium is native in tropical Africa and Asia and naturalized 

in America from Mexico to South America. It has been reported 

in Chihuahua (Espejo Serna et al, 2000).

330. Schizachyrium cirratum (Hack.) Wooton & Standl., New 

Mexico Agric. Exp. Sta. Bull. 81: 30. 1912. Andropogon 

cirratus Hack., Flora 68(7): 119. 1885.

FIGURE 213

Plants caespitose or short rhizomatous. Culms 31–75 cm 

tall, often decumbent, not rooting or branching at the lower 

nodes, glabrous, glaucous, sometimes purplish. Ligules 1–2.5 

mm long; blades 6–17 cm long, 2–4 mm wide, glabrous, without 

a longitudinal stripe of white, spongy tissue. Inflorescence rames 

4–6 cm long, usually exserted, straight, often somewhat stiff, 

not flexuous, appearing linear; internodes straight, with a tuft 

of hairs near the base, elsewhere glabrous or ciliate on the margins. Sessile spikelets 8–10 mm long; calluses 0.3–0.6 mm long, 

the hairs 0.5–1.2 mm long; glumes glabrous or scabrous; awns 

13–24 mm long; pedicels 3.5–5 mm long, 0.2–0.5 mm wide at 

the base, widening to 0.5–1 mm near apex, straight, with a tuft 

of hairs at the base, distal 1⁄2 usually ciliate on 1 side, sometimes 

on both sides; pedicellate spikelets 6–8 mm long, about as long 

as the sessile spikelets, usually staminate, sometimes sterile, unawned. 2n = 20.

Distribution and Habitat. Schizachyrium cirratum grows on rocky slopes, mostly at elevations of 1,600 m or 

higher; it occurs from southern California to western Texas into 

Mexico and is found in South America.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 16.1 km W of Balleza and 77.9 km E of Guachochi, 18 

Sep 1991, bosque de encino [oak forest], 1990 m, P.M. Peterson, Annable & Valdés-Reyna 10750 (CIIDIR, US); 7.4 km W 

of Balleza on road to Guachochi, 18 Sep 1991, huizachal, 1660 

m, P.M. Peterson, Annable & Valdés-Reyna 10734 (CIIDIR, 

US). Batopilas: Yamuco, 1 mi E of hwy N of Rio Urique crossing towards Basihuare and Creel, 5–6 Sep 2008, P.M. Peterson & J.M. Saarela 22054 (US); SW Chihuahua, Aug 1885, E. 

Palmer 7-B (US). Chihuahua: near Chihuahua, 17 Oct 1885, 

C.G. Pringle 382 (US); Rancho La Campana, Potrero de La 

Sierra, 3 km Pte, carr. [hwy] Panamericana, 14 Sep 73, Pastizal 

con encino [pastureland with oak], 1680 m, Valdés-Reyna VR283 (RELC). Cuauhtémoc: 54 mi W of Cd. Chihuahua, 7 Oct 

1972, 6100 ft, L. H. Harvey & Witherspoon 9299 (ENCB). 

Guachochi: along Río Corareachi, 30 Aug 2003, slopes with 

Quercus, 1840–1900 m, P.M. Peterson & P. Catalán 17602

(CIIDIR); P.M. Peterson & Catalán 17626 (US); Small spring 

below Napuchis, 2 Sep 2003, bosque de pino [pine forest], 2162 

m, P.M. Peterson & P. Catalán 17665 (CIIDIR, US). Guadalupe 

y Calvo: Rio Verde Crossing, 21 mi SW of El Vergel on hwy 24, 

14 Sep 2006, 2330–2360 m, P.M. Peterson 20074, F. Sánchez 

Alvarado & E.P. Gómez Ruíz (CIIDIR, US). Guerrero: 38.6 km 

SW of La Junta and approx. 70.8 km N of Creel at P. Arroyo 

Ancho crossing, 21 km marker, 24 Sep 1988, 2200 m, P.M. 

Peterson & Annable 5843 (US); 33.7 mi W of La Junta on road 

to Parque Nacional Cascada Basaseachic, 30 Sep 1989, 2260 

m, P.M. Peterson & R.M. King 8219 (US). Janos: Chihuahua–

Sonora Border, Rancho Carretas, 27 Aug 1939, 1675 m, L. H. 

Harvey 1625 (US). Madera: Laguna de Babicora, Ejido Año de 

Hidalgo,15 Sep 1994, 2300 m, T. Lebgue, G. Quintana & E. 

Estrada 3768 (NMC); Laguna de Babicora, alrededores [surroundings] de Nicolas Bravo, 18 Aug 1994, 2200 m, Quintana, 

Lebgue & Estrada 3131 (NMC); 10 Km al N de Madera, 5 

Oct 74, bosque de pino–encino, 2000 m, Valdés-Reyna VR-874

(RELC). Ocampo: Parque Nacional “Cascada de Basaseachic,” 

a los lados [sides] del arroyo Basaseachic, 21 Sep 1990, 2100 

m, R. Corral RCD-3841 (NMC); Parque Nacional “Cascada 

de Basaseachic,” at overlook ca. 1 km airline S of Cascada, 3 

Oct 1986, 2100 m, Spellenberg, Soreng, R. Corral & T. Lebgue 

8688 (NMC); Parque Nacional “Cascada de Basaseachic,” in a 

canyon along Rio Basaseachi leading to falls, 4 Oct 1986, 1950 

m, Spellenberg, Soreng, R. Corral & T. Lebgue 8824 (NMC); 

Beside the road near Ocampo. 26 Jul 1990, 2000 m, P. Jenkins 

90-290 (ARIZ). Riva Palacio: Col. Cumbres de Majalca, 33.8 
322 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

km W of Mex 45, N of Chihuahua City, 7 Sep 1989, pine forest, 2190 m, P.M. Peterson, Annable & Y. Herrera 7960, 7965

(US). P.M. Peterson & Annable 5843 (US).

331. Schizachyrium sanguineum (Retz.) Alston, Handb. Fl. 

Ceylon 6: 334. 1931. Rottboellia sanguinea Retz., Observ. 

Bot. 3: 25. 1783.

Schizachyrium hirtiflorum Nees, Schizachyrium semiglabrum Nash.

FIGURE 214

Plants caespitose. Culms 40–120 cm tall, erect, not rooting or branching at the lower nodes, glabrous. Sheaths glabrous, 

rounded; ligules 0.7–2 mm long; blades 7–20 cm long, 1–6 mm 

wide, usually with long, papillose-based hairs basally, glabrous 

elsewhere, sometimes scabrous, without a longitudinal stripe of 

white, spongy tissue. Peduncles 4–6 cm long; rames 4–15 cm 

long, not open, usually almost fully exserted at maturity; internodes 4–6 mm long, straight, from mostly glabrous with a tuft 

of hairs at the base to densely hirsute all over. Sessile spikelets 

5–9 mm; calluses 0.5–1 mm long, the hairs to 2 mm long; lower 

glumes glabrous or densely pubescent; upper lemmas cleft for 

(2⁄3)3⁄4–7⁄8 of their length; awns 15–25 mm long; pedicels 3–6 mm 

long, 0.3–0.5 mm wide at the base, gradually widening to about 

0.6–0.8 mm at the top, straight; pedicellate spikelets 3–5 mm 

long, usually evidently shorter than the sessile spikelets, sterile or 

staminate, awned, the awns 0.3–6 mm long.

Distribution and Habitat. Schizachyrium 

sanguineum extends from the southern United States to Chile, 

Paraguay, and Uruguay.

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: Yamuco at 1 km E of Hwy towards Basihuare and 

Creel, N of Rio Urique crossing, 26 Aug 2003, bosque de pino 

[pine forest], 1891 m, P.M. Peterson & P. Catalán 17550 (US). 

Bocoyna: 24.7 mi N of San Juanito on road towards Cuauhtemoc, 5 Sep 2008, 2233 m, P.M. Peterson & J.M. Saarela 22026

(US). Chinipas: Saguarivo, 53 mi N of Alamos, 9 Sep 2008, 

slopes with oaks and pines, 1540 m, P.M. Peterson & J.M. Saarela 22128 (US). Chihuahua: 80 km al N de Chihuahua hacia 

cd. Juárez, 11 Oct 1980, pastizal mediano abierto [mostly open 

grassland], 1550 m, R. Serrato (ENCB); Rocky hills near Chihuahua, 29 Aug 1885, grassland, 1800 m, C.G. Pringle 383

(US) Isotipo; 87 km N Chihuahua 1 km S Arco Iris on Hwy 45, 

5 Oct 1986, 1500 m, Spellenberg, Soreng & R. Corral 8902

(NMC); La Campana, Potrero de la Sierrra, 4 km Pte. Carr. 

[hwy] Panamericana, 15 Oct 76, pastizal con encino [pastureland with oak], 1850 m, J.M. Peña s/n (RELC); Base de la Sierra 

de La Campana, 80 km al N de Chihuahua, 19 Oct 1974, 1700 

m, Rzedowski 32335 (ARIZ). Guachochi: small spring below 

Napuchis, 2 Sep 2003, bosque de pino, 2162 m, P.M. Peterson 

& P. Catalán 17665b (CIIDIR, US); Juárez: Ciudad Juárez, a 

lo largo [along] de la “Asequia Madre” entre [between] la Av. 

Américas & Paseo Triunfo de la República, 29 Sep 1995, 1140 

m, R. Corral, P. Olivas & L.M. Barraza RCD6407 (UACJ). 

Madera: Mesa del Yerbaìs, ejido El Largo, 12 Oct 1990, bosque 

FIGURE 213. Schizachyrium cirratum. A. Culm and inflorescence. 

B. Portion of inflorescence branch. Drawn by Linda Ann Vorobik; 

copyright Utah State University.
NUMBER 107 • 323

de encino, 1900 m, O. Bravo 1843 (CIIDIR); Laguna de Babicora, Arroyo Las Varas, 10 Sep 1994, 2300 m, G. Quintana & 

E. Estrada 3554 (NMC); 25 km al NE de las Varas, 28 Oct 77, 

bosque de pino–encino, 2100 m, J.M. Peña JMP-800 (RELC). 

Ocampo: Parque Nacional “Cascada de Basaseachic,” on ridge 

top SE side of canyon of Rio Candamena leading to falls, 4 Oct 

1986, 1800 m, Spellenberg, Soreng, R. Corral & T. Lebgue 

8710 (NMC). San Francisco del Oro: 21 km W of Parral and 

approx. 3.2 km N on dirt road to Torrencillo, 26 Sep 1988, 

grassland, 2000 m, P.M. Peterson & Annable 5968 (ENCB, 

US). Temosachi: Nabogame, 11 Sep 1987, oak woodland, 1800 

m, Laferr. 1125 (ARIZ).

332. Schizachyrium scoparium (Michx.) Nash, Fl. S.E. U.S. 59, 

1326. 1903. Andropogon scoparius Michx., Fl. Bor.-Amer. 

1: 57. 1803.

FIGURE 215

Plants caespitose or rhizomatous, green to purplish, sometimes glaucous. Culms 7–210 cm tall, usually 1–3 mm thick, not 

rooting or branching at the lower nodes. Sheaths rounded or 

keeled, glabrous or pubescent, sometimes glaucous; ligules 0.5–2 

mm long, collars neither elongate nor narrowed; blades 7–105 

cm long, 1.5–9 mm wide, without a longitudinal stripe of white, 

spongy tissue. Peduncles 0.8–10 cm long; rames 2.5–8 cm long, 

partially to completely exserted, usually somewhat open; internodes 3–7 mm long, usually arcuate at maturity, ciliate on at 

least the distal 1⁄2 (sometimes throughout), the hairs 1.5–6 mm 

long. Sessile spikelets 3–11 mm long; calluses 0.5–1(2) mm long, 

the hairs 0.3–4 mm long; lower glumes glabrous; upper lemmas 

membranous throughout, cleft to 1⁄2 their length; awns 2.5–17 

mm long. Pedicels 3–7.5 mm long, 0.1–0.2 mm wide at the base, 

flaring above midlength to 0.3–0.5 mm long, straight or curving outward. Pedicellate spikelets 0.7–10 mm long, sometimes 

shorter than the sessile spikelets, sterile or staminate, unawned 

or awned, awns to 4 mm long, when sterile, the lemma usually 

absent. 2n = 40. 

Distribution and Habitat. Schizachyrium 

scoparium is a widespread grassland species, extending from 

Canada to central Mexico. It is one of the principal grasses in 

the tallgrass prairies that used to dominate the central plains of 

North America. There are three varieties; only Schizachyrium 

scoparium var. neomexicanum (Nash) Hitchc. is found in Chihuahua (Espejo Serna et al., 2000). 

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 7.4 km W of Balleza on road to Guachochi, 18 Sep 

1991, huizachal, 1660 m, P.M. Peterson, Annable & ValdésReyna 10732 (CIIDIR, US). Guachochi: 39.2 km S of Creel on 

road to Batopilas at the Barranca El Cobre, 10 Sep 1989, 1930 

m, P.M. Peterson, Annable & Y. Herrera 8023 (US). Gómez 

Farías: Laguna de Babicora, 15 km al SO [SW] de San Jose de 

Babicora, 26 Aug 1994, 2250 m, C. Yen & E. Estrada 3467

(NMC). Madera: Laguna de Babicora, Arroyo Las Varas, 10 Sep 

1994, 2300 m, G. Quintana & E. Estrada 3552 (NMC).

333. Schizachyrium tenerum Nees, Fl. Bras. Enum. Pl. 2: 336. 

1829. Andropogon tener (Nees) Kunth, Révis. Gramin. 2: 

565, t. 197. 1832. 

FIGURE 216

Plants caespitose. Culms 60–100 cm tall, sometimes reclining or decumbent, glabrous. Collars not elongate, about as wide 

as the blade; ligules to 0.5 mm long, ciliolate; blades 5–15 cm 

long, 0.5–2 mm wide, involute or flat, glabrous or sparsely hairy 

basally, with a wide central zone of bulliform cells evident on the 

adaxial surfaces as a longitudinal stripe of white, spongy tissue. 

Rames 2–6 cm long, eventually long-exserted; internodes 2–4 mm 

FIGURE 214. Schizachyrium sanguineum. A. Culm and inflorescence. B. Portion of inflorescence branch. C. Lemma. Drawn by 

Linda Ann Vorobik; copyright Utah State University.
324 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

FIGURE 215. Schizachyrium scoparium var. scoparium. A. Habit. B. Collar. C. Portion of inflorescence branch. D. Distal end of spikelet pair. 

E. Upper lemma. Drawn by Linda Ann Vorobik; copyright Utah State University.
NUMBER 107 • 325

long, straight, glabrous. Sessile spikelets 3.5–4.5 mm long; calluses 

0.5–1 mm long, the hairs to 1.2 mm long; lower glumes glabrous; 

upper lemmas acute, entire; awns 6–10 mm long; pedicels 3–5 mm 

long, glabrous. Pedicellate spikelets usually as long as or slightly 

longer than the sessile spikelets, sterile, unawned. 2n = 60.

Distribution and Habitat. Schizachyrium 

tenerum is an uncommon species in the soouthwestern United 

States, where it grows on sandy soils in pine forest openings and 

coastal prairies. Its range extends to Central America and into 

South America.

Specimens Examined. MEXICO. Chihuahua. 

Guachochi: Río Osichi Canyon at jct of Río Basihuare. Up Río 

Osichi Canyon, 31 Aug 2003, bosque [forest] de Quercus–Pinus, 

1650 m, P.M. Peterson & P. Catalán 17626 (CIIDIR).

Scleropogon Phil.

Perennial; usually monoecious, less frequently dioecious, occasionally synoecious; bearing wiry, often arching, stolons with 

5–15 cm internodes, sometimes also weakly rhizomatous. Leaves 

mostly basal; sheaths short, strongly veined, basal leaves commonly hirsute or villous; ligules of hairs; blades firm, flat or folded. 

Inflorescence terminal, usually exceeding the upper leaves, spikelike racemes or contracted panicles with few spikelets, in bisexual 

plants staminate and pistillate florets in the same spikelet with the 

staminate florets below the pistillate florets or in separate spikelets, 

bisexual florets occasionally produced; branches not pectinate; 

disarticulation above the glumes and below the lowest pistillate 

floret in a spikelet, florets falling together, lowest floret with a 

bearded, sharp-pointed callus. Staminate spikelets with 5–10(20) 

florets; glumes membranous, pale, 1- to 3-veined, acuminate; lemmas 3-veined, similar to the glumes, unawned or awned, awns to 3 

mm long; paleas shorter than the lemmas, often conspicuously so. 

Pistillate spikelets appressed to the branch axes, usually the 3–5 

lower florets functional, upper florets reduced to awns; glumes 

lanceolate, acuminate, strongly 3-veined, membranous, occasionally with a few fine accessory veins; lemmas narrow, 3-veined, 

veins extending into awns, the awns (30)50–100(150) mm long, 

spreading or reflexed at maturity. x = 10. 

Scleropogon is a monotypic American genus with an amphitropical disjunct distribution (Peterson and Columbus, 1997).

334. Scleropogon brevifolius Phil., Anales Univ. Chile 36: 206. 

1870.

FIGURE 217

Stolons to 50 cm long, wiry, internodes 5–15 cm. Culms 

(5)10–20 cm tall, erect. Ligules about 1 mm long; blades 2–8(12) 

cm long, 1–2 mm wide. Bisexual spikelets 2–4 cm long, staminate florets below the pistillate florets. Staminate spikelets 2–3 

cm long. Pistillate spikelets subtended by a glume-like bract; 

lemma bodies 2.5–3 cm long. 2n = 40.

Distribution and Habitat. Scleropogon brevifolius grows on grassy plains and flats, generally being most abundant 

FIGURE 216. Schizachyrium tenerum. A. habit. B. Leaf blades, abaxial surface on left, adaxial surface on right. C. Portion of inflorescence branch. Drawn by Linda Ann Vorobik; copyright Utah State 

University.
326 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

on disturbed or overgrazed land. Its North American range extends 

from the southwestern United States to central Mexico; its South 

American range is from Chile to northwestern Argentina.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 7 km Pte. Sueco por carr. [hwy] Sueco–Buenaventura, 

21 Oct 74, Pastizal [pastureland], 1300 m, Valdés-Reyna VR-727 

(RELC). Aldama: 26 (rd) mi NE of Aldama along Hwy 16 near 

El Morrion, 15 Sep 1972, 1400 m, J. Henrickson 7560 (NMC); 

near Chihuahua, 31 Aug 1885, C.G. Pringle 484 (MEXU-1813, 

US); 3 km al NNE de San Diego de Alcalá, 10 Oct 1997, 1200 

m, E. Estrada & C. Yen 9003 (NMC); km 35 carr. Chihuahua–

Ojinaga, 28 Oct 74, Pastizal halófito [halophyte grassland], 1300 

m, Valdés-Reyna VR-721 (RELC). Ascensión: About 10–12 km 

ENE of Guzmán towards Laguna de Santa María, 22 Aug 1972, 

1150 m, M.C. Johnston, T.L. Wendt & F. Chiang 8791 (MEXU). 

Chihuahua: Near Chihuahua, 31 Aug 1885, 1780 m, C.G. Pringle 484 (US). Galeana: 145 km de Galeana, 8 Aug 1979, pastizal, 

1370 m, M. Siqueiros 303 (MEXU). Janos: Rancho El Carrizo, 30 

Sep 1982, 1600 m, pastizal mediano abierto [mostly open grassland], P. Rojas s.n. (CIIDIR); Salto de Ojo, 13 Oct 1994, pastizal, 1455 m, M.H. Royo M. s/n (MEXU); Cerros Prietos, 18 Sep 

1977, pastizal, 1400 m, Blanco & Gómez 20/77 (MEXU). Jiménez: About 5 mi SW of Jiménez, 6 Oct 1966, Reeder & C. Reeder 

4607 (ARIZ); 1 km al S of Hacienda El Berrendo on the Las 

Pampas ranch, 27 Aug 1972, matorral desértico [desert scrub], 

1475 m, F. Chiang, T. Wendt & M.C. Johnston 8878 (MEXU); El 

Hugo, Torreoncitos, 13 Aug 2010, terrenos de cultivo [farmland], 

1355 m, D. Ramírez & M.L. Juárez 3387 (CIIDIR).

Setaria P. Beauv.

Annual or perennial; caespitose, rarely rhizomatous. Culms 

erect or decumbent. Ligules membranous and ciliate or of hairs; 

blades flat, folded, or involute, or plicate and petiolate. Inflorescences terminal, panicles, usually dense and spikelike, occasionally loose and open; disarticulation usually below the glumes, 

spikelets falling intact, bristles persistent. Spikelets usually 

lanceoloid-ellipsoid, rarely globose, turgid, subsessile to short 

pedicellate, in involucres on short branches or single on a short 

branch, some or all subtended by 1 to several, terete bristles 

(sterile branchlets). Lower glumes membranous, not saccate, less 

than 1⁄2 as long as the spikelets, 1- to 7-veined; upper glumes 

membranous to herbaceous at maturity, 1⁄2 as long as to nearly 

equaling the upper lemmas, 3- to 9-veined; lower florets staminate or sterile; lower lemmas membranous, equaling or rarely 

exceeding the upper lemmas, rarely absent, not constricted or 

indurate basally, 5- to 7-veined; lower paleas usually hyaline to 

membranous at maturity, rarely absent or reduced, veins not 

keeled; upper florets bisexual; upper lemmas and paleas indurate, transversely rugose, rarely smooth; anthers 3, not penicillate; styles 2, free or fused basally, white or red. Caryopsis small, 

ellipsoid to subglobose, compressed dorsiventrally. x = 9. 

Setaria, a genus of about 113 species, grows predominantly 

in tropical and warm-temperate regions and is particularly well 

represented in Africa, Asia, and South America.

FIGURE 217. Scleropogon brevifolius. A. Staminate plant habit. 

B. Staminate spikelet. C. Staminate floret. D. Bisexual plant habit. 

E. Pistillate floret. Drawn by Linda Ann Vorobik and Cindy Roché; 

copyright Utah State University.
NUMBER 107 • 327

KEY TO SPECIES OF SETARIA

1. Bristles 4–12 below each spikelet; panicle dense, cylindric 

2. Perennial; rhizomes short and knotty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. parviflora

2. Annual; rhizomes absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. pumila

1. Bristles 1–3 (rarely 6) below each spikelet; panicle open, interrupted, evidently branched.

3. Bristles retrorsely scabrous; spikelets 1.5–2 mm long, with only 1 bristle, 1 or 2 times longer than the spikelet.

4. Margins of sheaths ciliate distally; blades scabrous on the abaxial surfaces; panicle branches verticilate . . . . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. verticillata

4. Margins of sheaths glabrous; blades strigose on the abaxial surfaces; panicle branches simple or in pairs, not verticilate 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. adhaerens

3. Bristles antrorsely scabrous; spikelets 1.8–3.2 mm long, generally with more than 1 bristle, bristles usually twice as long 

as the spikelets.

5. Perennial

6. Spikelets 2.8–3.2 mm long; blades densely villous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. villosissima

6. Spikelets 1.9–2.8(3) mm long; blades not villous.

7. Lower paleas narrow, 1⁄3–1⁄2 as long as the lemmas; spikelets elliptical; panicles 6–15 cm long, columnar; blades 

2–5(8) mm wide; culms and leaves light green to glaucous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. leucopila

7. Lower paleas broad, subequal to the lemmas in length; spikelets subspherical; panicles 8–30 cm long, dense, 

cylindrical; blades 7–15 mm wide; culms and leaves green-yellowish . . . . . . . . . . . . . . . . . . . S. macrostachya

5. Annual.

8. Upper glumes and lower lemmas with 7 veins, the outer pair of veins not coalescing with the inner 5; lower paleas 

absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. liebmannii

8. Upper glumes and lower lemmas 5- to 7-veined, all of which coalesce near the apex; lower paleas present, sometimes reduced.

9. Panicles loosely spicate, interrupted; rachises visible, hispid; culm nodes pubescent, hairs appressed . . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. grisebachii

9. Panicles densely spicate; rachises not visible, villous; culm nodes glabrous . . . . . . . . . . . . . . . . . . . . S. viridis

335. Setaria adhaerens* (Forssk.) Chiov., Nuovo Giorn. Bot. 

Ital. 26: 77. 1919. Panicum adhaerens Forssk., Fl. Aegypt.-

Arab. 20. 1775.

Annual. Culms 25–60 cm tall. Sheaths glabrous throughout; ligules 1–2 mm long, of hairs, white; blades usually less 

than 10 cm long, 5–10 mm wide, flat, broad basally, abaxial 

surfaces conspicuously strigose with papillose-based hairs, tapering abruptly at the apex; bristles solitary, about 5 mm long, 

retrorsely scabrous. Panicles 2–6 cm long, verticillate, green to 

purple; rachises retrorsely rough hispid. Spikelets 1.5–2.2 mm 

long; lower glumes about 1⁄2 as long as the spikelets, obtuse, 

1(3)-veined; upper glumes nearly as long as the spikelets, 5- to 

7-veined; lower lemmas equaling to slightly exceeding the upper 

lemmas; lower paleas less than 1⁄2 as long as the spikelets, scalelike; upper lemmas finely and transversely rugose; upper paleas 

similar to the upper lemmas. 2n = 18.

Distribution and Habitat. Setaria adhaerans

grows in subtropical regions throughout the world. In North 

America, it is known from the southern United States, northeastern Mexico, Guatemala, Cuba, and the Bahamas (Rominger, 

2003). It appears to be introduced and has been reported for 

Chihuahua (Espejo Serna et al., 2000).

336. Setaria grisebachii E. Fourn., Mexic. Pl. 2: 45. 1886.

Annual. Culms 30–100 cm tall; nodes pubescent, the hairs 

appressed. Sheaths with ciliate margins; ligules ciliate; blades to 

12(25) cm long, to 10(20) mm wide, flat, hirsute. Panicles 3–18 

cm long, loosely spicate, interrupted, often purple; rachises hispid; bristles 5–15 mm long, 1–3, flexible, antrorsely scabrous. 

Spikelets 1.5–2.2 mm long; lower glumes about 1⁄3 as long as 

the spikelets, distinctly 3-veined, lateral veins coalescing with 

the central veins below the apex; upper glumes nearly equaling the upper lemmas, obtuse, 5-veined; lower lemmas equaling 

the upper lemmas; lower paleas about 1⁄3 as long as the lower 

lemmas, narrow; upper lemmas finely and transversely rugose; 

upper paleas similar to the upper lemmas. 

Distribution and Habitat. Setaria grisebachii

is the most widespread and abundant native annual species of 

Setaria in the southwestern United States. It grows in open 

ground and extends along the central highlands of Mexico to 

Guatemala.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: near Chihuahua, 16 Sep 1885, C.G. Pringle 381

(US); 4 Sep 1935, LeSueur Mex-025 (US); km 14 N of Cd. Chihuahua, 15 Sep 1955, Hern.-Xol. N-1748 (US); 13 mi SW of 

Chihuahua on road to Cuauhtémoc, 6 Oct 1959, 1585 m, Soderstrom 910 (US); km 109 carr. [hwy] PanAmer., 28 Oct 76, matorral [scrub], S. González s/n (RELC). Cuautémoc: 21 km W of 

Cuauhtemoc, on hwy 16, 23 Aug 1990, 2000 m, P.M. Peterson 

& Annable 9592 (US). General Trías: km 40 carr. Chihuahua–

Cuahutémoc, 12 Aug 1976, Matorral, 1693 m, J.M. Peña & S. 

González 536 (RELC). Gran Morelos: km 20 Cd. Cuauhtémoc 
328 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

de Cd. Chihuahua, 27 Oct 1954, 1500 m, Hern.-Xol. N-266

(US). Janos: Chihuahua–Sonora Border, Rancho Carretas, 26 

Aug 1939, L. H. Harvey 1596 (US). Madera: Paraje Sirupa, 

ejido Cebollitas, 16 Oct 1990, bosque de encino [oak forest], 

1200 m, O. Bravo 1922 (CIIDIR). Riva Palacio: Col. Cumbres 

de Majalca, 33.8 km W of Mex 45, N of Chihuahua City, 7 Sep 

1989, pine forest, 2190 m, P.M. Peterson, Annable & Y. Herrera 

7953 (US).

337. Setaria leucopila (Scribn. & Merr.) K. Schum., Just ́s Bot. 

Jahresber. 28(1): 417. 1902. Chaetochloa leucopila Scribn. 

& Merr., Bull. Div. Agrostol. U.S.D.A. 21: 26, f. 14. 1900.

FIGURE 218

Caespitose perennial. Culms 20–100 cm tall. Sheaths compressed, glabrous, margins villous distally; ligules 1–2.5 mm 

long, ciliate; blades 8–25 cm long, 2–5 mm wide, flat or folded, 

scabrous on both surfaces. Panicles 6–15 cm long, tightly spikelike, pale green; rachises scabrous or villous; bristles 4–15 mm 

long, usually solitary, ascending. Spikelets 2.1–2.8(3) mm long, 

elliptical; lower glumes 1⁄3–1⁄2 as long as the spikelets, 3-veined; 

upper glumes from 3⁄4 as long as to equaling the florets, 5-veined; 

lower lemmas equaling the upper lemmas, 5-veined; lower paleas 1⁄2–3⁄4 as long as the upper paleas, lanceolate; upper lemmas 

apiculate, finely and transversely rugose; upper paleas similar. 2n

= 54, 68, 72.

Distribution and Habitat. Setaria leucopila

grows in the southwestern United States and northern Mexico. It 

is the most common of the perennial plains bristle grasses.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 10 km al S de Moctezuma, 30 Jul 1994, 1200 m, R. 

Corral, E. Pérez, A. Domínguez & F. Félix RCD5338 (UACJ). 

Casas Grandes: 17 mi S of Nuevo Casas Grandes on Mex 2, 

1585 m, P.M. Peterson & R.M. King 8144b (US). Chihuahua: 

near Chihuahua, 23 Aug 1885, C.G. Pringle 488 (US); 20 Aug 

1935, LeSueur Mex-010 (US); km 14 N of Cd. Chihuahua, 15 

Sep 1955, Hern.-Xol. N-1758 (US); 3 km al Oeste [west] de Cd. 

Chihuahua, 9 Aug 1996, pastizal [pastureland], 1500 m, E. Estrada & C. Yen 4875 (NMC); La Campana, Potrero La Sierra 

1 km Pte. carr. [hwy] PanAmer., 18 Sep 73, pastizal, 1500 m, 

Valdés-Reyna VR-310 (RELC). Jiménez: 14 mi SE of Jiménez, 3 

Sep 1967, Reeder & C. Reeder 4839 (ARIZ); El Hugo, Torreoncitos, 13 Aug 2010, matorral [scrub] de Prosopis sp., 1355 m, 

D. Ramírez & M.L. Juárez 3399 (CIIDIR). Juárez: aprox. 7 km 

al N del poblado [village] de Samalayuca, a los lados [sides] de la 

carr., 30 Jul 1994, 1200 m, R. Corral, E. Pérez, A. Domínguez 

& F. Félix RCD5302 (UACJ); a orillas [edge] de la Carr. No 2 

Juárez–Janos, km 128, 11 Aug 1996, P. Olivas, R. Rivas & I. 

Enríquez POS813 (UACJ); Ciudad Juárez, a lo largo [along] de 

la “Asequia Madre” entre [between] la Av. Américas & Paseo 

Triunfo de la República, 29 Sep 1995, 1140 m, R. Corral, P. Olivas & L.M. Barraza RCD6410 (UACJ). Madera: Paraje Sirupa, 

ejido Cebadilla de Dolores, 24 Ag 1990, bosque de encino [oak 

forest], 1220 m, O. Bravo 1260 (CIIDIR).

FIGURE 218. Setaria leucopila. A. Culm, inflorescence, and leaf 

blade. B. Spikelet showing lower glume. C. Spikelet showing upper 

glume. D. Lower palea. Drawn by Linda Ann Vorobik and Annaliese Miller; copyright Utah State University.
NUMBER 107 • 329

338. Setaria liebmannii E. Fourn., Mex. Pl. 2: 44. 1886. 

Setaria rariflora J. Presl.

Annual. Culms 30–90 cm tall. Sheaths glabrous, margins 

ciliate; ligules ciliate; blades to 20 cm long, 10–20 mm wide, flat, 

scabrous on both surfaces. Panicles 10–25 cm long, loosely spicate; rachises scabrous; bristles 7–15 mm long, solitary, slender, 

antrorsely scabrous. Spikelets 2–2.7(3) mm long; lower glumes 

about 1⁄3 as long as the spikelets, 3-veined; upper glumes and 

lower lemmas 7-veined, the 5 central veins coalescing at the 

apex; lower paleas absent; upper lemmas gibbous, strongly and 

coarsely transversely rugose; upper paleas similar to the upper 

lemmas. 2n = 18.

