Smithsonian Institution

Scholarly Press

Smithsonian Institution

Scholarly Press

Grasses of Washington, D.C.

Kamal M. Ibrahim 

and 

Paul M. Peterson

smithsonian contributions to botany • number 99

Smithsonian Institution

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smithsonian contributions to botany • numb e r 9 9

Grasses of Washington, D.C.

Kamal M. Ibrahim 

and 

Paul M. Peterson

washington d.c.

2014
ABSTRACT

Ibrahim, Kamal M., and Paul M. Peterson. Grasses of Washington, D.C. Smithsonian Contributions 

to Botany, number 99, viii + 128 pages, 190 figures, 2014.—A vegetative key, descriptions, and illustrations for the identification of 182 native and naturalized grasses that occur in Washington, D.C., are 

presented. In addition, we provide a glossary of terms and indexes to scientific and common names. 

The key is based on vegetative characters to allow identification of specimens that primarily do not have 

flowering structures (inflorescences and spikelets).

Cover images, from left to right: Cinna arundinacea panicle (Figure 47, detail); Andropogon glomeratus inflorescence (Figure 18, detail); Pleioblastus argenteostriatus fo. glaber habit, herbarium specimen 

(from Figure 157); Setaria faberi panicle (Figure 169, detail); Tridens flavus var. flavus panicle (Figure 

186, detail).

Published by SMITHSONIAN INSTITUTION SCHOLARLY PRESS

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Copyright © 2014 Smithsonian Institution

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Library of Congress Cataloging-in-Publication Data

Ibrahim, Kamal (Kamal M.)

Grasses of Washington, D.C. / Kamal M. Ibrahim and Paul M. Peterson.

 p. cm. — (Smithsonian contributions to botany ; no. 99)

1. Grasses—Washington (D.C.)—Identification. I. Peterson, Paul M. II. Title. III. Series: 

Smithsonian contributions to botany ; no. 99.

QK495.G74I25 2014

584'.909753—dc23

2013044771

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

c 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

Morphological Characters 1

Identification 7

Acknowledgements 9

VEGETATIVE KEY TO THE GRASSES OF WASHINGTON, D.C. 11

DESCRIPTIONS 23

GLOSSARY OF TERMS 115

REFERENCES 121

INDEX OF COMMON NAMES 123

INDEX OF SCIENTIFIC NAMES 127

Figures

1. General morphology 2

2. Growth forms 3

3. Types of sheaths, auricles, and collars 4

4. Ligule types, shapes, and margins 5

5. Leaf blade apices, bases, and margins 6

6. Leaf blade characteristics 7

7. Inflorescence types 8

8. Inflorescence and spikelet characteristics 9

9. Agrostis capillaris 23

10. Agrostis elliottiana 24

11. Agrostis gigantea 24

12. Agrostis hyemalis 25

13. Agrostis perennans 25

14. Aira caryophyllea 26

15. Alopecurus carolinianus 26

16. Alopecurus myosuroides 27

17. Andropogon gerardii 27

18. Andropogon glomeratus 28

19. Andropogon gyrans 28

20. Andropogon ternarius 29

21. Andropogon virginicus 29

22. Anthoxanthum odoratum 30

23. Apera spica-venti 30

24. Aristida dichotoma 31

25. Aristida longespica 31

26. Aristida oligantha 32

27. Aristida purpurascens 32

28. Arrhenatherum elatius 33

29. Arthraxon hispidus 33

30. Avena sativa 34

31. Avenella flexuosa 34

32. Brachyelytrum erectum 35

33. Bromus catharticus 35

34. Bromus commutatus 36

35. Bromus hordeaceus 36
v i • smithsonian contributions to botany

36. Bromus inermis 37

37. Bromus japonicus 37

38. Bromus pubescens 38

39. Bromus racemosus 38

40. Bromus secalinus 39

41. Bromus sterilis 39

42. Bromus tectorum 40

43. Calamagrostis cinnoides 40

44. Cenchrus longispinus 41

45. Chasmanthium latifolium 41

46. Chasmanthium laxum 42

47. Cinna arundinacea 42

48. Coleataenia anceps 43

49. Coleataenia rigidula 43

50. Cynodon dactylon 44

51. Dactylis glomerata 44

52. Danthonia compressa 45

53. Danthonia spicata 45

54. Dichanthelium aciculare 46

55. Dichanthelium acuminatum 46

56. Dichanthelium annulum 47

57. Dichanthelium boscii 47

58. Dichanthelium clandestinum 48

59. Dichanthelium columbianum 48

60. Dichanthelium commutatum 49

61. Dichanthelium depauperatum 49

62. Dichanthelium dichotomum 50

63. Dichanthelium ensifolium 50

64. Dichanthelium latifolium 51

65. Dichanthelium laxiflorum 51

66. Dichanthelium linearifolium 52

67. Dichanthelium lucidum 52

68. Dichanthelium mattamuskeetense 53

69. Dichanthelium meridionale 53

70. Dichanthelium oligosanthes 54

71. Dichanthelium ravenelii 54

72. Dichanthelium scabriusculum 55

73. Dichanthelium scoparium 55

74. Dichanthelium sphaerocarpon 56

75. Dichanthelium villosissimum 56

76. Dichanthelium yadkinense 57

77. Digitaria ciliaris 57

78. Digitaria filiformis 58

79. Digitaria ischaemum 58

80. Digitaria sanguinalis 59

81. Diplachne fusca subsp. fascicularis 59

82. Echinochloa crusgalli 60

83. Echinochloa muricata 60

84. Echinochloa walteri 61

85. Eleusine indica 61

86. Elymus canadensis 62

87. Elymus elymoides 62

88. Elymus glabriflorus 63

89. Elymus hystrix 63
number 99

• vii

90. Elymus macgregorii 64

91. Elymus repens 64

92. Elymus riparius 65

93. Elymus villosus 65

94. Elymus virginicus 66

95. Eragrostis capillaris 66

96. Eragrostis cilianensis 67

97. Eragrostis frankii 67

98. Eragrostis hypnoides 68

99. Eragrostis minor 68

100. Eragrostis pectinacea 69

101. Eragrostis pilosa 69

102. Eragrostis spectabilis 70

103. Erianthus giganteus 70

104. Eriochloa contracta 71

105. Festuca filiformis 71

106. Festuca myuros 72

107. Festuca octoflora 72

108. Festuca paradoxa 73

109. Festuca rubra 73

110. Festuca subverticillata 74

111. Festuca trachyphylla 74

112. Glyceria canadensis 75

113. Glyceria laxa 75

114. Glyceria septentrionalis 76

115. Glyceria striata 76

116. Gymnopogon ambiguus 77

117. Holcus lanatus 77

118. Hordeum jubatum 78

119. Hordeum murinum 78

120. Hordeum pusillum 79

121. Hordeum vulgare 79

122. Leersia oryzoides 80

123. Leersia virginica 80

124. Lolium arundinaceum 81

125. Lolium multiflorum 81

126. Lolium perenne 82

127. Lolium pratense 82

128. Melica mutica 83

129. Microstegium vimineum 83

130. Miscanthus sinensis 84

131. Muhlenbergia capillaris 84

132. Muhlenbergia frondosa 85

133. Muhlenbergia glomerata 85

134. Muhlenbergia schreberi 86

135. Muhlenbergia sobolifera 86

136. Muhlenbergia sylvatica 87

137. Muhlenbergia tenuiflora 87

138. Panicum capillare 88

139. Panicum dichotomiflorum 88

140. Panicum flexile 89

141. Panicum gattingeri 89

142. Panicum miliaceum 90

143. Panicum philadelphicum 90
viii • smithsonian contributions to botany

144. Panicum verrucosum 91

145. Panicum virgatum 91

146. Paspalum dilatatum 92

147. Paspalum dissectum 92

148. Paspalum floridanum 93

149. Paspalum laeve 93

150. Paspalum pubiflorum 94

151. Paspalum setaceum 94

152. Phalaris arundinacea 95

153. Phalaris canariensis 95

154. Phleum pratense 96

155. Phragmites australis subsp. australis 96

156. Piptochaetium avenaceum 97

157. Pleioblastus argenteostriatus fo. glaber 97

158. Pleioblastus pygmaeus 98

159. Poa annua 98

160. Poa autumnalis 99

161. Poa compressa 99

162. Poa cuspidata 100

163. Poa palustris 100

164. Poa pratensis 101

165. Poa sylvestris 101

166. Poa trivialis 102

167. Schizachyrium scoparium 102

168. Secale cereale 103

169. Setaria faberi 103

170. Setaria italica 104

171. Setaria parviflora 104

172. Setaria pumila 105

173. Setaria verticillata 105

174. Setaria viridis 106

175. Sorghastrum nutans 106

176. Sorghum bicolor 107

177. Sorghum halepense 107

178. Spartina cynosuroides 108

179. Spartina pectinata 108

180. Sphenopholis intermedia 109

181. Sphenopholis nitida 109

182. Sphenopholis obtusata 110

183. Sporobolus compositus 110

184. Sporobolus neglectus 111

185. Sporobolus vaginiflorus 111

186. Tridens flavus var. flavus 112

187. Tripidium ravennae 112

188. Tripsacum dactyloides 113

189. Triticum aestivum 113

190. Zizania aquatica 114
Introduction

The most accurate way to identify grasses is to use floral characteristics. However, 

it is often necessary to identify grasses without having mature plants or only portions 

of those plants without complete spikelets. Under such conditions conventional botanical manuals offer little assistance. Moreover, identification using floral characteristics 

requires special training in grass taxonomy that is not available to most agronomists, 

technical field staff, and/or interested amateurs. Vegetative characters can be easily used 

for plant identification until a flowering specimen is obtained for positive verification. 

Vegetative structures of the grasses are easily visible and do not require any tool except 

a pocket hand lens (10–14×). Some vegetative characters are not particularly constant, 

so it is important to use characters that are less mutable and subject to environmental 

influences.

This publication presents a vegetative key, descriptions, illustrations, and glossary 

for the identification of 182 native and naturalized grasses that occur in Washington, 

D.C. Our list of species is primarily based on Shetler and Orli (2002), and we have 

consulted Hitchcock (1951), Brown and Brown (1984), Gleason and Cronquist (1991), 

Barkworth et al. (2003, 2007), Steury (2004), Clayton et al. (2006), Terrell and Peterson 

(2009), Weakley et al. (2012), Tropicos (2013), Soreng et al. (2013), and Steury et al. 

(2013). We follow the accepted names in the Catalogue of New World Grasses and a 

worldwide generic classification based principally on molecular DNA sequence studies 

(Soreng et al., 2013). Very few floristic characteristics were used to construct the key for 

identification. Diagrammatic illustrations, not made to scale but drawn to emphasize the 

structural characteristics, are presented for each species. A description of each species is 

presented in alphabetical order, and indexes to the scientific and common names and a 

glossary are included. 

Morphological Characters

The common grass habit for most species is an upright, cylindrical, rarely compressed culm (stem) anchored in the soil by adventitious roots. The culm consists of 

nodes and internodes with leaves distichously arising from the nodes. The inflorescence 

usually comprises numerous spikelets that are composed of one or more florets that 

Grasses of Washington, D.C.

Kamal M. Ibrahim and Paul M. Peterson, Department of Botany, National Museum of Natural 

History, Smithsonian Institution, MRC 166, Post 

Office Box 37012, Washington, D.C. 20560-

7012, USA. Correspondence: peterson@si.edu.

Manuscript received 26 March 2013; accepted 

22 August 2013.
2 • smithsonian contributions to botany

contain the flower parts (pistil and stamens). The general morphology of a grass is illustrated in detail in Figures 1–8.

Roots. The luxuriant fibrous root system anchors 

the growing plant and is comprised of adventitious roots originating from the lower culm nodes (Figure 2). In some grasses 

additional prop roots emerge from the lower culm nodes just 

above ground level. Most grasses with geniculate culms root at 

the lower nodes.

Rhizomes. A rhizome is a more or less horizontal 

underground stem whose leaves are reduced to scales. Eventually, 

it emerges above the ground surface to form a new flowering 

shoot or culm.

Stolons. A stolon is a trailing or reclining, aboveground stem that produces roots and flowering shoots from the 

nodes.

Culms. The grass stem is known as a culm (Figure 

1). It is made up of a series of internodes and nodes. The internodes at the base of a culm are very short, and in the upper portion of a culm they extend to a considerable length. Internodes 

are usually hollow but sometimes are solid, as in Saccharum,

FIGURE 1. General morphology. a. Culm. b. Rhizome and stolon. c. Sheath, ligule, and blade.
number 99 • 3

or filled with white pith, as in Sorghum. The plant height varies considerably because of the stage of growth, environmental 

conditions, and the species genetic makeup. Culms are mostly 

glabrous, particularly the sections enveloped by the leaf sheaths. 

Nodes vary, and in some species they are hairy, whereas in other 

they are glabrous. 

Branching is from the buds situated below the leaf sheath 

at the nodes. Branching usually occurs at basal nodes only or 

from basal, middle, and upper nodes. If the shoot initial remains 

within the sheath that envelops the node, the branching is intravaginal. If the shoot initial grows laterally in a manner that 

ruptures the enveloping sheath, the branching habit is extravaginal. Branches from the base of the plant are known as tillers. 

Leaves. A grass leaf is divided into the following 

parts: the leaf sheath (at the base) and the blade, also known as 

the lamina.

Sheaths. The leaf sheath originates at a node and 

protects the growing zone of the internode and structurally 

strengthens the culm. Sheaths are usually open, sometimes split 

with overlapping margins or with margins fused for all or part 

of their length. The sheath may be compressed or round or occasionally keeled at the midrib. In some species, sheaths are longer 

FIGURE 2. Growth forms. A. Erect. B. Geniculate. C. Prostrate. D. Decumbent.
4 • smithsonian contributions to botany

than the blades, and in a few species they are longer than the adjacent internodes. Usually, sheaths are of a paler shade of green 

than the blades and are often tinged with pink or purple at the 

base. They are also tinted, with darker color near the blades. The 

tints are not consistent enough to be of much value in identification. Presence or absence of hairs on the sheath margins, surface, 

and the junction with the blade is an important characteristic 

for use in the identification (Figure 3). The base of culms sometimes have many butt sheaths, or the old remnant portions of 

the leaves.

Auricles. Auricles are appendages that project from 

each side of the collar that marks the divisions between the 

sheath and blade. Auricles may be horizontally clawed, rudimentary, and fully or slightly rounded. Most species do not possess 

auricles (Figure 3).

Ligules. A ligule is a tissue clasping the stem or bud 

shoots, inside the leaf at the junction of the blade and sheath on 

the adaxial (adjacent) surface. Ligules are usually present, and 

they may be simply a fringe of hairs, membranous or hyaline, 

ciliolate or ciliate membrane, or absent. The length of ligules 

may vary within a species (Figure 4). The shape and margin are 

usually quite constant, and they provide reliable distinguishing 

characteristics for identification. 

Collars. The collar is also found at the junction between the blade and the sheath (Figure 3). It may be vertically 

broad or narrow, continuous or divided by a midrib. If the collar 

extends diagonally, it is referred to as oblique. Collars are usually 

smooth but may be hairy over the whole surface or only on the 

inner and lowermost portion of the margin. Collars are usually 

green or yellowish green and may be tinged with yellow or red.

FIGURE 3. Types of sheaths, auricles, and collars.
number 99 • 5

Blades. The blade, or lamina, is the upper portion of 

the leaf above the collar, ligule, and auricle. There is considerable 

variation in the length and the width of the blades, and the ratio 

between these two characteristics is useful for identification (Figures 5, 6). Blades are usually linear to lanceolate, but in some species, blades are filiform or ovate. There is a great deal of variation 

among species in the shape of the blade apex and base and hairiness of the upper and lower surfaces and margins. Blade venation 

is usually parallel, although sometimes there are evident cross 

veins. Frequently, there are considerable differences between 

blades from the upper and lower parts of the same plant and 

between blades taken from different plants of the same species. 

Reproductive Structures. The spikelet is the 

characteristic floral structure in grasses. In most grass species, 

the inflorescence comprises numerous spikelets that are aligned 

in different sequences. In this study, the different types of inflorescences, spikelet shapes, and awn types are included. In the 

vegetative key no reference is made to the detailed spikelet parts.

FIGURE 4. Ligule types, shapes, and margins.
6 • smithsonian contributions to botany

Inflorescences. Different inflorescence types are 

distinguished by the presence or absence of pedicels and the 

branching of the main axis. Aside from the basic forms of a spike, 

raceme, and panicle, there are many subtypes (Figures 7, 8).

Spikes. In a spike (Figure 7) the spikelets are attached directly to the unbranched main axis without pedicels. 

The inflorescence may be an individual terminal spike as in Elymus and Lolium or several spikes attached to the main axis in 

different patterns (these are panicles), in pairs as in Paspalum, 

racemosely attached as in Leptochloa, or digitately attached as 

in Cynodon.

Racemes. A raceme is an unbranched inflorescence 

with each spikelet borne on a single pedicel directly on the axis 

(Figure 7). This type of inflorescence is rare in the grasses, but 

there are many species where more than one raceme is found 

in the inflorescence, which is then technically referred to as a 

panicle.

Panicles. A panicle is an inflorescence in which the 

main axis has several lateral, whorled or individual indeterminate 

branches, each branch terminating in a pedicellate spikelet (Figures 7, 8). A true panicle does not have any leaf sheaths within 

the inflorescence. A rame is a compound inflorescence in the tribe 

Andropogoneae consisting of one to many units (branches) of 

one sessile and one or two pedicellate spikelets. This arrangement is typical of the Andropogonodae, and in many of the 

older, published flora, it was referred to as “racemes.”

Spikelets. Spikelets are the primary inflorescence 

unit (Figure 8), usually consisting of a short axis (rachilla) bearing two basal glumes and one or more distal florets. Each floret 

usually consists of a lower lemma and upper palea.

FIGURE 5. Leaf blade apices, bases, and margins.
number 99 • 7

Identification

Descriptions. The grass descriptions were recorded from plant specimens at the United States National 

Herbarium (US), Department of Botany, National Museum of 

Natural History, Smithsonian Institution. Information from 

these specimens was verified with the descriptions of species reported in the references. Each description includes the complete 

scientific name (with authorities and place of publication) and 

common name(s); introduced species are marked with an asterisk (*), and native species are unmarked.

Illustrations. Plant illustrations used in this study 

were drawn from herbarium plant specimens and verified against 

illustrations appearing in Hitchcock (1951) and Barkworth et al. 

(2003, 2007). Care should be taken not to confuse grasses with 

“grasslike” species that occur under natural conditions and can 

be confused with true grasses. These belong chiefly to the sedge 

family (Cyperaceae) and the rush family (Juncaceae). Since this 

publication deals only with grasses, it is necessary to differentiate between true grasses and other grasslike species. In grasses, 

leaves are two-ranked and arise at solid conspicuous nodes along 

hollow stems (culms), which are circular in cross section. A leaf 

is comprised of a blade and a sheath surrounding the culm and 

is open down the side in most cases to the base. Commonly, the 

top of the sheath has a membranous projection (ligule) pressed 

against the culm. Sometimes the ligule is represented by a fringe 

of hairs or a shallow rim. In other cases it is absent. In contrast 

to grasses, the majority of sedges have solid stems that are mostly 

FIGURE 6. Leaf blade characteristics.
8 • smithsonian contributions to botany

triangular in cross section. The base of the leaf usually forms a 

closed sheath around the stem, and there is no ligule. However, 

sometimes there is a projection at the top of the sheath, opposite of the leaf blade, instead of between the blade and the culm 

as with grass species. Rushes have solid stems and are usually 

round in cross section, and the nodes are indistinct. The leaves of 

rushes are usually three-ranked and usually not stiff, ligules are 

absent or weakly developed, and auricles are absent.

Keys. Since we are dealing with 182 grasses in Washington, D.C., the keys have been constructed to make use of 

easily visible characteristics. The only additional aids necessary 

are a short metric scale, graduated in millimeters, and a hand 

lens with a magnification of 10–14×. The identification key is 

composed of two parts: a key to major groups and keys to each 

group. Although many readers are familiar with the use of a dichotomous key, a note on how to use the vegetative key seems 

appropriate here. The key contains a series of two contrasting 

statements. Start with the beginning of the key and read both 

groups of characteristics in couplet 1, then decide which group 

fits the specimen best and note the number following the group. 

Proceed to the couplet with that number and repeat the process. 

Read each half of every couplet carefully before deciding which 

description best fits the specimen. Following this pattern, you 

will arrive at the stop in the key where a species name appears at 

FIGURE 7. Inflorescence types.
number 99 • 9

the end of a half couplet. Turn to the text for a description and 

illustration of the species, which are arranged alphabetically. In 

using the key you may need to refer to the glossary, which immediately follows the descriptions. Note also that for the purpose 

of this key and in the descriptions of species, “blade” refers only 

to mature laminas just above the collar.

Acknowledgements

We thank the United States National Herbarium (US), 

Department of Botany, National Museum of Natural History, 

Smithsonian Institution, for allowing the first author work 

space; Robert J. Soreng (US) for providing valuable information 

from the Catalogue of New World Grasses (Poaceae); and Deborah Bell (US) for assistance. In addition, we thank Kitt Repass 

for preparing the illustrations and revising a few initial drawings 

made by Heidi Nevin. We give special thanks to Karen Dillon for 

help with Photoshop, to Kate Nicolette for typing the text, and to 

Wesley Knapp and Chris Frye for many helpful comments aimed 

at improving the manuscript. Finally, we thank all the dedicated 

agrostologists, past and present, who collected extensive material and recorded their findings in books, manuals, floras, and 

published papers.

FIGURE 8. Inflorescence and spikelet characteristics. Labels indicate the following: a, spikelet; b, 

lemma; c, upper glume; d, lower glume; e, pedicel; f, palea; g, anther; h, stigma; i, filament; j, ovary; 

k, lodicule; l, grain; m, rachilla; n, awn; o, raceme; p, peduncle; q, spatheole; r, spathe; s, single 

straight awn; t, single geniculated awn; u, twisted divided awn.

1a. Bamboo-like or reedlike . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Group 1

1b. Not bamboo-like or reedlike . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2a. Plant habit mat forming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Group 2

2b. Plant habit not mat forming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3a. Internodes solid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Group 3

3b. Internodes not solid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4a. Auricles present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Group 4

4b. Auricles lacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5a. Leaf blades filiform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Group 5

5b. Leaf blades not filiform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6a. Leaf blade apices attenuate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Group 6

6b. Leaf blade apices not attenuate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

7a. Leaf sheaths keeled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Group 7

7b. Leaf sheaths not keeled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

8a. Leaf blade bases cordate or broadly rounded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Group 8

8b. Leaf blade bases not cordate or broadly rounded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

9a. Oral hairs present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Group 9

9b. Oral hairs lacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

10a. Leaf blades lanceolate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Group 10

10b. Leaf blades not lanceolate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

11a. Lower nodes rooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Group 11

11b. Lower nodes not rooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

12a. Culms branching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Group 12

12b. Culms not branching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

13a. Rhizomes present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Group 13

13b. Rhizomes absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

14a. Ligules a fringe of hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Group 14

14b. Ligules not a fringe of hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

15a. Internodes pubescent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Group 15

15b. Internodes not pubescent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

16a. Ligules ciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Group 16

16b. Ligules eciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

17a. Leaf blade margins pubescent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Group 17

17b. Leaf blade margins not pubescent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Vegetative Key to the Grasses 

of Washington, D.C.
1 2 • smithsonian contributions to botany

18a. Leaf sheaths closed or partially closed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Group 18

18b. Leaf sheaths open . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

19a. Plants annuals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Group 19

19b. Plants perennials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Group 20

GROUP 1. BAMBOO-LIKE OR REEDLIKE

1a. Plants 1–5 m, tall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1b. Plants usually less than 85 cm tall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2a. Rhizomes elongated; culms not spongy . . . . . . . . . . . . . . . . . . . . . . . . . . . . (147) Phragmites australis subsp. australis

2b. Rhizomes not elongated; culms spongy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (182) Zizania aquatica

3a. Oral setae present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (149) Pleioblastus argenteostriatus fo. glaber

3b. Oral setae lacking or at least poorly developed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (150) Pleioblastus pygmaeus

GROUP 2. MAT FORMING

1a. Rhizomes present, elongated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (42) Cynodon dactylon

1b. Rhizomes absent or, if present, short . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2a. Leaf blades elliptic or oblong . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (121) Microstegium vimineum

2b. Leaf blades not elliptic or oblong . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3a. Leaf blades lanceolate, bases broadly rounded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (57) Dichanthelium laxiflorum

3b. Leaf blades linear, bases not broadly rounded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4a. Leaf blades bases amplexicaul . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (21) Arthraxon hispidus

4b. Leaf blades bases not amplexicaul . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5a. Stolons present, culms unbranched . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (90) Eragrostis hypnoides

5b. Stolons absent, culms branched . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6a. Rhizomes short . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (139) Paspalum dissectum

6b. Rhizome absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

7a. Blade margins spinulose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (75) Echinochloa muricata

7b. Blade margins scabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (69) Digitaria ciliaris

GROUP 3. INTERNODES SOLID

1a. Butt sheaths with white hairs; ligules a fringe of hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . (180) Tripsacum dactyloides

1b. Butt sheaths without white hairs; ligules ciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2a. Nodes bearded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (132) Panicum flexile

2b. Nodes glabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (179) Tripidium ravennae

GROUP 4. AURICLES PRESENT

1a. Auricles claw-like or falcate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Subgroup 4A

1b. Auricles acute-erect or obtuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Subgroup 4B

SUBGROUP 4A. AURICLES CLAW-LIKE OR FALCATE

1a. Rhizomes present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1b. Rhizomes absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2a. Rhizomes elongated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (83) Elymus repens

2b. Rhizomes short . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (116) Lolium arundinaceum

3a. Leaf blade apices attenuate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3b. Leaf blade apices acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4a. Ligules erose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (81) Elymus hystrix

4b. Ligules truncate or entire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (119) Lolium pratense
number 99 • 1 3

5a. Oral hairs ciliate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (181) Triticum aestivum

5b. Oral hairs lacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6a. Ligules erose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (111) Hordeum murinum

6b. Ligules truncate or entire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

7a. Leaf blade margins glabrous or sparsely hairy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

7b. Leaf blade margins scabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

8a. Plants perennials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

8b. Plants annuals or biennials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

9a. Leaves mostly basal; lemma awns curved, spreading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (79) Elymus elymoides

9b. Leaves basal and cauline; lemma awns, if present, straight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (118) Lolium perenne

10a. Ligules very short, 0.2–0.8 mm long; nodes brown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (112) Hordeum pusillum

10b. Ligules 1–2 mm long; nodes not brown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

11a. Plants annuals; lower leaf sheaths pilose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (113) Hordeum vulgare

11b. Plants annuals or biennials; leaf sheaths glabrous or hirsute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (160) Secale cereale

12a. Butt sheaths scarious . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (80) Elymus glabriflorus

12b. Butt sheaths not scarious . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

13a. Leaves mostly basal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

13b. Leaves basal and cauline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

14a. Ligules purple; leaves drooping; spikes straight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (82) Elymus macgregorii