Distribution and Habitat. Setaria liebmannii

in the United States is known only from southern Arizona, but it 

is a common species along the Pacific slope of northern Mexico 

to Nicaragua (Espejo Serna et al., 2000).

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: SW Chihuahua, Batopilas, Aug 1885, E. Palmer 52, 

110D (US); Intersección Arroyo de Santiago con el Río Batopilas, 6 km antes del pueblo [before town] de Batopilas, 10 Sep 

1999, 600 m, T. Lebgue, Quintana & E. Estrada 2366 (NMC). 

Jiménez: El Hugo, Torreoncitos, 13 Aug 2010, terrenos de 

cultivo [farmland], 1355 m, D. Ramírez & M.L. Juárez 3384

(CIIDIR). Moris: Along the trail south of Moris, near the Moris 

River, 23 Sep 1991, 700 m, P. Jenkins 91-112 (ARIZ). Ocampo: 

Ca 1 km W of W boundary of Parque Nacional “Cascada de 

Basaseachic,” 18 km from the Cahuisori–Ocampo road on the 

road to Candamena, 7.5 km below Cruz, 24 Sep 1994, 1260 m, 

Spellenberg, Corral & Estrada 12184 (NMC). Uruachi: few km 

south of Moris, 23 Sep 1991, 700 m, P. Jenkins 91-76-A (ARIZ).

339. Setaria macrostachya Kunth, Nov. Gen. Sp. (quarto ed.) 1: 

110. 1815.

FIGURE 219

Densely caespitose perennial. Culms 60–120 cm tall, rarely 

branched distally, scabrous below the nodes and panicles. Sheaths 

keeled, glabrous, usually with a few white hairs at the throat; ligules 2–4 mm long, densely ciliate; blades 15–20 cm long, 7–15 

mm wide, flat, adaxial surface scabrous. Panicles 10–30 cm long, 

1–2 cm wide, uniformly thick from the base to the apex, dense, 

rarely lobed basally; rachises scabrous and loosely pilose; bristles 10–20 mm long, usually solitary, soft, antrorsely scabrous. 

Spikelets 2–2.3 mm long, subspherical; lower glumes 1⁄3–1⁄2 as 

long as the spikelets, 3- to 5-veined; upper glumes about 3⁄4 as 

long as the spikelets, 5- to 7-veined; lower lemmas equaling the 

FIGURE 219. Setaria macrostachya. A. Inflorescence and leaf blade. 

B. spikelet. C. Upper lemma. D. Lower palea. Drawn by Linda Ann 

Vorobik and Annaliese Miller; copyright Utah State University.
330 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

upper lemmas, 5-veined; lower paleas nearly equaling the upper 

paleas in length and width; upper lemmas transversely rugose; 

upper paleas convex, ovate. 2n = 54.

Distribution and Habitat. Setaria macrostachya is abundant in the desert grasslands of the southwestern 

United States, particularly in southern Arizona and Texas. It extends south through the highlands of central Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Aldama: Santo Domingo, 50 km SW of Coyame of Mex 16 between Presidio, Texas and Chihuahua, 22 Sep 1988, 1400 m, 

P.M. Peterson & Annable 5751 (US); Rancho El torreño # 3, 

25 Sep 1982, matorral inerme parvifolio [unarmed small-leaved 

scrub], 1150 m, G. Melgoza 35 (CIIDIR). Chihuahua: 54 mi N 

of Ciudad Chihuahua, 2 Sep 1958, Reeder & C. Reeder 3196

(US). Guadalupe: NE Chihuahua, vicinity of Rancho El Pino, 

ca 10 km, SE of Sierra Rica, 23 Sep 1942, bosque de encino 

[oak forest], 1100 m, R.M. Stewart 2396 (US). Juárez: km 32 

Juárez–Chih., 13 Oct 1997, matorral de gobernadora [governor’s scrub], 1300 m, I. Enríquez, S. Ordoñez & J. Leyva IEA3

(UACJ). Manuel Benavides: E Chihuahua, Coalhuila boundary, 

1 mi E of Pozo de Villa, along rd from Ojinaga to Castillon, via 

La Mula, Trincheras, 12 Aug 1941, I.M. Johnston 8174 (US).

340. Setaria parviflora (Poir.) Kerguélen, Lejeunia, n.s. 120: 

161. 1987. Cenchrus parviflorus Poir., Encycl. 6: 52. 1804.

Setaria geniculata P. Beauv.

FIGURE 220

Perennial; with short, knotty rhizomes. Culms 30–120 cm 

tall; nodes glabrous. Sheaths glabrous; ligules shorter than 1 mm 

long, of hairs; blades to 25 cm long, 2–8 mm wide, flat, scabrous 

above. Panicles 3–8(10) cm long, of uniform width throughout 

their length, densely spikelike; rachises scabrous to hispid; bristles 2–12 mm long, 4–12, antrorsely barbed, yellow to purple. 

Spikelets 2–2.8 mm long, elliptical and turgid; lower glumes 

about 1⁄3 as long as the spikelets, 3-veined; upper glumes 1⁄2–2⁄3

as long as the spikelets, 5-veined; lower florets often staminate; 

lower lemmas occasionally indurate and faintly transversely rugose; lower paleas equaling the lower lemmas; upper lemmas 

distinctly transversely rugose, often purple-tipped. 2n = 36, 72.

Distribution and Habitat. Setaria parviflora

is a common, native species of moist ground. It is most frequent 

along the Atlantic and Gulf coasts, but it also grows from the 

Central Valley of California east through the central United 

States and southward through Mexico to Central America 

(Rominger 2003).

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: aprox. 25 km al N del poblado [village] Flores 

Magón, 7 Oct 1995, 1140 m, R. Corral, P. Olivas & J.O. Torres RCD6455 (UACJ). Balleza: 56.4 km W of Parral on road 

to Balleza and 35.5 km S of Balleza on Mex 432, near Corral 

de Duarte, 18 Sep 1991, bosque de pino–encino [pine–oak forest], 2210 m, P.M. Peterson, Annable & Valdés-Reyna 10714

(CIIDIR, US). Batopilas: Yamuco at 1 km E of hwy towards 

FIGURE 220. Setaria parviflora. A. Culm base. B. Culm and inflorescence. Spikelet. D. Upper lemma. Drawn by Linda Ann Vorobik 

and Annaliese Miller; copyright Utah State University.
NUMBER 107 • 331

Basihuare and Creel, N of Rio Urique crossing, 26 Aug 2003, 

bosque de pino, 1891 m, P.M. Peterson & P. Catalán 17548 

(US). Bocoyna: 3.7 km N of San Juanito on road to Creel, near 

km 53 marker, 24 Sep 1988, pine woods, 2200 m, P.M. Peterson & Annable 5861b (US). Chinipas: Saguarivo, 53 mi N of 

Alamos, 9 Sep 2008, slopes with oaks and pines, 1540 m, P.M. 

Peterson & J.M. Saarela 22117 (US). Chihuahua: La Campana; 

1 km Pte. carr. [hwy] PanAmer., 14 Sep 1973, pastizal mediano 

abierto [mostly open grassland], 1570 m, Valdés-Reyna VR-275

(RELC); La Campana, Jardín de observación [observation garden], 6 Oct 1974, 1500 m, Valdés-Reyna VR-609 (RELC). Cuautémoc: 21 km W of Cuauhtemoc, on hwy 16, 23 Aug 1990, 

2000 m, P.M. Peterson & Annable 9599 (US). Guerrero: 11 

km E of Tomochic on rd to La Junta, 5 Oct 1986, 2100 m, 

Spellenberg, R Soreng, R. Corral & T. Lebgue 8893 (NMC); 

entre [between] Cuahutémoc & La Junta, 12 Aug 1976, orilla 

[edge] de carr., 2135 m, S. González & J.M. Peña 552 (RELC). 

Julímes: Rancho La Tiznada, 26 Aug 1973, cultivo de zacate 

[cultivated grass] Alicia, 1500 m, Valdés-Reyna VR-30 (RELC). 

Madera: Paraje El Negro, ejido El Largo, 1 Sep 1990, bosque 

de pino–encino, 1940 m, O. Bravo 1434 (CIIDIR); proximidad 

a la Col. Chuichupa, 1 Nov 1990, pastizal & bosquete [pastureland and grove] de Juniperus deppeana, 2240 m, A. Benítez 

2164 (CIIDIR); Laguna de Babicora, alrededores [surroundings] 

de Nicolas Bravo, 18 Aug 1994, 2200 m, Quintana, Lebgue 

& Estrada 3143 (NMC). Ocampo: Parque Nacional “Cascada 

de Basaseachic”, 22 Sep 1990, 2100 m, R. Corral RCD-3926

(NMC); Parque Nacional “Cascada de Basaseachic,” between 

parking lot and top of falls, along the trail to the top of the 

falls, 1 Aug 1988, 2000 m, Spellenberg, R. Corral, J Brunt & L. 

Huenneke 9591 (NMC); Parque Nacional “Cascada de Basaseachic,” at overlook ca. 1 km airline S of Cascada, 3 Oct 1986, 

2100 m, Spellenberg, Soreng, R. Corral & T. Lebgue 8802 

(NMC); Parque Nacional Cascada basaseachic, por la vereda 

que va de la parte alta de la cascada [along the path from the 

top of the waterfall] a “La Ventana”, 22 Sep 1990, bosque de 

pino–encino, 1980 m, R. Corral RCD3926 (UACJ); 37 km W of 

Mex 45, and ca. 3.2 km W of Col. Cumbres de Majalca, 2170 

m, P.M. Peterson, Annable & Y. Herrera 7979 (US).

341. Setaria pumila* (Poir.) Roem. & Schult., Syst. Veg. (ed. 15 

bis) 2: 891. 1817. Panicum pumilum Poir., Encycl., Suppl. 

4(1): 273. 1816.

Setaria lutescens (Weigel ex Stuntz) F. T. Hubb.

FIGURE 221

Annual. Culms 30–130 cm tall. Sheaths glabrous; ligules 

ciliate; blades 4–10 mm wide, flat to loosely twisted, adaxial surface with papillose-based hairs. Panicles 3–15 cm long, 

densely spicate, erect; rachises hispid; bristles 3–8 mm long, 

4–12, antrorsely scabrous, yellowish. Spikelets 3–3.4 mm long, 

strongly turgid; lower glumes 1⁄3 as long as the spikelet, 3-veined, 

acute; upper glumes about 1⁄2 as long as the spikelet, 5-veined, 

ovate; lower lemmas equaling the upper lemmas; lower paleas 

equaling the lower lemmas; upper lemmas conspicuously exposed, strongly transversely rugose. 2n = 36, 72.

Distribution and Habitat. In Chihuahua we 

have Setaria pumila subsp. pumila, which is a common weed of 

lawns and cultivated fields throughout North America to central 

Mexico. This subspecies is native to Eurasia.

FIGURE 221. Setaria pumila. A. Habit. B. Inflorescence. C. Spikelet. 

Drawn by Linda Ann Vorobik and Annaliese Miller; copyright Utah 

State University.
332 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Specimens Examined. MEXICO. Chihuahua. 

Camargo: 5 km W of Camargo, 1220 m, 5 Aug 1939, L.H. Harvey 1413 (US). Meoqui: Lazaro Cardenas, 7 Aug 1974, 1250 m, 

C. Rodríguez, O. Agundis & S. Acosta 1222 (US). 

342. Setaria verticillata* (L.) P. Beauv., Ess. Agrostogr. 51, 171, 

178. 1812.

Annual. Culms 30–100 cm tall; nodes glabrous. Sheaths 

glabrous, margins ciliate distally; ligules to 1 mm long, densely 

ciliate; blades 5–15 mm wide, flat, abaxial surfaces scabrous. 

Panicles 5–15 cm long, tapering to the apex; rachises retrorsely 

rough hispid; bristles 4–7 mm long, solitary, retrorsely scabrous. 

Spikelets 2–2.3 mm long; lower glumes about 1⁄3 as long as the 

spikelets, obtuse, 1(3)-veined; upper glumes nearly as long as the 

spikelets; lower paleas about 1⁄2 as long as the spikelets, broad; 

upper lemmas finely and transversely rugose; upper paleas similar to the upper lemmas. 2n = 18, 36, 54, 72, 108.

Distribution and Habitat. Setaria verticillata

is a European adventive that is now common throughout the 

cooler regions of the contiguous United States and southern Canada and introduced to northern Mexico (Rominger, 2003). This 

species has been reported for Chihuahua (Dávila et al., 2006).

343. Setaria villosissima (Scribn. & Merr.) K. Schum., Just’s Bot. 

Jahresber. 28(1): 417. 1902. Chaetochloa villosissima Scribn. 

& Merr., Bull. Div. Agrostol., U.S.D.A. 21: 34, f. 19. 1900.

Caespitose perennial. Culms 40–100 cm tall. Sheaths villous 

distally, margins ciliate; ligules about 1 mm long, densely ciliate, 

hairs white; blades 15–30 cm long, 5–8 mm wide, both surfaces 

villous. Panicles 10–20 cm long, loosely spicate; bristles 10–20 

mm long, usually solitary. Spikelets 2.8–3.2 mm long; lower 

glumes about 1⁄3 as long as the spikelets, broadly ovate, 3-veined; 

upper glumes nearly equaling the spikelets, 5- to 7-veined; lower 

lemmas equaling the upper lemmas, 5-veined; lower paleas about 

1⁄5 as long as the upper paleas, lanceolate; upper lemmas finely 

and transversely undulate-rugose basally, striate and punctate 

distally; upper paleas similar, ovate-lanceolate. 2n = 54.

Distribution and Habitat. Setaria villosissima is a rare species that grows on granitic soils in southwestern 

Texas and northern Mexico. This species has been reported for 

Chihuahua (Espejo Serna et al., 2000; Dávila et al., 2006).

344. Setaria viridis* (L.) P. Beauv., Ess. Agrostogr. 51: 178. 

1812. Panicum viride L., Syst. Nat. (ed. 10) 2: 870. 1759.

FIGURE 222

Annual. Culms 20–250 cm tall; nodes glabrous. Sheaths 

glabrous, sometimes scaberulous, margins ciliate distally; ligules 

1–2 mm long, ciliate; blades to 20 cm long, 4–25 mm wide, flat, 

scabrous or smooth, glabrous. Panicles 3–20 cm long, densely spicate, nodding only from near the apex; rachises hirsute and villous; 

bristles 5–10 mm long, 1–3, antrorsely scabrous, usually green, 

rarely purple. Spikelets 1.8–2.2 mm long; lower glumes about 1⁄3

as long as the spikelets, triangular-ovate, 3-veined; upper glumes 

FIGURE 222. Setaria viridis. A. Ligule. B. Culm and inflorescence. 

C. Spikelet showing lower glume. D. Spikelet showing upper glume. 

Drawn by Linda Ann Vorobik and Annaliese Miller; copyright Utah 

State University.
NUMBER 107 • 333

nearly equaling the upper lemmas, elliptical, 5- to 6-veined; lower 

lemmas slightly exceeding the upper lemmas, 5-veined; lower paleas about 1⁄3 as long as the lower lemmas, hyaline; upper lemmas very finely and transversely rugose, pale green, 5- to 6-veined; 

upper paleas similar to the upper lemmas. 2n = 18.

Distribution and Habitat. Setaria viridis is an 

aggressive weed native to Eurasia (Rominger, 2003).

Specimens Examined. MEXICO. Chihuahua. 

Manuel Benavides: entre [between] Manuel Benavides & Pocitos, 2 

Aug 1976, matorral [scrub], 1454 m, S. González & J.M. Peña 475

(RELC). Riva Palacio: km 109 carr. [hwy] Chihuahua–El Sueco, 6 

Oct 1978, matorral de prosopis, 1675 m, A. Melgoza s.n. (CIIDIR).

Setariopsis Scribn.

Annual. Culms solid, branching above the base. Sheaths 

open; ligules of hairs; blades flat. Inflorescence a terminal panicle 

with pilose rachises; branches with spikelets congested, shortly 

pedicellate, subtended by a terete bristle; disarticulation below 

the glumes. Spikelets dorsally compressed, with 2 florets, lower 

florets usually sterile, upper florets bisexual. Lower glumes about 

1⁄4 the length of spikelets, 5- to 7-veined, subclasping; upper 

glumes slightly shorter than the spikelets, 11- to 19-veined, 

indurate at maturity, constricted at the base, auriculate above 

the point of constriction; lower lemmas longer than the glumes, 

membranous but somewhat indurate at the base; lower paleas 

usually present, short; upper lemmas indurate, finely transversely 

rugose, apiculate, margins clasping the paleas; upper paleas similar to the lemmas in length and texture; lodicules 2; anthers 3, 

purple; ovaries glabrous; style branches 2, free to the base. Caryopsis ovate, plano-convex; embryos about 1⁄2 as long as the caryopsis. x = 9.

Setariopsis includes two species that are found in open, 

mostly tropical forests of North, Central, and South America.

KEY TO SPECIES OF SETARIOPSIS

1. Sheaths mostly glabrous, with soft hairs near the ligule; upper glumes 2–2.2 mm long, margins involute, resembling auricles; 

sterile lemmas 2–2.5 mm long, ovate, thicker on margins, apex obtuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. auriculata

1. Sheaths hispid, with papillose-based hairs; upper glumes 3–3.2 mm long, oblate, not auriculate at base; sterile lemmas 3–3.5 

mm long, apex oblong, emarginate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. latiglumis

345. Setariopsis auriculata (E. Fourn.) Scribn., Publ. Field Columbian Mus., Bot. Ser. 1(3): 289. 1896. Setaria auriculata

E. Fourn., Mexic. Pl. 2: 43. 1886.

Caespitose annual. Culms 15–60 cm tall, weak, erect or ascending, glabrous or with a few short, appressed hairs on and 

immediately below the nodes. Sheaths mostly glabrous with soft 

hairs near the ligule; ligules 1–1.5 mm long; blades 3–25 cm long, 

2–12 mm wide, apex acuminate, glabrous or with a few hairs on 

the collars. Panicles 3–15 cm long, 0.8–1.5 cm wide; branches 

0.5–2 cm long, spikelets congested, shortly pedicellate; pedicels 

to 0.5 mm long, oblong, subtended by a terete bristle; bristles 

3–8 mm long, persistent, antrorsely barbed. Spikelets 2–2.5 mm 

long, ovate, apex obtuse, falling entire; rachilla internodes elongated between glumes; glumes unequal, same size as florets, thinner than fertile lemma; lower glumes about 1 mm long, 3-veined, 

oblate, membranous, apex obtuse; upper glumes 2–2.2 mm long, 

11- to 13-veined, ovate, gibbous, membranous or coriaceous at 

maturity, margins involute (resembling auricles), apex obtuse; 

sterile lemmas 2–2.5 mm long, ovate, membranous or coriaceous 

at maturity, thicker on margins, sulcate, apex obtuse, paleas 1⁄4

the length of the lemma, hyaline; fertile lemmas 2–2.5 mm long, 

indurate, transversely rugose, margins involute, apex acute; palea 

indurate, rugose; anthers 0.8–1 mm long, purple. 2n = 18.

Distribution and Habitat. Setariopsis auriculata occurs in moist, shady habitats and ranges from Arizona 

through Mexico and Central America to Colombia and Venezuela. 

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: southwestern Chihuahua, Aug 1885, E. Palmer 78 (US).

346. Setariopsis latiglumis (Vasey) Scribn., Publ. Field Colombian Mus. Bot. Ser. 1(3): 289–290, t. 11. 1896. Setaria latiglumis Vasey, Bull. Torrey Bot. Club 13(12): 229. 1886.

Caespitose annual. Culms (40)70–100 cm tall, erect;

nodes papillous-hispid. Sheaths hispid, with papillose-based 

hairs; ligules 2–2.5 mm long, a fringe of hairs; blades 10–30 

cm long, 5–9 mm wide, scaberulous and sparsely hairy, margins scabrous. Panicles 4–20 cm long, 1–2 cm wide, spiciform, 

linear or lanceolate, truncate or rounded at the ends, or tapering above; branches with spikelets congested, short pedicellate, 

subtended by a terete bristle, the bristles 7–10 mm long, persistent, antrorsely scaberulous. Spikelets 3–3.5 mm long, oblong 

or ovate, gibbous, falling entire; glumes unequal, oblate, gibbous, exceeding or reaching apex of florets, thinner than fertile 

lemmas; lower glumes 1–1.3 mm long, 2-veined, upper glumes 

3–3.2 mm long, 17- to 19-veined, herbaceous or indurate, 

firmer above, apex entire to erose, obtuse to cuspidate; sterile 

lemmas 3–3.5 mm long, 9-veined, membranous or coriaceous 

at maturity, firmer above, emarginate, paleas 1⁄5 as long as the 

sterile lemma, pilose; fertile lemmas 2–3 mm long, 5-veined, 

finely rugulose to tuberculate over the surface, indurate, pallid, 

lightly keeled, margins involute, apex cuspidate; paleas almost 

as long as lemma, indurate, thinner on margins, surface tuberculate; anthers 3, 0.5–0.7 mm long. Caryopsis ovoid, with adherent pericarp. 2n = 18. 

Distribution and Habitat. Setariopsis latiglumis grows in tropical forests and thorny scrub. This species is endemic to Mexico, occurring in Chiapas, Chihuahua, 
334 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Guanajuato, Guerrero, México, Michoacán, Morelos, Nayarit, 

and Puebla (Dávila et al., 2006).

Specimens Examined. MEXICO. Chihuahua. Chihuahua: km 20 Cd. Cuauhtémoc de Cd. Chihuahua, Aug 1885, E. 

Palmer 117A (US). Ocampo: Ca 1 km W of W boundary of Parque 

Nacional “Cascada de Basaseachic,” 18 km from the Cahuisori–

Ocampo road on the road to Candamena, 7.5 km below Cruz, 

24 Sep 1994, 1260 m, Spellenberg, Corral & Estrada 12187-A

(NMC). Uruachi: Rio Mayo between Moris and San Bernardo. 25 

Sep 1991, grassland, 580 m, P. Jenkins 91-78 (ARIZ).

Sorghastrum Nash

Annual or perennial; caespitose, sometimes rhizomatous. 

Culms erect, nodding or clambering, unbranched; nodes densely 

pubescent, particularly in young plants. Leaves not aromatic; 

ligules membranous, glabrous or pubescent; blades flat, involute, 

or folded. Inflorescence a terminal, secund or equilateral panicle 

with evident rachises and numerous branches, not subtended 

by modified leaves; branches capillary, rebranching, with many 

rames; disarticulation in the rames, beneath the sessile spikelets. 

Spikelets sessile, subtending a hairy pedicel (2 pedicels in the terminal spikelet units), dorsally compressed; callus blunt or sharp; 

glumes coriaceous; lower glumes pubescent, 5- to 9-veined, 

acute; upper glumes slightly longer, usually glabrous, 5-veined, 

truncate; lower florets reduced to a hyaline lemma; upper florets 

bisexual, lemmas hyaline, bifid, awned from the sinuses; awns 

usually once- or twice-geniculate, often spirally twisted, shortly 

strigose, brownish; anthers 3; ovaries glabrous. Caryopsis flattened; pedicels slender, not fused to the rame axes; pedicellate 

spikelets absent. x = 10. 

Sorghastrum includes about 21 species.

KEY TO SPECIES OF SORGHASTRUM

1. Panicles with only a few branches near the apex of the inflorescence, the branches flexuous and elongate, the spikelets 

inserted at the end of the branches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. nudipes

1. Panicles with numerous branches near the apex, these appearing dense and crowded, the spikelets numerous along the 

branches, the branches usually rebranched . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. nutans

347. Sorghastrum nudipes Nash, N. Amer. Fl. 17(2): 129. 1912.

Caespitose perennial with elongated rhizomes; basal innovations extravaginal. Culms 55–120 cm tall, 1–2.5 mm thick, erect, 

glabrous. Sheaths smooth, glabrous; ligules 15–25 mm long, 

eciliate membrane; blades 10–30 cm long, 2–5 mm wide, flat, 

smooth, glabrous or pubescent, margins scabrous, apex acute. 

Panicles 8–22 cm long, open, lax, with only a few branches near 

the apex, the branches flexuous and long, the spikelets inserted 

at the end of the branches; rachis internodes filiform. Spikelets 

5.5–7.5(9) mm long, lanceolate, hirsute, falling entire; bisexual 

spikelets with 1 basal sterile floret and 1 fertile; glumes equal, 

firmer than fertile lemma, as long as spikelet, oblong, chartaceous or coriaceous; lower glumes 7- to 9-veined, pubescent, 

apex truncate; upper glumes 5-veined, glabrous or pubescent, 

hairy below, apex acute; sterile lemmas 5–6.5 mm long, oblong, 

hyaline, 2-veined, ciliate on margins, apex 2-lobed, palea minute; fertile lemmas 3.5–5.3 mm long, oblong, hyaline, 3-veined, 

ciliolate on margins, apex 2-lobed, awned, the awn 12–18 mm 

long, straight or geniculate, with twisted column, column hirsute, palea absent or minute; anthers 3–4 mm long. Caryopsis 

2–3 mm long.

Distribution and Habitat. Sorghastrum nudipes is native to Mexico and is known from Chihuahua and Durango (Herrera Arrieta, 2014).

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: SW Chihuahua, Aug 1885, E. Palmer 11 (US). Guachohi: 2 km al NE de Norogachic (Tucheachi), 24 Sep 1985, 

bosque de pino–encino [pine–oak forest], 2100 m, Dávila, 

Tenorio & I. Solis 132 (CIIDIR); 16 km al E de la desviación 

[deviation] a la Bufa, en el camino [road] Guachochi–Creel, 25 

Sep 1985, P. Dávila 142 (ARIZ). Madera: Laguna de Babicora, 

Arroyo Las Varas, 10 Sep 1994, 2300 m, G. Quintana & E. Estrada 3565 (NMC). Ocampo: Parque Nacional “Cascada de 

Basaseachic,” at overlook ca. 1 km airline S of Cascada, 3 Oct 

1986, 2100 m, Spellenberg, Soreng, R. Corral & T. Lebgue 

8693 (NMC).

348. Sorghastrum nutans (L.) Nash, Fl. S.E. U.S. 66, 1326. 

1903. Andropogon nutans L., Sp. Pl. 2: 1045. 1753.

FIGURE 223

Perennial; with elongated, stout, and scaly rhizomes. Culms 

50–230 cm tall, 1.5–4.5 mm thick below, erect, glabrous. 

Sheaths glabrous or sparsely hispid; ligules 2–5 mm long, eciliate 

membrane, auricles thick and pointed; blades 10–50 cm long, 

1–4 mm wide, glabrous or pubescent, margins scabrous, apex 

attenuate. Panicles 10–35 cm long, open to loosely contracted, 

oblong, dense, yellowish to brownish, with numerous branches 

near the apex, these appearing dense and crowded, the spikelets 

numerous along the branches, the branches usually rebranched; 

rachis terete. Spikelets 5–8.7 mm long, lanceolate, falling entire; bisexual spikelets bearing 1 basal sterile floret and 1 fertile, 

callus bearded; glumes equal, 5–8 mm long, firmer than fertile 

lemma, as long as spikelet, oblong, coriaceous, light brown; 

lower glumes 7- to 9-veined, pubescent, apex truncate; upper 

glumes 5-veined, glabrous, apex acute; sterile lemmas 4–6 mm 
NUMBER 107 • 335

long, oblong, hyaline, 2-veined, ciliate on margins, apex 2-lobed, 

palea minute; fertile lemmas 3.5–5.5 mm long, oblong, hyaline, 

3-veined, ciliolate on margins, apex 2-lobed, awned, the awns 

10–22 mm long, geniculate, with twisted column, column hirsute, palea absent or minute; anthers 3–5 mm long. Caryopsis 

2.3 mm long. 2n = 20, 40, 80.

Distribution and Habitat. Sorghastrum nutans grows in a wide range of habitats, from prairies to woodlands, savannahs, and scrubland vegetation. It is native in 

North America from Canada to Mexico, and South America 

in Brazil.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: La Campana, 24 Sep 76, Jardines de observación 

[observation gardens], 1500 m, S. González 767 (RELC). Guachochi: Entering Barranca El Cobre, 28.3 km S of Cusarare on 

road to Guachochi, 25 Sep 1988, pine forest, 1900 m, P.M. Peterson & Annable 5903 (ENCB, US); 1–2 km S of Río Osichi 

Canyon and Río Basihuare jct, 1 Sep 2003, bosque [forest] de 

Quercus–Pinus, 1600 m, P.M. Peterson & P. Catalán 17630

(CIIDIR, US). Madera: 25 km al NW de Las Varas, 28 Oct 

1976, bosque de pino encino [pine–oak forest], 2100 m, J.M. 

Peña JMP-809 (RELC). Ocampo: Parque Nacional “Cascada de 

Basaseachic,” on ridge top SE side of canyon of Rio Basaseachic 

leading to falls, 4 Oct 1986, 1800 m, Spellenberg, Soreng, R. 

Corral & T. Lebgue 8731 (NMC); 122.5 km W of La Junta on 

road to Parque Nacional Cascada de Basaseachic and 56.7 km 

W of Tomochic, 1 Oct 1989, 2100 m, P.M. Peterson & R.M. 

King 8229 (US).

Sorghum Moench

Annual or perennial. Culms internodes solid. Leaves not 

aromatic, basal and cauline; auricles absent; ligules membranous and ciliate or of hairs; blades usually flat. Inflorescence 

a terminal, panicle with evident rachises; primary branches 

whorled, compound, the ultimate units rames; rames with most 

spikelets in heterogamous sessile-pedicellate spikelet pairs, terminal spikelet unit on each rame usually a triplet of 1 sessile 

and 2 pedicellate spikelets, rame axes without a translucent median line; disarticulation in the rames below the sessile spikelets, 

sometimes also below the pedicellate spikelets (cultivated taxa 

not or only tardily disarticulating); pedicels slender, neither appressed nor fused to the rame axes. Sessile spikelets dorsally 

compressed, calluses blunt or pointed; lower glumes dorsally 

compressed and rounded basally, 2-keeled or winged distally, 

5- to 15-veined, usually unawned; upper glumes 2-keeled, sometimes awned; lower florets reduced to hyaline lemmas; upper 

florets pistillate or bisexual, lemmas hyaline, sometimes awned. 

Pedicellate spikelets staminate or sterile, well-developed, often 

subequal to the sessile spikelets in size. x = 10. 

Most of the approximately 32 species of Sorghum are native 

to tropical and subtropical regions of the Eastern Hemisphere 

(Liu et al., 2014).

FIGURE 223. Sorghastrum nutans. A. Habit. B. Inflorescence. 

C. Sessile spikelet. Drawn by Linda Ann Vorobik and Annaliese 

Miller; copyright Utah State University.
336 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

KEY TO SPECIES OF SORGHUM

1. Perennials with rhizomes; spikelets disarticulating at maturity; caryopsis not exposed at maturity . . . . . . . . . S. halepense

1. Plants usually annual, sometimes short-lived perennial; spikelets either not disarticulating or doing so tardily; caryopsis 

often longer than glumes and exposed at maturity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. bicolor

349. Sorghum bicolor* (L.) Moench, Methodus 207. 1794.

FIGURE 224

Annual or short-lived perennial; often tillering, without rhizomes. Culms 50–500+ cm tall, 1–5 cm thick, sometimes branching above the base; nodes glabrous or appressed-pubescent; 

internodes glabrous. Ligules 1–4 mm long; blades 5–100 cm 

long, 5–100 mm wide, sometimes glabrous. Panicles 5–60 cm 

long, 3–30 cm wide, open or contracted, primary branches compound, terminating in rames with 2–7 spikelet pairs; disarticulation usually not occurring or tardy. Sessile spikelets 3–9 mm 

long, lanceolate to ovate, bisexual; calluses blunt; glumes coriaceous to membranous, glabrous, densely hirsute, or pubescent, 

keels usually winged; upper lemmas unawned or with a geniculate, twisted awn, the awn 5–30 mm long; anthers 2–2.8 mm 

long. Pedicellate spikelets 3–6 mm long, usually shorter than the 

sessile spikelets, staminate or sterile; pedicels 1–2.6 mm long. 

Caryopsis usually exposed at maturity. 2n = 20, 40.