14b. Ligules not colored; leaves ascending; spikes deflexed or drooping . . . . . . . . . . . . . . . . . . . . . . (78) Elymus canadensis

15a. Plants perennials; spikelet packing broadside to rachis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (86) Elymus virginicus

15b. Plants annuals or short lived perennials; spikelet packing adaxial, 2-rowed . . . . . . . . . . . . . . (117) Lolium multiflorum

SUBGROUP 4B. AURICLES ACUTE-ERECT OR OBTUSE

1a. Rhizomes elongated and scaly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (167) Sorghastrum nutans

1b. Rhizomes absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2a. Leaf blade apices acuminate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (14) Anthoxanthum odoratum

2b. Leaf blade apices acute or obtuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3a. Leaf blades filiform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (97) Festuca filiformis

3b. Leaf blades linear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4a. Leaf sheaths closed for less than 1/3 their length, butt sheaths persistent, fibrous . . . . . . . . . (103) Festuca trachyphylla

4b. Leaf sheaths open, butt sheaths not fibrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5a. Leaf blade margins pubescent or sparsely hairy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (85) Elymus villosus

5b. Leaf blade margins scaberulous or scabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6a. Culms slender; ligules erose; leaf blades lax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (84) Elymus riparius

6b. Culms not slender; ligules obtuse or acute; leaf blades straight . . . . . . . . . . . . . . . . . . . . . . . . . . (146) Phleum pratense

GROUP 5. LEAF BLADES FILIFORM

1a. Culms zigzag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (16) Aristida dichotoma

1b. Culms not zigzag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2a. Leaf sheaths tubular 3/4 of their length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (101) Festuca rubra

2b. Leaf sheaths open . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3a. Ligules a fringe of hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (44) Danthonia compressa

3b. Ligules eciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4a. Leaf sheath margins smooth, becoming curled when old . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (23) Avenella flexuosa

4b. Leaf sheath margins scabrous, straight when old . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5a. Plants annuals; culms usually solitary; leaf sheaths scabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . (6) Aira caryophyllea

5b. Plants perennials, caespitose; culms numerous; leaf sheaths glabrous or sparsely hairy . . . . . . . . . . . . . . . . . . . . . . . . . 6

6a. Leaf sheaths closed 1/3 of their length, butt sheaths fibrous, investing in culm bases . . . . . . (103) Festuca trachyphylla

6b. Leaf sheaths open, butt sheaths not fibrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (148) Piptochaetium avenaceum
1 4 • smithsonian contributions to botany

GROUP 6. LEAF BLADE APICES ATTENUATE

1a. Rhizomes present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1b. Rhizomes absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2a. Rhizomes short and knotty; leaf sheaths keeled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (178) Tridens flavus var. flavus

2b. Rhizomes elongated and scaly; leaf sheaths not keeled . . . . . . . . . . . . . . . . . . . . . . . . . . (127) Muhlenbergia sobolifera

3a. Leaf blades flaccid; culms robust; leaf blade margins cartilaginous . . . . . . . . . . . . . . . . . . . . . . . . . (162) Setaria italica

3b. Leaf blades firm; culms not robust; leaf blade margins not cartilaginous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4a. Ligules ciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4b. Ligules not ciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

5a. Plants perennials; leaf blade bases broadly rounded . . . . . . . . . . . . . . . . . . . . . . . . . . (67) Dichanthelium villosissimum

5b. Plants annuals; leaf blade bases not rounded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (130) Panicum capillare

6a. Ligules a fringe of hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

6b. Ligules eciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

7a. Culms wiry; lemma awns 3-branched . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (18) Aristida oligantha

7b. Culms not wiry; lemmas awnless, mucornate or short-awned, never 3-branched . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

8a. Leaf blades sheaths inflated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (176) Sporobolus neglectus

8b. Leaf blades sheaths not inflated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

9a. Leaf sheaths longer than internodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

9b. Leaf sheaths shorter than internodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

10a. Culms very slender; leaf blade margins sparsely hairy . . . . . . . . . . . . . . . . . . . . . . . . (58) Dichanthelium linearifolium

10b. Culms not slender; leaf blade margins pubescent . . . . . . . . . . . . . . . . . . . . . . . . . . . (53) Dichanthelium depauperatum

11a. Rootstocks evident . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (54) Dichanthelium dichotomum

11b. Rootstocks lacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

12a. Caespitose perennials; leaf blades lanceolate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (46) Dichanthelium aciculare

12b. Solitary or caespitose annuals; leaf blades linear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

13a. Leaf blades 2−8 mm wide; panicles erect; spikelets not subtended by bristles . . . . . . . . . . . . . (96) Eriochloa contracta

13b. Leaf blades 10−20 mm wide; panicles nodding; spikelets subtended by (1–)3(–6) bristles. . . . . . . . . (161) Setaria faberi

14a. Ligules erose; plants perennials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (81) Elymus hystrix

14b. Ligules not erose; plants annuals or short-lived perennials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

15a. Ligules acute or attenuate; leaf blade with midrib widened . . . . . . . . . . . . . . . . (73) Diplachne fusca subsp. fascicularis

15b. Ligules truncate; leaf blade midrib not widened . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (98) Festuca myuros

GROUP 7. LEAF SHEATHS KEELED OR CONSPICUOUSLY COMPRESSED

1a. Leaf blades distichous, apices pungent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (41) Coleataenia rigidula

1b. Leaf blades not distichous, apices not pungent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2a. Oral hairs ciliate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (36) Cenchrus longispinus

2b. Oral hairs lacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3a. Culm internodes elliptical in cross section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3b. Culm internodes terete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4a. Rhizomes elongated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (153) Poa compressa

4b. Rhizomes lacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (77) Eleusine indica

5a. Leaf blade apices abruptly acute, obtuse, or hooded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

5b. Leaf blade apices not abruptly acute or obtuse or hooded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

6a. Rhizomes present, elongated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (156) Poa pratensis

6b. Rhizomes absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

7a. Leaf blades flaccid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (155) Poa palustris

7b. Leaf blades firm, straight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

8a. Plants annuals; stolons absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (151) Poa annua

8b. Plants perennials; stolons present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (158) Poa trivialis

9a. Ligules absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (74) Echinochloa crusgalli

9b. Ligules present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
number 99 • 1 5

10a. Ligules ciliate or ciliolate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

10b. Ligules eciliate membrane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

11a. Leaf blade margins glabrous; culms branching, ample . . . . . . . . . . . . . . . . . . . . . . . . . . . . (13) Andropogon virginicus

11b. Leaf blade margins scabrous; culms branching, sparse . . . . . . . . . . . . . . . . . . . . . . . . . . . . (10) Andropogon glomeratus

12a. Rhizomes present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

12b. Rhizomes lacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

13a. Culm lateral branches ample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (159) Schizachyrium scoparium

13b. Culms unbranched . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

14a. Leaf sheaths laterally compressed, glabrous or pilose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (40) Coleataenia anceps

14b. Leaf sheaths keeled, scaberulous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (125) Muhlenbergia glomerata

15a. Basal innovations flabellate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (43) Dactylis glomerata

15b. Basal innovations subterete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

16a. Leaf blade margins glabrous; butt sheaths with white hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . (70) Digitaria filiformis

16b. Leaf blade margins not glabrous; butt sheaths without white hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

17a. Plants annuals; culms decumbent or prostrate, much branched . . . . . . . . . . . . . . . . . . . . . . . (72) Digitaria sanguinalis

17b. Plants perennials; culms erect or geniculately ascending, unbranched . . . . . . . . . . . . . . . . . . . . . . (141) Paspalum laeve

GROUP 8. LEAF BLADE BASES BROADLY ROUNDED, CORDATE, OR AMPLEXICAUL

1a. Leaf blade bases broadly rounded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1b. Leaf blade bases cordate or amplexicaul . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2a. Rhizomes present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2b. Rhizomes absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3a. Leaves distichous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (108) Gymnopogon ambiguus

3b. Leaves not distichous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4a. Internodes glandular (below nodes); lateral branches ample . . . . . . . . . . . . . . . . . . . . . . (65) Dichanthelium scoparium

4b. Internodes not glandular; culms unbranched . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (143) Paspalum setaceum

5a. Nodes glabrous; leaf blade margins cartilaginous . . . . . . . . . . . . . . . . . . . . . . . . . . . . (62) Dichanthelium oligosanthes

5b. Nodes bearded; leaf blade margins not cartilaginous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6a. Lateral branches ample or sparse; leaf blade bases tuberculate-ciliate . . . . . . . . . . . . . (47) Dichanthelium acuminatum

6b. Lateral branches lacking; leaf blade bases scabrous . . . . . . . . . . . . . . . . . . . . . . (60) Dichanthelium mattamuskeetense

7a. Leaf blade bases amplexicaul . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (51) Dichanthelium columbianum

7b. Leaf blade bases cordate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

8a. Internodes glandular (below nodes); butt sheaths woolly . . . . . . . . . . . . . . . . . . . . . . . . . (65) Dichanthelium scoparium

8b. Internodes not glandular; butt sheaths not woolly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

9a. Rootstocks evident . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

9b. Rootstocks lacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

10a. Ligules ciliate membranes; leaf blades flaccid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (56) Dichanthelium latifolium

10b. Ligules a fringe of hairs or absent; leaf blades firm or stiff . . . . . . . . . . . . . . . . . . . . (52) Dichanthelium commutatum

11a. Leaf blade apices acuminate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

11b. Leaf blade apices acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

12a. Ligules a fringe of hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (50) Dichanthelium clandestinum

12b. Ligules eciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (64) Dichanthelium scabriusculum

13a. Culms from knotted crowns; ligules ciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (49) Dichanthelium boscii

13b. Culms not from knotted crowns; ligules a fringe of hairs or absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

14a. Butt sheaths villous with white hairs; leaf blade surfaces pubescent . . . . . . . . . . . . . . (47) Dichanthelium acuminatum

14b. Butt sheaths glabrous or sparsely hairy; leaf blade surfaces glabrous . . . . . . . . . . . (66) Dichanthelium sphaerocarpon

GROUP 9. ORAL HAIRS BEARDED

1a. Rootstocks evident; culms robust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (95) Erianthus giganteus

1b. Rootstocks not evident; culms not robust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1 6 • smithsonian contributions to botany

2a. Ligules ciliolate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (122) Miscanthus sinensis

2b. Ligules not ciliolate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3a. Ligules eciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (30) Bromus pubescens

3b. Ligules a fringe of hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4a. Culms with ample branching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (89) Eragrostis frankii

4b. Culms not branched . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5a. Leaf sheaths tubular or closed most of their length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (48) Dichanthelium annulum

5b. Leaf sheaths open . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6a. Leaf blades filiform, curled or flexuous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (45) Danthonia spicata

6b. Leaf blades linear straight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

7a. Plants annuals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

7b. Plants perennials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

8a. Leaf sheath surfaces glabrous, outer margins hairy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (87) Eragrostis capillaris

8b. Leaf sheath surfaces glabrous below, hairy at summit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (92) Eragrostis pectinacea

9a. Leaf blade margins scabrous, apices acuminate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (163) Setaria parviflora

9b. Leaf blade margins glabrous, apices acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (94) Eragrostis spectabilis

GROUP 10. LEAF BLADES LANCEOLATE

1a. Rhizomes present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1b. Rhizomes absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2a. Rhizomes elongated, scaly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (169) Sorghum halepense

2b. Rhizomes short, knotty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3a. Leaf blade apices acute; ligules ciliolate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (38) Chasmanthium laxum

3b. Leaf blade apices acuminate; ligules eciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . (24) Brachyelytrum erectum

4a. Leaf blade bases abruptly and strongly constricted . . . . . . . . . . . . . . . . . . . . . . . . . . . . (55) Dichanthelium ensifolium

4b. Leaf blade bases not constricted . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5a. Ligules eciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (142) Paspalum pubiflorum

5b. Ligules ciliate membranes or a fringe of hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6a. Ligules ciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

6b. Ligules a fringe of hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

7a. Plants annuals, rooting at lower nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (133) Panicum gattingeri

7b. Plants perennials, lower nodes not rooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

8a. Leaf blade margins scabrous, tapering at both ends . . . . . . . . . . . . . . . . . . . . . . . . . . . . (68) Dichanthelium yadkinense

8b. Leaf blade margins glabrous, not tapering at both ends . . . . . . . . . . . . . . . . . . . . . . . . . . . (59) Dichanthelium lucidum

9a. Leaf blade apices acuminate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (63) Dichanthelium ravenelii

9b. Leaf blade apices acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

10a. Leaf blade margins sparsely hairy; lateral branches sparse (61) . . . . . . . . . . . . . . . . . . . . . Dichanthelium meridionale

10b. Leaf blade margins hairy cartilaginous; lateral branches ample . . . . . . . . . . . . . . . . . (62) Dichanthelium oligosanthes

GROUP 11. ROOTING AT LOWER NODES

1a. Leaf sheaths tubular or closed 1/3 to 1/2 of their length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1b. Leaf sheaths open . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2a. Leaf sheaths tubular . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (106) Glyceria septentrionalis

2b. Leaf sheaths closed 1/3 to 1/2 of their length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (158) Poa trivialis

3a. Leaf blades ribbed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3b. Leaf blades not ribbed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4a. Leaf blade apices acuminate; rhizomes elongated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (3) Agrostis gigantea

4b. Leaf blade apices acute; rhizomes absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (5) Agrostis perennans

5a. Ligules absent; leaf blade margins spinulose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (75) Echinochloa muricata

5b. Ligules present; leaf blade margins not spinulose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6a. Leaf blades flaccid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (115) Leersia virginica

6b. Leaf blades firm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
number 99 • 1 7

7a. Rhizomes present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

7b. Rhizomes absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

8a. Rhizomes elongated; leaf blade margins spinulose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (114) Leersia oryzoides

8b. Rhizomes short; leaf blade margins not spinulose . . . . . . . . . . . . . . . . . . . . . . . . . . . (51) Dichanthelium columbianum

9a. Ligules a fringe of hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (136) Panicum verrucosum

9b. Ligules not a fringe of hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

10a. Leaf blade apices attenuate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (133) Panicum gattingeri

10b. Leaf blade apices not attenuate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

11a. Ligules ciliate or ciliolate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

11b Ligules eciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

12a. Culms branching freely; leaf blade margins scabrous . . . . . . . . . . . . . . . . . . . . . . . . . . (131) Panicum dichotomiflorum

12b. Culms unbranched; leaf blade margins glabrous or sparsely hairy . . . . . . . . . . . . . . . . . . (126) Muhlenbergia schreberi

13a. Leaf blade apices obtuse or abruptly acute, hooded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (151) Poa annua

13b. Leaf blade apices acute, not hooded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

14a. Plants annuals; lemma awns present, straight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (84) Elymus riparius

14b. Plants perennials; lemmas awnless . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (71) Digitaria ischaemum

GROUP 12. CULMS BRANCHED

1a. Culms sparsely branched . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1b. Culms with ample branches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2a. Leaf blade apices abruptly acute or obtuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2b. Leaf blade apices acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3a. Rhizomes present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (154) Poa cuspidata

3b. Rhizomes absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4a. Plants perennials; leaf blades flaccid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (155) Poa palustris

4b. Plants annuals; leaf blades firm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5a. Leaf sheaths closed for 1/3 of their length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (151) Poa annua

5b. Leaf sheaths open . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (99) Festuca octoflora

6a. Ligules a fringe of hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

6b. Ligules ciliate or ciliolate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

7a. Plants annuals; leaf blade margins tuberculate-ciliate . . . . . . . . . . . . . . . . . . . . . . . . . . (135) Panicum philadelphicum

7b. Plants perennials; leaf blade margins glabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (19) Aristida purpurascens

8a. Ligules eciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (15) Apera spica-venti

8b. Ligules ciliate or ciliolate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

9a. Plants annuals; leaf blade margins pubescent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (134) Panicum miliaceum

9b. Plants perennials; leaf blade margins scabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

10a. Leaf blade venations with distinct cross veins; rhizomes knotty . . . . . . . . . . . . . . . . . . . (37) Chasmanthium latifolium

10b. Leaf blade venations without distinct cross veins; rhizomes, if present, not knotty . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

11a. Butt sheaths sparsely hairy or pubescent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (11) Andropogon gyrans

11b. Butt sheaths glabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (9) Andropogon gerardii

12a. Culms wiry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

12b. Culms not wiry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

13a. Culms zigzag; lemma awns briefly coiled at base of limb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (16) Aristida dichotoma

13b. Culms straight; lemma awns not coiled at base of limb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (17) Aristida longespica

14a. Ligules a fringe of hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (135) Panicum philadelphicum

14b. Ligules not a fringe of hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

15a. Ligules eciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

15b. Ligules ciliate or ciliolate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 

16a. Plants annuals; ligules decurrent, attenuate; leaf blade margins glabrous . . . . . . . . . . . . . . . (7) Alopecurus carolinianus

16b. Plants perennials; ligules erose; leaf blade margins scabrous . . . . . . . . . . . . . . . . . . . . . (159) Schizachyrium scoparium

17a. Rhizomes knotty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (12) Andropogon ternarius

17b. Rhizomes not knotty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (51) Dichanthelium columbianum
1 8 • smithsonian contributions to botany

GROUP 13. RHIZOMES PRESENT

1a. Rhizomes short . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Subgroup 13A

1b. Rhizomes elongated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Subgroup 13B

SUBGROUP 13A. RHIZOMES SHORT

1a. Leaf blade apices abruptly acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (154) Poa cuspidata

1b. Leaf blade apices not abruptly acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2a. Leaf blade apices acuminate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (24) Brachyelytrum erectum

2b. Leaf blade apices acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3a. Basal innovations flabellate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (138) Paspalum dilatatum

3b. Basal innovation subterete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4a. Rhizomes knotty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4b. Rhizomes not knotty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

5a. Leaf blade margins scabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (37) Chasmanthium latifolium

5b. Leaf blade margins sparsely hairy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (38) Chasmanthium laxum

6a. Rhizomes scaly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (115) Leersia virginica

6b. Rhizomes not scaly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

7a. Leaf blade margins glabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (107) Glyceria striata

7b. Leaf blade margins not glabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

8a. Leaf sheaths closed most of their length; culms wiry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (120) Melica mutica

8b. Leaf sheaths open; culms not wiry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

9a. Leaf blade margins pubescent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (140) Paspalum floridanum

9b. Leaf blade margins scabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

10a. Ligules lacerate; lemmas awnless . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (104) Glyceria canadensis

10b. Ligules obtuse or truncate; lemma awns straight or geniculate . . . . . . . . . . . . . . . . . . . . . . . (20) Arrhenatherum elatius

SUBGROUP 13B. RHIZOMES ELONGATED

1a. Leaf blade apices abruptly acute, hooded; sheaths closed 1/4 to 1/2 of their length . . . . . . . . . . . . . (156) Poa pratensis

1b. Leaf blade apices not abruptly acute; sheaths open . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2a. Leaf blade apices attenuate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (1) Agrostis capillaris

2b. Leaf blade apices not attenuate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3a. Leaf blade apices acuminate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3b. Leaf blade apices acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4a. Leaf blade surfaces ribbed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (3) Agrostis gigantea

4b. Leaf blade surfaces not ribbed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5a. Leaf blades linear flat when fresh, involute when dry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (171) Spartina pectinata

5b. Leaf blades linear flat and remain so when dry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (170) Spartina cynosuroides

6a. Ligules a fringe of hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (175) Sporobolus compositus

6b. Ligules not a fringe of hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

7a. Basal innovations flabellate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (40) Coleataenia anceps

7b. Basal innovations subterete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

8a. Leaf blade margins serrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (144) Phalaris arundinacea

8b. Leaf blade margins not serrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

9a. Leaf sheath margins hyaline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

9b. Leaf sheath margins not hyaline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

10a. Culms wiry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (128) Muhlenbergia sylvatica

10b. Culms not wiry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (124) Muhlenbergia frondosa

11a. Leaf blade margins pubescent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (35) Calamagrostis cinnoides

11b. Leaf blade margins scabrous or scabridulous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

12a. Ligules ciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (137) Panicum virgatum

12b. Ligules eciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
number 99 • 1 9

13a. Rhizomes scaly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (129) Muhlenbergia tenuiflora

13b. Rhizomes not scaly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (28) Bromus inermis

GROUP 14. LIGULES A FRINGE OF HAIRS

1a. Plants perennials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (175) Sporobolus compositus

1b. Plants annuals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2a. Culms wiry, scabrous; leaf sheaths often inflated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (177) Sporobolus vaginiflorus

2b. Culms not wiry, glabrous; leaf sheaths not inflated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3a. Leaf blade margins scabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3b. Leaf blade margins glabrous or glandular . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4a. Leaf sheath outer margins hairy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (166) Setaria viridis

4b. Leaf sheath outer margins not hairy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (164) Setaria pumila

5a. Leaf blade surfaces scabrous, glandular or eglandular . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (91) Eragrostis minor

5b. Leaf blade surfaces glabrous, sometimes glandular . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6a. Crateriform glands wartlike below the nodes; collars indistinct . . . . . . . . . . . . . . . . . . . . . . . (88) Eragrostis cilianensis

6b. Glands lacking below the nodes; collars divided . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (93) Eragrostis pilosa

GROUP 15. INTERNODES PUBESCENT

1a. Ligules absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (76) Echinochloa walteri

1b. Ligules present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2a. Ligules ciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (134) Panicum miliaceum

2b. Ligules eciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3a. Plants perennials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3b. Plants annuals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

4a. Leaf blade margins pubescent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (109) Holcus lanatus

4b. Leaf blade margins scabrous or glabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (30) Bromus pubescens

5a. Leaf sheath surfaces glabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (8) Alopecurus myosuroides

5b. Leaf sheath surfaces densely pilose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6a. Leaf sheath surfaces densely pilose; ligules erose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (27) Bromus hordeaceus

6b. Leaf sheath surfaces retrorsely pilose; ligules obtuse or lacerate . . . . . . . . . . . . . . . . . . . . . . . . . (29) Bromus japonicus

GROUP 16. LIGULES CILIATE OR CILIOLATE MEMBRANES

1a. Plants stout or robust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1b. Plants not stout or robust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2a. Leaf sheath surfaces hispid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (134) Panicum miliaceum

2b. Leaf sheath surfaces glabrous or appressed pubescent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (168) Sorghum bicolor

3a. Leaf blade margins scabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3b. Leaf blade margins glabrous or pubescent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4a. Plants perennials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (172) Sphenopholis intermedia

4b. Plants annuals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5a. Ligules ciliate membranes; upper leaf blade surfaces sparsely hairy . . . . . . . . . . . . . . . . . . . . . . . . (164) Setaria pumila

5b. Ligules ciliate membranes; leaf blade abaxial surfaces scabrous . . . . . . . . . . . . . . . . . . . . . . . . (165) Setaria verticillata

6a. Leaf blade margins glabrous or sparsely hairy; ligules ciliolate membranes . . . . . . . . . . . (126) Muhlenbergia schreberi

6b. Leaf blade margins pubescent; ligules eciliate membranes or ciliate membranes . . . . . . . . (174) Sphenopholis obtusata

GROUP 17. LEAF BLADE MARGINS PUBESCENT OR SPARSELY HAIRY

1a. Leaf blade margins pubescent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1b. Leaf blade margins sparsely hairy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2a. Leaf blade surfaces hirsute or pilose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2b. Leaf blade surfaces scabrous or pubescent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 0 • smithsonian contributions to botany

3a. Leaf sheaths (lower) densely hairy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (26) Bromus commutatus

3b. Leaf sheaths retrorsely villous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (31) Bromus racemosus

4a. Ligules lacerate; lemmas awned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (34) Bromus tectorum

4b. Ligules erose-ciliate; lemmas awnless . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (174) Sphenopholis obtusata

5a. Ligules a fringe of hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (18) Aristida oligantha

5b. Ligules eciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6a. Leaf sheath surfaces hispid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (33) Bromus sterilis

6b. Leaf sheath surfaces not hispid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

7a. Ligules truncate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (112) Hordeum pusillum

7b. Ligules obtuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (32) Bromus secalinus

GROUP 18. LEAF SHEATHS TUBULAR OR PARTIALLY CLOSED

1a. Leaf sheaths tubular for much of their length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1b. Leaf sheaths closed part of their length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2a. Culms wiry; leaf blade margins glabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (107) Glyceria striata

2b. Culms not wiry; leaf blade margins scabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (120) Melica mutica

3a. Leaf blade margins scabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (100) Festuca paradoxa

3b. Leaf blade margins glabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4a. Basal innovations intravaginal; butt sheaths fibrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (103) Festuca trachyphylla

4b. Basal innovations usually extravaginal; butt sheaths not fibrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5a. Ligules erose; leaf blades stiff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (102) Festuca subverticillata

5b. Ligules truncate or obtuse; leaf blades flaccid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (157) Poa sylvestris

GROUP 19. PLANTS ANNUAL

1a. Leaf blades ribbed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (2) Agrostis elliottiana

1b. Leaf blades not ribbed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2a. Apices acuminate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (22) Avena sativa

2b. Apices acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3a. Leaf blade margins spinulose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (75) Echinochloa muricata

3b. Leaf blade margins not spinulose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4a. Leaf blade apices obtuse, abruptly acute, hooded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (151) Poa annua

4b. Leaf blade apices acute, not hooded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5a. Leaf blade margins scabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (145) Phalaris canariensis

5b. Leaf blade surfaces glabrous or sparsely hairy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6a. Ligules erose-ciliate membranes, more or less lacerate, leaf blade margins pubescent . . . . (174) Sphenopholis obtusata

6b. Ligules truncate or obtuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

7a. Leaves basal and cauline; nodes brown; inflorescence a spike . . . . . . . . . . . . . . . . . . . . . . . . . (112) Hordeum pusillum

7b. Leaves mostly basal; nodes not brown; inflorescence a panicle . . . . . . . . . . . . . . . . . . . . . . . . . . . (99) Festuca octoflora

GROUP 20. PLANTS PERENNIAL

1a. Leaf blade apices abruptly acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1b. Leaf blade apices acute or acuminate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2a. Stolons present; leaf blades flaccid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (158) Poa trivialis

2b. Stolons absent; leaf blades stiff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (155) Poa palustris

3a. Leaf blade apices acuminate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3b. Leaf blade apices acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4a. Solitary perennials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (39) Cinna arundinacea

4b. Caespitose perennials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5a. Butt sheaths glabrous; ligules obtuse, strongly decurrent . . . . . . . . . . . . . . . . . . . . . . . . . (123) Muhlenbergia capillaris

5b. Butt sheaths papery; ligules truncate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (14) Anthoxanthum odoratum
number 99 • 2 1

6a. Basal innovations flabellate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (43) Dactylis glomerata

6b. Basal innovations subterete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

7a. Leaf sheaths ribbed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (5) Agrostis perennans

7b. Leaf sheaths not ribbed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

8a. Ligules absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (76) Echinochloa walteri

8b. Ligules present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

9a. Leaf sheaths pilose with reflexed hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (30) Bromus pubescens

9b. Leaf sheaths not pilose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

10a. Leaf blades flaccid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (152) Poa autumnalis

10b. Leaf blades firm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

11a. Leaf blade margins glabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (4) Agrostis hyemalis

11b. Leaf blade margins scabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

12a. Ligules ciliate, erose-ciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (172) Sphenopholis intermedia

12b. Ligules eciliate membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

13a. Ligules erose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

13b. Ligules not erose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

14a. Culms slender; leaf blades lax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (84) Elymus riparius

14b. Culms not slender; leaf blades ascending . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (105) Glyceria laxa

15a. Butt sheaths scarious . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (80) Elymus glabriflorus

15b. Butt sheaths not scarious . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

16a. Butt sheaths pubescent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (25) Bromus catharticus

16b. Butt sheaths glabrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

17a. Ligules less than 1 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (110) Hordeum jubatum

17b. Ligules more than 1–6 mm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

18a. Ligules lacerate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (173) Sphenopholis nitida

18b. Ligules acute, obtuse, or truncate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

19a. Leaves cauline; butt sheaths brown; lemmas awnless . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (146) Phleum pratense

19b. Leaves mostly basal; butt sheaths not brown; lemma awns straight or geniculate . . . . . . . . (20) Arrhenatherum elatius

1. Agrostis capillaris* L.

Figure 9

Agrostis capillaris* L., Sp. Pl. 1: 62. 1753.