Distribution and Habitat. Sorghum bicolor

was domesticated in Africa 3,000 years ago, reaching northwestern India before 2500 BCE (Before the Common Era), and 

became an important crop in China after the Mongolian conquest. It was introduced to the Western Hemisphere in the early 

sixteenth century and is now an important crop in the United 

States and Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Práxedis G. Guerrero: Rancho Escuela, km 65 carr. [hwy] 

Juárez–Porvenir, 16 Aug 1997, cultivo de sorgo [cultivated Sorghum], 1400 m, I. Enríquez, S. Ordoñez, L. Sushii, A. Perales & 

N. Loyola IEA12 (UACJ).

350. Sorghum halepense* (L.) Pers., Syn. Pl. 1: 101. 1805. Holcus halepensis L., Sp. Pl. 2: 1047–1048. 1753.

FIGURE 225

Perennial; rhizomatous. Culms 50–200 cm tall, 0.4–2 cm 

thick; nodes appressed-pubescent; internodes glabrous. Ligules 

2–6 mm long, membranous, conspicuously ciliate; blades 10–90 

cm long, 8–40 mm wide. Panicles 10–50 cm long, 5–25 cm wide, 

primary branches compound, terminating in rames of 1–5 spikelet pairs; disarticulation usually beneath the sessile spikelets, 

sometimes also beneath the pedicellate spikelets. Sessile spikelets 3.8–6.5 mm long, 1.5–2.3 mm wide, bisexual; calluses blunt; 

glumes indurate, shiny, appressed-pubescent; upper lemmas unawned, or with a geniculate, twisted awn, the awn to 13 mm 

long; anthers 1.9–2.7 mm long. Pedicellate spikelets 3.6–5.6 mm 

long; glumes membranous to coriaceous, unawned, staminate; 

pedicels 1.8–2.7 mm long. Caryopsis not exposed at maturity. 2n

= 20, 40, and several dysploid counts also reported.

Distribution and Habitat. Sorghum halepense

is native to the Mediterranean region. It is sometimes grown for 

forage in North America, but it is considered a serious weed in 

warmer parts. It hybridizes readily with S. bicolor and derivatives of such hybrids are widespread.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: aprox. 7 km al N del poblado [village] de Samalayuca, a los lados [sides] de la carr. [hwy], 30 Jul 1994, 1200 m, 

R. Corral, E. Pérez, A. Domínguez & F. Félix RCD5286 (UACJ). 

Ascensión: a los lados de la carr. Juárez–Janos, en los alrededores 

[around] de la Falla del Camello, area de transición del desierto 

[desert transition area] “Cabeza de Vaca”, 11 Jun 2005, 1180 m, 

R. Corral, M. Vargas & H. Gutiérrez RCD7169 (UACJ). Chihuahua: La Campana, 24 Sep 76, Jardines de observación [observation gardens], 1500 m, S. González 268, 768, 770 (RELC). 

Galeana: Cerro Angostura Spring, 2.4 mi by Mexico hwy 10, N 

of Angostura, 3.7 mi E of hwy, Rio Santa Maria Valley at N tip 

of Cerro Angostura, 8 Oct 1982, 2200 m, F.W. Reichenbacher 

1308 (ARIZ). Juárez: a orillas [edges] de la Carr. No 2 Juárez–

Janos, km 128, 11 Aug 1996, P. Olivas, R. Rivas & I. Enríquez 

POS815 (UACJ); Ciudad Juárez a lo largo [along] de la “Asequia Madre” al N del fracc. Rincones de San Marcos, 13 Oct 

1995, 1140 m, R. Corral, P. Olivas & L.M. Barraza RCD6548

(UACJ); Parque “El Chamizal”, 7 Sep 1995, maleza de prados 

& canales de riego [grass meadow and irrigation canals], 1120 

m, R. Corral RCD6297 (UACJ); Ciudad Juárez a lo largo de la 

“Asequia Madre” desde la intersección de las calles [from the 

intersection of streets] Mejía & Santos Degollado, hasta el túnel 

bajo [until tunnel under] el Viaducto Díaz Ordaz, 3 Jun 1995, 

1140 m, R. Corral & L.M. Barraza RCD6118 (UACJ); Ciudad 

Juárez, a lo largo de la “Asequia Madre” entre [between] la Av. 

Américas & Paseo Triunfo de la República, 29 Sep 1995, 1140 

m, R. Corral, P. Olivas & L.M. Barraza RCD6426 (UACJ). Jiménez: El Hugo, Torreoncitos, 13 Aug 2010, terrenos de cultivo 

[farmland], 1355 m, D. Ramírez & M.L. Juárez 3383 (CIIDIR). 

Práxedis G. Guerrero: Rancho Escuela, km 65 carr. Juárez–Porvenir, 13 Oct 1997, pastizal [pastureland], 1300 m, I. Enríquez, 

S. Ordoñez & J. Leyva IEA13 (UACJ).

Sphenopholis Scribn.

Plants usually perennial, rarely winter annual; usually 

caespitose. Culms sometimes solitary, leaves evenly distributed. 

Sheaths open; auricles absent; ligules membranous, erose; blades 

flat or involute, glabrous or pubescent. Inflorescence a panicle, 
NUMBER 107 • 337

FIGURE 224. Sorghum bicolor. A. Habit. B. Spikelet pair. Drawn 

by Linda Ann Vorobik and Hana Pazdírková; copyright Utah State 

University.

FIGURE 225. Sorghum halpense. A. Habit. B. Spikelet pair. Drawn 

by Linda Ann Vorobik and Hana Pazdírková; copyright Utah State 

University.
338 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

open or contracted, nodding to erect; disarticulation below the 

glumes, the distal floret sometimes disarticulating first. Spikelets pedicellate laterally compressed, with 2–3 florets; rachillas 

glabrous or pubescent, prolonged beyond the base of the distal 

floret as a slender bristle; glumes almost equaling the lowest floret, dissimilar in width, membranous to subcoriaceous, margins 

scarious, apex unawned; lower glumes narrower than the upper 

glumes, 1(3)-veined, strongly keeled, apex acute; upper glumes 

elliptical to oblanceolate, obovate, or subcucullate, 3(5)-veined, 

strongly to slightly keeled, apex acuminate, acute, rounded, or 

truncate; calluses glabrous; lemmas herbaceous, not indurate, 

rounded on the lower back, smooth or partly or wholly scabrous, 

usually keeled near the apex, 3(5)-veined, veins usually not visible, unawned or awned from just below the apex, awns straight 

or geniculate; paleas hyaline, shorter than the lemmas; lodicules 

2, free, membranous, glabrous, toothed or entire; anthers 3; ovaries glabrous. Caryopsis shorter than the lemmas, concealed at 

maturity, linear-ellipsoid, glabrous; endosperm liquid. x = 7.

Sphenopholis includes five species and is most diverse in 

the southeastern United States (Finot et al., 2004). One species, 

Sphenopholis obtusata, extends outside the United States to 

southern Mexico and the Caribbean.

351. Sphenopholis obtusata (Michx.) Scribn., Rhodora 8(92): 

144. 1906. Aira obtusata Michx. Fl. Bor.-Amer. 1: 62. 1803.

FIGURE 226

Culms (9)20–130 cm tall. Sheaths glabrous or hairy, sometimes scaberulous; ligules (1)1.5–2.5 mm long, erose-ciliate, 

more or less lacerate; blades 5–14 cm long, (1)2–8 mm wide, usually flat, rarely slightly involute, scabrous or pubescent. Panicles 

(2)5–15(25) cm long, 0.5–2 cm wide, usually erect, often spikelike, spikelets usually densely arranged. Spikelets 2.2–3.6 mm 

long; lower glumes less than 1⁄3 as wide as the upper glumes; 

upper glumes 1.5–2.5 mm long, subcucullate, width:length ratio 

0.3–0.5, apex rounded to truncate; lowest lemmas 1.9–2.8 mm 

long, usually scaberulous distally; distal lemmas usually smooth 

on the sides, occasionally scabrous, unawned; anthers 0.2–1 mm 

long. 2n = 14.

Distribution and Habitat. Sphenopholis 

obtusata grows in prairies, marshes, dunes, forests, and waste 

places up to 2,500 m. Its range extends from British Columbia to 

New Brunswick, through most of the United States to southern 

Mexico and the Caribbean (Finot et al., 2004). This species has 

been reported from Chihuahua (Espejo Serna et al., 2000).

FIGURE 226. Sphenopholis obtusata. A. habit. B. Glumes. C. Lower floret. 

D. Upper floret. Drawn by Linda Ann Vorobik and Hana Pazdírková; copyright Utah State University.
NUMBER 107 • 339

Sporobolus R. Br.

Annual or perennial; sometimes rhizomatous, rarely stoloniferous. Culms 10–250 cm tall, erect, rarely mat-forming, caespitose (often forming large clumps), glabrous. Sheaths longer or 

shorter than the internodes usually with smooth margins, occasionally ciliate; ligule ciliate, a line of hairs; blades 3–70 cm long, 

1–15 mm wide at base, filiform or linear, flat, involute, or terete, 

not pungent, cauline without auricles. Inflorescence 0.5–80 cm 

long, 0.3–30 cm wide, a panicle or spikes (multiple branches) 

that bear 2 rows on 2 sides of a somehat flattened, triangular 

rachis (that superficially appears to be 1-sided or pectinate); 

exserted or partially included in upper sheath; rachis smooth; 

primary branches appressed, spreading, divaricate, or reflexed 

from the main axis, solitary or loosely whorled, sometimes with 

capillary branches terminating in a spikelet; secondary branches 

appressed or spreading; pedicels erect, rarely secund, glabrous, 

scaberulous or scabrous; cleistogamous spikelets occassionally 

present, in axillary inflorescences. Spikelets 1–4(7) mm long, solitary, laterally or dorsally compressed, sometimes terete; disarticulation usually above the glumes, commonly above the upper 

glume, occasionally below with the lemma and palea falling as 

a unit; glumes shorter or longer than the florets, very unequal, 

smooth, glabrous; lower glume without midvien or 1-veined; 

upper glume about the same length as the lemma, usually awnless, 1-veined; florets 1 per spikelet; lemma entire, awnless, glabrous or hairy, pubescent to pilose, 1-veined, rarely 3-veined, 

membranous with glabrous veins; palea glabrous, smooth, membranous, margins not enfolding the fruit, 2-veined, often splitting as grain matures; lodicules 2 or sometimes absent, truncate; 

stamens 2 or 3; anthers yellow, reddish-purple, or olivaceousplumbeous; stigmas 2. Modified caryopsis a follicoid fruit with 

a free pericarp, commonly swelling and mucilaginous when wet; 

hilum punctiform; embryo with an epiblast, scutellar tail, and 

elongated mesocotyl internode, endosperm hard. x = 9, 10.

Sporobolus is a cosmopolitan genus of nearly 200 species 

that grow in tropical, subtropical, and warm-temperate regions 

throughout the world (Peterson et al., 2003, 2004, 2014b). 

Eleven species are present in Chihuahua. The genus as currently 

circumscribed includes all species formerly placed in Spartina

Schreb., Crypsis Aiton, and Calamovilfa (A. Gray) Hack. ex 

Scribn. & Southw. (Peterson et al., 2014b).

KEY TO SPECIES OF SPOROBOLUS

1. Inforescence composed of 3–25 spikes, each spike 5–15 cm long bearing sessile spikelets on 2 rows on 2 sides of a somehat 

flattened, triangular rachis (that superficially appears to be 1-sided or pectinate) . . . . . . . . . . . . . . . . . . . . S. alterniflorus

1. Inflorescence a true panicle with branches that rebranch and the spikelets pedicellate.

2. Annuals; culms 10–40 cm tall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. pyramidatus

2. Perennials; culms 30–250 cm tall.

3. Sheaths and collar with a conspicuous tuft of white hairs.

4. Panicles contracted, spikelike; branches appressed.

5. Culms 35–100(120) cm tall, 2–4 mm diameter near the base . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. contractus

5. Culms 100–200 cm tall, (3)4–10 mm diameter near the base . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. giganteus

4. Panicles open, branches spreading at least from the middle of the rachis to the apex, the base sometimes included.

6. Panicles usually exserted, branches divaricate and flexuous, usually tangled with each other; lower glumes 

0.9–1.5 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. flexuosus

6. Panicles usually included at the base, branches erect, not markedly flexuous and not tangled; lower glumes 

0.6–1.1 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. cryptandrus

3. Sheaths and collar glabrous.

7. Panicles 0.3–3 cm wide, spikelike, the branches appressed to the main axis.

8. Panicles 9–15(20) cm long, 3–5(10) mm wide, whitish; culms tufted; glumes unequal, more than 2⁄3 as long as 

the floret . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. spiciformis

8. Panicles 20–35(50) cm long, 3–22(3) mm wide, stramineous; culms weakly tufted; glumes about equal, less than 

2⁄3 as long as the floret . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. indicus

7. Panicles 3–25 cm wide (sometimes only 0.3 cm wide in immature S. pyramidatus), open, the branches widely 

spreading at least from the middle of the rachis to the apex.

9. Panicle branches capillary, the proximal ones solitary; pedicels capillary, 2.5–3(4) mm long, flexuous; upper 

glumes 0.7–1 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. trichodes

9. Panicle branches not capillary, the proximal ones whorled; pedicels not capillary, 0.3–3 mm long, spreading or 

appressed; upper glumes (0.8)1.4–2.5 mm long. 

10. Panicle branches widely divaricate and flexuous, usually tangled with each other . . . . . . . . . S. flexuosus

10. Panicle branches widely open or erect, not tangled.

11. Culms 10–40 cm tall, delicate perennials, plants small; leaf blades borne near the base; sheaths glabrous or with few ciliate hairs on the margins and summit . . . . . . . . . . . . . . . . . . . . S. pyramidatus
340 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

11. Culms 30–100(120) cm tall, robust perennials, often forming large tough leafy tussocks; leaf blades 

cauline; sheaths usually bearded with long hairs on the margins and summit.

12. Panicles 10–45 cm long, the branches naked near the base; pedicels 0.5–2 mm long, usually erect, 

spreading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. airoides

12. Panicles 20–60 cm long, the branches densely flowered near the base; pedicels 0.2–0.5 mm long, 

appressed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. wrightii

352. Sporobolus airoides (Torr.) Torr. subsp. airoides, Pacific 

Railr. Rep. Parke, Bot. 7: 21. 1856.

FIGURE 227

Densely caespitose perennial. Culms 35–120 (150) cm tall, 

erect, stout, glabrous below the nodes; base diameter 1–2(3.5) 

mm wide, rounded; internodes glabrous. Sheaths 2⁄3 to about as 

long as the internodes above, glabrous, shinny, sometimes with 

a few long hairs near the summit, these hairs up to 6 mm long; 

ligules 0.1–0.3 mm; blades (3)10–45(60) cm long, (1)2–5(6) mm 

wide, flat to involute, glabrous below and scaberulous to scabrous above; margins mostly smooth to scaberulous. Panicles 

(10)15–45 cm long, 15–25 cm wide, open, diffuse, subpyramidal, often included in the uppermost sheath; branches 1.5–13 

cm long, ascending to widely spreading 30°–90° from culm 

axis; secondary branches mostly spreading and not floriferous 

on lower 1⁄4 to 1⁄3; pulvini in axils of primary branches glabrous; 

pedicels 0.5–2 mm long, spreading, glabrous to scabrous. Spikelets 1.3–2.8 mm long, spreading, purplish or greenish; glumes 

0.5–2.4(2.8) mm long, lanceolate to ovate, membranous, unequal; lower glume 0.5–1.8 mm long, often appearing without 

a midvein, the apex acute; upper glume 1.1–2.4(2.8) mm long, 

apex acute to obtuse; lemmas 1.2–2.5 mm long, ovate, membranous, glabrous, the apex acute; paleas 1.1–2.4 mm long, ovate, 

membranous, glabrous, the apex acute to obtuse; stamens 3; anthers 1.1–1.8 mm long, yellowish to purplish. Modified caryopses 1–1.4 mm long, ellipsoid, reddish-brown, striate. 2n = 80, 

90, 108, 126.

Distribution and Habitat. Sporobolus airoides occurs throughout the arid portions of northwestern North 

America and in Mexico south to Puebla. It is common in dry to 

sandy gravelly flats or slopes usually associated with alkaline soils, 

occurring with Atriplex canescens, Larrea tridentata, and Distichlis spicata. In northern Mexico, S. airoides is a halophytic species 

forming the alkali zacaton grasslands where the edaphic effects of 

a diverse combination of chloride carbonates and sulfates accumulates to form very saline conditions. Sporobolus airoides subsp. 

regis (I. M. Johnst.) Wipff & S.D.Jones, known only from Coahuila, differs from the typical subspecies in having elongate rhizomes, pilose sheaths on the lower surface, and panicle branches 

with a tuft of hairs in the lower axils (Peterson et al., 2004).

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: Villa Ahumada, 10–20 Oct 1935, LeSueur Mex-071

(US); 64 mi SW of Cd. Juarez, N of Guzman near , 14 Sep 1974, 

J. Henrickson 14100 (US); 10 mi S of Villa Ahumada along Hwy 

45 between Ciudad Juárez and Chihuahua, 1 Aug 1975, matorral [scrub], 1220 m, G. & L. Davidse 9255 (MEXU). Ascensión: 

13 km E of Guzman on winding road to Laguna de Santa María, 

22 Aug 1972, 1130 m, F. Chiang, T. Wendt & M.C. Johnston 

8800 (MEXU). Chihuahua: Rancho Experimental La Campana, 

en el km 83 de la carr. [hwy] PanAmer. en el tramo [section] 

Chih.–Juárez, 23 Jul 1988, pastizal [pastureland], G. Jiménez s/n

(MEXU); Camino el Sauz–Nueva Delicias, 29 Jul 76, maleza en 

cultivo de pepino & maíz [weeds in cultivated cucumbers and 

corn], 1550 m, M.S. González 301 (RELC). Galeana: 145 km 

de Galeana, 8 Aug 1979, pastizal, 1370 m, M. Siqueiros 290, 

294 (MEXU). Guerrero: Santo Tomas on railroad NW of San 

FIGURE 227. Sporobolus airoides subsp. airoides. A. Habit. B. Spikelet. Drawn by Hana Pazdírková; copyright Utah State University.
NUMBER 107 • 341

Isidro, Sierra Madre Occidental, 18 Sep 1934, grassed prairie, 

1950–1960 m, Pennel 18994 (MEXU). Ignacio Zaragoza: 1 km 

al N of Sta María de Guadalupe on right bank of Río Casas 

Grandes; 18 Aug 1972, 1250 m, F. Chiang, T. Wendt & M.C. 

Johnston 8687 (MEXU). Janos: Mexican boundary line near 

White Water, 11 Sep 1893, E.A. Mearns 2303 (US); 7 km NE 

of the town of Janos, below the archeological basaltic hillsite of 

Juanaquena, 4 Sep 1998, K.R. Adams s.n. (ARIZ). Jiménez: 2 

km NW of hacienda el berrendo on las pampas ranch, 25 Aug 

1972, mezquital, 1450 m, F. Chiang, T. Wendt & M.C. Johnston 

8857, 8858 (MEXU). Juárez: Between Cd. Juárez and Cd. chihuahua on hwy 45, 28 mi from U.S. border, 7 Aug 1984, matorral, D. Randolph 160 (MEXU); 4.1 (rd.) mi N of Samalayuca 

along hwy 45, 13 Sep 1972, Vegetación de dunas [dune vegetation], 4700ft, J. Henrickson 7451 (MEXU). Julimes: Ca. 5 km 

SE of Sierra del Roque, ca. 20 km by winding road N of Julimes, 

19 Jun 1973, deteriorated grassland, 1300 m, M.C. Johnston, 

T.L. Wendt & F. Chiang 11377 (MEXU). Meoqui: Meoqui, 24 

Aug 1935, LeSueur Mex-034 (US).

353. Sporobolus alterniflorus (Loisel.) P. M. Peterson & Saarela. 

Taxon 63(6): 1236. 2014. Spartina alterniflora Loisel., Fl. 

Gall. 719. 1807.

FIGURE 228

Plants perennial rhizomatous; rhizomes elongate, flaccid, 

white, scales inflated, not or only slightly imbricate. Culms to 

250 cm tall, (0.3)5–15(20) mm thick, erect, solitary or in small 

clumps, succulent, glabrous, having an unpleasant, sulphurous 

odor when fresh. Sheaths mostly glabrous, throat glabrous or 

minutely pilose, lower sheaths often wrinkled; ligules 1–2 mm; 

blades to 60 cm long, 3–25 mm wide, lower blades shorter than 

those above, usually flat basally, becoming involute distally, abaxial surfaces glabrous, adaxial surfaces glabrous or sparsely pilose, margins usually smooth, sometimes slightly scabrous, apex 

attenuate. Panicles 10–40 cm long, with 3–25 spikelike branches, 

often partially enclosed in the uppermost sheath; spikes 5–15 cm 

long, loosely appressed, not twisted, more or less equally subremote to moderately imbricate throughout the panicle, axes often 

prolonged beyond the distal spikelets, with 10–30 sessile spikelets. Spikelets 8–14 mm long, straight, usually divergent, more or 

less equally imbricate on all the branches; glumes straight, sides 

usually glabrous, sometimes pilose near the base or appressedpubescent, hairs to 0.3 mm long; lower glumes 4–10 mm long, 

acute; upper glumes 8–14 mm long, keels glabrous, lateral veins 

not present, apex acuminate to obtuse, occasionally apiculate; 

lemmas glabrous or sparsely pilose, apex usually acuminate; paleas slightly exceeding the lemmas, thin, papery, apex obtuse or 

rounded; anthers 3–6 mm long. 2n = 62 

Distribution and Habitat. Sporobolus alterniflorus is found on muddy banks, usually along margins of saline lakes or marshes, more commonly along the coast in eastern 

North and South America (Mobberley, 1956). This species has 

been cited for Chihuhua in Espejo Serna et al. (2000).

FIGURE 228. Sporobolus alterniflorus. A. Habit. B. Inflorescence. 

C. Spikelet. Drawn by Linda Ann Vorobik and Linda Bea Miller; 

copyright Utah State University.
342 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

354. Sporobolus contractus Hitchc., Amer. J. Bot. 2: 303. 1915.

FIGURE 229

Caespitose perennial. Culms 35–100(120) cm tall, erect, glabrous below the nodes, rounded near base, internodes glabrous; 

base diameter 2–4(5) mm long. Sheaths 3⁄4 to longer than the internodes above, glabrous; margins with ciliate hairs especially 

on the upper portions, these hairs up to 3 mm long forming a 

conspicuous tuft near the summit; ligules 0.4–1 mm long; blades 

(2)4–35 cm long, 3–8 mm wide, flat to involute, glabrous below 

and above; margins whitish, somewhat scaberulous. Panicles 

(10)15–45(50) cm long, 0.2–0.8(1) cm wide, narrow, tightly contracted, dense and spikelike, usually included in the uppermost 

sheath; primary branches 0.3–1.5 cm long, appressed; secondary 

branches appressed and floriferous to base; pulvini in axils of 

primary branches glabrous; pedicels 0.2–2 mm long, appressed, 

scaberulous. Spikelets 1.7–3.2 mm long, whitish to plumbeous; 

glumes 0.7–3.2 mm long, narrow lanceolate, membranous, unequal, prominently keeled, scaberulous along the keel; lower 

glumes 0.7–1.7 mm long, rarely without a midvein, the apex 

acute to acuminate; upper glumes 2–3.2 mm long, the apex acute; 

lemmas 2–3.2 mm long, linear membranous, glabrous, the apex 

acute; paleas 1.8–3 mm long, linear-lanceolate, membranous, glabrous, the apex acute; stamens 3; anthers 0.3–0.5 mm long, light 

yellowish. Modified caryopses 0.8–1.2 mm long, ellipsoid, laterally flattened, light brownish or translucent. 2n = 36.

Distribution and Habitat. In Mexico, S. contractus ranges from Baja California, Chihuahua, and Sonora to 

Coahuila and Nuevo León on dry to moist sandy soils, occasionally in salt-desert scrub associated with Atriplex confertifolia, 

A. canescens, Artemisia tridentata Nutt. and in desert grasslands 

with pinyon–juniper woodlands at elevations of 300–2,300 m. 

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 2 mi N of Gallego, 16 Sep 1960, Reeder, C. Reeder 

& Soderstrom 3490 (ARIZ). Aldama: 50 km SW of Coyame of 

Mex 16 between Presidio, Texas and Chihuahua, 22 Sep 1988, 

1400 m, P.M. Peterson & Annable 5758 (US). Camargo: 20 km S 

of Cd. Camargo, 2 Aug 1939, L. H. Harvey 1397 (US). Chihuahua: Chihuahua, 10–20 Oct 1935, LeSueur Mex-013, Mex-058

(US); 1 km al E del Rancho el 45, 28 Sep 1973, pastizal [pastureland], 1450 m, Valdés-Reyna VR-365 (CIIDIR, ENCB, RELC); 

10 km de Chihuahua por carr. [hwy] Chihuahua–Delicias, 27 Jul 

1979, pastizal, 1370 m, M.E. Siqueiros 143 (MEXU). Guerrero: 

6 km N Ciudad Guerrero, 02 Dic 1999, pastizal natural, 2000 

m, López S. 17501 (MEXU). Jiménez: 50 km al S de Jiménez, 15 

Aug 2010, 1442 m, D. Ramírez & M.L. Juárez 3419 (CIIDIR). 

Juárez: carr. No. 2 Juárez–Janos, km 42, 11 Aug 1996, matorral 

de médanos [dune scrub], 1250 m, P. Olivas, R. Rivas & I. Enríquez POS803 (UACJ); 23 km al S del poblado [village] de Samalayuca, por la carr. PanAmer., 9 Sep 1995, 1250 m, R. Corral 

& P. Olivas RCD6347 (UACJ); aprox. 7 km al N del poblado de 

Samalayuca, a los lados [sides] de la carr., 30 Jul 1994, 1200 m, 

R. Corral, E. Pérez, A. Domínguez & F. Félix RCD5305 (UACJ); 

5 km N de Samalayuca, 24 Oct 74, zona de médanos [dune 

FIGURE 229. Sporobolus contractus. A. Inflorescence. B. Portion 

of culm showing sheath and blade. C. Spikelet. D. Lower glume. 

Drawn by Linda Ann Vorobik and Hana Pazdírková; copyright 

Utah State University.
NUMBER 107 • 343

zone], J. Valdés-Reyna VR-777, VR-778 (RELC); Medanos de 

Samalayuca, 13 Oct 1997, km 70, I. Enríquez, S. Ordoñez & 

J. Leyva IEA20 (UACJ); 10 km carr. Juárez–Casas Grandes, 

24 Oct 74, matorral, 1127 m, Valdés-Reyna VR-774 (RELC). 

Jiménez: Reserva de la Biosfera de Mapimí, Laguna Palomas, 

31 Oct 1998, matorral xerófilo [xerophilous scrub], 1055 m, 

A. García 3179 (CIIDIR); Costado del Rio Florido, Torreoncitos, 4 Aug 2010, 1330 m, D. Noya & M.L. Juárez 3401-b

(CIIDIR). Julimes: Balneario San Diego, 30 Jul 76, pastizal halófito [halophytic grassland], 1190 m, S. González & J.M. Peña 

359 (RELC).

355. Sporobolus cryptandrus (Torr.) A. Gray, Manual 576. 

1848.

FIGURE 230

Caespitose perennial. Culms 30–100(120) cm tall, erect to 

decumbent, base flattened to rounded, glabrous below the nodes, 

internodes glabrous; base diameter 1–3.5 mm wide. Sheaths 

2⁄3–3⁄4 as long as the internodes above, glabrous to scaberulous, 

sometimes ciliate along the upper margins, summit with a conspicuous tuft of white hairs up to 4 mm long; ligules 0.5–1 mm 

long; blades (2)5–26 cm long, 2–6 mm wide, flat to involute, 

mostly glabrous below and scaberulous above; margins scaberulous. Panicles 15–40 cm long, 2–12(14) cm wide, narrowly pyramidal, ultimately open, main axis ascending and straight, lower 

branches longest, usually included in the uppermost sheath; primary branches 0.6–6 cm long, appressed or ascending, spreading up to 130o from the culm axis; secondary branches mostly 

appressed not floriferous on lower 1⁄8–1⁄4; pulvini in axils of primary branches ascending, glabrous; pedicels 0.1–1.3 mm long, 

appressed, glabrous to scaberulous. Spikelets 1.5–2.5(2.7) mm 

long, brownish, plumbeous or purplish-tinged; glumes 0.6–

2.5(2.7) mm long, linear-lanceolate to ovate, membranous, unequal; lower glumes 0.6–1.1 mm long, rarely without a midvein, 

the apex acute to acuminate; upper glumes 1.5–2.7 mm long, the 

apex acute; lemmas 1.4–2.5(2.7) mm long, ovate to lanceolate, 

membranous, glabrous, the apex acute; paleas 1.2–2.4 mm long, 

lanceolate, membranous, glabrous, the apex acute; stamens 3; 

anthers 0.5–1 mm long, yellowish to purplish. Modified caryopses 0.7–1.1 mm long, ellipsoid, light brownish to reddish-orange. 

2n = 36, 38, 72.

Distribtion and Habitat. In Mexico, 

S. cryptandrus ranges from Baja California, Chihuahua, and Sonora to Coahuila, Nuevo León, and Tamaulipas. This species is 

found on sandy soils, rocky slopes, washes, calcareous ridges, 

and roadsides in salt-desert scrub with Atriplex spp. and Lycium, 

pinyon–juniper woodlands, yellow pine forests, and grasslands 

at elevations of 60–2,900 m. 

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: Camino a Presidio Texas, 2 km al E de carr. [hwy] 

Panamericana, 24 Oct 74, Valdés-Reyna VR-771 (RELC). Ascensión: Por la carr. a Palomas, justo al N del entronque [junction] 

con la carr. a casas Grandes, 11 Jun 2005, 1183 m, R. Corral, 

FIGURE 230. Sporobolus cryptandrus. A. Habit. B. Glumes. C. Floret. Drawn by Linda Ann Vorobik and Hana Pazdírková; copyright 

Utah State University.
344 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

M. Vargas & H. Gutiérrez RCD7129 (UACJ). Camargo: Rancho 

la Urraca, acceso [access] de Camargo hacia [toward] Ojinaga, 

desviar hacia [divert toward] Hércules por terracería [dirt road], 

aprox. 60 km tomar a la izquierda [take left] 30 km, 20 Oct 

2000, Matorral [scrub], G. Gómez 562 (MEXU). Chihuahua: 

near Chihuahua, 4 Oct 1885, C.G. Pringle 419 (US); camino 

[road] El Saúz–Nuevo Delicias, 27 Sep 76, maleza en cultivo de 

Pepino & maíz [weeds in cultivated cucumber and corn], 1550 

m, S. González & J.M. Peña 309 (RELC); Rancho La Gregoria, 

15 Oct 1981, matorral, 1400 m, E. Blanco 1710-A (MEXU). 

Delicias: Col. Vicente Guerrero, 26 Jul 1988, planicies pedregosas [private property], 2450 m, M. Carrasco 10 (MEXU). Jiménez: Near la Reserva de la Biosfera de Mapimí, 15 Sep 83, 

Dunas, Ruíz de Esparza 371 (RELC); 5 km al N de Samalayuca, 

24 Sep 74, zona de médanos [dune zone], 1270 m, Valdés-Reyna 

VR-777 (RELC); Costado del Rio Florido, Torreoncitos, 4 Aug 

2010, 1330 m, D. Noya & M.L. Juárez 3404 (CIIDIR).

356. Sporobolus flexuosus (Thurb. ex Vasey) Rydb., Bull. Torrey 

Bot. Club 32: 601. 1905.

FIGURE 231

Caespitose perennial; rarely appearing annual. Culms 30–

100(120) cm tall, erect to decumbent, base flattened to rounded, 

glabrous below the nodes and on internodes; base diameter 1–3 

mm wide. Sheaths 2⁄3–3⁄4 as long as the internodes above, glabrous to scaberulous, sometimes ciliate along the upper margins, 

summit with a tuft of hairs up to 4 mm long; ligules 0.5–1 mm 

long; blades (2)5–24 cm long, 2–4(6) mm wide, flat to involute, mostly glabrous below and scaberulous to scabrous above; 

margins scaberulous. Panicles 10–30 cm long, 4–12 cm wide, 

open, subovate to oblong, the main axis flexuous and drooping, lower branches no longer than those in the middle, usually with the base included in the uppermost sheath; primary 

branches 1–8(12) cm long, widely spreading to reflexed, flexuous and tangled, mostly spreading 70°–130° from the culm axis; 

secondary branches widely spreading not floriferous on lower 

1⁄8–1⁄2; pulvini in the axils of primary branches recurved, pubescent; pedicels 0.3–3 mm long, mostly spreading, scaberulous. 

Spikelets 1.8–2.5 mm long, plumbeous, the apex acute; glumes 

0.9–2.5 mm long, ovate, membranous, unequal; lower glumes 

0.9–1.5 mm; upper glumes 1.4–2.5 mm; lemmas 1.4–2.5 mm 

long, lanceolate to ovate, membranous, glabrous; paleas 1.4–2.4 

mm long, ovate, membranous, stamens 3; anthers 0.4–0.7 mm 

long, yellow. Modified caryopses 0.6–1 mm long, ellipsoid, light 

brownish to reddish-orange. 2n = 36, 38.