Common names: browntop, colonial bent, Rhode Island bent.

Caespitose perennials; rhizomes elongated; stolons absent 

or present. Culms 10–75 cm tall, erect or geniculately ascending; 

nodes glabrous; internodes smooth. Leaves mostly basal; sheaths 

smooth, margins glabrous; ligules 0.3–2 mm long (shorter than 

wide), eciliate membranes, apex truncate to rounded, sometimes 

lacerate; blades 3–10 cm long, 1–5 mm wide, linear, flat, surfaces 

ribbed, smooth or scaberulous, margins glabrous, apex attenuate. Panicles 3–20 cm long, (1–)2–12 cm wide, oblong to ovate, 

open; primary branches whorled at lower nodes. Spikelets 1–3.5 

mm long, lanceolate or oblong, laterally compressed; lemmas 

awnless.

2. Agrostis elliottiana Schult.

Figure 10

Agrostis elliottiana Schult., Mant. 2: 202. 1824. 

Common name: Elliott’s bent.

Delicate caespitose annuals. Culms 8–45 cm tall, weak, 

erect, sometimes geniculate at the base; internodes glabrous; 

nodes glabrous. Leaves mostly basal; sheaths smooth, glabrous, 

margins glabrous; ligules 1.4–4.5 mm long, eciliate membranes, 

apex obtuse; blades 3–15 cm long, 0.7–2.5 mm wide, linear, flat 

or conduplicate, ribbed, margins glabrous, apex acute. Panicles 

3–20 cm long, 2–12 cm wide, open, oblong to ovate, diffuse, 

whorled at most nodes. Spikelets 1.2–2.2 mm long, elliptic, laterally compressed; principal lemma awns 3.5–8 mm long, subapical, flexuous without a column. 

Descriptions

FIGURE 9. Agrostis capillaris. A. Habit. B. Sheath, ligule, and 

blade. C. Branch apex with spikelets. Drawn from Hitchcock s.n. 

(US-838334).
2 4 • smithsonian contributions to botany

3. Agrostis gigantea* Roth

Figure 11

Agrostis gigantea* Roth, Tent. Fl. Germ. 1: 31. 1788. 

Common name: redtop.

Caespitose perennials; rhizomes elongated. Culms 15–82 

cm tall, geniculately ascending or decumbent; sometimes rooting 

from lower nodes; internodes smooth. Leaves basal and cauline; 

sheaths smooth or scaberulous; ligules 1–4.5 mm long, eciliate 

membranes, apex rounded to truncate; blades 4–10 cm long 

and 3–8 mm wide, flat, surfaces ribbed, scaberulous, margins 

scabrous, apex acuminate. Panicles 8–25(–30) cm long, (1.5–)

3–15 cm wide, open, oblong to ovate, diffuse; primary branches 

whorled at most nodes. Spikelets 2–3 mm long, lanceolate or 

oblong, laterally compressed; principle lemmas awnless, rarely 

mucronate, 0.4–1 mm long.

4. Agrostis hyemalis (Walter) 

Britton, Sterns & Poggenb.

Figure 12

Agrostis hyemalis (Walter) Britton, Sterns & Poggenb., Prelim. 

Cat. 68. 1888. 

Common names: hair grass, tickle grass.

Caespitose perennials. Culms 15–82 cm tall, erect, glabrous or 

sparsely hairy. Leaves cauline and basal; sheaths glabrous; ligules 

(0.7–)1.2–4 mm long, eciliate membranes, apex lacerate; blades 

3–10 cm long, 1–2 mm wide, flat, becoming involute or folded, 

linear, surfaces and margins glabrous, apex acute. Panicles (5–)10–

25(–36) cm long, 4–24 cm wide, open, ovate; diffuse with spikelets 

clustered toward branch tips; primary branches widely spreading 

or drooping. Spikelets 1.5–2.1 mm long, ovate to narrowly ovate, 

elliptic, laterally compressed; principle lemmas awnless.

FIGURE 11. Agrostis gigantea. A. Culm base. B. Sheath, ligule, and 

blade. C. Panicle. D. Glumes. A−C drawn from Lamson-Scribner 

s.n. (US-746800); D modified from Barkworth et al. (2007).

FIGURE 10. Agrostis elliottiana. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. Drawn from Hotchkiss 1952 (US-1256692).
number 99 • 2 5

5. Agrostis perennans (Walter) Tuck.

Figure 13

Agrostis perennans (Walter) Tuck., Amer. J. Sci. Arts 45: 44. 1843. 

Common names: autumn bent, upland bent grass.

Caespitose perennials. Culms 20–80 cm tall, decumbent, 

weak, sometimes rooting at the lower nodes. Leaves cauline; 

sheaths ribbed, smooth, glabrous; ligules (0.7–)1.5–7.3 mm 

long, eciliate membranes, apex lacerate; blades 6–20 cm long, 

2–5 mm wide, linear, flat, surface ribbed, scaberulous, margins 

glabrous, apex acute. Panicles 10–25 cm long, 2.5–11 cm wide, 

open, ovate, diffuse; whorled at most nodes; branches flexuous. 

Spikelets 2.2–2.9 mm long, spreading, oblong, laterally compressed; principal lemmas awnless.

6. Aira caryophyllea* L.

Figure 14

Aira caryophyllea* L., Sp. Pl. 1: 66. 1753. 

Common names: common silver hair grass, silver hair grass; silvery hair grass.

Delicate annuals. Culms 4.5–55 cm tall, erect, decumbent, 

usually solitary, glabrous. Leaves mostly basal; sheaths scaberulous, occasionally smooth; ligules 1.2–8 mm long, eciliate membranes, erose, apex obtuse; blades 0.3–13.5 cm long, 0.3–2.5 

mm wide, filiform, involute, surfaces scaberulous, margins scabrous, apex acute. Panicles 1.2–13.5 cm long, 1.5–10 cm wide, 

open, ovate. Spikelets 2.4–3.1 mm long, oblong to ovate, laterally compressed; principal lemma awns 2.6–3.6 mm long, dorsal, 

arising just above the base, geniculate.

FIGURE 12. Agrostis hyemalis. A. Habit. B. Sheath, ligule, and 

blade. C. Glumes. Drawn from Ward s.n. (US-156641).

FIGURE 13. Agrostis perennans. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelet. Drawn from Chase 2621 (US-746990).
2 6 • smithsonian contributions to botany

7. Alopecurus carolinianus Walter

Figure 15

Alopecurus carolinianus Walter, Fl. Carol. 74. 1788.

Common names: tufted alopecurus, tufted foxtail, tufted 

meadow foxtail.

Caespitose annuals. Culms 5–50 cm tall, glabrous, erect 

or geniculate at or near the base; branches ample at the base; 

nodes glabrous, dark color. Leaves basal and cauline; sheaths 

glabrous, loose or somewhat inflated, especially at the base; ligules 2.8–4.5 mm long, eciliate membranes, decurrent, attenuate 

to rather blunt and usually erose at the tip; blades 5–12 cm long, 

0.9–3 mm wide, linear, flat, upper surfaces scabrous, lower glabrous, margins glabrous, apex acute. Panicles 1–7 cm long, 3–6 

cm wide, spiciform, linear. Spikelets 1.8–3 mm long, elliptic, laterally compressed; principal lemma awns 3–5 mm long, dorsal, 

arising just above the base, geniculate, with a twisted column. 

8. Alopecurus myosuroides* Huds.

Figure 16

Alopecurus myosuroides* Huds., Fl. Angl. 1: 23. 1762. 

Common names: slender alopecurus, slender foxtail, slender 

meadow foxtail.

Caespitose annuals. Culms (10–)40–85 cm tall, geniculately 

ascending or decumbent; culm internodes pubescent. Leaves 

basal and cauline; sheath surfaces glabrous; ligules 2–6 mm long, 

eciliate membranes, apex obtuse; blades 3–16 cm long, (2–)3.5–6 

mm wide, flat, linear, surfaces scaberulous, rough adaxially or 

on both sides (abaxially), margins scabrous, apex acute. Panicles 

4–12 cm long, 3–7 cm wide, spiciform, linear, tapering above. 

Spikelets 4.5–7 mm long, oblong, laterally compressed; principal 

lemma awns 8–14 mm long, dorsal, arising just above the base, 

geniculate, clearly exserted from spikelet, with a twisted column.

FIGURE 14. Aira caryophyllea. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. Drawn from Leonard 540 (US-1769679).

FIGURE 15. Alopecurus carolinianus. A. Habit. B. Sheath, ligule, 

and blade. C. Spikelet. A, B drawn from Steury 020430.1 (US3442323); C modified from Barkworth et al. (2007).
number 99 • 2 7

9. Andropogon gerardii Vitman

Figure 17

Andropogon gerardii Vitman, Summa Pl. 6: 16. 1792. 

Common names: big bluestem, bluejoint turkeyfoot.

Caespitose perennials, often forming large clump; rhizomes 

absent or short; butt sheaths glabrous, scarious. Culms 1–3 m 

tall, often glabrous; lateral branches sparse. Leaves basal and 

cauline; ligules 0.4–2.5 mm long, ciliolate membranes; sheaths 

glabrous or pilose; blades 5–50 cm long, (2–)5–10 mm wide, 

green or glaucous, linear, flat, surfaces glabrous or hirsute, margins scabrous, apex acute. Rames 2–7 per culm, paired or digitate, terminal; each rame 4–11 cm long, exerted at maturity, 

usually purplish, sometimes yellowish. Spikelets in pairs; fertile 

spikelets 5–11 mm long, oblong, sessile, scabrous, dorsally compressed; pedicelled spikelets 3.5–11 mm long, staminate, usually 

well developed, elliptic; principal lemma awns 8–25 mm long, 

arising from a sinus, geniculate with a twisted column.

10. Andropogon glomeratus (Walter) 

Britton, Sterns & Poggenb.

Figure 18

Andropogon glomeratus (Walter) Britton, Sterns & Poggenb., 

Prelim. Cat. 67. 1888.

Common names: bushy beard grass, bushy bluestem.

Caespitose perennials; basal innovations flabellate. Culms 

20–250 cm tall, erect; internodes sometimes glaucous, compressed; 

branches erect. Leaves basal and cauline; sheaths keeled, glabrous, 

outer margins glabrous or hairy; ligules 0.6–2.2 mm long, ciliolate 

membranes; blades 13–109 cm long, 2.9–9.5 mm wide, flat, linear, 

surfaces glabrous or sparsely hairy, margins scabrous, apex acute. 

Inflorescence units 10–600 per culm, numerous, paniculate (oblong), terminal and axillary, dense, feathery; each rame 1.5–3 cm 

long, embraced at base by subtending leaf or spatheole; spatheole 

FIGURE 16. Alopecurus myosuroides. A. Habit. B. Sheath, ligule, 

and blade. C. Spikelet. Drawn from Chase 6899 (US-906856).

FIGURE 17. Andropogon gerardii. A. Base of culm. B. Upper culm 

habit. C. Sheath, ligule, and blade. D. Inflorescence with three rames. 

E. Spikelet pair. A−D drawn from Steele s.n. (US-363231); E modified from Hitchcock (1951).
2 8 • smithsonian contributions to botany

1.5–3 cm long, lanceolate. Spikelets in pairs; fertile spikelets 3–5 

mm long, lanceolate, sessile, dorsally compressed; pedicelled 

spikelets vestigial or absent; principal lemma awns 6–19 mm long, 

from a sinus, straight.

11. Andropogon gyrans Ashe

Figure 19

Andropogon gyrans Ashe, J. Elisha Mitchell Sci. Soc. 15: 113. 

1898.

Common names: Elliott’s beard grass, Elliott’s bluestem.

Caespitose perennials; butt sheaths sparsely hairy or pubescent. Culms 30–100(–140) cm tall, erect; internodes usually glaucous; branches erect. Leaves basal and cauline; sheaths 

smooth; ligules 0.3–1.5 mm long, ciliolate membranes; blades 

6–48 cm long, 0.8–5 mm wide, linear, flat or conduplicate, surfaces glabrous or densely pubescent, margins scabrous, sparsely 

hairy, apex acute. Inflorescence units 2–31 per culm, fasciculate, 

terminal and axillary; each rame 3–4 cm long, subtended by an 

inflated sheath and a lanceolate spatheole, exserted or included 

in the sheath. Spikelets in pairs; fertile spikelets (3–)3.9–4.7

(–5.7) mm long, lanceolate, sessile, dorsally compressed; pedicellate spikelets vestigial or absent; principal lemma awns 

10–15 mm long overall, from a sinus, geniculate with twisted 

column. 