Distribution and Habitat. In Mexico, S. flexuosus occurs in Chihuahua, Coahuila, and Sonora on sandy to 

gravelly slopes, flats, and roadsides in desert scrub with Atriplex spp., Larrea tridentata, and Lycium, plains grasslands, pinyon–juniper woodlands, and yellow pine forests at elevations of 

760–2,100 m. 

Specimens Examined. MÉXICO. Chihuahua. 

Ahumanda: 5 km al N de Samalayuca, 24 Oct 74, Médanos 

FIGURE 231. Sporobolus flexuosus. A. Habit. B. Pulvinus. C. Spikelet. Drawn by Linda Ann Vorobik and Hana Pazdírková; copyright 

Utah State University.
NUMBER 107 • 345

[dunes], 1270 m, Valdés-Reyna VR-779 (RELC); 1 km al N del 

Rancho Santa Fé, 18 Oct 74, Zona de Médanos, 1400 m, ValdésReyna VR-650 (RELC). Casas Grandes: Col. Díaz, 20–21 Sep 

1899, E.W. Nelson 6458 (US). Jiménez: Reserva de la Biosfera de 

Mapimí, dunas de arena [sand dunes] Ejido La Soledad, 31 Aug 

1997, pastizal [pastureland], 1140 m, A. García 2768 (CIIDIR). 

Juárez: 30 km al N de Samalayuca, 23 Oct 74, suelo muy arenoso 

[very sandy soil], 1200 m, Valdés-Reyna VR-763 (RELC); Sand 

Dunes, 10–20 Oct 1935, LeSueur Mex-080 (MEXU); 4.1 (rd.) 

mi N of Samalayuca along Hwy 45, 13 Sep 1972, Vegetación de 

dunas [dune vegetation], 4700ft, J. Henrickson 7452 (MEXU); 

Sand Hills near of Paso del Norte, 28 Sep 1886, C.G. Pringle 

815 (MEXU, US).

357. Sporobolus giganteus Nash, Bull. Torrey Bot. Club 25: 88. 

1898.

FIGURE 232

Robust perennial. Culms 100–200 cm tall, erect, stout, glabrous below the nodes, base rounded, internodes glabrous; base 

diameter (3)4–10 mm wide. Sheaths longer than the internodes 

above, glabrous, striate, margins with ciliate hairs especially on 

upper portions, these hairs up to 2 mm long forming a conspicuous tuft near the summit; ligules 0.5–1.5 mm long; blades 10–50 

cm long, (3)4–10(13) mm wide, flat, glabrous below and above; 

margins whitish, scaberulous. Panicles 25–75 cm long, 1–4 cm 

wide, narrow, contracted, dense and spikelike, usually included 

in the uppermost sheath; primary branches mostly 0.5–6 cm 

long, appressed to spreading up to 30° from the culm axis; secondary branches appressed and floriferous to base; pulvini in 

axils of primary branches glabrous; pedicels 0.5–2 mm long, appressed. Spikelets 2.6–3.5(4) mm long, whitish to plumbeous; 

glumes 0.6–3.5 mm long, narrow lanceolate, membranous, 

unequal, prominently keeled, somewhat scaberulous along the 

keel; lower glumes 0.6–2 mm long, the apex acute to acuminate; upper glumes 2–3.5(4) mm long, the apex acute; lemmas 

2.5–3.5(4) mm long, linear-lanceolate, membranous, glabrous, 

the apex acute; paleas 2.4–3.4(3.8) mm long, linear-lanceolate, 

membranous, glabrous, the apex acute; stamens 3; anthers 0.6–1 

mm long, yellowish. Modified caryopses 0.8–1.7 mm long, ellipsoid, light yellowish-brown sometimes translucent. 2n = 36.

Distribution and Habitat. Sporobolus giganteus grows in sand dunes, sandy areas along rivers, calcareous 

slopes, and roadsides associated with Acacia constricta, Larrea 

tridentata, Jatropa dioica, Juniperus, and Atriplex canescens at 

760–1,220 m. 

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: ca. 67.7 km S of Juarez on Mex 45, 7 Sep 1989, grassland, 1800 m, P.M. Peterson & Annable 7935 (ENCB, US); 10 

km al S de Moctezuma, 30 Jul 1994, 1200 m, R. Corral, E. Pérez, 

A. Domínguez & F. Félix RCD5351 (UACJ). Juárez: Al W de la 

Sierra Juárez, 1 km al W de El Parabién, 27 Aug 1997, matorral 

de dunas arenosas [sand dune scrub], Izotal con mezquite, 1200 

m, A. Aquino AA67 (UACJ); Area of high sand dunes 5 km N of 

FIGURE 232. Sporobolus giganteus. A. Culm and Inflorescence. 

B. Spikelet. Drawn by Linda Ann Vorobik and Hana Pazdírková; 

copyright Utah State University.
346 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Samalayuca on the Juárez hwy, 28 Oct 1972, desiertos arenosos 

[sandy deserts], 1250 m, T.L. Wendt, F. Chiang & M.C. Johnston 9926 (MEXU); Area of high sand dunes 8 km N of Samalayuca on the Juárez hwy, 28 Oct 1972, desiertos arenosos, 1300 

m, T.L. Wendt, F. Chiang & M.C. Johnston 9937A (MEXU); 

Sand Dunas, 11 Dic 1935, LeSueur Mex-013 (MEXU); 4.1 (rd.) 

mi N of Samalayuca along Hwy 45, 13 Sep 1972, Vegetación de 

dunas [dune vegetation], 4700 ft, J. Henrickson 7427 (MEXU).

358. Sporobolus indicus (L.) R. Br., Prodr. 170. 1810.

FIGURE 233

Caespitose perennial or at least long-living annual with 

tough fibrous roots. Culms 30–100(120) cm tall, erect, base 

mostly flattened, glabrous below the nodes, internodes glabrous; 

base diameter 1–3.5(5) mm wide. Sheaths 1⁄2 to about as long 

as the internodes, glabrous; ligules 0.2–0.5 mm long; blades 

(6)10–30(50) cm long, 1–5 mm wide, flat, glabrous below and 

above. Panicles 20–35(50) cm long, 0.3–2.2(3) cm wide, narrow, 

contracted, sometimes included in the uppermost sheath; primary branches mostly 0.4–2.5(5) cm long, appressed sometimes 

ascending spreading up to 40° from the culm axis; secondary 

branches appressed and floriferous to base; pulvini in axils of primary branches glabrous; pedicels 0.1–1.8 mm long, appressed. 

Spikelets 2.0–2.6(2.7) mm long, plumbeous to light brownish; 

glumes 0.4–1.6 mm long, ovate or obovate, membranous, subequal; lower glumes 0.3–1 mm long, often without a midvein, 

the apex acute, obtuse to truncate, often erose; upper glumes 

0.6–1.6 mm long, the apex acute obtuse to truncate, often erose; 

lemmas 1.4–2.6(2.7) mm long, ovate, membranous, glabrous, 

the apex acute or obtuse; paleas 1.3–2.4 mm long, ovate, membranous, glabrous, the apex acute; stamens 3; anthers 0.5–1.1 

mm long, white, sometimes purple-tinged. Modified caryopses 

0.6–1.2 mm long, ellipsoid-quadrate, truncate toward apex, flattened laterally, reddish brown. 2n = 18, 24, 36.

Distribution and Habitat. Sporobolus indicus

is found throughout the Western Hemishphere and is common in 

disturbed places, open areas, roadsides, and pastures and along 

lake shores and beaches in sandy or clay soils associated with 

many plant communities at elevations of 3–2,460 m. 

Specimens Examined. MEXICO. Chihuahua. 

Batopilas: Yamuco, 1 mi E of hwy N of Rio Urique crossing towards Basihuare and Creel, 6 Sep 2008, P.M. Peterson & J.M. Saarela 22056 (US); Yamuco at 1 km E of hwy towards Basihuare and 

Creel, N of Rio Urique crossing, 26 Aug 2003, pine forest, 1891 

m, P.M. Peterson & P. Catalán 17541 (US); SW Chihuahua, Aug 

1885, E. Palmer 29 (US). Bocoyna: 24.7 mi N of San Juanito on 

road towards Cuauhtemoc, 5 Sep 2008, 2233 m, P.M. Peterson & 

J.M. Saarela 22025 (US). Guachochi: Just N of Guachochi (1 km), 

26 Sep 1988, pine forest, 2500 m, P.M. Peterson & Annable 5922

(ENCB, US); 37.4 km S of Creel on road to Batopilas, 10 Sep 

1989, pine forest, 2045 m, P.M. Peterson, Annable & Y. Herrera 

8013 (ENCB, US); small spring below Napuchis, 2 Sep 2003, pine 

forest, 1950 m, P.M. Peterson & P. Catalán 17654 (CIIDIR); 24.6 

km W of Guachochi and 0.6 km S of Rocheachi, 2340 m, P.M. 

Peterson, Annable & Valdés-Reyna 10795 (US); 1–2 km S of Rio 

Osichi and Rio Basihuare jct, 1 Sep 2003, bosque de encino [oak 

forest], 1600 m, P.M. Peterson & P. Catalán 17632 (CIIDIR, US); 

Cusarare, S of Creel, 10 Sep 1973, 2150 m, Bye 5008 (MEXU, 

NMC); Cusarare along arroyo just NW of Cusarare church, 16 

Oct 1977, 2140 m, Bye & W.A. Weber 8178 (MEXU); Near 

FIGURE 233. Sporobolus indicus. A. Habit. B. Spikelet. Drawn by 

Hana Pazdírková; copyright Utah State University.
NUMBER 107 • 347

cusarare S of Creel–La Bufa road arroyo crossing, 11 Aug 1972, 

occasional in open fields, 7000 ft, Bye 2741 (MEXU); 5 km antes 

del entronque [before junction] a la Bufa carr. [hwy] Guachochic–Creel, 4 Sep 1981, pine forest, 2500 m, M.E. Siqueiros 1625

(MEXU). Guerrero: 38.6 km SW of La Junta and approx. 70.8 

km N of Creel at P. Arroyo Ancho crossing, 21 km marker, 24 

Sep 1988, pine woods, 2200 m, P.M. Peterson & Annable 5853

(ENCB, US); carr. la Junta–San Juanito 17 km, 22 Sep 1997, 2290 

m, B. Tah V. 21 (MEXU); Tomochi 2 km alrededor del poblado 

[around the village], 24 Sep 1997, pine forest, 2100 m, M.A. Vergara 147 (MEXU); 78 km de la Junta Basaseachic, 10 Oct 1981, 

bosque esclerófilo caducifolio [deciduous sclerophyllous forest], 

1230 m, R. Fierros 1701 (MEXU). Ocampo: Llano de Chabacan, 

above crossing with Rio La Haciendita, 3 km SE of La Bateria, 

Rio mayo Region, 29 Aug 1986, 1650 m, P.S. Martin s.n. (ARIZ); 

122.5 km W of La Junta on road to Parque Nacional Cascada de 

Basaseachic and 56.7 km W of Tomochic, 1 Oct 1989, 2100 m, 

P.M. Peterson & R.M. King 8225 (US). Temosachi: Nabogame, 

29 Jul 1987, 1800 m, Laferr. 586 (MEXU).

359. Sporobolus pyramidatus (Lam.) Hitchc., Man. Grasses 

W. Ind. 84. 1936.

FIGURE 234

Caespitose annual with intravaginal branching at base. 

Culms 7–35(60) cm tall, erect or decumbent, base rounded, glabrous below the nodes, internodes glabrous; base diameter 1–1.6 

mm wide. Sheaths 1⁄2 to almost as long as the internodes above, 

glabrous or with ciliate hairs on the margins and summit, the 

hairs up to 3 mm long; ligules 0.3–1 mm long; blades 2–12(20) cm 

long, 2–6 mm wide, flat, glabrous below and scaberulous above, 

sometimes with a few hirsute hairs, mostly borne near base; margins ciliate-pectinate. Panicles 4–15(18) cm long, 0.3–6 cm wide, 

open and pyramidal with verticillate branches spreading 30°–90°, 

contracted and narrow when immature; primary branches 0.5–

4.5 cm long, not floriferous on the lower 1⁄3–1⁄2, lowest branches 

whorled in verticels of 7–12(15), lower portions of each branch 

with elongated glands; secondary branches appressed; pedicels 0.1–0.5 mm long, appressed. Spikelets 1.2–1.8 mm long, 

plumbeous or brownish, often secund along the branch; glumes 

0.3–1.8 mm long, ovate to obovate, membranous, unequal; lower 

glumes 0.3–0.7 mm long, without a midvein, the apex acuminate, 

obtuse or irregularly truncate; upper glumes 1.2–1.8 mm long, 

the apex acute or acuminate and sometimes scaberulous; paleas 

1.1–1.6 mm long, ovate to elliptic, membranous, the apex acute 

to obtuse; stamens 3; anthers 0.2–0.4 mm long, yellow or purplish. Modified caryopsis 0.6–1 mm long, obovoid, faintly striate, 

light brownish. 2n = 24, 36, 54.

FIGURE 234. Sporobolous pyramidatus. A. Habit. B. Spikelet. Drawn by Linda Ann Vorobik 

and Hana Pazdírková; copyright Utah State University.
348 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Distribution and Habitat. Sporobolus pyramidatus is common throughout Mexico, occurring on disturbed soils, roadsides and railways, coastal sands, and alluvial 

slopes in many plant communities at 5–1,750 m. 

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: km 26 SW Villa Ahumada, 22 Oct 1954, Hern.-Xol. 

& C. Tapia N-77 (US); 44 km al N del poblado [village] Villa 

Ahumada por la carr. [hwy] PanAmer. (Méx 45), 7 Oct 1995, 

1200 m, R. Corral, P. Olivas & J.O. Torres RCD6442 (UACJ); 

35 mi N of Moctezuma, 16 Aug 1950, Reeder,C. Reeder & 

L.N. Gooding 1710 (ARIZ). Aldama: Sta María en Valle de Aldama, 15 Sep 1955, Hern.-Xol. & V. Mathus N-1745 (US). Ascensión: 4 mi W of Guzman, 21 Aug 1972, zacaton [grassland] 

with Sporobolus and halofitas [halophytes], 1180 m, F. Chiang, 

T. Wendt & M. C. Johnston 8782B (MEXU); 13 km E of Guzman on winding road to Laguna de santa María, 22 Aug 1972, 

zacatonal, 1130 m, Chiang, T. Wendt & M. C. Johnston 8799

(MEXU); 64 mi SW of Cd. Juarez, N of Guzman near, 14 Sep 

1974, with Prosopis, Suaeda, Atriplex acanthocarpa, A. canescens, 1200 m, J. Henrickson14097 (MEXU). Chihuahua: 

Rancho La Presa, Chih., 21 Oct 1954, 1100 m, Hern.-Xol. & 

C.Tapia N-68 (US); near Chihuahua, 22 Sep 1886, C.G. Pringle 

816 (US); La Campana, 4 km Ote. [W] carr. Panamericana, 6 Sep 

73, lotes de producción de semilla [seed-production lots], 1500 

m, Valdés-Reyna VR-100 (RELC); El Bajío, 14 km Ote. carr. 

PanAmer., 25 Aug 73, pastizal [pastureland], 1400 m, ValdésReyna VR-11 (RELC). Delicias: km 13 S of Cd. Delicias, 1 Nov 

1954, 950 m, Hern.-Xol. & C. Tapia N-553 (US). Gómez Farías: 

Laguna de Babicora, Cerro Canoas, 3 Sep 1994, 2400 m, T. Lebgue, G. Quintana & E. Estrada 3234 (NMC); Laguna Babicora, 

9 Sep 1994, 2150 m, G. Quintana & E. Estrada 3514 (NMC). 

Jiménez: Reserva de la Biosfera de Mapimí, Laguna Palomas, 

31 Oct 1998, matorral xerófilo [xerophilous scrub], 1055 m, 

A. García 3178 (CIIDIR); El Hugo, Torreoncitos, 13 Aug 2010, 

bordo de agua [water margins], 1355 m, D. Ramírez & M.L. 

Juárez 3390 (CIIDIR); Costado del Rio Florido, Torreoncitos, 

4 Aug 2010, 1330 m, D. Noya & M.L. Juárez 3403 (CIIDIR). 

Juárez: km 32 Nuevo Casas Grandes–Galeana, 23 Oct 1954, 

Hern.-Xol. & C. Tapia N-127 (US); km 2052 rd to Juárez, 82 

km S of Cd. Juárez, 21 Oct 1954, Hern.-Xol. & C. Tapia N-50 

(US). Ojinaga: 17.5 air km S of Ojinaga on Chihuahua hwy 18, 

21 Oct 1990, 1100 m, Spellenberg, M. Mahrt & L. Rayburn 

10743 (MEXU); E Chihuahua, about 5.5 mi S of Ojinaga, rd 

from Ojinaga S to Alamos Chapo, 10 Aug 1941, I.M. Johnston 

8005 (MEXU, US).

360. Sporobolus spiciformis Swallen, Proc. Biol. Soc. Wash. 56: 

78. 1943.

FIGURE 235

Caespitose perennial. Culms 30–70 cm tall, erect, mostly 

glabrous; base diameter 1–1.8 mm wide. Sheaths shorter than 

the internodes, rounded, striate, scaberulous, hairy only at the 

corners; ligules 0.8–1 mm long, densely ciliate; blades 7–20 cm 

long, 1.5–2 mm wide at the base, flat or becoming involute or 

at least boat shaped in section, firm, flexuous, adaxial surface 

with white ridges. Panicles 9–17 cm long, 3–5(10) mm wide, 

spiciform and spikelike, white, often the lower portion included 

in the sheath. Spikelets 1.6–2.3 mm long; glumes 0.8–1.8 mm 

long, unequal, hyaline, the apex obtuse to acute, minutely erose; 

lower glumes 0.8–1.2 mm long; upper glumes 1–1.8 mm long, 

FIGURE 235. Sporobolus spiciformis. A. Habit. B. Inflorescence. 

C. Spikelet. Drawn by Cathy Pasquale for Smithsonian Institution, 

Department of Botany.
NUMBER 107 • 349

1-veined; lemmas 1.6–2.3 mm long, the apex obtuse to acute, 

minutely erose; paleas 1.6–2.3 mm long, the apex minutely 

2-toothed; anthers 1–1.3 mm long, yellow. Modified caryopses 

0.8–1 mm long, ellipsoid. 2n = 40. 

Distribution and Habitat. Sporobolus spiciformis is endemic to the Chihuahuan Desert Region, reported 

from Chihuahua, Coahuila, and Nuevo León, where it is restricted to saline or gypsum-derived soils associated with Yucca, 

Ephedra, Nama, Suaeda, Chilopsis linearis, and Prosopis; at 

410–1,750 m.

Specimens Examined. MEXICO. Chihuahua. 

Jiménez: Reserva de la Biosfera de Mapimí, 1 km de Las Palomas, 6 Jul 1997, matorral xerófilo [xerophilous scrub], 1055 m, 

A. García 2638 (CIIDIR, MEXU).

361. Sporobolus trichodes Hitchc., Contr. U.S. Natl. Herb. 

17(3): 311. 1913.

Perennial; caespitose. Culms erect; slender; 20–60 cm long; 

wiry. Leaves mostly basal; sheaths persistent and investing base 

of culm with fibrous dead sheaths; ligules 3–5 mm long, fringe of 

hairs, pilose-membranose; blades 5–10 cm long, 1–2 mm wide, 

involute. Panicle 5–10 cm long, 5–10 cm wide, open, ovate, effuse; branches capillary, spreading. Spikelets 2.5–3(4) mm long, 

solitary, bisexual; pedicels filiform, flexuous, with 1 fertile floret; 

florets 1.5–2 mm long, lanceolate, subterete, purple or brown; 

disarticulating below each fertile floret; glumes shorter than 

spikelet, 1⁄2 as long as the adjacent fertile lemma, membranous, 

deciduous; lower glumes 0.6–0.7 mm long, lanceolate, without 

keels, 1-veined, apex acute; upper glume 0.7–1 mm long, ovate, 

without keels, 1-veined, apex acute; fertile lemmas 1.5–2 mm 

long, ovate, membranous, light brown or purple, without keels, 

1-veined, apex acute; palea similar to lemma, 2-veined, keels approximate; stamens 3; anthers 1–1.1 mm long, purplish. Modified caryopses about 1 mm long. 

Distribution and Habitat. Sporobolus trichodes is a Mexican endemic widely distributed in Aguascalientes, 

Chihuahua, Guanajuato, Guerrero, Jalisco, México, Michoacán, 

Morelos, Veracruz, and Zacatecas.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 24.2 km W of Balleza on Mex 127 towards Guachochi, 

13 Sep 1989, pine forest, 2380 m, P.M. Peterson, Annable & 

Y. Herrera 8088 (ENCB, US); 56.4 km W of Parral on road to 

Balleza and 35.5 km S of Balleza, 18 Sep 1991, pine–oak, 2210 

m, P.M. Peterson, Annable & Valdés-Reyna 10699 (CIIDIR, US). 

Guerrero: near Guerrero, 9 Sep 1887, C.G. Pringle 1426 (US).

362. Sporobolus wrightii Munro ex Scribn., Bull. Torrey Bot. 

Club 9: 103. 1882.

FIGURE 236

Densely caespitose perennial. Culms 90–250 cm tall, erect, 

stout, glabrous below the nodes, base rounded, internodes glabrous; base diameter 2–9 mm wide. Sheaths 2⁄3 to a little longer 

than the internodes above, glabrous, shinny, rarely with a few 

long hairs near the summit, these hairs up to 6 mm long; ligules 1–2 mm long; blades 20–70 cm long, 3–10 mm wide, flat 

rarely involute, glabrous below and scabrous above; margins 

scabrous roughened. Panicles 20–60 cm long, 12–26 cm wide, 

open, broadly lanceolate, exserted; primary branches 1.5–10 cm 

long, ascending to widely spreading 20°–70° from the culm axis; 

secondary branches appressed and floriferous to base; pulvini in 

axils of primary branches glabrous; pedicels mostly 0.2–0.5 mm 

FIGURE 236. Sporobolus wrightii. A. Habit. B. Spikelet. Drawn 

by Linda Ann Vorobik and Hana Pazdírková; copyright Utah State 

University.
350 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

long, appressed. Spikelets 1.5–2.5 mm long, crowded and appressed, purplish or greenish; glumes 0.5–2 mm long, lanceolate 

to ovate, membranous, unequal; lower glumes 0.5–1 mm long, 

often appearing without a midvein, the apex acute; upper glumes 

0.8–2 mm long, the apex acute to obtuse; lemmas 1.2–2.5 mm 

long, ovate, membranous, glabrous, the apex acute to obtuse; 

paleas 1.1–2.5 mm long, ovate, membranous, glabrous, the apex 

acute to obtuse; stamens 3; anthers 1.1–1.3 mm long, yellowish to purplish. Modified caryopses 1–1.4 mm long, ellipsoid, 

reddish-brown or blackish, striate. 2n = 36.

Distribution and Habitat. Sporobolus 

wrightii grows in moist clay flats and rocky slopes near saline 

habitats associated with Atriplex, Acacia, Suaeda, Prosopis, and 

Opuntia at elevations of 5–1,800 m.

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: 11 km al N de Villa Ahumada Chihuahua km 98 

carr. [hwy] Chihuahua–Cd Juárez, 13 Sep 1978, 1120 m, 

Valdés-Reyna, R. Grether & H. Quero s.n. (MEXU). Ascensión: alrededores del cruce [near the crossing] del río Casas 

Grandes con la carr. Juárez–Ascensión, 11 Jun 2005, 1180 m, 

R. Corral, M. Vargas & H. Gutiérrez RCD7143 (UACJ). Camargo: 20 km S of Cd. Camargo, 2 Aug 1939, 1220 m, L. H. 

Harvey 1382 (US); entre [between] los Ángeles & Jaco, 3 Aug 

1976, matorral [scrub], 1265 m, J.M. Peña & S. González 499

(RELC). Casas Grandes: near Casas Grandes, 30 Aug 1899, 

E.W. Nelson 6344 (US). Chihuahua: Rancho La Gregoria, 15 

Oct 1982, matorral, 1400 m, E. Blanco 1707 (MEXU). Ignacio Zaragoza: 1 km N of rancho Santa María de Guadalupe 

on right bank of rio Casas Grandes, 18 Aug 1972, 1250 m, 

F. Chiang, T. Wandt & M.C. Johnston 8688 (MEXU). Janos: 

Chihuahua–Sonora border, Rancho Carretas, 26 Aug 1939, 

1460 m, L. H. Harvey 1606 (US); 7 km NE of the town of 

Janos, at the archaeological site of Juanaquena, 4 Sep 1988, 

K.R. Adams s.n. (ARIZ). Jiménez: 10 km E of Cd. Jiménez, 31 

Jul 1939, L. H. Harvey 1350 (US); Costado del Rio Florido, 

Torreoncitos, 4 Aug 2010, 1330 m, D. Noya & M.L. Juárez 

3405 (CIIDIR). Juárez: Medanos de Samalayuca, 13 Oct 1997, 

km 70, I. Enríquez, S. Ordoñez & J. Leyva IEA19 (UACJ). 

Julimes: Baños de San Diego, 12 Aug 1975, J.M. Peña JMP159 (RELC). Madera: between Col. García and Pratt’s Rancho below Pacheco, 22-24 Aug 1899, E.W. Nelson 6243 (US). 

Manuel Benavides: E Chihuahua, vicinity of Pirámide, 12 Aug 

1941, I.M. Johnston 8034, 8139 (MEXU), 8139 (MEXU, US). 

Meoqui: In town of Meoqui, along hwy 45, SE of city of Chihuahua, 25 Sep 2004, 1140 m, R.M. King & R.M. Garvey 

13463 (CIIDIR). Ojinaga: km 10 carr. Ojinaga–Camargo, 18 

Aug 74, matorral, 1200 m, Valdés-Reyna VR-580 (RELC).

Stenotaphrum Trin.

Annual or perennial; sometimes rhizomatous or stoloniferous. Culms usually compressed; internodes solid. Leaves cauline; 

sheaths shorter than the internodes, compressed; ligules membranous and ciliate or of hairs; blades flat or folded. Inflorescences 

spikelike panicles; branches very short, with fewer than 10 

spikelets, appressed to and partially embedded in the flattened, 

corky rachises; disarticulation below the glumes, often with a 

segment of the branch. Spikelets lanceolate to ovate, unawned, 

lower glumes oriented away from the branch axes; glumes membranous; lower glumes scalelike, usually without veins; upper 

glumes 5- to 7-veined; lower florets staminate or sterile, lemmas 

3- to 9-veined; upper florets bisexual; upper lemmas longer than 

the glumes, papery to subcoriaceous, 3- to 5-veined; upper paleas generally indurate, 2-veined; anthers 3. Caryopsis lanceolate 

to ovate, often failing to develop. x = 9. 

Stenotaphrum is a genus of seven species that usually grow 

on the seashore or near the coast, primarily along the rim of the 

Indian Ocean. Three species are endemic to Madagascar, and S. 

secundatum, although thought to be introduced to Mexico, is 

probably native to the southeastern United States (Sauer 1972).

363. Stenotaphrum secundatum* (Walter) Kuntze, Revis. Gen. 

Pl. 2: 794. 1891.

Plants stoloniferous. Culms 10–30 cm tall, decumbent, 

rooting at the lower nodes, branched above the base, with 

prominent prophylls. Sheaths sparsely pilose, constricted at the 

summit; ligules about 0.5 mm long, membranous, ciliate; blades 

3–15(18) cm long, 4–10 mm wide, thick, flat, glabrous, apex 

blunt. Panicles 4.5–10 cm long, less than 1 cm wide; rachises 

flattened, winged; branches 12–20, with 1–5 spikelets. Spikelets 

3.5–5 mm long, partially embedded on 1 side of the branch axes; 

lower glumes about 1 mm long, rounded, irregularly toothed; 

upper glumes and lower lemmas 3–4 mm, about equal; upper 

lemmas papery, 5-veined, margins weakly clasping the paleas; 

anthers 2–2.5 mm long, tan or purple. Caryopsis about 2 mm 

long, oblong to obovate. 2n = 18.

Distribution and Habitat. Stenotaphrum secundatum grows at the edges of swamps and lagoons and along 

inland streams and lakes. It is known from Aguascalientes, Chiapas, Chihuahua, Jalisco, Morelos, Puebla, Quintana Roo, and 

Tabasco. This species has been reported from Chihuahua (Espejo 

Serna et al., 2000).

Thinopyrum Á. Löve

Perennial; caespitose or not, sometimes rhizomatous. Culms 

usually erect. Sheaths glabrous or ciliate; auricles present or 

absent; ligules membranous; blades convolute or flat. Inflorescences terminal, distichous spikes, usually not disarticulating at 

maturity; disarticulation usually beneath the florets and tardy, 

occasionally in the rachises. Spikelets 1–3 times the length of 

the middle internodes, solitary, appressed to ascending, often 

arching outward at maturity; glumes oblong to lanceolate, stiff 

and thick, indurate to coriaceous, glabrous or with hairs, keeled 

or rounded at the base, usually more strongly keeled distally 

than below, margins often with a hyaline margin, apex truncate to acute, sometimes mucronate, unawned, without lateral 

teeth; lemmas 5-veined, stiff, thick and coriaceous, glabrous or 
NUMBER 107

• 351

with hairs, truncate, obtuse, or acute, sometimes mucronate or 

awned, awns to 3 cm; anthers 3. x = 7. 

Thinopyrum includes seven species, most of which are al-

kaline tolerant. It is native from the Mediterranean region to 

western Asia.

364. Thinopyrum intermedium* (Host) Barkworth & D. R. 

Dewey, Amer. J. Bot. 72(5): 772. 1985. 

Agropyron barbulatum Schur., Verh. Mitth. Siebenburg. Vereins Naturwiss. 

Hermannstadt 4: 91. 1853.

FIGURE 237

Plants rhizomatous, often glaucous. Culms 52–115 cm tall, 

glabrous or hairy, sometimes hairy only on the nodes, lowest in-

ternode plus sheath about 3 mm thick. Sheaths mostly glabrous, 

often ciliate on the margins; auricles 0.5–1.3 mm long; ligules 

0.1–0.8 mm long; blades 2–8 mm wide, flat, abaxial surfaces 

glabrous, adaxial surfaces usually sparsely strigose, sometimes 

also with shorter pubescence, margins whitish, thicker than the 

veins. Spikes 8–21 cm long, erect or lax; middle internodes 7–12 

mm long; rachises pubescent, not disarticulating at maturity. 

Spikelets 11–18 mm long, with 3–10 florets; glumes oblong, 

weakly keeled distally, glabrous and mostly smooth or strigose 

with 1–1.5 mm long hairs, hairs usually evenly distributed, keels 

scabrous, at least distally, midvein usually more prominent and 

longer than the lateral veins, margins not hyaline or hyaline near 

the apex, apex obliquely truncate or obtuse to acute, sometimes 

mucronate; lower glumes 4.5–7.5 mm long, 1.5–2.5 mm wide, 

5- or 6-veined; upper glumes 5.5–8 mm long, 2–3 mm wide, 

5- to 7-veined; lowest lemmas 7.5–10 mm long, glabrous or with 

1–1.5 mm long hairs, hairs usually evenly distributed, some-

times only on the outer portion of the lemmas, apex occasionally 

awned, the awns to 5 mm long; paleas 7–9.5 mm long, keels 

usually ciliate on upper 1⁄2; anthers 5–7 mm long. 2n = 42, 43.

Distribution and Habitat. Thinopyrum intermedium is native to Europe and western Asia. It is one of the 

most common species of the genus and is widely introduced in 

western North America for erosion control, revegetation, forage, 

and hay. One of its advantages for erosion control and revegeta-

tion is that it establishes itself rapidly in many different habitats.

Specimens Examined. MEXICO. Chihuahua. 

Chihuahua: La Campana, 24 Sep 76, Jardines de Observación 

Forrajera [forage observation garden], 1500 m, S. Gonzalez 771

(RELC). Práxedis G. Guerrero: Rancho Escuela, 18 Oct 1997, 

I. Enriquez, S. Ordoñez, L. Sushii, S. Carrasco, A. Perales & 

N. Loya IEA10 (UACJ).

FIGURE 237. Thinopyrum intermedium. A. Base of culm. B. Ligule 

with auricles. C. Inflorescence. D. Spikelet. E. Floret, dorsal view. F. 