12. Andropogon ternarius Michx.

Figure 20

Andropogon ternarius Michx., Fl. Bor.-Amer. 1: 57. 1803. 

Common names: split-beard bluestem, split-beard little bluestem.

FIGURE 18. Andropogon glomeratus. A. Habit. B. Sheath, ligule, 

and blade. C. Inflorescence. D. Spikelet pair. A, B, drawn from Chase 

s.n. (US-1037180); C modified from Hitchcock (1951); D modified 

from Barkworth et al. (2003).

FIGURE 19. Andropogon gyrans. A. Habit. B. Sheath, ligule, and 

blade. C. Inflorescence. D. Sessile spikelet. A, B drawn from Lamson-Scribner s.n. (US-740474); C, D modified from Barkworth et 

al. (2003).
number 99 • 2 9

Caespitose perennials; butt sheaths glabrous, pilose, or 

villous with white hairs. Culms 70–150 cm tall, erect, knotty 

rhizomes; lateral branches ample in upper half to two-thirds. 

Leaves basal and cauline; sheath surfaces glabrous or villous; 

ligules 0.4–1.5 mm long, ciliolate membranes; blades 20–70 

cm long, 1–3 mm wide, linear, flat or conduplicate, surfaces 

pubescent or glabrous and glaucous, margins smooth, apex 

acute. Inflorescence units 2–30 per culm, terminal and axillary; each rame 3–4 cm long, feathery, subtended by a linear 

spatheole. Spikelets in pairs; fertile spikelets 4.5–8.4 mm long, 

lanceolate, sessile, dorsally compressed; pedicellate spikelets 

1–2 mm long, sterile, represented by single glume; principal 

lemma awns 15–25 mm long, from a sinus, geniculate with 

twisted column.

13. Andropogon virginicus L.

Figure 21

Andropogon virginicus L., Sp. Pl. 2: 1046. 1753.

Common name: broomsedge.

Caespitose perennials, dense and cylindrical; butt sheaths scarious. Culms 40–210 cm tall, erect; nodes glabrous; internodes usually glaucous, upper two-third freely branching. Leaves basal and 

cauline; sheaths keeled, glabrous on surface or hispid, outer margins glabrous or hairy; ligules 0.2–1 mm long, ciliolate membranes; 

blades 11–52 cm long, 1.7–6.5 mm wide, linear, flat or conduplicate, surfaces glabrous, pilose on the upper surface near the base, 

sometimes glaucous, margins glabrous, apex acute. Inflorescence 

units 6–195 per culm, lax, terminal and axillary, feathery; each 

rame 2–3 cm long, paired or digitate, subtended by a spatheole, embraced at base by subtending leaf. Spikelets in pairs; fertile spikelets 

FIGURE 20. Andropogon ternarius. A. Habit. B. Sheath, ligule, and 

blade. C. Inflorescence with two rames. D. Spikelet pair. A, D drawn 

from Kanal 647 (US-3268279); B drawn from Steury 980921 (US3385694); C modified from Hithchcock (1951).

FIGURE 21. Andropogon virginicus. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet pair. Drawn from Kanal 080 (US-30775156 and 

Hitchcock s.n. (US-740532).
3 0 • smithsonian contributions to botany

2.5–4 mm long, sessile, lanceolate, dorsally compressed; pedicellate 

spikelets vestigial to absent, represented by only a pedicel; principal 

lemma awns 10–26 mm long, from a sinus, straight. 

14. Anthoxanthum odoratum* L.

Figure 22

Anthoxanthum odoratum* L., Sp. Pl. 1: 28. 1753. 

Common name: sweet vernal grass.

Caespitose perennials; butt sheaths papery. Culms (10–)25–60

(–100) cm tall, with 1–3 nodes, erect or geniculately ascending; lateral branches lacking. Leaves mostly basal; auricles less than 1 mm 

long or absent; sheath surface and margins pubescent; ligules 2–7 

mm long, eciliate membranes, apex truncate; blades 1–31 cm long, 

3–10 mm wide, aromatic, linear, flat, surfaces scabrous and pubescent, hairy on both sides, margins glabrous, apex acuminate. Panicles (3–)4–14 cm long, 0.6–1.5 cm wide, spiciform, oblong or ovate, 

continuous or interrupted. Spikelets 7–9.5 mm long, lanceolate, 

laterally compressed; principal lemma awns of upper sterile floret 

6–9 mm long, dorsal, arising near the base to middle, geniculate. 

15. Apera spica-venti* (L.) P. Beauv.

Figure 23

Apera spica-venti* (L.) P. Beauv., Ess. Agrostogr. 31, 151. 1812. 

Common name: loose silkybent grass.

Caespitose annuals. Culms 20–80(–120) cm tall, geniculately 

ascending or decumbent, stout, sparsely branched. Leaves mostly 

basal; sheath usually purplish, glabrous; ligules 3–6(–12) mm 

long, eciliate membranes, apex acute or lacerate; blades 6–16(–25) 

cm long and 2–5(–10) mm wide, linear, flat, surfaces scabrous, 

rough adaxially or on both sides, margins scabrous, apex acute. 

Panicles (5–)10–35 cm long, (2–)3–15 cm wide, open, ovate, diffuse; primary panicle branches spreading, whorled at most nodes. 

Spikelets 2.5–3 mm long, oblong, laterally compressed; principal 

lemma awns 5–10 mm long, subapical, flexuous.

FIGURE 22. Anthoxanthum odoratum. A. Habit. B. Sheath, ligule, 

and blade. C. Spikelet. Drawn from Donald 129 (US-3557150).

FIGURE 23. Apera spica-venti. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. Drawn from Chase 2128 (US-2043976).
number 99 • 3 1

16. Aristida dichotoma Michx.

Figure 24

Aristida dichotoma Michx., Fl. Bor.-Amer. 1: 41. 1803. 

Common names: churchmouse threeawn, poverty grass.

Caespitose annuals. Culms 15–60 cm tall, wiry; lateral 

branches ample, arising from mid culm and upper culm glabrous. Leaves basal and cauline; sheaths glabrous on surface 

or sparsely pilose; ligule less than 0.5 mm long, fringe of hairs; 

blades 3–10 cm long, 1–2 mm wide, flat or conduplicate, apically filiform, surfaces glabrous or pilose, sparsely hairy, margins 

glabrous, apex acute. Panicles 2–11 cm long, 0.4–1.1 cm wide, 

contracted, linear. Spikelets 4–10 mm long, linear, subterete; 

lower glumes 1-veined; lemmas 3-awned, central awns 3–9 mm 

long, lateral (2) awns 1–4 mm long, the 3 awns briefly coiled at 

base of limb, without a column.

17. Aristida longespica Poir.

Figure 25

Aristida longespica Poir., Encycl., Suppl. 1(2): 452. 1811. 

Common names: red threeawn, slim-spike threeawn.

Caespitose annuals; butt sheaths glabrous or pilose with 

white hairs. Culms 15–65 cm tall; internodes glabrous, geniculately ascending, wiry, usually much branched. Leaves basal and 

cauline; sheaths glabrous on surface, oral hairs ciliate; ligules 

about 0.5 mm long, fringe of hairs; blades 5–14 cm long, 1–2 mm 

wide, flat to involute, surfaces and margins glabrous, apex acute. 

Panicles 6–22 cm long, 1–4(–6) cm wide, contracted, lanceolate. 

Spikelets 3–4 mm long, linear, subterete; lower glumes 1-veined; 

lemmas 3-awned, central awns 6–36 mm long, erect or reflexed, 

lateral awns absent or up to 18 mm long, the 3 awns not coiled 

at base, without a column.

FIGURE 25. Aristida longespica. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Smith s.n. (US-1963256); 

C modified from Barkworth et al. (2003).

FIGURE 24. Aristida dichotoma. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Kanal 082 (US-3075155); 

C modified from Barkworth et al. (2003).
3 2 • smithsonian contributions to botany

18. Aristida oligantha Michx.

Figure 26

Aristida oligantha Michx., Fl. Bor.-Amer. 1: 41. 1803. 

Common name: prairie threeawn.

Caespitose annuals. Culms 25–55 cm tall, wiry; culm internodes distally glabrous; lateral branches ample. Leaves basal 

and cauline; sheaths glabrous on surface, oral hairs lacking or 

pubescent; ligules less than 0.5 mm long, fringe of hairs; blades 

4–12 cm long, 1–2 mm wide, flat or conduplicate, surfaces glabrous or hispid, sparsely hairy, margins glabrous or sparsely 

hairy, apex attenuate. Panicles (5–)7–20 cm long, 2–4 cm wide, 

spicate or racemose, open, oblong, bearing few spikelets. Spikelets 18–25 mm long, linear, subterete; lower glumes 3–7-veined; 

lemmas 3-awned, awns 12–70 mm long, all the same length, 

spreading, without a column. 

19. Aristida purpurascens Poir.

Figure 27

Aristida purpurascens Poir., Encycl., Suppl. 1(2): 452. 1811. 

Common name: arrowfeather threeawn.

Caespitose perennials, bases knotty, sometimes with very 

short rhizomes. Culms 40–100 cm tall, 1–4 mm diameter at the 

base, slender; lateral branches sparse. Leaves basal and cauline; 

sheaths glabrous on surface, sometimes pubescent; ligules 0.2–

0.3 mm long, fringe of hairs; blades 10–25 cm long, 1–3 mm 

wide, linear, flat or involute, surfaces glabrous, lax, hairless 

except near base, margins glabrous, apex acute. Panicles (15–)

20–55 cm long, 0.5–2(–3) cm wide, contracted, linear. Spikelets 

7–10 mm long, linear, subterete; lower glumes 1- or 2-veined; 

lemmas 3-awned, awns 8–25 mm long, all subequal in length, 

arcuate or spirally coiled at the base, without a column, central 

awns twice as thick as lateral awns.

FIGURE 27. Aristida purpurascens. A. Habit. B. Sheath, ligule, 

and blade. C. Spikelet. A, B drawn from Swallen 36 (US-246734); 

C modified from Barkworth et al. (2003).

FIGURE 26. Aristida oligantha. A. Habit. B. Sheath, ligule, and 

blade. C. Glumes. D. Floret. A, B drawn from Chickering s.n. (US820678); C, D modified from Hitchcock (1951).
number 99 • 3 3

20. Arrhenatherum elatius* (L. ) P. Beauv. 

ex J. Presl & C. Presl

Figure 28

Arrhenatherum elatius* (L. ) P. Beauv. ex J. Presl & C. Presl, Fl. 

Čech. 17. 1819.

Common name: tall oatgrass.

Caespitose perennials; butt sheath glabrous. Culms 50–140

(–180) cm tall, erect, sometimes rhizomatous, swollen, forming 

moniliform corms, or not swollen; nodes glabrous or pubescent. 

Leaves mostly basal; sheaths smooth or scaberulous, glabrous on 

surface, or pilose; ligules 1–3 mm long, eciliate membranes, apex 

obtuse or truncate, sometimes slightly ciliate; blades 5–32 cm 

long, (1–)3–8(–10) mm wide, linear, flat, surfaces scaberulous, 

pilose, sparsely hairy adaxially, margins scabrous, apex acute. 

Panicles 7–30(–36) cm long, 1–6(–10) cm wide, open, lanceolate or oblong, equilateral or nodding. Spikelets 7–11 mm long, 

oblong, laterally compressed, 2-flowered; awns of lower lemmas 

10–20 mm long, twisted below, geniculate; awns of upper lemmas absent or up to 5 mm long, subapical, straight or geniculate. 

21. Arthraxon hispidus* (Thunb.) Makino

Figure 29

Arthraxon hispidus* (Thunb.) Makino, Bot. Mag. (Tokyo) 26 

(307): 214. 1912.

Common names: arthraxon, small carp grass.

Mat-forming annuals. Culms 5–100(–200) cm long, rambling, slender, rooting from lower nodes; internodes glabrous; 

nodes pubescent, much branched. Leaves basal and cauline; 

sheaths glabrous on surface, pilose or hispid, with tuberclebased hairs, outer margins glabrous or hairy; ligules 0.4–3.5 mm 

long, ciliolate membranes; blades 1–7.5 cm long, 4–20 mm wide, 

lanceolate or ovate, flat, base amplexicaul, surface glabrous or 

FIGURE 29. Arthraxon hispidus. A. Habit. B. Sheath, ligule, and 

blade. C. Inflorescence branch with three spikelets. A, B drawn from 

Wester s.n. (US-1963329); C modified from Barkworth et al. (2003).

FIGURE 28. Arrhenatherum elatius. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelet. A−C drawn from Allard 9935 (US1846950); D modified from Hitchcock (1951).
3 4 • smithsonian contributions to botany

pilose, sparsely hairy, hairy on both sides, margins tuberculateciliate, hairy all along or at base, apex acute. Panicles 1.3–7 cm 

long, flabellate or contracted; 12–20 rames per culm; each rame 

1–6(–11) cm long. Spikelets 3–8 mm long, in pairs; sessile spikelets fertile, lanceolate, laterally compressed; pedicellate spikelets 

absent; principal lemma awns 0–10 mm long, dorsal, sometimes 

geniculate, straight or twisted. 

22. Avena sativa* L.

Figure 30

Avena sativa* L., Sp. Pl. 1: 79. 1753. 

Common names: oats, cultivated oats.