Floret, ventral view. Drawn by Cindy Roché and Annaliese Miller; 

copyright Utah State University.
352 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Trachypogon Nees

Annual or perennial; caespitose or short rhizomatous. 

Culms unbranched; internodes semi-solid. Leaves cauline, not 

aromatic; sheaths shorter than the internodes, rounded; ligules 

membranous; blades flat to involute. Inflorescences terminal, 

solitary racemes of heterogamous subsessile-pedicellate spikelet pairs (rarely of 2 digitate spikelike branches), axes slender, 

without a translucent median groove; disarticulation beneath 

the pedicellate spikelets. Subsessile spikelets staminate or sterile, 

without a callus and unawned, otherwise similar to the pedicellate spikelets. Pedicels slender, not fused to the rames axes. Pedicellate spikelets bisexual; calluses sharp, strigose; glumes firm, 

enclosing the florets; lower glumes several-veined, encircling the 

upper glumes; upper glumes 3-veined; lower florets sterile; upper 

florets bisexual, lemmas firm but hyaline at the base, tapering 

to an awn; awns twisted, pubescent to plumose; paleas absent; 

anthers 3. x = 10.

Trachypogon is a tropical or warm-temperate genus of 

four species that is native to Africa and tropical to subtropical 

America.

365. Trachypogon spicatus (L. f.) Kuntze, Revis. Gen. Pl. 2: 794. 

1891. Stipa spicata L. f., Suppl. Pl. 111. 1781.

Trachypogon secundus (J. Presl) Scribn.

Trachypogon plumosus (Humb. & Bonpl. ex Willd.) Nees.

Perennial. Culms 60–120 cm long, erect; nodes appressedhirsute. Sheaths sparsely appressed-pilose; ligules 2–5 mm long, 

stiff, acute; blades usually 12–35 cm long, 3–8 mm wide, with a 

broad midrib. Racemes 10–18 cm long, the internodes glabrous. 

Pedicellate spikelets 6–8 mm long; glumes pilose; awns 4–6 cm 

long, pilose below, the hairs 1–2 mm long, nearly glabrous distally; anthers 4–5 mm long, orange. 2n = 20.

Distribution and Habitat. Trachypogon spicatus is found in sandy prairies, woodlands, rocky hills, and canyons in well-drained soils.

Specimens Examined. MEXICO. Chihuahua.

Balleza: 16.1 km W of Balleza and 77.9 km E of Guachochi, 

18 Sep 1991, oak forest, 1990 m, P.M. Peterson, Annable & 

Valdés-Reyna 10746 (CIIDIR, US); 43.5 km W of Balleza and 

51.6 km E of Guachochi, 18 Sep 1991, pine forest, 2320 m, P.M. 

Peterson, Annable & Valdés-Reyna 10755 (CIIDIR, US). Batopilas: Yamuco at 1 km E of hwy towards Basihuare and Creel, 

N of Rio Urique crossing, 26 Aug 2003, bosque de pino [pine 

forest], 1891 m, P.M. Peterson & P. Catalán 17535 (US); SW 

Chihuahua, Aug 1885, E. Palmer 26 (US). Chinipas: Saguarivo, 

53 mi N of Alamos, 9 Sep 2008, slopes with oaks and pines, 

1540 m, P.M. Peterson & J.M. Saarela 22124 (US). Chihuahua: 

near Chihuahua, 19 Aug 1885, C.G. Pringle 495 (US); 3 Sep 

1935, LeSueur Mex-015 (US); 87 km N of Chihuahua, 1 km 

S of Arco iris on hwy 45, 5 Oct 1986, grassland, Spellenberg, 

Soreng & R. Corral 8900 (CIIDIR); 87 km N Chihuahua 1 km S 

Arco Iris on Hwy 45, 5 Oct 1986, 1500 m, Spellenberg, Soreng 

& R. Corral 8900 (NMC); La Campana, Potrero la Sierra, 3 km 

Pte. carr. [hwy] Panamericana, 7 Sep 73, pastizal con encino 

[pastureland with oak], 1500 m, Valdés-Reyna VR-138 (RELC). 

Guachochi: Whute-tuff volcanic outcrops surrounding Napuchis, 2 sep 2003, bosque de pino–pastizal, 2140 m, P.M. Peterson & P. Catalán 17680 (CIIDIR, US); 8.5 km S of Cusarare 

on road to Guachochi, 25 Sep 1988, pine forest, 2400 m, P.M. 

Peterson & Annable 5880 (ENCB, US). Madera: Mesa del Yerbanís, ejido El Largo, 12 Oct 1990, bosque de encino, 1900 m, 

O. Bravo 1828 (CIIDIR); La Tinaja, ejido El Largo, 29 Aug 

1990, bosque de encino–pino, 1840 m, O. Bravo 1336 (CIIDIR, 

ENCB). Matamoros: 19.3 km S of Villa Matamoros on hwy 

45 to Durango, 27 Sep 1988, pastizal, 1800 m, P.M. Peterson 

& Annable 5972 (ENCB, US); 12 mi S of Villa Matamoros on 

hwy 45 towards Parral, 8 Oct 1966, Reeder & C. Reeder 4630

(ARIZ). Ocampo: Parque Nacional “Cascada de Basaseachic,” 

at overlook ca. 1 km airline S of Cascada, 3 Oct 1986, 2100 

m, Spellenberg, Soreng, R. Corral & T. Lebgue 8652 (NMC); 

Mesa Redonda, 4 Nov 1989, 1700 m, J. Boyer, P.S. Martin, 

M.K. O’Rourke & G. Ferguson s.n. (ARIZ); 122.5 km W of La 

Junta on road to Parque Nacional Cascada de Basaseachic and 

56.7 km W of Tomochic, 1 Oct 1989, 2100 m, P.M. Peterson & 

R.M. King 8240 (US). 

Tragus Haller

Annual or perennial; caespitose. Culms herbaceous, usually rooting at the lower nodes; nodes and internodes glabrous. 

Leaves cauline; sheaths open, usually shorter than the internodes, mostly glabrous but long-ciliate at the edges of the collar; ligules membranous, truncate, ciliate; blades usually flat, 

margins ciliate. Inflorescences terminal, exceeding the upper 

leaves, narrow, cylindrical panicles; branches resembling burs, 

with 2–5 spikelets; disarticulation at the base of the branches. 

Spikelets crowded, attached individually to the branches, with 

1 floret; proximal spikelet(s) bisexual, larger than the distal 

spikelet(s); terminal spikelets often sterile; glumes unequal; 

lower glumes absent or minute, veinless, membranous; upper 

glumes usually exceeding the florets, 5- to 7-veined, with 5–7 

longitudinal rows of straight or uncinate spine-like projections; lemmas 3-veined; paleas 2-veined, hyaline, membranous. 

x = 10. 

Tragus has seven species, all of which are native to the tropics and subtropics of the Eastern Hemisphere; one is introduced 

into Chihuahua (Peterson et al., 2016).

366. Tragus berteronianus* Schult., Mant. 2: 205. 1824.

Annual. Culms (2)3.5–45 cm tall. Ligules 0.5–1 mm long; 

blades (0.5)0.7–8.5 cm long, 1.2–5 mm wide, glabrous. Panicles 

(1)2–13 cm long, (3)4–8 mm wide; rachises pubescent; branches 

(0.5)0.7–2.7 mm long, pubescent, with 2(3) spikelets, axes occasionally extending past the distal spikelets; proximal internodes 0.2–0.6(0.7) mm long, shorter than the second internodes. 

Lower spikelets (1.8)2–4.3 mm long; upper spikelets (0.8)1–3.9 

mm long, sometimes sterile; lower glumes 0.1–0.6 mm long, 
NUMBER 107 • 353

membranous, minutely pubescent; upper glumes 1.8–4.3 mm 

long, minutely pubescent, 5-veined, rarely with 1–2 additional 

veins adjacent to the midvein; glume projections (4)6–14, in 5 

rows, (0.2)0.3–1 mm long, uncinate; lemmas (1.5)1.8–3.1 mm 

long, sparsely pubescent on the back, midveins occasionally excurrent, the mucros to 0.6 mm long; paleas (1.3)1.5–2.4 mm 

long; anthers 3, 0.4–0.6 mm long, yellow, occasionally purple or 

green-tinged. Caryopsis (0.9)1.2–2 mm long, 0.4–0.8 mm wide. 

2n = 20.

Distribution and Habitat. Tragus berteronianus is native to Africa and Asia and is now established in Arizona, New Mexico, and Texas to Mexico and Central and South 

America.

Specimens Examined. MEXICO. Chihuahua.

Buenaventura: 7 km al sur [S] de Buenaventura, 5 Sep 76, pastizal [pastureland], 1574 m, A. Melgoza 347 (RELC). Camargo: 

E Chihuahua, 10 mi SE of Organos, N slopes of the igneous 

Sierra de los Organos, 5 Oct 1941, Stewart & Johnston 2036

(US). Chihuahua: near Chihuahua, 19 Aug 1885, C.G. Pringle 

421 (US); 15 Oct 1935, LeSueur Mex-033 (US); 5 mi SW of 

Chihuahua on rd to Cuauhtémoc, 6 Oct 1959, Soderstrom 900

(US); La Campana Experimental Station and Rancho El Arco 

Iris, 81–84 km along Pan American Hwy to Chihuahua City, 

Oct 1977, 1500 m, J.K. Meents & W.H. Moir 95 (NMC); La 

Campana; potrero El Plan, 3 km Ote. [W] carr. [hwy] Panamericana, 31 Aug 1973, pastizal, 1500 m, Valdés-Reyna VR-49

(RELC); 5 km Ote. carr. Panamericana, 18 Sep 73, orilla de 

camino [wayside], 1500 m, Valdés-Reyna VR-324 (RELC); km 

54 carr. Panamericana entrada [entry] a El Sauz, 9 Oct 74, pastizal, 1500 m, Valdés-Reyna VR-639 (RELC). Janos: Chihuahua–Sonora border, Rancho Carretas, 26 Aug 1939, 1460 m, 

L. H. Harvey 1614 (US); Rancho El Carrizo, 30 Sep 1982, pastizal, P. Rojas s.n. (CIIDIR). Jiménez: 9 mi W of Jiménez, 6 Sep 

1967, Reeder & C. Reeder 4832 (ARIZ); 33 mi SE of Jiménez, 

27 Sep 1963, Reeder & C. Reeder 3612 (ARIZ); Costado del 

Río Florido, Torreoncitos, 4 Aug 2010, 1330 m, D. Noya & 

M.L. Juárez 3411 (CIIDIR). Juárez: Médanos de Samalayuca, 

13 Oct 1997, km 70, I. Enríquez, S. Ordoñez & J. Leyva IEA22

(UACJ). Riva Palacio: Arroyo del Nido, 1.2 mi by dirt road, E of 

Rancho El Nido, 8 Oct 1982, grassland, 1400 m, F.W. Reichenbacher 1327 (ARIZ).

Tridens Roem. & Schult.

Perennial; usually caespitose, often with short, knotty rhizomes, occasionally with elongate rhizomes, never stoloniferous. Culms erect, mostly glabrous, lower nodes sometimes with 

hairs. Sheaths shorter than the internodes, open; ligules membranous and ciliate or of hairs; blades flat or involute, margins not 

thick and cartilaginous. Inflorescences terminal, usually panicles 

(sometimes reduced to racemes), exceeding the upper leaves, 

exserted. Spikelets laterally compressed, with 4–11(16) florets, 

more than 1 floret bisexual; sterile florets distal to the bisexual 

spikelets; disarticulation above the glumes; glumes from shorter 

than to equaling the distal florets; lower glumes 1(3)-veined; 

upper glumes shorter than or about equal to the lower glumes, 

1- to 3(9)-veined, unawned; calluses usually glabrous, sometimes 

pilose; lemmas hyaline or membranous, 3-veined, veins usually 

shortly hairy below, apex rounded to truncate, emarginate to bilobed, midvein often excurrent to 0.5 mm long, lateral veins not 

or more shortly excurrent; paleas glabrous or shortly pubescent 

on the lower back and margins, veins glabrous or ciliolate, margins widened or bowed-out below; lodicules 2, free or adnate 

to the palea; anthers 3, reddish-purple. Caryopsis dorsiventrally 

compressed and reniform in cross section, dark brown; embryos 

about 2⁄5 as long as the caryopsis. x = 10. 

Tridens, a genus of 16 species, is native to the Americas; 2 

species are found in Chihuahua (Peterson et al., 2016).

KEY TO SPECIES OF TRIDENS

1. Panicles 0.3–4 cm wide, dense and spikelike; primary panicle branches appressed to strongly ascending; pedicels 1–2 mm 

long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T. albescens

1. Panicles 1–20 cm wide, open, never spikelike; primary panicle branches ascending to reflexed; pedicels (2)3–6 mm long 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T. texanus

367. Tridens albescens (Vasey) Wooton & Standl., New Mexico 

Agric. Exp. Sta. Bull. 81: 129. 1912.

Plants caespitose, often with hard, knotty, short rhizomatous 

bases. Culms 30–100 cm tall; lower nodes sometimes sparsely 

bearded. Sheaths glabrous, not or obscurely keeled; ligules to 

0.5 mm long, membranous, ciliate; blades 1–4 mm wide, folded 

or involute, glabrous, apex sharp. Panicles 8–25 cm long, 0.5–

1.3 cm wide, dense; branches appressed, lowest branches 2–6 

cm long; pedicels 1–2 mm long. Spikelets 4–10 mm long, with 

4–11 florets; glumes about as long as the adjacent lemmas, thin, 

1-veined, acute or apiculate; lower glumes 4–4.5 mm long; upper 

glumes 4–4.5 mm long; lemmas 3–4(5) mm long, thin, papery, 

mostly white, often purple distally, glabrous or the lateral veins 

with a few short hairs toward the base, all veins ending before 

the distal margin; paleas 3–3.5 mm long, glabrous, bowed-out at 

the base; anthers 1–1.5 mm long. Caryopsis 1.5–1.8 mm long. 

2n = 60, 64, 72.

Distribution and Habitat. Tridens albescens

grows in plains and open woods, often in clay soils that periodically receive an abundance of water. Its range extends into 

northern Mexico.

Specimens Examined. MEXICO. Chihuahua.

Cuauhtémoc: 16 mi NW of Zavalza, 3 Oct 1966, Reeder & 

C. Reeder 4573 (ARIZ).
354 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

368. Tridens texanus (S. Watson) Nash, Fl. S.E. U.S. 142. 1903.

Plants caespitose, with knotty, short rhizomatous bases. 

Culms 20–75 cm tall, slender, strictly erect; nodes glabrous; internodes often pilose. Sheaths mostly glabrous or pilose throughout, 

collar and distal portion of the margins densely pilose; ligules to 

0.5 mm long, membranous, ciliate; blades 1–3(5) mm wide, flat 

or becoming inrolled, hispid, with long hairs on the adaxial surface just above the ligule, apex attenuate. Panicles 5–16 cm long, 

2–9 cm wide, open or loosely contracted; branches (2)4–7 cm 

long, slender, lax, strongly divergent to drooping, basal portion 

naked, spikelets confined to the distal portion; pedicels (2)3–6 mm 

long. Spikelets 6–13 mm long, with 6–12 florets; glumes glabrous, 

1-veined; lower glumes 3 mm long; upper glumes 3.5–4 mm long, 

veins bright green; lemmas 3–4.5 mm long, usually purple or 

rosy-purple at maturity, veins pilose to midlength, lateral veins 

often excurrent as short points; paleas 3–3.5 mm long, glabrous, 

abruptly broadened and bowed-out below; anthers 1–1.5 mm 

long. Caryopsis 1.5–2 mm long. 2n = 40.

Distribution and Habitat. Tridens texanus

grows in clayey and sandy loam soils, often in the protection of 

shrubs and along fenced road rights-of-way. Its range extends 

from southern Texas into northern Mexico. This species has 

been reported from Chihuahua (Espejo Serna et al., 2000).

Tridentopsis P. M. Peterson

Plants caespitose perennials; with knotty, short rhizomatous bases. Culms 20–80 cm tall, nodes often bearded, the hairs 

up to 2 mm long, soft. Leaf sheaths glabrous, scabrous, often 

pilose; ligules 0.4–1.5 mm long; blades up to 15 cm long, 1–5 

mm wide, flat to involute. Panicles 7–28 cm long, 1–6 cm wide, 

narrow spreading; branches up to 13 cm long, erect appressed. 

Spikelets 7–13 mm long, 2- to 11-flowered, laterally compressed; 

disarticulation above the glumes; glumes 3–10 mm long, 1- to 

7-veined, glabrous; lemmas 3.5–7 mm long, 3-veined, usually 

purple tinged, midveins sometimes excurrent, pubescent to pilose along the veins; paleas 1.5–5 mm long, shorter than the 

lemmas, glabrous or hairy. Caryopsis 1.5–2.6 mm long, dorsally 

flattened and deeply concave to folded on the dorsal or hilar 

surface and thickened toward the margin below, surface is reticulate, reddish-brown. 2n = 40.

The genus Tridentopsis has two species; both are distributed 

in the southwestern United States, northern Mexico, and the Caribbean (Peterson et al., 2014a, 2016). Plants occur on clay to 

sandy and rocky soils in arid environments from 0 to 2,000 m. 

Tridentopsis differs from Tridens Roem. & Schult. in having paleas that are not widened or bowed-out below and caryopses that are dorsally flattened and deeply concave to folded 

on the dorsal or hilar surface, and thickened toward the margin 

below, the surface reticulate, reddish-brown (Peterson et al., 

2014a).

369. Tridentopsis mutica (Torr.) P. M. Peterson var. mutica, 

Taxon 63(2): 284. 2014. Tridens muticus (Torr.) Nash, Fl. 

S.E. U.S. 143. 1903. Tricuspis mutica Torr., Pacif. Railr. 

Rep. 4(5): 156. 1857. 

FIGURE 238

Plants caespitose, with knotty, short rhizomatous bases. 

Culms 20–80 cm tall; nodes often with soft, 1–2 mm hairs. Sheaths 

rounded, lower sheaths often strigose or pilose, upper sheaths glabrous or scabrous; ligules 0.5–1 mm long, membranous, ciliate; 

blades 1–4 mm wide, usually involute or loosely infolded, glabrous, 

scabrous, or sparsely pilose, attenuate distally. Panicles 7–20(25) 

cm long, 0.3–0.8 cm wide; branches erect, spikelets imbricate but 

usually not crowded; pedicels 1–2 mm. Spikelets 8–13 mm long, 

with 5–11 florets; glumes glabrous, usually purple-tinged; lower 

glumes 3–8(10) mm long, 1- to 3-veined; upper glumes 4–10 mm 

long, 1- to 7-veined; lemmas 3.5–7 mm long, usually purple-tinged, 

midveins pilose on the basal 1⁄3–1⁄2, rarely excurrent, lateral veins 

pilose to well above midlength, never excurrent; paleas 1–2 mm 

shorter than the lemmas, margins pubescent; anthers 1–1.5 mm 

long. Caryopsis 1.5–2.3 mm long. 2n = 40.

Distribution and Habitat. Tridentopsis mutica var. mutica is a common species on dry, sandy or clay soils 

in the arid southwestern United States and adjacent Mexico. Tridentopsis mutica var. elongata (Buckley) P. M. Peterson & Romasch., known only from Texas, differs in having longer, widely 

spaced primary branches that are usually spreading up to 80° 

from the culm axis (Valdés-Reyna, 2003; Peterson et al., 2016).

Specimens Examined. MEXICO. Chihuahua. 

Ahumada: ca 23 (air) mi ENE of Villa Ahumada in NW canyon of Sierra de la Alcaparra, 12 Sep 1973, J. Henrickson 

12840 (NMC). Aldama: km 50 Chihuahua–Ojinaga, 24 Aug 

1978, matorral inerme parvifolio [unarmed small-leaved scrub], 

Molinar-Rodríguez & Baray 24 (CIIDIR); 91 km carr. [hwy] Chihuahua–Ojinaga, 29 Aug 1978, matorral, 1395 m, R. Molinar 

67 (MEXU); km 50 Chihuahua–Ojinaga, 24 Aug 1978, matorral, 

1250 m, R. Gutierrez 17 (MEXU); 38 (rd) mi NE of Aldama along 

hwy 16 (km 88), on broad, 15 Sep 1972, pastizal [pastureland], 

4700 ft, J. Henrickson 7609, 7687 (MEXU). Allende: Rancho La 

Reforma, Valle de Allende, 18 Sep 1981, matorral mediano subinerme [mostly unarmed scrub], 1600 m, J.S. Sierra Tristán s.n.

(CIIDIR). Buenaventura: Ejido El Apache, 6 Oct 1981, pastizal, 

1600 m, B. Ferreiro 1731 (MEXU). Camargo: 16 mi SE of Camargo, 3 Oct 1966, Reeder & C. Reeder 4841 (ARIZ). Coyame: 

km 180 carr. Chihuahua–Ojinaga, 18 Oct 74, matorral, 1650 m, 

Valdés-Reyna VR-719 (RELC). Jiménez: 33 mi SE of Jiménez, 27 

Sep 1963, Reeder & C. Reeder 3615 (ARIZ); 50 km al S de Jiménez, 15 Aug 2010, 1442 m, D. Ramírez & M.L. Juárez 3413

(CIIDIR). La Cruz: Carret. Camargo–Chih., km 18, 29 Sep 1995, 

matorral, 1220 m, Quiñones 109 (MEXU). Meoqui: JulímesFelipe Ángeles, 31 Aug 1976, matorral, 1290 m, S. González & 

J.M. Peña 385 (RELC). Ojinaga: Carr. Panamericana, 2 km al N 

de carr. a Presidio, 24 Oct 74, matorral, 1400 m, Valdés-Reyna 

VR-770 (RELC). Práxedis G. Guerrero: Sierra San Ignacio, 7.5 

km al W de Col. Esperanza, 18 Mar 1995, en lecho [bed] de arroyo, 1190 m, R. Corral, P. Olivas & E. Pérez RCD6052 (UACJ).
NUMBER 107 • 355

FIGURE 238. Tridentopsis mutica var. mutica. A. Habit. B. Inflorescence. C. Spikelet. D. Floret showing 

palea. E. Floret showing lemma. Drawn by Linda Ann Vorobik and Karen Klitz; copyright Utah State 

University.
356 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Triniochloa Hitchc.

Perennial; caespitose or rhizomatous. Leaves narrow; 

sheaths with the edges united. Inflorescences in form of a terminal panicle. Spikelets with 1 floret, disarticulating over the 

glumes; glumes subequal, 1-veined, purple, usually short; florets 

slender, subcylindrical; lemmas 7- to 9-veined, faintly veined, the 

margins somehow inrolled over the paleas, firmer than glumes; 

callus oblique, barbed with straight hairs; lemma apex acuminate, membranous, 2-toothed, the awn inserted above the half of 

the back; paleas almost as long as lemmas, 2-veined, veins very 

close to each other, scabrous; rachilla not extended farther than 

the palea. 

Triniochloa is an American genus with six species; five are 

found in Mexico.

370. Triniochloa laxa Hitchc., Contr. U.S. Natl. Herb. 17(3): 

304. 1913.

Plants perennial; rhizomatous, rhizomes 0.8–1 mm thick. 

Culms 40–80 cm tall. Sheaths pubescent; ligules 1.5–2.5 (3) mm 

long; blades 15–25 cm long, 3–5 mm wide, persistent. Panicles 

7–13 cm long, partially exserted, erect, narrow, with 6–18 spikelets. Spikelets 10–15 mm long; glumes subequal, 1-veined, purple, lower glumes 7.5–13 mm long, upper glumes 10–15 mm; 

lemmas 10–14.5 mm long, 7-veined, margins somehow inrolled 

over the palea, firmer than glumes, awns 12–22 mm long, dorsal, 

geniculate; paleas almost as long as lemmas, 2-veined, veins very 

close to each other, scabrous; rachilla not extended farther than 

the palea; anthers 5–7 mm long.

Distribution and Habitat. Triniochloa laxa is 

known only from Chihuahua, Mexico. Triniochloa laxa differs 

from other Mexican species of Triniochloa in having upper 

glumes about as long as the lemma, leaf blades 3–4 mm wide, 

and ligules 1.5–2.5 (3) mm long (Hitchcock 1913, 1935). 

Specimens Examined. MEXICO. Chihuahua.

Guerrero: On road between Tomochic and Bassaseachic, 20 mi 

E of jct w/ road S to San Juanito, 1.8 mi W of Aqua Caliente, 

5 Oct 1986, 2000 m, Spellenberg, Soreng, R. Corral & T. Lebgue 8876 (NMC).

Tripsacum L.

Perennial; monoecious, staminate and pistillate spikelets 

evidently distinct, located in the same inflorescences, pistillate 

spikelets below the staminate spikelets. Culms 0.7–5 m. Leaves 

not aromatic; sheaths open; ligules membranous, erose to ciliate. Inflorescences terminal and axillary, panicles of 1 to several 

subdigitate to racemose rames; rames with pistillate spikelets 

proximally and staminate spikelets distally; disarticulation in the 

rames, beneath the pistillate spikelets and at the base of the staminate portions. Pistillate spikelets exposed, solitary, embedded 

in the indurate rame axes; lower glumes coriaceous, closing the 

hollows in the rachises and concealing the florets; upper glumes 

similar but smaller; lower florets sterile; upper florets pistillate; 

lemmas and paleas hyaline, unawned; styles 2, not fused; staminate spikelets paired, both sessile or both subsessile, or 1 sessile and the other pedicellate; glumes coriaceous, chartaceous, 

or membranous; lemmas and paleas hyaline, unawned; pedicels 

(when present) not fused to the rame axes. x = 9.

Tripsacum is a genus of 12 species. All are native to tropical 

and subtropical regions of the Western Hemisphere, and three 

are native to North America.

KEY TO SPECIES OF TRIPSACUM

1. Superior spikelets of the staminate pair with slender pedicels 2–5 mm long; staminate portion of the inflorescence flexuous 

and pendulous; culms 1–2 m tall; terminal inflorescence with 2–5(9) racemes . . . . . . . . . . . . . . . . . . . . . . T. lanceolatum

1. Staminate spikelets on every pair sessile or almost sessile, or the superior with a thick pedicel 1–2 mm long, staminate portion of the inflorescence erect or lightly curved; inflorescence with 2 to 3 racemes, sometimes solitary.

2. Culms 0.6–1.2(1.5) m tall, 3–4 mm thick at the base; blades 0.5–1(1.6) cm wide, usually forming basal tufts at the flowering time; spike solitary, rarely 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T. zopilotense

2. Culms 2–4 m tall, 5–10 mm thick at the base; blades 1.5–2.5 cm wide, generally cauline; spikes usually 2 or 3, occasionally solitary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T. dactyloides

371. Tripsacum dactyloides (L.) L., Syst. Nat. (ed. 10) 2: 1261. 

1759. Coix dactyloides L., Sp. Pl. 2: 972. 1753.

FIGURE 239

Plants with short, knotty rhizomes. Culms 1–2(4) m tall, 

3–5 mm thick below, clumped. Sheaths usually glabrous, occasionally slightly pilose; ligules ciliate; blades 30–75(120) cm long, 

9–35(45) mm wide, flat, usually glabrous, tapering to attenuate 

apex. Terminal inflorescences erect, with (1)2–3(6) rames; rames 

12–25 cm long. Pistillate spikelets 6–8 mm long, 3–5.5 mm wide; 

staminate spikelets all sessile or subsessile; glumes 5–12 mm 

long, coriaceous, blunt, acute, or bifid; pedicels, when present, 

about 1 mm long, 0.5–0.8 mm wide, triangular in cross section, 

rigid. 2n = 36, 54, 72.

Distribution and Habitat. Tripsacum dactyloides grows in water courses and limestone outcrops from central and eastern United States through Mexico to northern South 

America. Plants from the United States and northern Mexico 

belong to Tripsacum dactyloides var. dactyloides. This variety 

differs from the other two varieties in having erect stems and sessile staminate spikelets (Barkworth, 2003b).

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 7.4 km W of Balleza on road to Guachochi, 18 Sep 1991, 

huizachal, 1660 m, P.M. Peterson, Annable & Valdés-Reyna 
NUMBER 107 • 357

10736 (CIIDIR, US); 11 mi SE of Balleza on road to Parral, 

1800, P.M. Peterson, M.B. Knowles, C.H. Dietrich & S.M. 

Braxton 13521 (US); 19.3 km SE of Balleza towards Parral, 26 

Sep 1988, oak woods, 1800 m, P.M. Peterson & Annable 5943

(US). Chinipas: Sierra Saguarivo, 1.3 mi W of Curahui, 9 Sep 

2008, tropical deciduous forest, 1001 m, P.M. Peterson & J.M. 

Saarela 22155 (US). Madera: Paraje Sirupa, ejido Cebollitas, 26 

Aug 1990, bosque de encino [oak forest], 1200 m, A. Benítez 

1998 (CIIDIR); Paraje Agua Caliente, predio particular [private 

property] El Chorrito, 26 Aug 1990, bosque de encino, 1500 m, 

O. Bravo 1301 (CIIDIR).

372. Tripsacum lanceolatum Rupr. ex E. Fourn., Mexic. Pl. 2: 

68. 1886.

FIGURE 240

Plants rhizomatous. Culms 1–2 m tall, 2–4 mm thick below. 

Lower sheaths hispid; upper sheaths essentially glabrous; ligules erose, not ciliate; blades to 100 cm long, 8–30 mm wide, 

glabrous or slightly pubescent. Terminal inflorescences with 

4–7(10) rames. Pistillate spikelets 2–3 mm wide, beadlike in appearance; staminate spikelets in sessile-pedicellate pairs; glumes 

5–10 mm long, 1.5–2 mm wide, usually membranous, acute; 

pedicels 2–5 mm long, less than 0.3 mm wide, almost flat to 

plano-convex in cross section, flexible. 2n = 72.

Distribution and Habitat. Tripsacum lanceolatum grows in moist soil (often in canyon bottoms) of mountains from southeastern Arizona and southwestern New Mexico 

through Mexico to Guatemala.

Specimens Examined. MEXICO. Chihuahua. 

Bocoyna: cerca [near] de Estación Divisadero, 16 Aug 1976, 

bosque de pino–encino [pine–oak forest], 1875 m, S. González 

693 (RELC). El Tule: 19.3 km SE of Balleza towards Parral, 26 

Sep 1988, oak woods, 1800 m, P.M. Peterson & Annable 5943

(ENCB). Chinipas: 1 mi E of Saguarivo, 10 Sep 2008, small arroyo with oaks and pines, 1490 m, P.M. Peterson & J.M. Saarela 

22161 (US). Guachochi: 24.6 km S of Mex 127 and 11.1 km NE 

of La Bufa, 11 Sep 1989, 2000 m, P.M. Peterson, Annable & 

Y. Herrera 8052 (ENCB, US). Moris: 9 mi E of Yécora on hwy 

16 towards Maycoba and 5 mi SE on a dirt road towards Talayote, 13 Oct 1992, bosque de Encino, 1800 m, P.M. Peterson 

& Annable 12480 (US).

373. Tripsacum zopilotense Hern.-Xol. & Randolph, Folleto 

Técn. de Estud. Espec. México 4: 22. 1950.

Plants caespitose, in large groups. Culms 0.6–1.2(1.5) m 

tall, 3–4 mm thick on the base, pilose or glabrous below the 

spikes. Inferior sheaths strongly hispid, the superior hirsute to 

glabrous; blades 25–35 cm long, 0.5–1(1.6) cm wide, pilose 

on both surfaces, forming basal tufts at flowering time. Inflorescences 10–16 cm long, a solitary raceme, rarely 2 then digitate, the pistilate portion 4–7 cm long, 2–2.5 mm thick when 

mature, rounded, with 5–11 pistilate spikelets, 5–7 mm long. 

Staminate spikelets 5–7 mm long, sessile; inferior glumes coriaceous. 2n = 36.

FIGURE 239. Tripsacum dactyloides. A. Culm base with short, 

knotty rhizome. B. Inflorescence and leaf blades. C. Inflorescence 

branch with staminate spikelets. D. Pistillate spikelet. Drawn by Linda 

Ann Vorobik and Hana Pazdírková; copyright Utah State University.
358 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Distribution and Habitat. Tripsacum zopilotense grows in grasslands, oak woodlands, and pine forests; it is 

known from Mexico and Central America.

Specimens Examined. MEXICO. Chihuahua.

Guachochi: slopes above Barranca de Basihuare, 28 Aug 2003, 

with Quercus–Pinus ponderosa, 1815 m, P.M. Peterson & 

P. Catalán 17574 (CIIDIR, US); W of Munérachi, 7 Sep 2003, 

matorral espinoso [thorny scrub], 1200 m, P.M. Peterson & 

P. Catalán 17715 (US). Ocampo: Parque Nacional “Cascada de 

Basaseachic,” ca. 130 air km W of Cuauhtemoc, 12 Sep 1987, 

1700 m, Spellenberg & D. Jewell 9260 (NMC); Parque Nacional 

“Cascada de Basaseachic,” ca. 100 m upstream from the top of 

the falls along the Rio Basaseachi, 17 Jun 1993, 2000 m, Spellenberg, L. Brouillet & E. Ulaszek 11871 (NMC); Beside the road 

near Ocampo, 26 Jul 1990, 2000 m, P. Jenkins 90-295 (ARIZ).

Trisetum Pers.

Annual or perennial; sometimes rhizomatous, sometimes 

caespitose. Culms glabrous or pubescent, basal branching extravaginal. Sheaths open the entire length or fused at the base; 

auricles absent; ligules membranous, often erose to lacerate, 

sometimes ciliolate; blades rolled in the bud. Inflorescence a terminal panicle, open and diffuse to dense and spikelike; branches 

antrorse-scabrous. Spikelets usually subsessile to pedicellate, 

rarely sessile, laterally compressed, with 2–5 florets; reduced florets (if present) distal; rachillas hairy, internodes evident, prolonged beyond the distal bisexual florets; disarticulation usually 

above the glumes and between the florets, subsequently below 

the glumes, in some species initially below the glumes; glumes 

subequal or unequal, keels scabrous, apex usually acute and unawned, often apiculate; lower glumes 1(3)-veined; upper glumes 

3(5)-veined, lateral veins less than 1⁄2 the glume length; calluses 

hairy; lemmas 3- to 7-veined, margins hyaline, unawned or 

awned from above the middle with a single awn, apex usually 

bifid, sometimes entire; paleas subequal, equal to, or longer than 

the lemmas, membranous, 2-veined, veins usually extended as 

bristlelike tips; lodicules 2, shallowly and usually slenderly lobed 

to fimbriate; anthers 3; ovaries glabrous or pubescent; styles 2. 

Caryopsis elongate-fusiform, compressed, brown; embryos elliptic, to 1⁄3 the length of the caryopsis; endosperm milky. x = 7. 

Trisetum is a genus of approx. 96 species occuring primarily 

in temperate, subarctic, and alpine regions and is currently being 

re-evaluated (Soreng et al., 2017b). There are approximately 38 

species in North America (Finot et al., 2004).

KEY TO SPECIES OF TRISETUM

1. Lemma apically entire, slightly 2-toothed or irregularly toothed, veins not prolonged farther than the apex; lemmas muticous to short-awned, the awn subapical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T. filifolium

1. Lemma 2-toothed on the apex, intermediate veins and/or marginal ones elongated beyond the apex forming 2–4 apical 

bristles; apical teeth veinless; lemmas awned, the awns well-developed, inserted on the distal 1⁄3, 1⁄2, or proximal 1⁄3 of the 

lemma, never subapical.

FIGURE 240. Tripsacum lanceolatum. A. Inflorescence and leaf 

blades. B. Inflorescence branch with staminate spikelets. Drawn by 

Linda Ann Vorobik and Hana Pazdírková; copyright Utah State 

University.
NUMBER 107 • 359

2. Awns always inserted on the distal 1⁄3 of the lemma (occasionally so in T. palmeri); glumes unequal, the lower glumes 

shorter and narrower than upper glumes; apex of the lemma with 2 bristles formed by the projection of the intermediate 

veins; lemmas clearly keeled in cross section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T. spicatum

2. Awns inserted on the proximal 1⁄3 or nearly 1⁄2 of the lemma; glumes subequal, almost as long as the spikelets or longer; 

lemmas with apical teeth lacking prolongations of the intermediate veins or having 2–4 bristles; lemma rounded in cross 

section.

3. Lemmas with the apex 2-lobed and 4-awned as teeth or bristles.

4. Ligules 3–6 mm long; paleas as long as or slightly longer than the lemmas; hairs of the rachilla 0.5–1(1.4) mm long 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T. palmeri

4. Ligules 0.5–1(2) mm long; paleas shorter than the lemmas; hairs of the rachilla 1.5–3 mm long . . . . . . T. viride

3. Lemmas with the apex 2-lobed, unawned or having additional bristles.

5. Spikelets bearing (4)5–6 florets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T. spellenbergii

5. Spikelets bearing 2–4 florets.

6. Ligules 3–6 mm long; paleas as long as or slightly longer than the lemmas; hairs of the rachilla 0.5–1(1.4) mm 

long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T. palmeri

6. Ligules 0.5–1(2) mm long; paleas shorter than the lemmas; hairs of the rachilla 1.5–3 mm long . . . . T. viride

374. Trisetum filifolium Scribn. ex Beal, Grass. N. Amer. 2: 375. 

1896.

Perennial; caespitose. Culms 30–60 cm tall, glabrous. 

Sheaths glabrous, escabrous or pubescent; ligule (0.2)1–3.5 mm 

long, membranous, truncate, glabrous; blades 5–22 cm long, 

0.5–2 mm wide, involute, filiform, curves and flexuous, glabrous 

to slightly scabrous. Panicles 12–15 cm long, 2–3 cm wide, lax, 

little spread, narrow, exserted, branches semiverticillate, with 

3–7(8) branches per node, the inferior 4–6 cm long, rachis glabrous. Spikelets 3.5–6 mm long, with (1)2–3 florets, pedicels 

scabrous, rachilla 1–1.2 mm long, with hairs 1.5 mm long, longer than the apex; glumes subequal, lower glumes 2.5–6 mm 

long, 1(3)-veined, upper glumes 3–7 mm long, 3-veined; lemmas 

3.5–5 mm long, obscurely veined, scabrous-pubescent, apex entire to shallowly bifid, every lobule muticous to mucronate, the 

mucro 0.2–0.5 mm long; paleas 3–4.5 mm long, keels ciliate or 

scabrous; anthers 1–2 mm long. Caryopsis 1.5–2 mm long with 

solid endosperm.

Distribution and Habitat. Trisetum filifolium 

is a Mexican species with two varieties, only Trisetum filifolium

var. aristatum Scribn. ex Beal grows in the moist, forested areas 

of Chihuahua and Durango.

Specimens Examined. MEXICO. Chihuahua. 

Bocoyna: Sánchez, 8000 ft, Hitchcock 7682 (MEXU); SW of 

Creel along Rio Oteros and in stand of Picea chihuahuana; 14 

Aug 1977, Bye 8018 (MEXU); S of San Ignacio Arareco, south 

of airstrip, SE of Creel, 27.7°N, 107.7°W, 20 Jul 1972, 2255 m, 

Bye 2404a (MEXU). Guachochic: Approx. 22.5 mi NE of Cieneguita de Barranca on road towards Creel, 5 Sep 2003, bosque de 

pino [pine forest], 2160 m, P.M. Peterson & P. Catalán 17696

(US); 5 km antes del entronque [before junction] a la Bufa carr. 

[hwy] Guachochic–Creel, 24 Sep 1981, 2500 m, M.E. Siqueiros 

1613 (MEXU). Guadalupe y Calvo: on high ledges, on summit 

of Sierra Mohinora, 16–17 Oct 1959, 10,000–10,300 ft, Correll 

& Gentry 23176 (MEXU, US); Sierra Mohinora, 13 Sep 2006, 

3076 m, P.M. Peterson, F.Sánchez Alvarado & E.P. Gómez Ruíz 

20050 (CIIDIR, US). Ocampo: Parque Nacional “Cascada de 

Basaseachic,” along river falls, 25 Abr [Apr] 1986, 1980 m, 

Spellenberg, Soreng, R. Corral & T. Lebgue 8434 (NMC); Memelichi, Rio Mayo, 14 Sep 1936, Gentry 2716 (MBO).

375. Trisetum palmeri Hitchc., Contr. U.S. Natl. Herb. 17: 325. 

1913.

Caespitose perennial. Culms 60–100 cm tall, glabrous. 

Sheaths glabrous to scabrous; ligules 3–6 mm long, truncate, 

toothed, ciliate on the apex; blades 10–20 cm long, 1–3(5) mm 

wide, involute or flat, stiff, scabrous, sometimes glaucous. Panicles 

10–20 cm long, 2–6 cm wide, lax, spread to narrow, branches 

4–6, verticillate, rachis and pedicels glabrous. Spikelets 5–6.5 mm 

long, bearing 2–3 florets, rachilla 2 mm long, pubescent, the hairs 

1–1.5 mm long; glumes subequal, linear-lanceolate, margin hyaline, apex acute; lower glumes 3.5–4.5 mm long, 1-veined; upper 

glumes 4–5 mm long, 3-veined; lemmas 4–5.3(6) mm long, fragile, 

translucent, 5-veined, awned, the awns 5–7 mm long, emerging 

from the proximal 1⁄3 of the lemma back, geniculate, twisted; paleas 4–5.5(6) mm long; anthers 2–2.5 mm long. 

Distribution and Habitat. Trisetum palmeri

grows in moist meadows and forests. This species is known from 

Chihuahua, Coahuila, Durango, Jalisco, Nuevo León, Sinaloa, 

and Sonora.

Specimens Examined. MEXICO. Chihuahua.

Madera: Laguna de Babicora, 4 km N del Ejido La Raiz, 10 Sep 

1994, 2300 m, G. Quintana & E. Estrada 3666 (NMC).

376. Trisetum spellenbergii Soreng, Finot & P. M. Peterson, 

Ann. Missouri Bot. Gard. 91: 1–30. 2004.

Perennial; with short rhizomes. Culms 40–60 cm tall, geniculate on the base, glabrous. Leaf sheaths open only at the 

apex, lower sheaths pilose, upper sheaths glabrous; ligules 

4.5–6 mm long, glabrous; lacerate, eciliate; blades 20–30 cm 

long, 2–3.5 mm wide, the superior smaller, 10–20 cm long, flat, 

soft, glabrous to sparsely pilose. Panicles 9–14 cm long, 2–8 cm 

wide, lax, spread, exserted, branches 2–5 per node. Spikelets 

7–9 mm long, bearing (4)5–6 florets, rachilla 1.5 mm long, 
360 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

pubescent, hairs 1–1.5 mm long, prolongate beyond of the superior floret, with 1 reduced floret; glumes subequal, green, purple over the apex and margins, lower glumes 5.5–6.5 mm long, 

0.3–0.5 mm wide, 1-veined, upper glumes 6.5–7.5 mm long, 

0.6–0.8 mm wide; lemmas 4–6.5 mm long, 5-veined, glabrous, 

apex bilobed, lobes 2 mm long, awns 8–12 mm long, emerging 

midlength, twisted, geniculate; paleas 3.5–5 mm long, 2-veined, 

veins scabrous-ciliate; stamens 3, anthers 1.2–2.5 mm long. 

Distribution and Habitat. Trisetum spellenbergii grows in moist meadows in forests; it is a Mexican endemic found in Chihuahua and Sonora.

Specimens Examined. MEXICO. Chihuahua.

Ocampo: Parque Nacional “Cascada de Basaseachic,” at overlook ca. 1 km airline S of Cascada, 3 Oct 1986, 2100 m, Spellenberg, Soreng, R. Corral & T. Lebgue 8654 (NMC); 122.5 km 

W of La Junta and 56.7 km W of Tomochic in Parque Nacional 

Cascada de Basaseachic, 2100 m, P.M. Peterson & R.M. King 

8246 (US); at Mirador Cascada Basaseachic, 2084 m, steep 

slopes below ridge with Pinus, 7 Sep 2008, P.M. Peterson & J.M. 

Saarela 22105 (US).

377. Trisetum spicatum (L.) K. Richt., Pl. Eur. 1: 59 .1890. Aira 

spicata L., Sp. Pl. 1: 64. 1753. 

FIGURE 241

Perennial; with both fertile and sterile shoots; caespitose, 

not rhizomatous. Culms 10–120 cm tall, erect, usually glabrous, sometimes scaberulous or villous. Leaves mostly basal or 

evenly distributed; sheaths variously pubescent or glabrous; ligules 0.5–4 mm long, truncate or rounded; blades (3)10–20(40) 

cm long, 1–5 mm wide, flat, folded, or involute, erect and stiff 

or ascending and lax. Panicles (5)20–30(50) cm long, (0.5)1–

2.5(5) cm wide, from spikelike to open, often interrupted basally, green, purplish, or tawny, usually silvery-shiny; branches 

with the spikelets evenly distributed. Spikelets 5–7.5 mm long, 

sessile, subsessile, or on pedicels to 1.5(3.5) mm long, with 2(3) 

florets; rachilla internodes 0.5–1.5 mm long; rachilla hairs up 

to 1 mm long; glumes subequal to unequal, lanceolate, usually smooth, sometimes scattered scabrous or pilose, with wide 

scarious margins, apex acute to acuminate, sometimes apiculate; lower glumes 3–4(5.5) mm long; upper glumes 4–7 mm 

long, equaling or exceeding the lowest florets, less than twice 

as wide as the lower glumes; callus hairs to 1 mm long; lemmas 3–6(7) mm long, narrowly to broadly lanceolate, glabrous, 

scaberulous, or pilose, apex bifid, teeth usually less than 1 mm 

long, awned, awns 3–8 mm long, arising from the upper 1⁄3 of the 

lemmas, geniculate, twisted basally; anthers 0.7–1.4 mm long. 

Caryopsis 1.5–3(4) mm long, glabrous. 2n =14, 28, 42.

Distribution and Habitat. Trisetum spicatum

grows in moist meadows, forests, rock ledges, and tundra slopes 

and screes up to 4,300 m. Its range includes both North and 

South America and Eurasia.

Specimens Examined. MEXICO. Chihuahua.

Balleza: 19.6 km W of Balleza and 74.2 km E of Guachochi, 

FIGURE 241. Trisetum spicatum. A. Habit. B. Ligule. C. Culm and 

Inflorescence. D. Spikelet. E. Floret. Drawn by Cindy Roché; copyright Utah State University.
NUMBER 107 • 361

18 Sep 1991, 2120 m, P.M. Peterson, Annable & Valdés-Reyna 

10752 (CIIDIR). Bocoyna: 20 km S of San Juanito on road to 

Creel and 3 km S of Bocoyna, 24 Sep 1988, pine forest, 2200 

m, P.M. Peterson & Annable 5873 (ENCB, US); 24.2 km S of 

San Juanito and 4.8 km N of Creel on Mex 127, 10 Sep 1989, 

pine forest, 2520 m, P.M. Peterson, Annable & Y. Herrera 8007

(ENCB, US). Guerrero: 38.6 km SW of La Junta and approx. 

70.8 km N of Creel at p. Arroyo Ancho crossing, 21 km marker, 

24 Sep 1988, pine woods, 2200 m, P.M. Peterson & Annable 

5848 (ENCB, US).

378. Trisetum viride (Kunth) Kunth, Révis. Gramin. 1: 101. 

1829. Avena viridis Kunth, Nov. Gen. Sp. (quarto ed.) 1: 

147. 1815.

Caespitose perennial. Culms 50–150 cm tall, erect, glabrous, simple, the lower 1⁄2 with few leaves. Sheaths retrorsely 

scaberulous to glabrous when mature; ligules 0.5–6 mm long, 

membranous, truncate, to sometimes pilose; blades 15–20 cm 

long, 2–6(9) mm wide, flat or some involute. Panicles 15–35 cm 

long, 4–6 mm wide, lax, to somewhat contracted, main axis 

scabrous, branches 5–16 cm long, ascending to some flexuous, 

naked on the lower 1⁄2. Spikelets 5–8(9.5) mm long, with 2- to 

3(5)-flowered, disarticulating above glumes and between the 

florets; rachilla pilose, the hairs 0.5–1 mm long, sometimes finishing in a rudimentary floret; glumes subequal; lower glumes 

3.5–6 mm long, 1-veined; upper glumes 4–7 mm long, 3-veined; 

lemma of the inferior florets 4–6 mm long, subcylindrical, margins involute, apex 2-toothed, the teeth acute or rounded, erose 

or with extended veins forming 4 slender teeth, awned, awns 

5–10 mm long, inserted on the lower 1⁄2, geniculate, flexuous, 

twisted; paleas equal or not as long as the lemmas, hyaline, the 

keels scabrous; stamens 3, anthers 1.5–2.5 mm long. Caryopses 

2–2.5 mm long, soft, endosperm liquid. 2n = 28.

Distribution and Habitat. Trisetum viride is 

found in pinyon forests in Chihuahua; it is known from Mexico 

to Central America.

Specimens Examined. MEXICO. Chihuahua. 

Bocoyna: Cabecera de la cañada de Recogoata, 22 Sep 1997, 

bosque de pino–encino [pine–oak forest], 2400 m, A. Carrillo 

30-A (MEXU). Chinipas: 1 mi E of Saguarivo, 10 Sep 2008, 

small arroyo with oaks and pines, 1490 m, P.M. Peterson & 

J.M. Saarela 22162 (US). Guachochi: 5.8 mi N of Creel on road 

(hwy 25) towards San Juanito, 5 Oct 2000, bosque de pino, 

2480 m, P.M. Peterson & J. Cayouette 15366 (US). Guadalupe y 

Calvo: Hwy 24, 103.5 km SW of Hidalgo del Parral, 2 Sep 1975, 

pine–oak–madroño woodland, 2500 m, N.H. Holmgren 8049 

(MEXU). Ocampo: Cordon Capellina, 5 km west of Huajumar 

air strip. 18 Aug 1989, pine–oak forest, 2500 m, P. Jenkins, P.S. 

Martin, R. Rondeau & W.M. Pierce 89-219 (ARIZ).

Triticum L.

Annual. Culms solitary or branched at the base; internodes usually hollow throughout in hexaploids, usually solid 

for about 1 cm below the spike in diploids and tetraploids, 

even if hollow below. Sheaths open; auricles present, often deciduous at maturity; ligules membranous; blades flat, glabrous 

or pubescent. Inflorescences usually terminal spikes, distichous, with 1 spikelet per node, occasionally branched; disarticulation in the rachis, the spikelets usually falling with the 

internode below to form a wedge-shaped diaspore, sometimes 

falling with the adjacent internode to form a barrel-shaped 

diaspore, domesticated taxa usually nondisarticulating, or disarticulating only under pressure. Spikelets usually 1–3 times 

the length of the internodes, appressed to ascending, with 2–9 

florets, the distal florets often sterile; glumes subequal, ovate, 

rectangular, or lanceolate, chartaceous to coriaceous, usually 

stiff, tightly to loosely appressed to the lower florets, with 1 

prominent keel, at least distally, keels often winged and ending in a tooth or awn, a second keel or prominent lateral vein 

present in some taxa; lemmas keeled, chartaceous to coriaceous, 2 lowest lemmas usually awned, scabrous, distal lemmas unawned or awned; paleas hyaline-membranous, splitting 

at maturity in diploid taxa; anthers 3. Caryopsis tightly (hulled 

wheats) or loosely (naked wheats) enclosed by the glumes and 

lemmas, lemmas and paleas not adherent; endosperm flinty or 

mealy. x = 7. 

Triticum is a genus of approximately 25 wild and domesticated species. It was first cultivated in western Asia at least 9,000 

years ago and is now the world’s most important crop, being 

planted more widely than any other genus.

379. Triticum aestivum* L., Sp. Pl. 1: 85. 1753.

FIGURE 242

Culms 14–150 cm tall; nodes glabrous or pubescent; internodes usually hollow, even immediately below the spikes. Leaf 

blades 6–15(20) mm wide, glabrous or pubescent. Spikes (3.5)6–

18 cm long, usually thicker than wide to about as thick as wide, 

wider than thick in compact forms; rachises shortly ciliate at 

the nodes and margins, not disarticulating. Spikelets 10–15 mm 

long, appressed or ascending, with 3–9 florets, 2–5 seed-forming; 

glumes 6–12 mm long, ovate, coriaceous, loosely appressed to 

the lower florets, usually keeled in the upper 1⁄2, sometimes prominently keeled to the base, terminating in a tooth or awn, the 

awns to 4 cm long; lemmas 10–15 mm long, toothed or awned, 

the awns to 12 cm long; paleas not splitting at maturity. Caryposis with mealy to flinty endosperm. 2n = 42.

Distribution and Habitat. Triticum aestivum

is the most widely cultivated wheat. Both winter and spring types 

are grown in Mexico.

Specimens Examined. MEXICO. Chihuahua.

Chihuahua: 38 km W of hwy 45 on road towards Benito Juárez, 

17 Oct 1992, pinyon woodlands, 2230 m, P.M. Peterson & Annable 12572 (US). Juárez: Area of high sand dunes 5 km N of 

Samalayuca on the Juárez hwy, 28 Oct 1972, desiertos arenoso 

[sandy deserts], 1250 m, T.L. Wendt, F. Chiang & M.C. Johnston 9934 (MEXU).
362 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Urochloa P. Beauv.

Annual or perennial; usually caespitose, sometimes matforming, sometimes stoloniferous. Culms herbaceous, erect, geniculate, or decumbent and rooting at the lower nodes. Sheaths 

open; auricles rarely present; ligules apparently of hairs, the 

basal membranous portion inconspicuous; blades ovatelanceolate to lanceolate, flat. Inflorescences terminal or terminal and axillary, usually panicles of spikelike primary branches 

in 2 or more ranks, rachises not concealed by the spikelets; 

primary branches usually alternate or subopposite, spikelike, 

and 1-sided, less frequently verticillate, axes flat or triquetrous, 

usually terminating in a well-developed, rudimentary spikelet; 

secondary branches present or absent, axes flat or triquetrous; 

disarticulation beneath the spikelets. Spikelets solitary, paired, 

or in triplets, subsessile or pedicellate, divergent or appressed, 

ovoid to ellipsoid, dorsally compressed, in 1–2(4) rows, with 

2 florets, lower or upper glumes adjacent to the branch axes; 

glumes not saccate basally; lower glumes usually 1⁄5–2⁄3 as long 

as the spikelets, occasionally equaling the upper florets, (0)1- to 

11-veined; upper glumes 5- to 13-veined; lower florets sterile 

or staminate; lower lemmas similar to the upper glumes, 5- to 

9-veined; lower paleas if present, usually hyaline, 2-veined; 

upper florets bisexual, sessile, ovoid to ellipsoid, usually planoconvex, usually glabrous, not disarticulating, mucronate or 

acuminate; upper lemmas indurate, transversely rugose and verrucose, 5-veined, margins involute, apex round to mucronate, 

or aristate; upper paleas rugose, shiny or lustrous; lodicules 2, 

cuneate, truncate; anthers 3. Caryopsis ovoid to elliptic, dorsally compressed; embryos 1⁄2–3⁄4 as long as the caryopsis. x = 7, 

8, 9, or 10. 

Urochloa is a genus of about 136 tropical and subtropical 

species. There are four species that occur in Chihuahua (Morrone and Zuloaga 1993).

KEY TO SPECIES OF UROCHLOA

1. Inflorescence with racemes alternate and inserted distichously; spikelets solitary at mid-branch length; in 1–2 series; pedicels 

all of equal length.

2. Rachis of the racemes triquetrous, not winged, 0.4–0.8(1) mm wide; rachilla internodes inconspicuous; lower glumes 

3-veined; plants perennial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . U. meziana

2. Rachis of the racemes flat, winged, 1–2.5 mm wide; rachilla internodes evident between the glumes; lower glumes 9- to 

11-veined; plants annual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . U. plantaginea

1. Inflorescence with racemes alternate, subopposite, or verticillate, inserted on all sides of the main axis; spikelets paired at 

mid-branch length, sometimes solitary distally, in 2–4 series; pedicels unequal in length.

3. Inflorescence branch axes densely hairy, the hairs papillose-based; spikelets 3.2–4 mm long . . . . . . . . . . . U. arizonica

3. Inflorescence branch axes sometimes densely hairy, with few or no papillose-based hairs; spikelets 2–3 mm long . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . U. fusca

380. Urochloa arizonica (Scribn. & Merr.) Morrone & Zuloaga, Darwiniana 32(1–4): 61. 1993. Brachiaria arizonica 

(Scribn. & Merr.) S. T. Blake

Annual. Culms 15–65 cm tall, erect or geniculate, branching from the lower nodes; nodes glabrous or hispid. Sheaths 

glabrous or with papillose-based hairs, margins ciliate distally; 

ligules 1–1.6 mm long; blades 5–15 cm long, 5–12 mm wide, 

glabrous. Panicles 6–20 cm long, 2–5 cm wide, ovoid, with 6–12 

raceme-like branches in more than 2 ranks; primary branches 

3–7 cm long, divergent, axes about 0.4 mm wide, triquetrous, densely pubescent with papillose-based hairs; secondary 

branches short, divergent; pedicels shorter than the spikelets, 

with papillose-based hairs. Spikelets 3.2–4 mm long, 1.2–1.6 

mm wide, mostly paired, in 2 rows, appressed to the branches; 

glumes scarcely separate, rachilla internodes short, not pronounced; lower glumes 1.5–2 mm long, to 1⁄2 as long as the spikelets, glabrous, 5-veined, sometimes with evident cross venation 

near the apex; upper glumes 2.5–3.2 mm long, glabrous or short 

hirsute, 7-veined, with evident cross venation distally; lower florets staminate or sterile; lower lemmas 2.5–3.2 mm long, about 

as long as the spikelet, glabrous or short hirsute, 5-veined; lower 

paleas present; upper lemmas 2.8–3 mm long, 1.2–1.6 mm wide, 

acute, beaked or mucronate; anthers 0.8–1 mm long. Caryopsis 

1.5–2 mm long; hila punctiform. 2n = 36.

Distribution and Habitat. Urochloa arizonica

is native to the southwestern United States and northern Mexico.

Specimens Examined. MEXICO. Chihuahua.

Aquiles Serdán: 20 km al S de Chihuahua, carr. [hwy] Chihuahua–Delicias, 26 Oct 76, matorral [scrub], 1450 m, Valdés-Reyna 

VR-810 (RELC). Bocoyna: entre [between] barrancas del cobre 

& Bachipere, 17 Aug 1976, bosque bajo de leguminosas [low 

legume forest], 1025 m, S. González & J.M. Peña 729 (ENCB, 

RELC). Buenaventura: km 11 San Buenaventura–El Carmen 

23 Oct 1954, matorral xerófilo [xerophilous scrub], 1400 m, 

Hern.-Xol. & Tapia N-137 (ENCB, US). Camargo: 20 km S of 

cd Camargo, 2 Aug 1939, 1220 m, L. H. Harvey 1391 (ENCB). 

Chihuahua: near Chihuahua, 16 Jul 1936, LeSueur 124 (US); 

LeSueur Mex-012 (US); 23 Aug 1885, C.G. Pringle 487 (US); 

13 mi SW of Chihuahua on road to Cuauhtémoc, 6 Oct 1959, 

1585 m, Soderstrom 916-A, 924 (US); 54 mi N of Chihuahua, 23 

Oct 1957, G. Morrow 7950 (US); 5 mi SW of Chihuahua on road 

to Cuauhtémoc, 6 Oct 1959, 1463 m, Soderstrom 902 (US); km 

14 al N de Cd. Chihuahua, 15 Sep 1955, 1400 m, Hern.-Xol. & 

V. Mathus N-1753 (US); 6 mi N of Chihuahua, 8 Oct 1959, 1494 
NUMBER 107 • 363

m, Soderstrom 924 (US); 12 mi N of Chihuahua city on road to 

cd. Juárez, 14 Aug 1950, mesquite savanna, Reeder, C. Reeder & 

Goodding 1688 (ENCB); 6 mi N of Chihuahua, 8 Oct 1959, Soderstrom 924 (ENCB, US); La Campana Experimental Station & 

Rancho El Arco Iris, 81–84 km along Pan American hwy to Chihuahua City, Oct 1977, 1500 m, J.K. Meents & W.H. Moir 73

(NMC); La Campana, Potrero El Plan, 1 km Ote. [W] carr. Panamericana, 9 Sep 73, pastizal [pastureland], 1500 m, Valdés-Reyna 

VR-164 (RELC). Janos: Chihuahua–Sonora border, Rancho Carretas, 26 Aug 1939, 1460 m, L. H. Harvey 1601 (ENCB, US); 2 

km W of Carretas, 21 Aug 1939, 1645 m, L. H. Harvey 1571 

(ENCB, US). Jiménez: 8 mi N of Jiménez on Mex 45 Chihuahua, 

30 Aug 1971, 4400 ft, L. H. Harvey 8892 (ENCB); Sierra de 

Santa Eulalia, 18 Jul 1939, 1400 m, L. H. Harvey 1532 (ENCB, 

US). Meoqui: Meoqui, 24 Aug 1935, LeSueur Mex-037 (US).

381. Urochloa fusca (Sw.) B. F. Hansen & Wunderlin, Novon 

11(3): 368. 2001. Panicum fuscum Sw., Prodr. 23. 1788. 

Brachiaria fasciculata (Sw.) Parodi, Urochloa fasciculata var. reticulata (Torr.) 

R. D. Webster.

Caespitose annual. Culms 15–120 cm tall, geniculate; nodes 

glabrous or shortly pilose. Sheaths glabrous or hispid, margins 

ciliate; ligules 1–1.5 mm long; blades 3–33 cm long, 5–20 mm 

wide, glabrous or sparsely pilose on both surfaces, margins 

smooth or scabrous; collars pubescent. Panicles 5–15 cm long, 

2–8 cm wide, simple, with 5–30 raceme-like primary branches 

inserted in more than 2 ranks; primary branches 2–10 cm long, 

appressed to divergent, axils glabrous, axes 0.3–0.5 mm wide, 

triquetrous, scabrous or sparsely pilose; secondary branches 

usually present on the lower primary branches; pedicels shorter 

than the spikelets, scabrous and pubescent. Spikelets 2–3.4 mm 

long, 1.2–1.8 mm wide, obovoid, yellowish to reddish-brown 

or bronze-colored at maturity, mostly paired, in 2–4 rows, appressed to the branches; glumes sparsely separate, rachilla internodes short, not pronounced; lower glumes 1–1.5 mm long, at 

least 1⁄3 as long as the spikelets, glabrous, (1)3- to 5-veined; upper 

glumes (2)2.2–3.1 mm long, glabrous, 7- to 9-veined, cross venation evident throughout; lower florets usually staminate, sometimes sterile; lower lemmas 2–3.1 mm long, usually glabrous, 

7-veined, cross venation evident throughout; lower paleas present; upper lemmas 1.8–2.9 mm long, 1.1–1.7 mm wide, apex 

acute to rounded, mucronate; anthers 1–1.6 mm long. Caryopsis 

1–1.7 mm long; hila punctiform. 2n = 18, 36.

Distribution and Habitat. Urochloa fusca

ranges from the southern United States to Peru, Paraguay, and 

Argentina; usually in moist, often disturbed areas at low elevations. It frequently occurs as a weed but is occasionally grown 

for forage and grain.

Specimens Examined. MEXICO. Chihuahua.

Ahumada: 5 km al N de Flores Magón, 7 Oct 1995, 1220 m, 

R. Corral, P. Olivas & J.O. Torres RCD6501 (UACJ). Batopilas: SW Chihuahua, Aug 1885, E. Palmer 1-A (US); 12.3 km 

N of Batopilas near the Río Batopilas, 12 Sep 1989, oak forest, 800 m, P.M. Peterson, Annable & Y. Herrera 8059 (US).

FIGURE 242. Triticum aestivum. A. Culm base. B. Inflorescence. 

C. Spikelet. Drawn by Cindy Roché, Hana Pazdírková, and Christine Roberts; copyright Utah State University.
364 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Camargo: 6 mi W of Piloncillo, rd from Jimenez to Camargo, 

24 Sep 1938, I.M. Johnston 7863 (US); Arroyo 20 km S of Cd. 

Camargo, 2 Aug 1939, 1220 m, L. H. Harvey 1391 (US); 25 mi 

NE of Camargo, 25 Sep 1938, F. Shreve 8891 (US). Chinipas: Sierra Saguarivo, 1.3 mi W of Curahui, 9 Sep 2008, 1001 m, P.M. 

Peterson & J.M. Saarela 22174 (US). Chihuahua: plains near 

Chihuahua, 2 Sep 1885, C.G. Pringle 379, 380 (US). Guazapares: W side RR tracks of Chihuahua al pacifico RR at Tacuina, 

13 Aug 1967, I.W. Knobloch 2283 (ENCB).

382. Urochloa meziana (Hitchc.) Morrone & Zuloaga, Darwiniana 32(1–4): 68. 1993. Brachiaria meziana Hitchc., Contr. 

U.S. Natl. Herb. 12(3): 140. 1908.