Solitary annuals. Culms 35–180 cm tall, erect. Leaves cauline; sheaths smooth or scaberulous; ligules 2–8 mm long, eciliate 

membrane, apex truncate to acute; blades 8–45 cm long, 3–14

(–25) mm wide, linear, flat, surfaces and margins scaberulous, 

rough on both sides, apex acuminate. Panicles (6–)15–40 cm 

long, 5–15 cm wide, open, pyramidal, diffuse, nodding. Spikelets 

(18–)25–32 mm long, pendulous, cuneate, laterally compressed; 

principal lemma awns 25–35 mm long or sometimes unawned, 

dorsal, arising about halfway from the base, geniculate, twisted.

23. Avenella flexuosa (Trin.) Drejer

Figure 31

Avenella flexuosa (Trin.) Drejer, Fl. Excurs. Hafn. 32. 1838. 

[Syn. Deschampsia flexuosa (L.) Trin.] 

Common names: common hair grass, crinkled hair grass, wavy 

hair grass.

Caespitose perennials, culms glabrous or pilose; rhizomes 

absent or elongated. Culms 30–80 cm long, erect or geniculate 

at the base, wiry. Leaves mostly basal; sheaths glabrous; ligules 

1.5–3.6 mm long, eciliate membranes, apex obtuse, sometimes 

FIGURE 31. Avenella flexuosa. A. Base of culm. B. Sheath, ligule, 

and blade. C. Panicle. D. Spikelet. A−C drawn from Leonard 10244

(US-1769822); D modified from Barkworth et al. (2007).

FIGURE 30. Avena sativa. A. Habit. B. Sheath, ligule, and blade. C. 

Spikelet. A, B drawn from Ward s.n. (US-156655); C modified from 

Barkworth et al. (2007).
number 99 • 3 5

acute; blades 12–25 cm long, 0.3–0.5 mm wide, filiform, involute, stiff, surfaces and margins smooth, becoming curled when 

old, apex abruptly acute or acute. Panicles 5–15 cm long, (2–)

4–12 cm wide, open, ovate, diffuse. Spikelets 4–7 mm long, oblong or cuneate, laterally compressed; principal lemma awns 4–7 

mm long overall, dorsal, arising just above the base of lemma, 

geniculate, twisted below. 

24. Brachyelytrum erectum 

(P. Beauv. ex Schreb.) P. Beauv.

Figure 32

Brachyelytrum erectum (P. Beauv. ex Schreb.) P. Beauv., Ess. 

Agrostogr. 39, 155. 1812.

Common name: southern shorthusk.

Caespitose perennials; rhizomes short, knotty. Culms 34–

102 cm tall; internodes distally glabrous or pubescent; nodes 

pubescent. Leaves cauline; sheaths hispid; ligules 2–3.5 mm 

long, eciliate membranes, apex lacerate or erose, truncate to 

acute; blades 8.5–17.5 cm long, (9–)11–17(–20) mm wide, linear or lanceolate, flat, venations without cross veins or with 

obscure cross veins, surfaces scabrous, sparsely pubescent beneath, margins scabrous, ciliate, apex acuminate. Panicles (5.5–)

9.1–14.3(–18.5) cm long, 0.4–0.8 cm wide, open, linear or oblong. Spikelets 10–11 mm long, lanceolate, dorsally compressed 

to terete; principal lemma awns 13–20 mm long. 

25. Bromus catharticus* Vahl.

Figure 33

Bromus catharticus* Vahl., Symb. Bot. 2: 22. 1791.

Common name: rescue grass.

Caespitose annuals or perennials; butt sheaths pubescent. 

Culms 30–120 cm tall, erect or geniculately ascending. Leaves 

basal and cauline; sheaths pubescent; ligules 1–4 mm long, eciliate 

membranes, apex obtuse, lacerate to erose; blades 4–30 cm long, 

FIGURE 32. Brachyelytrum erectum. A. Habit. B. Sheath, ligule, and 

blade. C. Upper portion of culm with panicle. D. Floret. A−C drawn 

from Kanal 035 (US-3073417; D modified from Hitchcock (1951).

FIGURE 33. Bromus catharticus. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelet. Drawn from Kanal 434 (US-3279029).
3 6 • smithsonian contributions to botany

2–10 mm wide, linear, flat, surfaces glabrous or hairy, margins 

scabrous, apex acute. Panicles 10–40 cm long, open, oblong, diffuse; branches flexuous. Spikelets (17–)20–40 mm long, 4–10 mm 

wide, elliptic to lanceolate, strongly laterally compressed; lower 

glumes 5–7(–9)-veined; lemmas 9–13-veined, strongly keeled; 

principal lemma awns absent or up to 3.5 mm long, subapical. 

26. Bromus commutatus* Schrad.

Figure 34

Bromus commutatus* Schrad., Fl. Germ. 353. 1806. 

Common names: hairy chess, meadow brome, upright chess.

Caespitose or solitary annuals. Culms 40–120 cm tall, erect 

or geniculately ascending. Leaves mostly basal; lower sheaths 

densely hairy, often with retrorse hairs, upper sheaths pubescent 

or glabrous; ligules 1–2.5 mm long, eciliate membranes, apex 

obtuse, erose; blades 9–18 cm long, 2–4 mm wide, linear, flat, 

surfaces hirsute, margins pubescent, apex acute. Panicles 7–16 cm 

long, 3–6 cm wide, open, elliptic or oblong, diffuse, nodding. 

Spikelets 14–18(–30) mm long, 4.5–7 mm wide, lanceolate or oblong, terete to laterally compressed; lower glumes 5-veined; lemmas 7 (9)-veined; principal lemma awns 4–10 mm long, straight, 

subapical.

27. Bromus hordeaceus* L.

Figure 35

Bromus hordeaceus* L., Sp. Pl. 1: 77. 1753.

Common names: soft brome, soft chess.

Solitary or caespitose annuals. Culms 10–70 cm tall, erect 

or geniculately ascending; nodes pubescent. Leaves mostly basal; 

lower sheaths densely pilose, the hairs retrorse; upper sheaths 

pubescent or glabrous; ligules 1–1.5 mm long, eciliate membranes, apex erose; blades 2–19 cm long, 1–4 mm wide, linear, 

FIGURE 35. Bromus hordeaceus. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Blake s.n. (US-1646029); C 

modified from Barkworth et al. (2007).

FIGURE 34. Bromus commutatus. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelet. Drawn from Leonard 5465 (US1769745).
number 99 • 3 7

flat, surfaces and margins hirsute, apex acute. Panicles 1–13 cm 

long, 1–4 cm wide, open, ovate, equilateral or nodding. Spikelets (11–)14–20(–23) mm long, 3.5–6(–8) mm wide, ovate, terete to laterally compressed; lower glumes 3–5-veined; lemmas 

7–9-veined; principal lemma awns 5–10 mm long, subapical.

28. Bromus inermis* Leyss.

Figure 36

Bromus inermis* Leyss., Fl. Halens. 16. 1761. 

Common names: awnless brome, common brome, smooth brome.

Solitary or caespitose perennials; rhizomes elongated; butt 

sheaths glabrous to pubescent, persistent, and investing base 

of culm, with fibrous dead sheaths. Culms 50–130 cm tall; internodes usually glabrous, rarely pubescent; nodes glabrous or 

pubescent. Leaves basal and cauline, sheaths glabrous or puberulous; ligules up to 3 mm long, eciliate membranes, apex truncate 

to erose; blades 11–35(–42) cm long, 5–15 mm wide, flat, linear, surfaces glabrous, rarely pubescent or pilose, scabrous on 

both sides, glabrous, margins scabrous, apex acute. Panicles 

10–15 cm long, 4–10 cm wide, open or contracted, ovate, dense, 

equilateral or nodding. Spikelets 20–40 mm long, 3–5 mm wide, 

elliptic to lanceolate, terete to moderately laterally compressed; 

lower glumes 1 (3)-veined; lemmas usually 7-veined; principal 

lemma awns absent or up to 2–3 mm long, straight, subapical. 

29. Bromus japonicus* Thunb. ex Murray

Figure 37

Bromus japonicus* Thunb. ex Murray, Syst. Veg. (ed. 14) 119. 

1784. 

Common names: Japanese brome, Japanese chess.

Solitary annuals. Culms (22–)30–70 cm tall, erect or geniculately ascending; internodes pubescent. Leaves basal and cauline; 

FIGURE 37. Bromus japonicus. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. Drawn from Allard 630 (US-1678979).

FIGURE 36. Bromus inermis. A. Habit. B. Sheath, ligule, and blade. 

C. Panicle. D. Spikelet. A−C drawn from Kanal 148 (US-3117677); 

D modified from Barkworth et al. (2007).
3 8 • smithsonian contributions to botany

sheaths densely pilose; ligules 1–2.2 mm long, eciliate membranes, apex obtuse, lacerate; blades 10–20 cm long, 2–4 mm 

wide, usually pilose on both sides, linear, flat, surfaces and margins pubescent, apex acute. Panicles 10–22 cm long, 4–13 cm 

wide, open, ovate, diffuse; primary panicle branches spreading 

or drooping. Spikelets 15–35(–40) mm long, ovate, terete to 

moderately laterally compressed; lower glumes (3) 5-veined; lemmas 7 (9)-veined; principal lemma awns 5–16 mm long, shorter 

on the lower florets, subapical, curved, spreading or reflexed.

30. Bromus pubescens Muhl. ex Willd.

Figure 38

Bromus pubescens Muhl. ex Willd., Enum. Pl. 1: 120. 1809. 

Common names: Canada brome, hairy woodland brome.

Caespitose perennials. Culms 65–120(–150) cm tall; internodes distally glabrous or pubescent; nodes pubescent, sometimes 

glabrous. Leaves cauline; sheaths pilose, with reflexed hairs, upper 

sheaths glabrous or nearly so, oral hairs lacking or ciliate; collars hairy or glabrous; ligules 0.5–2 mm long, eciliate membrane, 

apex erose, truncate or obtuse; blades 12–32 cm long, 5–15(–19) 

mm wide, linear, flat, surfaces glabrous or hairy adaxially or on 

both sides, margins glabrous or scabrous, apex acute. Panicles 

10–25 cm long, open, oblong, primary panicle branches spreading or drooping. Spikelets (13–)15–30 mm long, oblong, terete to 

moderately laterally compressed; lower glumes 1-veined; lemmas 

usually 7-veined; principal lemma awns 3–8 mm long, straight, 

subapical. 

31. Bromus racemosus* L.

Figure 39

Bromus racemosus* L., Sp. Pl. (ed. 2) 1: 114. 1762. 

Common names: bald brome, smooth brome, smooth cheat.

Solitary or caespitose annuals. Culms 40–190 cm tall, erect 

or geniculately ascending. Leaves basal and cauline; sheaths retrorsely villous; ligules 2–3.5 mm long, eciliate membranes, apex 

FIGURE 39. Bromus racemosus. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelet. Drawn from Steele s.n. (US-557855).

FIGURE 38. Bromus pubescens A. Habit. B. Sheath, ligule, and 

blade. C. Upper portion of culm with panicle. D. Spikelet. A−C 

drawn from Kanal 239 (US-32146000); D modified from Barkworth et al. (2007).
number 99 • 3 9

erose; blades 10–60 cm long and 6–15 mm wide, linear, flat, surfaces pilose on both sides, margins pubescent, apex acute. Panicles 15–40 cm long and 1.5–4 cm wide, open, elliptic or oblong, 

dense, equilateral. Spikelets 20–40 mm long and 3.5–5 mm wide, 

oblong or lanceolate, terete to moderately laterally compressed; 

lower glumes (3) 5-veined; lemmas 7 (9)-veined; principal lemma 

awns 5–10 mm long, straight, subapical.

32. Bromus secalinus* L.

Figure 40

Bromus secalinus* L., Sp. Pl. 1: 76. 1753. 

Common names: cheat, chess, rye brome.

Solitary or caespitose annuals. Culms 20–80 cm tall, erect, 

glabrous. Leaves basal and cauline; lower sheaths puberulent to 

glabrous; ligules 2–3 mm long, eciliate membranes, apex obtuse; 

blades 15–30 cm long, 4–10 mm wide, linear, flat, abaxial surface pilose or glabrous, adaxial pilose, margins sparsely hairy, 

apex acute. Panicles 5–23 cm long, 2.5–12 cm wide; open or 

contracted, ovate, equilateral or nodding. Spikelets 10–20 mm 

long, 4–7 mm wide, oblong or ovate, laterally compressed; lower 

glumes 3–5-veined; lemmas 7-veined; principal lemma awns 

0–8 mm long, straight or flexuous, subapical.

33. Bromus sterilis* L.

Figure 41

Bromus sterilis* L., Sp. Pl. 1: 77. 1753. 

Common names: barren brome, poverty brome.

Solitary or caespitose annuals. Culms 35–100 cm tall, erect 

or geniculately ascending. Leaves basal and cauline; sheaths hispid; ligules 2–2.5 mm long, eciliate membranes, apex erose; blades 

4–20 cm long, 1–6 mm wide, linear, flat, both surfaces pubescent, 

margins sparsely hairy, apex acute. Panicles 10–20 cm long, 5–2 

cm wide, open, ovate, diffuse, nodding; primary panicle branches 

drooping. Spikelets 20–35 mm long, cuneate, moderately laterally 

compressed; lower glumes 1 (3)-veined; lemmas 7 (9)-veined; principal lemma awns 15–40 mm long, straight, subapical.

FIGURE 41. Bromus sterilis. A. Habit. B. Sheath, ligule, and blade. 

C. Panicle. D. Spikelet. Drawn from Kanal 348 (US-3214573).

FIGURE 40.Bromus secalinus. A. Habit. B. Sheath, ligule, and blade. 

C. Panicle. D. Spikelet. Drawn from Balters 735 (US-2238762).
4 0 • smithsonian contributions to botany

34. Bromus tectorum* L.

Figure 42

Bromus tectorum* L., Sp. Pl. 1: 77. 1753.