Perennial; with short rhizomes. Culms 10–40 cm tall, 

branched in the inferior nodes. Sheaths pilose; ligules 0.6–1 mm 

long, a hairy row; blades 5–15 cm long, 5–10 mm wide, flat, 

rounded at the base, pilose. Inflorescence 2–5(9) cm long, 

1–4 cm wide, angled, sparse with 5–10 racemes, these alternately inserted and tightly distichous, the rachis triquetrous, the 

racemes 1–3 cm long. Spikelets 2.7–3.6 mm long, 1.5–1.7 mm 

wide, solitary, glabrous, ovate-acute, with pilose pedicels; 

lower glumes 1–1.5(1.8) mm long, subacute, 3-veined, upper 

glumes 3–3.4 mm long, 5(7)-veined, rachilla internode inconspicuous; inferior lemmas equal to the upper glumes, 5-veined, 

ribbed on the middle part of the dorse, inferior palea translucid, widely ellipsoid; superior florets bisexual, superior lemma 

hardened, papillose. Caryopsis 2.4–2.6 mm long, 1.1–1.3 mm 

wide, ovoid. 

Distribution and Habitat. Urochloa meziana grows in grasslands, xerophytic scrub, and pine forests. 

It is known from Aguascalientes, Chihuahua, Coahuila, Colima, Distrito Federal, Durango, Guanajuato, Hidalgo, Jalisco, 

México, Michoacán, Nuevo León, Oaxaca, Puebla, Querétaro, 

San Luis Potosí, Tamaulipas, Veracruz, and Zacatecas (Espejo 

Serna et al., 2000).

Specimens Examined. MEXICO. Chihuahua.

Chihuahua: valley near Chihuahua, 20 Sep 1885, C.G. Pringle 375 (US); km 71 Cd. Chihuahua–Cuauhtémoc, 27 Oct 

1954, 1700 m, Hern.-Xol. & C. Tapia N-320 (US). Guachochi: 

37.4 km S of Creel on road to Batopilas, 10 Sep 1989, pine forest, 2045 m, P.M. Peterson, Annable & Y. Herrera 8010 (ENCB, 

US). Gran Morelos: 10 mi W of General Trías off hwy 16, 19 Jul 

1975, 5850 ft, Ellis, Dunn & Wallace 935 (ENCB).

383. Urochloa plantaginea* (Link) R. D. Webster, Syst. Bot. 

13(4): 607. 1988. Brachiaria plantaginea (Link.) Hitchc., 

Contr. U.S. Natl. Herb. 12(6): 212. 1909.

FIGURE 243

Annual. Culms 20–100 cm long, decumbent, geniculate, 

branching and rooting at the lower nodes; nodes glabrous. 

Sheaths mostly glabrous, except the margins ciliate, with 

papillose-based hairs; ligules 0.5–1.5 mm long; blades 3–21 cm 

long, 6–20 mm wide, glabrous, bases subcordate to cordate, 

clasping the stems, margins sometimes ciliate basally. Panicles 

6–25 cm long, 2–7 cm wide, with 3–8 racemes, these alternately 

inserted and distichous; primary branches 2–11 cm long, axes 

1–1.5 mm wide, flat, margins scabrous; secondary branches absent; pedicels shorter than the spikelets, glabrous or scabrous. 

Spikelets (4)4.5–6 mm long, 1.9–2.2 mm wide, solitary, appressed to the branch axes, in 2 rows; glumes separated by an 

internode of about 0.5 mm; lower glumes 1.5–2.5 mm long, 

about 1⁄3 as long as the spikelets, broadly ovate, glabrous, 9- to 

11-veined; upper glumes 3–4.2 mm long, glabrous, 7(9)-veined, 

without evident cross venation; lower florets sterile; lower lemmas 3–4.2 mm long, glabrous, 5-veined; lower paleas present; upper lemmas 2.7–3.6 mm long, 1.5–2 mm wide, apex 

rounded; anthers 0.7–1 mm long. Caryopsis 2–2.5 mm long. 

2n = 36, 72.

Distribution and Habitat. Urochloa plantaginea, native to western and central Africa, is found from the 

southern United States to Argentina. It is now established in the 

southeastern United States and northern Mexico, growing in 

loose sand and loamy soils. This species has been reported in 

Chihuahua (Espejo Serna et al., 2000).

Zea L.

Annual or perennial; monoecious, inflorescences unisexual 

or bisexual with the pistillate spikelets basal and the staminate 

spikelets distal. Culms solitary or several to many together, 

monopodial, often branching (branches frequently highly reduced and hidden within the subtending leaf sheath), usually 

succulent when young, becoming woody with age; lower nodes 

with prop roots; internodes pith-filled. Leaves not aromatic, 

cauline, distichous; sheaths open; auricles sometimes present; 

ligules membranous, shortly ciliate; blades flat. Pistillate or partially pistillate inflorescences terminal on axillary branches; staminate inflorescences (tassels) paniculate, of 1 to many branches 

or rames, sometimes with secondary and tertiary branching. 

Wild taxa: Pistillate inflorescences solitary, distichous rames 

(ears), these often tightly clustered in false panicles, each usually 

wholly or partially enclosed by a thin prophyll and an equally 

thin bladeless leaf sheath; rames composed of 5–15 spikelets in 

2 ranks; disarticulation in the rame axes, dispersal units (fruit 

cases) consisting of an indurate, shiny rame segment and its embedded spikelet. Pistillate spikelets solitary, sessile, with 1 floret; pedicels and pedicellate spikelets suppressed; lower glumes 

exceeding the floret, indurate on the central, exposed portion, 

hyaline on the margins, concealing the caryopsis at maturity. 

Domesticated taxon: Pistillate inflorescences solitary, polystichous spikes (ears) terminating reduced branches, each spike 

surrounded by several to many, often bladeless leaf sheaths and 

a prophyll (husks), with 60–1000+ spikelets in 8–24 rows, neither spikes nor spikelets disarticulating at maturity. Pistillate 

spikelets in subsessile pairs, each spikelet with 1 functional floret; glumes shorter than the spikelets, indurate basally, hyaline 

distally; lower florets suppressed. All taxa: lemmas and paleas 
NUMBER 107 • 365

hyaline, unawned; lodicules absent; ovaries glabrous; styles 

(silks) 2, appearing solitary by being fused except at the very tip, 

filamentous, sides stigmatic. Caryopsis subspherical to dorsally 

compressed; hila round; embryos about 2⁄3 as long as the caryopsis. Wild taxa: Staminate panicles terminal on the culms and primary branches, sometimes also on the secondary branches and 

pistillate inflorescences; rames distichous, similar in thickness 

and structure, axes disarticulating below the sessile spikelets 

after pollination, abscission layers evident. Domesticated taxon: 

Staminate panicles terminal on the culms, central axes always 

much thicker than the lateral branches and irregularly polystichous, lateral branches distichous to more or less polystichous, 

not disarticulating, without abscission layers below the sessile 

spikelets. All taxa: Staminate spikelets in sessile-pedicellate 

pairs, each with 2 staminate florets; glumes membranous to 

chartaceous, stiff to flexible, sometimes with a pair of winged 

keels, 5- to 14(28)-veined, acute; lemmas and paleas hyaline; 

lodicules 2; anthers 3. x = 10. 

Zea is an American genus of five species, four of which are 

native to montane Mexico and Central America.

384. Zea mays L., Sp. Pl. 2: 971–972. 1753.

Annual. Culms (0.5)1–3(6) m tall, (0.5)1–5 cm thick. Blades 

mostly 30–90 cm long, 2.5–12 cm wide. Pistillate inflorescences 

rames or spikes, usually shortly pedunculate (sometimes sessile), 

solitary, 4–30(40) cm long, (0.5)1–10 cm thick, with 2 or more 

rows of paired spikelets, hence the spikelets 4 or more ranked, 

rarely terminating in an unbranched staminate inflorescence. 

Caryopsis concealed in fruit cases (wild taxa) or exposed (domesticated taxon); fruit cases of wild taxa distichous, triangular in side view; domesticated taxon without fruit cases, glumes 

reduced and shallow or collapsed and embedded in the rachis. 

Staminate panicles 10–25+ cm long, with 1–60(235) branches, 

internodes 1.5–8.2 mm long; spikelets 9–14 mm long, 2.5–5 mm 

wide; lower glumes rounded dorsally, flexible, translucent, papery, loosely enclosing the upper glumes, the 2 lateral veins subequal to the others, not winged. 2n = 20.

Distribution and Habitat. Zea mays has five 

subspecies, only the domesticated Z. mays subsp. mays, and the 

wild Z. mays subsp. mexicana grow in Chihuahua (Espejo Serna 

et al., 2000).

FIGURE 243. Urochloa plantaginea. A. Habit. 

B. Inflorescence. C. Spikelet showing lower 

glume. D. Spikelet showing upper glume. 

Drawn by Linda Ann Vorobik and Cindy 

Roché; copyright Utah State University.
366 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

KEY TO SUBSPECIES OF ZEA MAYS

1. Pistillate inflorescences cylindrical spikes, 2–5(10) cm thick, with 8–24+ rows of spikelets pairs, each inflorescence tightly 

and permanently enclosed by several leaf sheaths and a large prophyll, not disarticulating at maturity; caryopsis 60–1000+, 

not concealed by the glumes; staminate panicle branches not disarticulating below the sessile spikelets, lacking abscission 

layers; central axis of the staminate panicles polystichous, much thicker than the lateral branches; obligate domesticated 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Z. mays subsp. mays

1. Pistillate inflorescences cylindrical, distichous rames, less than 1 cm thick, with 2 rows of spikelet pairs, each rame usually enclosed by a single leaf sheath and a prophyll, disarticulating at maturity into fruit cases; caryopsis 4–15, each one 

concealed within a fruit case; staminate panicles composed of rames that disarticulate below the sessile spikelets and have 

evident abscission layers; central axis of the staminate panicles similar in width to the rames; wild . . . . . . . . . . . . . . . . . . 

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Z. mays subsp. mexicana

Zea mays L. subsp. mays

FIGURE 244

Distribution and Habitat. Known from Canada, United States, Mexico, Central and South America, and the 

Caribbean.

Zea mays subsp. mexicana Iltis, Annual Rev. Genetics 5: 450. 

1971.

FIGURE 245

Distribution and Habitat. Known from Mexico in Chihuahua, Distrito Federal, Durango, Guanajuato, Guerrero, Jalisco, Michoacán, Nuevo León, Oaxaca, Puebla, and 

Querétaro.

Zuloagaea Bess

Perennial; caespitose, rhizomatous, rhizomes short, thin. 

Culms clumped or solitary, often with hard, cormlike bases, 

slightly compressed, erect or geniculate at the lower nodes. 

Sheaths shorter than the internodes, keeled, often pilose, hairs 

papillose-based near the throat; ligules membranous-based, 

ciliate; blades flat, adaxial surfaces scabrous. Panicles pyramidal, open, bearing 4–40 branches, basal node with 1 branch; 

primary branches with 3–6 orders of branching, straight or 

flexible, ascending to reflexed; pedicels scaberulous, divergent. 

Spikelets ellipsoid or lanceoloid, purplish or greenish, glabrous, 

acute or obtuse; lower glumes about 2⁄3 as long as the upper 

glumes, 3- to 5-veined; upper glumes slightly shorter to subequal to the lower lemmas, glabrous, 5- to 7-veined; lower 

florets sterile or staminate; lower lemmas glabrous, 5-veined, 

acute; lower paleas 3–4 mm long, hyaline; upper florets exceeding the upper glumes, margins embracing the lower lemmas, 

dull, pale, finely transversely rugose, apex acute, puberulent; 

anthers yellow-brown; stigmas pale purple, plumose. Caryopsis

oblong, compressed, embryos about 1⁄3 the length of the caryopsis. x = 9. 

Zuloagaea is a monotypic genus that is native to western 

North America. 

385. Zuloagaea bulbosa (Kunth) E. Bess, Syst. Bot. 31: 656–670. 

2006. Panicum bulbosum Kunth, Nov. Gen. Sp. (quarto ed.) 

1: 99. 1815.

FIGURE 246

Culms 20–200 cm tall, 1–8 mm thick, erect or geniculate 

at the lower nodes; nodes glabrous or pilose; internodes glabrous. Sheaths shorter than the internodes, keeled, glabrous or 

pilose, hairs near the throat papillose-based; ligules with a 0.1–2 

mm long membranous base and 0.10–3 mm long ciliate fringe; 

blades (6)20–75 cm long, 1.5–15 mm wide. Panicles 9–75 cm 

long, width to about 2⁄3 length; branches straight or flexible, 

strongly ascending to reflexed; pedicels 0.2–5 mm long. Spikelets 2.5–5.5 mm long, 1–2 mm wide; lower glumes 1.2–3.5 mm 

long, 1⁄2–4⁄5 as long as the spikelets, 3- to 5-veined; upper glumes 

1.4–4 mm long; lower florets sterile or staminate; lower lemmas 

2.9–3.3 mm long; upper florets 2.1–5 mm long, 1–1.5 mm wide, 

lemma apex puberulent. 2n = 36, 54, 70, 72.

Distribution and Habitat. Zuloagaea bulbosa 

grows in roadside ditches and on gravelly river banks and moist 

mountain slopes, often in pine–oak forests. It is found from 

southern Nevada and Arizona to west Texas and central Mexico.

Specimens Examined. MEXICO. Chihuahua. 

Balleza: 15 mi E of El Vergel on road to Parral, 21 Oct 1959, 

on pine–oak slope of mountain, 7500 ft, D.S. Correl & Gentry 

23261 (ENCB); 56.4 km W of Parral on road to Balleza and 

35.5 km S of Balleza on Mex 432, near Corral de Duarte, 18 Sep 

1991, bosque de pino–encino [pine–oak forest], 2210 m, P.M. 

Peterson, Annable & Valdés-Reyna 10724 (CIIDIR); 3 km al S 

de Agua Blanca, 27 Jul 1986, bosque de pino, 2500 m, H. Cota 

7287 (ENCB). Batopilas: Yamuco at 1 km E of hwy towards 

Basihuare and Creel, N of Río Urique crossing, 26 Aug 2003, 

pine–oak forest, 1891 m, P.M. Peterson & P. Catalán 17538 

(CIIDIR). Bocoyna: 24.7 mi N of San Juanito on road towards 

Cuauhtemoc, 5 Sep 2008, 2233 m, P.M. Peterson & J.M. Saarela 22030 (US). Buenaventura: San Buenaventura, 9 Sep 1975, 

Quercus emoryi dominte, 1850 m, J. Passini & M.F. Robert 6583 

(ENCB). Chihuahua: near Chihuahua, 7 Aug 1885, C.G. Pringle 

377 (US); La Campana 4 km W carr [hwy] panamericana, 5 sep 

1973, pastizal amacollado con encino [grass pasture with oak], 
NUMBER 107 • 367

1700 m, Valdés-Reyna VR-87 (ENCB, RELC); Rancho La acampana, 82 km al N de la cd. de Chihuahua, 26 Aug 1978, jardines 

de observación [observation gardens], 1550 m, C.A. Fernández 

s.n. (ENCB).Guachochi: 8 km al W de Cabórachi, 12 Aug 1982, 

bosque de pino–encino, 2100 m, R. Hernández 8754 (CIIDIR); 

along Río Corareáchi, 30 Aug 2003, slopes with Quercus spp., 

Cupressus, Arbutus, and Juniperus, 1840–1900 m, P.M. Peterson & P. Catalán 17598 (CIIDIR, US); 24.6 km S of Mex 127 

and 11.1 km NE of La Bufa, 11 Sep 1989, oak forest, 2000 m, 

P.M. Peterson, Annable & Y. Herrera 8051 (ENCB, US); 8 km al 

W de Cabórachi, 12 Aug 1982, bosque de pino–encino, 2100 m, 

A. Carrillo 2001 (CIIDIR); entre [between] Creel & San Rafael, 

14 Aug 1976, bosque de pino–madroño–encino, 2501 m, S. 

González & J.M. Peña 683 (RELC). Guadalupe y Calvo: Mt. 

Mohinora, SW Chihuahua, 1 Sep 1898, E.W. Nelson 4901 (US). 

Guerrero: 32.3 km SW of La Junta on road to Creel, 10 Sep 1989, 

pine forest, 2310 m, P.M. Peterson, Annable & Y. Herrera 7987

(ENCB, US); 38.6 km SW of La Junta and approx. 70.8 km N of 

Creel at p. Arroyo Ancho crossing, 21 km marker, 24 Sep 1988, 

pine woods, 2200 m, P.M. Peterson & Annable 5855 (ENCB, 

US); entre Cuauhtémoc & La Junta, 12 Aug 1976, bosque de 

encino, 2185 m, S. Gonzáles & J.M. Peña 562 (ENCB). Ignacio Zaragoza: Ejido de León, 12 Sep 1975, 2100 m, J. Passini 

& M.F. Robert 6701, 6723 (ENCB). Janos: Chihuahua–Sonora 

Border, Rancho Carretas, 27 Aug 1939, 1460 m, L. H. Harvey 

1616 (US). Madera: Arroyo de la Quinta, ejido “El Largo”, 30 

Aug 1990, bosque de pino, 2340 m, A. Benítez 2088 (CIIDIR); 

Proximidad a la Col. Chuichupa, 1 Sep 1990, bosquete de junipero [juniper grove], 2240 m, A. Benítez 2166 (CIIDIR); Mesa 

de Tenuñes, ejido El Largo, 20 Aug 1990, bosque de encino, 

2120 m, O. Bravo 1170 (CIIDIR); Mesa del Yerbanís, ejido El 

Largo, 12 Oct 1990, bosque de Quercus, 1900 m, O. Bravo 

1840 (CIIDIR); Puerto del Tenedor, ejido El Largo, 21 Aug 1990, 

bosque de pino–encino, 2450 m, O. Bravo 1206 (CIIDIR); La 

Tinaja, ejido El Largo, 29 Aug 1990, bosque de encino–pino, 

1840 m, O. Bravo 1350 (CIIDIR); Near Col. Garcia in the Sierra 

Madre, 5 Aug 1899, 2300 m, C.H.T. Townsend & C.M. Barber 221 (NMC); Laguna de Babicora, alrededores [around] de 

Nicolas Bravo, 18 Aug 1994, 2200 m, Quintana, Lebgue & Estrada 3141 (NMC). Matamoros: 4 mi SW of Villa Matamoros, 

5 oct 1959, 6000–6300 ft, Correll & Gentry 22821 (ENCB). 

Ocampo: Parque Nacional “Cascada de Basaseachic”, 1 Aug 

1988, Sandy pockets in rocks, 2000 m, Spellenberg, R. Corral, 

J. Brunt & L. Huenneke 9617 (CIIDIR); Pinos Altos, 13 km 

FIGURE 244. Zea mays subsp. mays. A. Habit. B. Pistillate spike. C. 

Pistillate spikelet pair. D. Staminate branches. E. Staminate spikelets. 

F. Staminate lower glume. Drawn by Linda Ann Vorobik; copyright 

Utah State University.
368 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

FIGURE 245. Zea mays subsp. mexicana. A. Habit. B. Pistillate branches. C. Fruit case, ventral view. D. Fruit case, lateral 

view. E. Staminate branch. F. Staminate lower glume. Drawn 

by Linda Ann Vorobik; copyright Utah State University.

FIGURE 246. Zuloagaea bulbosa. A. Habit. B. Spikelet 

showing lower glume. C. Spikelet showing upper glume. 

D. Upper floret, ventral view. Drawn by Linda Ann Vorobik and Cindy Roché; copyright Utah State University.
NUMBER 107 • 369

al O de Basaseachic, 9 a 12 oct 1977, bosque de pino–encino, 

entre 1700 & 2000 m, J.D. Tejero & A. Muños 3982 (CIIDIR); 

Parque Nacional Cascada de Basaseachic, 100 m upstream from 

the top of the falls along the Rio Basaseachi, 1 Aug 1988, 2000 

m, Spellenberg, R. Corral, J Brunt & L. Huenneke 9617 (NMC); 

Parque Nacional “Cascada de Basaseachic,” at overlook ca. 

1 km airline S of Cascada, 3 Oct 1986, 2100 m, Spellenberg, 

Soreng, R. Corral & T. Lebgue 8651 (NMC); Parque Nacional Cascada basaseachic, por la vereda que va de la parte alta 

de la cascada [along the path from the top of the waterfall] a 

“La Ventana”, 22 Sep 1994, bosque de pino–encino, 1980 m, 

R. Corral, Spellenberg & E. Estrada RCD5448 (UACJ). Riva 

Palacio: Majalca (Pilares), 11 Aug 1939, 2075 m, L. H. Harvey 

1451 (ENCB); Col. Cumbres de Majalca, 33.8 km W of Mex 

45, N of Chihuahua City, 7 Sep 1989, pine forest, 2190 m, P.M. 

Peterson, Annable & Y. Herrera 7961 (ENCB, US). Temosachi: 

Nabogame, 7 Sep 1987, 1800 m, Laferr. 1025 (NMC). Urique: 

225 air km SW of Cd. Chihuahua on the Rio Batopilas, 5 km 

downstream from the bridge at La Bufa, 19 Oct 1986, 1160 m, 

Spellenberg & N. Zucker 8929 (NMC).

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Taxon names in bold are accepted; names in regular type are synonyms. Page numbers in 

bold italics denote account description.

Achnatherum curvifolium (Swallen) Barkworth, 15, 16

Achnatherum eminens (Cav.) Barkworth, 16, 17

Achnatherum hymenoides (Roem. & Schult.) Barkworth, 15, 17, 18

Achnatherum multinode (Scribn. ex Beal) Valdés-Reyna & Barkworth, 15, 18

Achnatherum robustum (Vasey) Barkworth, 15, 18, 19

Aegilops cylindrica Host, 19

Aegopogon cenchroides Humb. & Bonpl. Ex Willd., 221

Aegopogn imperfectus Nash, 237

Aegopogon tenellus (DC.) Trin., 276

Aegopogon tenellus var. abortivus (E. Fourn.) Beetle, 237

Agropyron arizonicum Scribn. & J. G. Sm., 137

Agropyron barbulatum Schur, 351

Agropyron cristatum (L.) Gaertn., 3, 20, 21

Agropyron cristatum subsp. desertorum (Fisch. ex Link) Á. Löve, 21

Agrostis exarata Trin., 21, 22

Agrostis hyemalis (Walter) Britton, 21, 22, 23

Agrostis scabra Willd., 21, 23, 24

Agrostis semiverticillata (Forssk) C. Chr., 319

Agrostis stolonifera var. palustris (Huds.) Farw., 3, 21, 24, 25

Agrostis subrepens (Hitchc.) Hitchc., 21, 25

Agrostis viridis Gouan, 319

Aira flexosa L., 50

Aira obtusata Michx., 338

Aira spicata L., 360

Alopecurus geniculatus L., 3, 26

Alopecurus monspeliensis L., 317

Andropogon annulatus Forrsk., 110

Andropogon barbinodis Lag., 52

Andropogon cirratus Hack., 321

Andropogon contortus L., 180

Andropogon fastigiatus Sw., 26, 27

Andropogon gerardii Vitman, 26, 27

Andropogon glomeratus (Walter) Britton, Sterns & Poggenb., 26, 28

Andropogon glomeratus var. pumilus (Vasey) Vasey, 28

Andropogon insularis L., 115

Andropogon laguroides Cat., 53

Andropogon melanocarpus Elliot, 181

Andropogon nutans L., 334

Andropogon perforatus Trin. ex E. Fourn., 54

Index to Scientific Names 

(Grasses)
376 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Andropogon scoparius Michx., 323

Andropogon tener (Nees) Kunth, 323

Andropogon wrightii Hack., 54

Anthoxanthum odoratum L., 3, 28, 29

Aristida adscensionis L., 30, 31

Aristida appressa Vasey, 30, 32

Aristida arizonica Vasey, 30, 32, 33

Aristida dissita I. M. Johnston, 38

Aristida divaricata Humb. & Bonpl. ex Willd., 

30, 33, 34, 36

Aristida eludens Allred & Valdés-Reyna, 30, 34

Aristida gentilis Henrard, 44

Aristida gibbosa (Nees) Kunth, 30, 34, 35

Aristida glauca (Nees) Walp., 40

Aristida gypsophila Beetle, 30, 35, 36

Aristida gypsophila fo. diffussa Allred & 

Valdés-Reyna, 36

Aristida gypsophila fo. gypsophiloides Allred 

& Valdés-Reyna, 36

Aristida hamulosa Henrard, 44

Aristida havardii Vasey, 30, 36

Aristida laxa Cav., 30, 37

Aristida laxa var. laxa, 37

Aristida longespica Poir., 30, 37

Aristida pansa Wooton & Standl., 30, 38

Aristida pansa fo. dissita (I. M. Johnston) 

Allred & Valdés-Reyna, 38

Aristida pansa fo. pansa, 38

Aristida purpurea Nutt., 30, 39

Aristida purpurea var. fendleriana (Steud.) 

Vasey, 39, 40

Aristida purpurea var. longiseta (Steud.) Vasey, 

39, 40

Aristida purpurea var. nealleyi (Vasey) Allred, 

39, 40, 41

Aristida purpurea var. perplexa Allred & 

Valdés-Reyna, 39, 41

Aristida purpurea var. purpurea, 41

Aristida purpurea var. wrightii (Nash) Allred, 

39, 41

Aristida roemeriana Scheele, 41

Aristida schiedeana Trin. & Rupr., 30, 42, 43

Aristida schiedeana var. orcuttiana (Vasey) 

Allred & Valdés-Reyna, 43

Aristida spanospicula Allred, Valdés-Reyna & 

Sánchez-Ken, 30, 44

Aristida stricta var. nealleyi Vasey, 40

Aristida ternipes Cav., 30, 44

Aristida ternipes var. gentilis (Henrard) 

Allred, 44

Aristida ternipes var. hamulosa (Henrard) 

Trent, 44

Aristida ternipes var. ternipes, 44

Aristida wrightii Nash, 41

Arundinaria acuminata Munro, 283

Arundo australis Cav., 304

Arundo donax L., 3, 46, 47

Arundo selloana Schult. & Schult. f., 101

Atheropogon medius E. Fourn., 72

Atheropogon radicosus E. Fourn., 73

Avena deyeuxioides Kunth, 298

Avena fatua L., 3, 47, 48

Avena sativa L., 3, 47, 48

Avena viridis Kunth, 361

Avenella flexuosa (L.) Drejer, 36

Bealia mexicana Scribn., 218

Berchtoldia bromoides J. Presl, 97

Berchtoldia oplismenoides E. Fourn., 131

Blepharidachne bigelovii (S. Watson) Hack., 51

Blepharoneuron shepherdii (Vasey) P. M. Peterson & Annable, 267

Blepharoneuron tricholepis (Torr.) Nash, 274

Bothriochloa barbinodis (Lag.) Herter, 51, 52

Bothriochloa barbinodis var. perforata (Trin. ex 

E. Fourn.) Gould, 54

Bothriochloa laguroides (DC.) Herter, 51, 53, 54

Bothriochloa laguroides var. torreyana (Steud.) 

M. Marchi & Longhi-Wagner, 54

Bothriochloa perforata (Trin. ex E. Fourn.) 

Herter, 51, 54

Bothriochloa saccharoides (Sw.) Rydb., 54

Bothriochloa springfieldii (Gould) Parodi, 51, 

54, 55

Bothriochloa wrightii (Hack.) Henrard, 51, 

54, 55

Bouteloua aristidoides (Kunth) Griseb., 56, 

58, 59

Bouteloua aristidoides var. aristidoides, 58, 59

Bouteloua barbata Lag., 57, 59

Bouteloua barbata var. barbata, 60

Bouteloua barbata var. rothrockii (Vasey) 

Gould, 60, 61

Bouteloua breviseta Vasey, 57, 60, 61

Bouteloua chihuahuana (M. C. Johnston) 

Columbus, 3, 57, 61, 62

Bouteloua chondrosioides (Kunth) Benth. ex 

S. Watson, 57, 62

Bouteloua curtipendula (Michx.) Torr., 3, 56, 

63, 79

Bouteloua curtipendula var. caespitosa Gould 

& Kapadia, 63, 64

Bouteloua curtipendula var. curtipendula, 63, 

64, 65

Bouteloua curtipendula var. tenuis Gould & 

Kapadia, 63, 65

Bouteloua dactyloides (Nutt.) Columbus, 56, 

65, 182

Bouteloua diversispicula Columbus, 56, 66

Bouteloua eludens Griffiths, 57, 66, 67

Bouteloua erecta (Vasey & Hack.) Columbus, 

56, 66, 67

Bouteloua eriopoda (Torr.) Torr., 57, 68

Bouteloua gracilis (Kunth) Lag. ex Griffiths, 3, 

57, 58, 69, 149, 151,155, 214

Bouteloua hirsuta Lag., 57, 70

Bouteloua hirsuta var. glandulosa (Cerv.) 

Gould, 70

Bouteloua hirsuta var. hirsuta, 70, 71

Bouteloua hirsuta var. palmeri Vasey ex Beal, 70

Bouteloua johnstonii Swallen, 57, 71, 72

Bouteloua karwinskii (E. Fourn.) Griffiths, 

58, 72

Bouteloua media (E. Fourn.) Gould & Kapadia, 

56, 72

Bouteloua parryi (E. Fourn.) Griffiths, 57, 72, 73

Bouteloua parryi var. parryi, 73

Bouteloua procumbens (P. Durand) Griffiths, 76

Bouteloua radicosa (E. Fourn.) Griffiths, 57, 

73, 74

Bouteloua ramosa Scribn. ex Vasey, 58, 74, 75

Bouteloua repens (Kunth) Scribn. & Merr., 57, 

75, 76

Bouteloua rigidiseta var. chihuahuana M.C. 

Johnston, 61

Bouteloua scorpioides Lag., 57, 76

Bouteloua simplex Lag., 57, 76, 77

Bouteloua trífida Thurb., 58, 77, 78

Bouteloua uniflora Vasey, 56, 77, 78, 79, 214

Bouteloua uniflora var. coahuilensis Gould & 

Kapadia, 79

Bouteloua uniflora var. uniflora, 79

Bouteloua warnockii Gould & Kapadia, 56, 79

Bouteloua williamsii Swallen, 57, 79

Brachiaria arizonica (Scribn. & Merr.) S. T. 

Blake, 362

Brachiaria fasciculata (Sw.) Parodi, 363

Brachiaria meziana Hitchc., 364

Brachiaria plantaginea (Link) Hitchc., 364

Brizopyrum obtusiflorum E. Fourn., 190

Bromus anomalus Rupr. ex E. Fourn., 80, 81

Bromus carinatus Hook. & Arn., 80, 82, 371

Bromus carinatus var. carinatus, 82

Bromus carinatus var. marginatus (Nees ex 

Steud.) Barkworth & Anderton, 82

Bromus catharticus Vahl, 3, 80, 83

Bromus ciliatus L., 86

Bromus frondosus (Shear) Wooton & Standl., 

80, 83, 84

Bromus japonicus Thunb., 3, 80, 85

Bromus mucroglumis Wagnon, 86

Bromus richardsonii Link, 80, 86, 87

Bromus tectorum L., 3, 80, 86, 87

Buchloë dactyloides (Nutt.) Engelm., 65

Bulbilis dactyloides (Nutt.) Raf. ex Kuntz, 65

Calamagrostis pringlei Beal, 88

Cathesticum brevifolium Swallen, 66

Cathestecum erectum Vasey & Hack., 66

Cenchrus americanus (L.) Morrone, 3, 89, 90

Cenchrus ciliaris L., 3, 89, 90, 91

Cenchrus clandestinus (Hochst. ex Chiov.) 

Morrone, 3, 89, 91, 92

Cenchrus durus (Beal) Morrone, 89, 92

Cenchrus echinatus L., 3, 92, 93

Cenchrus granularis L., 176

Cenchrus incertus M. A. Curtis, 95

Cenchrus michoacanus H. F. Gut. & Morrone, 

89, 92

Cenchrus multiflorus J. Presl, 89, 94

Cenchrus myosuroides Kunth, 89, 94

Cenchrus parviflorus Poir., 330

Cenchrus polystachios (L.) Morrone, 3, 89, 95

Cenchrus polystachios subsp. setosum (Sw.) 

P. M. Peterson & Y. Herrera, 95

Cenchrus setosus Sw., 95

Cenchrus spinifex Cav. 89, 95, 96

Chaboissaea decumbens (Swallen) J. & 

C. Reeder, 223

Chaboissaea ligulata E. Fourn., 240

Chaetaria gibbosa Nees, 34

Chaetium bromoides (J. Presl) Benth. ex 

Hemsl., 97

Chaetochloa leucopila Scribn. & Merr., 328

Chaetochloa villosissima Scribn. & Merr., 332

Chloris crinita Lag., 194
NUMBER 107 • 377

Chloris curtipendula Michx., 63

Chloris dubia Kunth, 122

Chloris elegans Kunth, 49

Chloris gayana Kunth, 3, 97, 98

Chloris plurifolia (E. Fourn.) Clayton, 195

Chloris submutica Kunth, 97, 98, 99

Chloris virgata Sw., 97, 98, 100

Chondrosum eriopodum Torr., 68

Chondrosum gracile Kunth, 69

Chondrosum parryi E. Fourn., 72

Coix dactyloides L., 356

Cornucopiae hyemalis Walter, 22

Cortaderia selloana (Schult. & Schult. f.) Asch. 

& Graebn., 3, 101, 102

Cottea pappophoroides Kunth, 102

Cynodon dactylon (L.) Pers., 3, 102, 103

Cynosurus aegyptius L., 104

Cynosurus indicus L., 134

Dactylis glomerata L., 3, 104, 105

Dactyloctenium aegyptium (L.) Willd., 3, 104, 

106

Dasyochloa pulchella (Kunth) Willd. ex Rydb., 

106, 107

Deschampsia danthonioides (Trin.) Munro, 

107, 108

Deschampsia elongata (Hook.) Munro, 107, 

108, 112

Deschampsia flexuosa (L.) Trin., 36

Deschampsia pringlei Scribn., 298

Dichanthelium oligosanthes (Schult.) Gould, 

109

Dichanthelium sphaerocarpon (Elliott) Gould, 

109

Dichanthium annulatum (Forssk.) Stapf, 3, 110

Digitaria bicornis (Lam.) Roem. & Schult., 

111, 112

Digitaria californica (Benth.) Henrard, 110, 

111, 113

Digitaria ciliaris (Retz.) Koeler, 111, 113, 114

Digitaria cognata (Schult.) Pilg., 110, 114, 115

Digitaria filiformis (L.) Koeler, 110, 115

Digitaria insularis (L.) Fedde, 110, 115

Digitaria sanguinalis (L.) Scop., 3, 111, 115, 116

Digitaria ternata (Hochst. ex A. Rich.) Stapf, 

111, 117

Dinebra aristidoides Kunth, 58

Dinebra chondrosoides Kunth, 62

Dinebra panicea (Retz.) P. M. Peterson & 

N. Snow, 117

Dinebra panicea subsp. brachiata (Steud.) 

P. M. Peterson & N. Snow, 118, 119

Dinebra panicea subsp. mucronata (Michx.) 

P. M. Peterson & N. Snow, 117, 118

Dinebra panicoides (J. Presl) P. M. Peterson & 

N. Snow, 117, 118

Dinebra repens Kunth, 75

Dinebra scabra (Nees) P. M. Peterson & 

N. Snow, 117, 118

Dinebra viscida (Scribn.) P. M. Peterson & 

N. Snow, 117, 120

Diplachne fusca (L.) P. Beauv. ex Roem. & 

Schult., 120, 121

Diplachne fusca subsp. fascicularis (Lam.) 

P. M. Peterson & N. Snow, 120, 122

Diplachne fusca subsp. uninervia (J. Presl) 

P. M. Peterson & N. Snow, 118, 120, 122

Diplachne viscida Scribn., 120

Disakisperma dubium (Kunth) P. M. Peterson 

& N. Snow, 3, 122, 123

Distichlis littoralis (Engelm.) H. L. Bell & 

Columbus, 124

Distichlis spicata (L.) Greene, 124, 125

Distichlis spicata var. mexicana Beetle, 125

Echinochloa colona (L.) Link, 3, 126, 127

Echinochloa crus-galli (L.) P. Beauv., 3, 126, 

127, 129

Echinochloa crus-galli var. crus-galli, 128

Echinochloa crus-galli var. zelayensis (Kunth) 

Hitchc., 128

Echinochloa crus-pavonis (Kunth) Schult., 126, 

128, 130

Echinochloa crus-pavonis var. crus-pavonis, 129

Echinochloa holciformis (Kunth) Chase, 126, 

129

Echinochloa muricata (P. Beauv.) Fernald, 126, 

129, 131

Echinochloa muricata var. microstachya 

Wiegand, 131

Echinochloa oplismenoides (E. Fourn.) Hitchc., 

126, 131, 132

Echinochloa polystachya (Kunth) Hitchc., 126, 

132

Echinochloa polystachya var. polystachya, 132

Echinochloa polystachya var. spectabilis (Nees 

ex Trin.) Mart. Crov., 132

Echinochloa walteri (Pursh) A. Heller, 126, 

132, 133

Eleusine indica (L.) Gaertn., 3, 134

Eleusine multiflora Hochst. ex A. Rich., 3, 134, 

135

Elionurus barbiculmis Hack., 135

Elionurus tripsacoides Humb. & Bonpl. ex 

Willd., 135, 136

Elymus arizonicus (Scribn. & J. G. Sm.) Gould, 

136, 137

Elymus canadensis L., 136, 137

Elymus elymoides (Raf.) Swezey, 136, 137

Elymus elymoides subsp. brevifolius (J. G. Sm.) 

Barkworth, 138, 139

Elymus repens (L.) Gould, 3, 6, 136, 139

Elymus trachycaulus (Link) Gould ex Shinners, 136, 139, 140, 141

Elymus trachycaulus subsp. trachycaulus, 141

Elytrigia arizonica (Scribn. & J. G. Sm.) D. R. 

Dewey, 137

Enneapogon desvauxii P. Beauv., 141, 142

Eragrostis barrelieri Daveau, 3, 143, 144

Eragrostis cilianensis (All.) Vignolo ex Janch., 

3, 143, 145

Eragrostis ciliaris (L.) R. Br., 3, 143, 146, 147

Eragrostis ciliaris var. ciliaris, 147

Eragrostis ciliaris var. laxa Kuntze, 147

Eragrostis curvula (Schrad.) Nees, 3, 143, 144, 

147

Eragrostis echinochloidea Stapf, 3, 143, 148

Eragrostis erosa Scribn. ex Beal, 144, 148, 149

Eragrostis intermedia Hitchc., 143, 149, 150

Eragrostis lehmanniana Nees, 3, 143, 144, 151

Eragrostis lugens Nees, 143, 144, 152

Eragrostis mexicana (Hornem.) Link, 143, 

152, 153

Eragrostis mexicana subsp. mexicana, 153

Eragrostis mexicana subsp. virescens (J. Presl) 

S. D. Koch & Sánchez Vega, 153, 154

Eragrostis obtusiflora (E. Fourn.) Scribn., 190

Eragrostis palmeri S. Watson, 144, 154, 155

Eragrostis pectinacea (Michx.) Nees, 143, 155

Eragrostis pectinacea var. miserrima (E. 

Fourn.) Reeder, 155

Eragrostis pectinacea var. pectinacea, 155, 156

Eragrostis pilosa (L.) P. Beauv., 3, 143, 157

Eragrostis pringlei Mattei, 143, 157

Eragrostis secundiflora J. Presl, 144, 158

Eragrostis secundiflora subsp. oxylepis, 158

Eragrostis secundiflora subsp. secundiflora, 158

Eragrostis sessilispica Buckley, 144, 158, 159, 

160

Eragrostis spectabilis (Pursh) Steud., 143, 160

Eragrostis superba Peyr., 3, 143, 160, 161

Eriochloa acuminata (J. Presl.) Kunth, 162

Eriochloa acuminata var. acuminata, 162

Eriochloa acuminata var. minor (Vasey) R. B. 

Shaw, 162, 163

Eriochloa aristata Vasey, 162, 163, 164

Eriochloa contracta Hitchc., 3, 164

Eriochloa gracilis (E. Fourn.) Hitchc., 162

Eriochloa lemmonii Vasey & Scribn., 162, 

164, 165

Eriochloa nelsonii Scribn. & J. G. Sm., 162, 165

Eriochloa nelsonii var. nelsonii, 165

Eriochloa punctata (L.) Desv. ex Ham., 162, 

165, 166

Erioneuron avenaceum (Kunth) Tateoka, 167

Erioneuron avenaceum var. avenaceum, 167

Erioneuron avenaceum var. grandiflorum 

(Vasey) Gould, 167

Erioneuron nealleyi (Vasey) Tateoka, 167, 168

Erioneuron pilosum (Buckley) Nash, 167, 168

Erioneuron pilosum var. pilosum, 168

Erioneuron pulchellum (Kunth) Tateoka, 106

Erucaria glandulosa Cerv., 70

Festuca amplissima Rupr. ex Fourn., 169, 170

Festuca arundinacea Schreb., 195

Festuca barbata Loefl. ex L., 320

Festuca diclina Darbysh., 3, 169, 170, 171

Festuca fascicularis L., 122

Festuca lugens (E. Fourn.) Hitchc. ex Hern.-

Xol., 169, 171

Festuca mirabilis Piper, 171

Festuca myuros L., 3, 169, 171

Festuca octoflora Walter, 169, 171, 172

Festuca pringlei St.-Yves, 169, 172

Festuca rosei Piper, 169, 172

Festuca rubra L., 169, 173

Festuca tolucensis Kunth, 169, 173, 174

Glyceria borealis (Nash) Batch., 175, 176

Glyceria striata (Lam.) Hitchc., 175, 176, 177

Glyceria striata var. striata, 176

Hackelochloa granularis (L.) Kuntze, 3, 176, 

178
378 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Hesperostipa neomexicana (Thurb.) 

Barkworth, 179

Heteropogon contortus (L.) P. Beauv. ex Roem. 

& Schult., 3, 180

Heteropogon melanocarpus (Elliott) Benth., 3, 

180, 181

Hilaria belangeri (Steud.) Nash, 181, 182

Hilaria cenchroides Kunth, 181, 182

Hilaria ciliata (Scribn.) Nash, 181, 182

Hilaria mutica (Buckley) Benth., 181, 182, 183

Hilaria rigida (Thurb.) Benth. ex Scribn., 181, 

184

Hilaria swallenii Cory, 181, 184

Holcus halpensis L., 336

Holcus lanatus L., 3, 185, 186

Hopia obtusa (Kunth) Zuloaga & Morrone, 186

Hordeum murinum L., 3, 187

Hordeum pusillum Nutt., 187, 188

Hordeum vulgare L., 3, 187, 188, 189

Hordeum vulgare subsp. vulgare, 189

Hydrochloa caroliniensis P. Beauv., 198

Hymenothecium unisetum Lag., 276

Imperata brevifolia Vasey, 189, 190

Kalinia obtusiflora (E. Fourn.) H. L. Bell & 

Columbus, 190, 191

Koeleria californica (Domin) Beetle, 191

Koeleria cristata Pers., 191

Koeleria macrantha (Ledeb.) Schult., 191

Koeleria pyramidata (Lam.) P. Beauv., 191, 192

Koeleria pyramidata subsp. pyramidata, 192

Lasiacis ruscifolia (Kunth) Hitchc., 193

Leersia hexandra Sw., 193, 194

Leptochloa crinita (Lag.) P. M. Peterson & 

N. Snow, 194, 195

Leptochloa dubia (Kunth) Nees, 122

Leptochloa fusca (L.) Kunth, 120

Leptochloa panicea (Retz.) Ohwi, 117

Leptochloa panicoides (J. Presl) Hitchc., 118

Leptochloa pluriflora (E. Fourn.) P. M. Peterson 

& N. Snow, 194, 195

Leptochloa scabra Nees, 118

Leptochloa viscida (Scribn.) Beal, 120

Leptoloma cognata (Schult.) Chase, 114

Lolium arundinaceum (Schreb.) Darbysh., 3, 

195, 196

Lolium multiflorum Lam., 3, 195, 196, 197

Lolium perenne L., 3, 195, 197

Luziola fluitans (Michx.) Terrell & H. Rob., 

198, 199

Lycurus phalaroides Kunth, 253

Lycurus phleoides Kunth, 254

Lycurus setosus (Nutt.) C. Reeder, 210

Megastachya panicoides J. Presl, 118

Megastachya uninervia J. Presl, 122

Melica montezumae Piper, 199, 200

Melica porteri Scribn., 199, 200

Melinis repens (Willd.) Zizka, 3, 200, 201

Microchloa kunthii Desv., 202

Mnesithea granularis (L.) de Koning & Sosef, 

176

Monanthochloe littoralis Engelm., 124

Muhlenbergia alamosae Vasey, 210

Muhlenbergia alopecuroides (Griseb.) P. M. 

Peterson & Columbus, 209, 210, 211, 218

Muhlenbergia annua (Vasey) Swallen, 201, 212

Muhlenbergia arenacea (Buckley) Hitchc., 206, 

212, 213

Muhlenbergia arenicola Buckley, 207, 208, 214

Muhlenbergia argentea Vasey, 3, 207, 208, 209, 

210, 214, 215, 216

Muhlenbergia arizonica Scribn., 208, 216, 217

Muhlenbergia asperifolia (Nees & Meyen ex 

Trin.) Parodi, 206, 217, 218

Muhlenbergia biloba Hitchc., 204, 218

Muhlenbergia brevigluma (Scribn.) Columbus, 

221

Muhlenbergia brevis C. O. Goodd., 205, 218, 

219

Muhlenbergia capillipes (M. E. Jones) P. M. 

Peterson & Annable, 204, 219, 220, 244

Muhlenbergia cenchroides (Humb. & Bonpl. 

ex Willd.) P. M. Peterson, 203, 221

Muhlenbergia ciliata (Kunth) Kunth, 221

Muhlenbergia ciliata (Kunth) Trin., 204, 221

Muhlenbergia crispiseta Hitchc., 204, 222

Muhlenbergia curvula Swallen, 278

Muhlenbergia decumbens Swallen, 3, 203, 223

Muhlenbergia depauperata Scribn., 205, 218, 

219, 223, 224

Muhlenbergia distichophylla (J. Presl) Kunth, 

207, 224

Muhlenbergia diversiglumis Trin., 205, 225, 226

Muhlenbergia dubia E. Fourn., 209, 226, 227

Muhlenbergia dumosa Scribn. ex Vasey, 206, 

226, 228

Muhlenbergia elongata Scribn. ex Beal, 208, 

209, 228, 229

Muhlenbergia eludens C. Reeder, 204, 230

Muhlenbergia emersleyi Vasey, 207, 230, 231, 

232, 241

Muhlenbergia filiformis (Thurb. ex S. Wats.) 

Rydb., 204, 233

Muhlenbergia flavida Vasey, 204, 205, 233, 234, 

235, 266

Muhlenbergia flaviseta Scribn., 206, 235

Muhlenbergia fragilis Swallen, 204, 235, 236

Muhlenbergia gigantea (E. Fourn.) Hitchc., 

207, 237, 238

Muhlenbergia glauca (Nees) B. D. Jacks., 206, 

237, 239

Muhlenbergia imperfecta (Nash) Columbus, 

203, 237, 240

Muhlenbergia implicata (Kunth) Trin., 205, 

225, 240

Muhlenbergia laxiflora Scribn., 249

Muhlenbergia ligulata (E. Fourn.) Scribn. & 

Merr., 203, 240, 241

Muhlenbergia lindheimeri Hitchc., 207, 209, 

241

Muhlenbergia longiligula Hitchc., 207, 231, 241

Muhlenbergia lucida Swallen, 208, 215, 242, 

271

Muhlenbergia macroura (Kunth) Hitchc., 209, 

243

Muhlenbergia majalcensis P. M. Peterson, 3, 

203, 220, 229, 243

Muhlenbergia microsperma (DC.) Kunth, 205, 

244, 245

Muhlenbergia minutissima (Steud.) Swallen, 

203, 244, 246

Muhlenbergia montana (Nutt.) Hitchc., 206, 

247, 271

Muhlenbergia mucronata (Kunth) Trin., 208, 

249, 250

Muhlenbergia palmeri Vasey, 209, 210, 227, 

250, 251

Muhlenbergia pauciflora Buckley, 210, 251, 252

Muhlenbergia pectinata C. O. Goodd., 205, 252

Muhlenbergia pereilema P. M. Peterson, 10, 

203, 245, 252, 253

Muhlenbergia peruviana (P. Beauv.) Steud., 

204, 222, 253

Muhlenbergia phalaroides (Kunth) P. M. Peterson, 209, 218, 253, 254

Muhlenbergia phleoides (Kunth) Columbus, 

209, 218, 254, 255

Muhlenbergia polycaulis Scribn., 206, 210, 239, 

255, 256

Muhlenbergia porteri Scribn.ex Beal, 208, 257

Muhlenbergia pubescens (Kunth) Hitchc., 207, 

258

Muhlenbergia pubigluma Swallen, 209, 258

Muhlenbergia purpusii Mez, 208, 210, 258, 259

Muhlenbergia quadridentata (Kunth) Trin., 

207, 259

Muhlenbergia ramulosa (Kunth) Swallen, 204, 

259, 260

Muhlenbergia repens (J. Presl) Hitchc., 206, 

260, 261, 262

Muhlenbergia richardsonis (Trin.) Rydb., 206, 

262

Muhlenbergia rigens (Benth.) Hitchc., 209, 

262, 263

Muhlenbergia rigida (Kunth) Kunth, 208, 249, 

250, 264, 271

Muhlenbergia robusta (E. Fourn.) Hitchc., 

207, 265

Muhlenbergia schmitzii Hack., 203, 254, 265, 

266

Muhlenbergia scoparia Vasey, 207, 238, 266

Muhlenbergia setifolia Vasey, 208, 266

Muhlenbergia shepherdii (Vasey) Swallen, 203, 

266, 267

Muhlenbergia sinuosa Swallen, 203, 267, 268

Muhlenbergia speciosa Vasey, 207, 268, 269

Muhlenbergia straminea Hitchc., 278

Muhlenbergia strictior Scribn.ex Beal, 205, 269

Muhlenbergia tarahumara P. M. Peterson & 

Columbus, 205, 269, 270, 271

Muhlenbergia tenuifolia (Kunth) Kunth, 204, 

205, 208, 210, 271, 272

Muhlenbergia texana Buckley, 203, 204, 272, 

273

Muhlenbergia torreyi (Kunth) Hitchc. ex Bush, 

208, 274, 275

Muhlenbergia tricholepis (Torr.) Columbus, 

203, 207, 209, 274

Muhlenbergia tricholepis (Torr.) P. M. Peterson, 274 

Muhlenbergia uniseta (Lag.) Columbus, 213, 

276
NUMBER 107 • 379

Muhlenbergia utilis (Torr.) Hitchc., 206, 261, 

277

Muhlenbergia vaginata Swallen, 204, 206, 277

Muhlenbergia villiflora Hitchc., 277, 278

Muhlenbergia villiflora var. villiflora, 278

Muhlenbergia virescens (Kunth) Kunth, 206, 

278, 279

Muhlenbergia wrightii Vasey ex J. M. Coult., 

209, 279, 280

Munroa pulchella (Kunth) L. D. Amarilla, 106

Munroa squarrosa (Nutt.) Torr., 280, 281

Nassella mucronata (Kunth) R. W. Pohl, 282

Oplismenus crus-pavonis Kunth, 128

Oplismenus burmannii (Retz.) P. Beauv., 282

Oplismenus burmannii var. burmannii, 282

Oplismenus burmannii var. nudicaulis (Vasey) 

McVaugh, 282

Oplismenus holciformis Kunth, 129

Oplismenus zelayensis Kunth, 128

Oryzopsis hymenoides (Roem. & Schult.) 

Ricker ex Piper, 17

Oryzopsis pringlei Beal, 307

Otatea acuminata (Munro) C. E. Calderón & 

Soderstr., 283

Otatea acuminata subsp. aztecorum (McClure & E. W. Sm.) R. Guzmán, Anaya & 

Santana, 283

Panicum adhaerens Forssk., 327

Panicum alatum Zuloaga & Morrone, 284

Panicum alatum var. minus (Anderson) 

Zuloaga & Morrone, 284

Panicum antidotale Retz., 3, 283, 284

Panicum bulbosum Kunth, 366

Panicum burmannii Retz., 282

Panicum californicum Benth., 111

Panicum ciliare Retz., 113

Panicum cognatum Schult., 114

Panicum colonum L., 126

Panicum crusgalli L., 127

Panicum dactylon L., 102

Panicum decolorans Kunth, 284, 285

Panicum dichotomiflorum Michx., 3, 284, 285

Panicum filiforme L., 115

Panicum fuscum Sw., 363

Panicum hallii Vasey, 284, 285, 286

Panicum havardii Vasey, 290

Panicum hirticaule J. Presl, 284, 286, 287, 288

Panicum hirticaule var. hirticaule, 287, 288

Panicum hirticaule var. verrucosum Zuloaga & 

Morrone, 287

Panicum lepidulum Hitchc. & Chase, 284, 287

Panicum obtusum Kunth, 186

Panicum oligosanthes Schult., 109

Panicum pampinosum Hitchc. & Chase, 284, 

287

Panicum parcum Hitchc. & Chase, 284, 288

Panicum plenum Hitchc. & Chase, 284, 288, 289

Panicum pumilum Poir., 331

Panicum ruscifolium Kunth, 193

Panicum sanguinale L., 115

Panicum sphaerocarpon Elliot, 109

Panicum trichoides Sw., 284, 289

Panicum vaseyanum Scribn.ex Beal, 284, 289, 

290

Panicum virgatum L., 3, 284, 290, 291

Panicum viride L., 332

Panicum walteri Pursh, 132

Pappophorum bicolor E. Fourn., 291

Pappophorum vaginatum Buckley, 291

Paspalum botterii (E. Fourn.) Chase, 292, 293

Paspalum convexum Humb. & Bonpl. ex 

Flüggé, 292, 293

Paspalum distichum L., 292, 294

Paspalum paucispicatum Vasey, 294

Paspalum plicatulum Michx., 292, 295

Paspalum prostratum var. prostratum 292, 294

Paspalum prostratum var. pygmaeum Scribn. 

& Merr., 295, 296

Paspalum pubiflorum Rupr. ex E. Fourn., 292, 

296

Paspalum setaceum Michx., 292, 297

Paspalum setaceum var. ciliatifolium (Michx.) 

Vasey, 297

Paspalum setaceum var. setaceum, 297

Pennisetum ciliare (L.) Link, 89

Pennisetum clandestinum Hochst. ex Chiov., 41

Pennisetum crinitum (Kunth) Spreng., 92

Pennisetum durum Beal, 92

Pennisetum glaucum (L.) R. Br., 89

Pennisetum polystachion (L.) Schult., 95

Pennisetum polystachion subsp. setosus (Sw.) 

Brunken, 95

Pereilema crinitum J. Presl, 252

Peyritschia deyeuxioides (Kunth) Finot, 298

Peyritschia pringlei (Scribn.) S. D. Koch, 298, 

299

Phalaris angusta Nees ex Trin., 299, 300

Phalaris aquatica L., 3, 299, 300, 301

Phalaris arundinacea L., 299, 301, 302

Phalaris canariensis L., 3, 299, 302

Phalaris caroliniana Walter, 299, 302, 303

Phalaris paradoxa L., 3, 299, 303, 304

Phragmites australis (Cav.) Steud., 304, 306

Phragmites australis subsp. americanus

Saltonstall, P. M. Peterson & Soreng, 304

Phragmites australis subsp. australis, 304

Phragmites australis subsp. berlandieri Saltonstall & Hauber, 304

Piptatherum acuminatum J. Presl, 162

Piptochaetium fimbriatum (Kunth) Hitchc., 

305, 306

Piptochaetium pringlei (Beal) Parodi, 305, 307, 

308

Piptochaetium virescens (Kunth) Parodi, 305, 

308

Pleuraphis mutica Buckley, 182

Pleuraphis rigida Thurb., 184

Poa annua L., 3, 309, 310

Poa annua var. stricta Vasey ex Scribn., 311

Poa bigelovii Vasey & Scribn., 309, 310, 311

Poa fendleriana (Steud.) Vasey, 309, 311, 312

Poa fendleriana subsp. albescens (Hitchc.) 

Soreng, 311, 312

Poa fendleriana subsp. fendleriana, 311, 312, 

313

Poa matri-occidentalis P. M. Peterson & 

Soreng, 309, 313, 314

Poa matri-occidentalis subsp. mohinorensis

Soreng & P. M. Peterson, 3, 313, 314

Poa panicea Retz., 117

Poa pilosa L., 157

Poa pratensis L., 309, 313, 315

Poa pratensis subsp. pratensis, 315

Poa pyramidata L., 191

Poa strictiramea Hitchc., 309, 316

Polypogon elongatus Kunth, 317, 318

Polypogon elongatus var. elongatus, 317

Polypogon elongatus var. strictus E. Desv., 317

Polypogon monspeliensis (L.) Desf., 3, 317, 318

Polypogon viridis (Gouan) Breistr., 3, 317, 319

Rhynchelytrum repens (Willd.) C. E. Hubb., 

200

Rottboellia sanguinea Retz., 322

Saccharum repens Willd., 200

Schedonorus arundinaceus (Schreb.) Dumort., 

195

Schismus arabicus Nees, 3, 320

Schismus barbatus (Loefl. ex L.) Thell., 3, 320

Schizachyrium brevifolium (Sw.) Nees ex Büse, 

320, 321

Schizachyrium cirratum (Hack.) Wooton & 

Standl., 320, 321, 322

Schizachyrium hirtiflorum Nees, 322

Schizachyrium sanguineum (Retz.) Alston, 

321, 322, 323

Scizachyrium scoparium (Michx.) Nash, 321,

323, 324

Scizachyrium scoparium var. neomexicanum 

(Nash) Hitchc., 323

Schizachyrium semiglabrum Nash, 322

Schizachyrium tenerum Nees, 320, 323, 325

Scleropogon brevifolius Phil., 325, 326

Sesleria dactyloides Nutt., 65

Setaria adhaerens (Forssk.) Chiov., 3, 327

Setaria auriculata E. Fourn., 333

Setaria geniculata P. Beauv., 330

Setaria grisebachii E. Fourn., 327

Setaria latiglumis Vasey, 333

Setaria leucopila (Scribn. & Merr.) K. Schum., 

327, 328

Setaria liebmannii E. Fourn., 327, 329

Setaria lutescens (Weigel ex Stuntz) F. T. Hubb., 

331

Setaria macrostachya Kunth, 327, 329, 330

Setaria parviflora (Poiret) Kerguélen, 327, 330

Setaria pumila (Poir.) Roem. & Schult.,3, 327, 

331

Setaria pumila subsp. pumila, 331

Setaria verticillata (L.) P. Beauv., 3, 327, 332

Setaria villosissima (Scribn. & Merr.) K. 

Schum., 327, 332

Setaria viridis (L.) P. Beauv., 3, 327, 332, 333

Setariopsis auriculata (E. Fourn.) Scribn., 333

Setariopsis latiglumis (Vasey) Scribn., 333

Sitanion elymoides Raf., 137

Sorghastrum nudipes Nash, 334

Sorghastrum nutans (L.) Nash, 334, 335

Sorghum bicolor (L.) Moench, 3, 336, 337

Sorghum halepense (L.) Pers., 3, 336, 337

Spartina alterniflora Loisel., 341
380 • SMITHSONIAN CONTRIBUTIONS TO BOTANY

Sphenopholis obtusata (Michx.) Scribn., 338

Sporobolus airoides (Torr.) Torr., 340

Sporobolus airoides subsp. airoides, 340

Sporobolus airoides subsp. regis (I. M. Johnst.) 

Wipff & S. D. Jones, 340

Sporobolus alterniflorus (Loisel.) P. M. Peterson & Saarela, 339, 341

Sporobolus capillipes M. E. Jones, 219

Sporobolus contractus Hitchc., 339, 342

Sporobolus cryptandrus (Torr.) A. Gray, 339, 

343

Sporobolus flexuosus (Thurb. ex Vasey) Rydb., 

339, 344

Sporobolus giganteus Nash, 339, 345

Sporobolus indicus (L.) R. Br., 339, 346

Sporobolus pyramidatus (Lam.) Hitchc., 339, 

347, 348

Sporobolus shepherdii Vasey, 266

Sporobolus spiciformis Swallen, 339, 348, 349

Sporobolus trichodes Hitchc., 339, 349

Sporobolus wrightii Munro ex Scribn., 340, 

349, 350

Stenotaphrum secundatum (Walter) Kuntze, 

3, 350

Stipa curvifolia Swallen, 15

Stipa eminems Cav., 16

Stipa fimbriata Kunth, 305

Stipa hymenoides Roem. & Schult., 17

Stipa multinodis Scribn. ex Beal, 18

Stipa neomexicana (Thurb.) Barkworth, 179

Stipa pennata var. neomexicana Thurb., 179

Stipa spicata L. f., 352

Stipa viridula var. robusta Vasey, 18

Thinopyrum intermedium (Host) Barkworth 

& D. R. Dewey, 3, 351

Trachypogon plumosus (Humb. & Bonpl. ex 

Willd.) Nees, 352

Trachypogon secundus (J. Presl) Scribn., 352

Trachypogon spicatus (L. f.) Kuntze, 352

Tragus berteronianus Schult., 3, 352, 353

Trichloris crinita (Lag.) Parodi, 194

Trichloris pluriflora E. Fourn., 195

Tricuspis mutica Torr., 354

Tridens albescens (Vasey) Wooton & Standl., 

353

Tridens avenaceus (Kunth) Hitchc., 167

Tridens muticus (Torr.) Nash, 354

Tridens pulchellus (Kunth) Hitchc., 106

Tridens texanus (S. Watson) Nash, 353, 354

Tridentopsis mutica (Torr.) P. M. Peterson, 354, 

355

Tridentopsis mutica var. elongata (Buckley) 

P. M. Peterson & Romasch., 354

Tridentopsis mutica var. mutica, 354, 355

Triniochloa laxa Hitchc., 3, 356

Triodia avenacea Kunth, 167

Triodia nealleyi Vasey, 167

Triodia pulchella Kunth, 106

Tripsacum dactyloides (L.) L., 356, 357

Tripsacum dactyloides var. dactyloides, 356

Tripsacum lanceolatum Rupr. ex E. Fourn., 

356, 357, 358

Tripsacum zopilotense Hern.-Xol. & Randolph, 

356, 357, 358

Trisetum deyeuxioides (Kunth) Kunth, 298

Trisetum filifolium Scribn. ex Beal, 358, 359

Trisetum filifolium var. aristatum Scribn. ex 

Beal, 359

Trisetum palmeri Hitchc., 359

Trisetum spellenbergii Soreng, Finot & P. M. 

Peterson, 359, 360

Trisetum spicatum (L.) K. Richt., 359, 360

Trisetum viride (Kunth) Kunth, 359, 361

Triticum aestivum L., 3, 361, 363

Triticum repens L., 139

Uniola lugens E. Fourn., 171

Uniola spicata L., 125

Uralepis pilosa Buckley, 168

Uralepis poaeoides Buckley, 311

Urochloa arizonica (Scribn. & Merr.) Morrone 

& Zuloaga, 362

Urochloa fasciculata var. reticulata (Torr.) R. D. 

Webster, 363

Urochloa fusca (Sw.) B. F. Hansen & Wenderlin, 

362, 363

Urochloa meziana (Hitchc.) Morrone & 

Zuloaga, 362, 364

Urochloa plantaginea (Link) R. D. Webster, 3, 

362, 364, 365

Vulpia myuros (L.) C. C. Gmel., 171

Vulpia octoflora (Walter) Rydb., 171

Zea mays L., 365

Zea mays subsp. mays, 3, 364, 365, 367

Zea mays subsp. mexicana Iltis, 364, 365, 368

Zizania fluitans Michx., 198

Zuloagaea bulbosa (Kunth) E. Bess, 366, 367, 368
SUMMARY OF REQUIREMENTS FOR SMITHSONIAN CONTRIBUTIONS SERIES

For comprehensive guidelines and specifications, visit https://scholarlypress.si.edu. 

ABSTRACTS must not exceed 300 words. 

TEXT must be prepared in a recent version of Microsoft Word; use a Times font in 12 point for regular text; be double 

spaced; and have 1” margins. 

REQUIRED ELEMENTS are title page, abstract, table of contents, main text, and references.

FIGURES must be numbered sequentially (1, 2, 3, etc.) in the order called out; have components lettered consistently (in 

size, font, and style) and described in captions; include a scale bar or scale description, if appropriate; include any legends 

in or on figures rather than in captions. Figures must be original and must be submitted as individual TIF or EPS files.

FIGURE FILES must meet all required specifications in the Digital Art Preparation Guide. Color images should be 

requested only if required. 

TAXONOMIC KEYS in natural history manuscripts should use the aligned-couplet form for zoology. If cross referencing 

is required between key and text, do not include page references within the key, but number the keyed-out taxa, using the 

same numbers with their corresponding heads in the text.

SYNONYMY IN ZOOLOGY must use the short form (taxon, author, year:page), with full reference at the end of the 

manuscript under “References.”

REFERENCES should be in alphabetical order, and in chronological order for same-author entries. Each reference should 

be cited at least once in main text. Complete bibliographic information must be included in all citations. Examples of the 

most common types of citations can be found at SISP’s website under Resources/Guidelines & Forms.