Common names: cheatgrass, downy brome, downy chess, June 

grass.

Solitary or caespitose annuals. Culms 5–90 cm tall, erect 

or geniculately ascending. Leaves basal and cauline, sheaths 

soft-pubescent, upper sheaths sometimes glabrous; ligules 2–3 

mm long, eciliate membranes, apex lacerate; blades 2–16 cm 

long, 1–6 mm wide, linear, flat, both surfaces and margins softpubescent, apex acute. Panicles 5–20 cm long, 3–8 mm wide, 

open or contracted, oblong, interrupted (branches clustered), 

nodding. Spikelets 10–20 mm long, cuneate, moderately laterally 

compressed; lower glumes 1-veined; lemmas 5–7-veined; principal lemma awns 10–25 mm long, straight, subapical. 

35. Calamagrostis cinnoides W. P. C. Barton

Figure 43

Calamagrostis cinnoides W. P. C. Barton [superfl. for Arundo 

canadensis Michx. = Calamagrostis canadensis (Michx.) 

P. Beauv.; next best name is Calamagrostis nuttalliana Steud.]. 

Common name: small reedgrass.

Loosely caespitose perennials, often glabrous; rhizomes 

elongated; butt sheaths glabrous. Culms (60–)80–140(–170) cm 

tall; internodes scabrous; lateral branches lacking. Leaves basal 

and cauline; sheaths smooth, antrorsely scabrous or glabrous; 

ligules (2–)3–4(–6) mm long, eciliate membranes, apex usually 

truncate, rarely obtuse, sometimes lacerate, collars glabrous to 

densely scabrous; blades (8–)10–35(–45) cm long, (3–)3.5–7.5

(–10) mm wide, flat or involute, linear, surfaces scabrous, margins pubescent, apex acute. Panicles (8–)12–20(–25) cm long, 1–3 

cm wide, contracted to open, lanceolate or ovate, dense or loose. 

FIGURE 43. Calamagrostis cinnoides. A. Habit. B. Sheath, ligule, 

and blade. C. Panicle. D. Spikelet. A−C drawn from Lehtonen & 

Young 62 (US-2858576); D modified from Barkworth et al. (2007).

FIGURE 42. Bromus tectorum. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Leonard 21830 (US-2462603); 

C modified from Barkworth et al. (2007).
number 99 • 4 1

Spikelets 5–7 (7.5) mm long, lanceolate, laterally compressed, 

1-flowered; florets with a rachilla extension 1 mm long; principal 

lemma awns 2–5 mm long, dorsal, straight, arising on upper 2/5 

of lemma. 

36. Cenchrus longispinus (Hack.) Fernald

Figure 44

Cenchrus longispinus (Hack.) Fernald, Rhodora 45(538): 388. 

1943. 

Common names: longspine sandbur, mat sandbur.

Caespitose annuals. Culms 20–90 cm long, geniculately ascending or decumbent; branches arising from the base. Leaves 

basal and cauline; sheaths strongly compressed-keeled, outer 

margin hairy, oral hairs ciliate; ligules 0.6–1.8 mm long, fringe 

of hairs; blades 4–27 cm long, 1.5–5(–7.5) mm wide, linear, flat, 

surfaces glabrous, scabrous, pilose or sparsely hairy, margins 

scabrous, apex acute. Panicles 1.5–8(–10) cm long, 1.2–2.2 cm 

wide, spiciform, linear, dense; fascicles (burs) 8.3–11.9 mm long, 

3.5–6 mm wide, somewhat globose, composed of bristles that 

are fused into a cup, bristles 3.5–7 mm long. Spikelets 6–7.8 

mm long, fertile spikelets sessile, 2–3 per fascicle, ovate, dorsally 

compressed, acuminate; lemmas awnless. 

37. Chasmanthium latifolium (Michx.) 

H. O. Yates

Figure 45

Chasmanthium latifolium (Michx.) H. O. Yates, Southw. Naturalist 11(4): 416. 1966.

Common names: broadleaf chasmanthium, Indian wood-oats, 

wild oats.

Caespitose perennials; rhizomes short, knotty. Culms 100–

150 cm tall, rarely branched. Leaves basal and cauline; ligules 

FIGURE 45. Chasmanthium latifolium. A. Habit. B. Sheath, ligule, and blade. C. Panicle. D. Spikelet. A−C drawn from Hitchcock 

15641 (US-3150886); D modified from Barkworth et al. (2003).

FIGURE 44. Cenchrus longispinus. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Babock s.n. (US-787176); C 

modified from Barkworth et al. (2003).
4 2 • smithsonian contributions to botany

0.7–1 mm long, ciliolate membranes; sheaths glabrous; collars glabrous, blades (7–)9–18 (–22) cm long, (4–)10–22 mm wide, lanceolate, flat, venation with distinct cross veins, surfaces glabrous, 

margins scabrous, apex acute. Panicles (8–)10–25(–35) cm long, 

open, ovate, primary panicle branches drooping. Spikelets 20–40 

mm long, 6–16 mm wide, 6–20(–26)-flowered, pendulous, elliptic 

or ovate, laterally compressed; lemmas 11–15-veined, awnless. 

38. Chasmanthium laxum (L.) H. O. Yates

Figure 46

Chasmanthium laxum (L.) H. O. Yates, Southw. Naturalist 

11(4): 433. 1966. 

Common names: slender chasmanthium, slender wood-oats.

Caespitose perennials; rhizomes short, knotty. Culms 40–

130 cm tall. Leaves basal and cauline; sheaths glabrous pubescent 

or hirsute; collars glabrous; ligule 0.2–0.4 mm long, a ciliolate 

membrane; blades (8–)15–35(–40) cm long, 3–8(–11) mm wide, 

linear-lanceolate, flat, surface glabrous or sparsely hairy, margin 

sparsely hairy, apex acute. Panicle (7–)12–35(–47) cm long, contracted, glomerate, linear, interrupted. Spikelets 4–9 mm long, 

2–6 mm wide, 3–5(–7)-flowered, cuneate, laterally compressed; 

lemmas 3–7-veined, awnless. 

39. Cinna arundinacea L.

Figure 47

Cinna arundinacea L., Sp. Pl. 1: 5. 1753. 

Common names: common woodreed, Indian reed, stout woodreed, sweet woodreed.

Solitary perennials. Culms 28–185 cm tall, erect; somewhat 

bulbous at base. Leaves basal and cauline; sheaths glabrous; collars glabrous; ligules 2–10 mm long, eciliate membranes, apex 

lacerate; blades 15–35 cm long, 3–19 mm wide, linear, flat, 

FIGURE 47. Cinna arundinacea. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelet. A−C drawn from Kanal 643 (US3075152); D modified from Hitchcock (1951). 

FIGURE 46. Chasmanthium laxum. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Steele s.n. (US-279381); C modified from Barkworth et al. (2003).
number 99 • 4 3

surfaces and margins scabrous, apex acuminate. Panicles 6.5–

55 cm long, ascending, open to somewhat contracted, elliptic, 

dense, nodding. Spikelets (3.5–)4–6(–7.5) mm long, elliptic, laterally compressed; lemmas 3 (5)-veined; principal lemma awns 

0.5–1.5 mm long, subapical.

40. Coleataenia anceps (Michx.) Soreng

Figure 48

Coleataenia anceps (Michx.) Soreng, J. Bot. Res. Inst. Texas 

4(2): 691. 2010. [Syn. Panicum anceps Michx.] 

Common names: flat-stemmed panic grass, beaked panic grass.

Caespitose perennials, rhizomes short or elongated, stout, 

scaly rootstocks; butt sheaths glabrous or pilose; basal innovations flabellate. Culms 30–130 cm long, terete to slightly compressed, nodes pallid or purple. Leaves mostly basal; sheaths 

laterally compressed, glabrous to pilose; ligules 0.2–0.5 mm 

long, eciliate membranes, apex erose, often brownish; collars 

glabrous or pilose; blades 10–50 cm long, 4–8 mm wide, erect, 

linear, flat or conduplicate, adaxial surface pilose at least basally, glabrous or pilose abaxially, margins scabrous, apex acute. 

Panicles 10–40 cm long, open or contracted, ovate; secondary 

branches tightly appressed. Spikelets 2.3–3.9 mm long, ovate, 

tilted on the pedicel, dorsally compressed; lemmas awnless.

41. Coleataenia rigidula

(Bosc. ex Nees) LeBlond

Figure 49

Coleataenia rigidula (Bosc. ex Nees) LeBlond, J. Bot. Res. Inst. 

Texas 5(2): 448. 2011. [Syn. Panicum rigidulum Bosc. ex Nees.]

Common name: red-top panic grass.

Densely caespitose perennials; rootstock evident; butt sheaths 

pubescent. Culms 35–150 cm long, decumbent, wiry. Leaves 

FIGURE 49. Coleataenia rigidula. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelets. A−C drawn from Swallen 105 (US2476688); D modified from Barkworth et al. (2003).

FIGURE 48. Coleataenia anceps. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelet. A−C drawn from Kanal 185 (US3142653); D modified from Barkworth et al. (2003).
4 4 • smithsonian contributions to botany

distichous; sheath strongly compressed or keeled, glabrous or 

sparsely pubescent; ligules 0.3–3 mm, eciliate membranes, apex 

erose or ciliate; blades 8–50 cm long and 2–12 mm wide, involute, 

stiff, linear, flat or folded, both surfaces usually glabrous or scaberulous, margins tuberculate; apex acute; pungent. Panicles 9–40 

cm long, 2–12 cm wide, open, ovate, spikelets clustered toward 

branch tips. Spikelets 1.6–3.8 mm long, in pairs, elliptic, dorsally 

compressed, acute; lemmas awnless. 

42. Cynodon dactylon* (L.) Pers.

Figure 50

Cynodon dactylon* (L.) Pers., Syn. Pl. 1: 85. 1805. 

Common names: Bermuda grass, scutch grass.

Mat-forming perennials; rhizomes elongated; stolons present. Culms 5–40(–50) cm long, geniculately ascending. Leaves 

basal and cauline; sheaths glabrous with scattered hairs; collars usually with long hairs, particularly at margins; ligules 

0.2–0.3 mm long, ciliolate membranes; blades 1–6(–16) cm long, 

(1–)2–4(–5) mm wide, linear, flat or conduplicate, glaucous, surfaces scaberulous, glabrous or pilose, sparsely hairy, margins 

glabrous, apex acute. Panicles 1.5–6(–8) cm long, with 4–6 digitately arranged unilateral branches; spikelet packing broadside 

to rachis, regular, 2-rowed. Spikelets 2–3.2 mm long, ovate, 

strongly laterally compressed; lemmas awnless. 

43. Dactylis glomerata* L.

Figure 51

Dactylis glomerata* L., Sp. Pl. 1: 71. 1753. 

Common name: orchard grass.

Caespitose perennials; basal innovations flabellate. Culms 

15–140 cm tall, erect or geniculately ascending. Leaves basal and 

cauline; sheaths, longer than internodes; usually keeled, glabrous; 

ligules 3–11 mm long, eciliate membranes, apex truncate to acuminate; blades 10–45 cm long, (2–)4–8(–10) mm wide, linear, lax, 

FIGURE 50. Cynodon dactylon. A. Rhizome. B. Habit. C. Sheath, 

ligule, and blade. D. Spikelet. A−C drawn from Kanal 432 (US3279031); D modified from Hitchcock (1951).

FIGURE 51. Dactylis glomerata. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelet. A−C drawn from Kanal 546 (US3208293); D modified from Hitchcock (1951).
number 99 • 4 5

conduplicate, surfaces glabrous, with conspicuous midrib, margins 

white scaberulous to scabrous, apex acute. Panicles 2–30 cm long, 

ovate, interrupted, secund, gathered into fascicles, lower branches 

spreading. Spikelets 5–8 mm long, oblong or cuneate, strongly laterally compressed; principal lemma awns 0.5–1.5 mm long, straight. 

44. Danthonia compressa Austin

Figure 52

Danthonia compressa Austin, Annual Rep. New York State 

Mus. Nat. Hist. 22(87): 55. 1869. 

Common names: Alleghany flyback, flattened poverty grass, flattened wild oatgrass, mountain oatgrass.

Caespitose perennials; rhizomes absent or short; butt sheaths 

scarious, fibrous. Culms 40–80 cm tall, geniculately ascending 

or decumbent, scabrous, glaucous, disarticulating at the nodes. 

Leaves mostly basal; sheaths compressed, glabrous, rarely sparsely 

pilose; oral hairs bearded; ligules fringe of hairs; collars glabrous 

or pubescent; blades 10–30 cm long, 2–4 mm wide, filiform, involute, flexible but not curled surfaces and margins glabrous, 

sometimes scabrous, apex acute. Panicles (4–)6–17 cm long, open, 

ascending, somewhat contracted, lanceolate. Spikelets (7–)10–16 

mm long, elliptic, terete or laterally compressed; principal lemma 

awns 6–10 mm long, from a sinus, geniculate, twisted below. 

45. Danthonia spicata (L.) 

P. Beauv. ex Roem. & Schult.

Figure 53

Danthonia spicata (L.) P. Beauv. ex Roem. & Schult., Syst. Veg. 

2: 690. 1817. 

Common names: poverty grass, poverty oatgrass, poverty wild 

oatgrass.

Caespitose perennials. Culms (7–)10–70(–100) cm tall, erect, 

disarticulating at the nodes when mature; nodes glabrous. Leaves 

mostly basal; sheaths glabrous rarely sparsely pilose, with simple 

FIGURE 52. Danthonia compressa. A. Base of culm. B. Sheath, ligule, and blade. C. Panicle. D. Spikelets. A−C drawn from Kearney 

s.n. (US-83892); D modified from Hitchcock (1951).

FIGURE 53. Danthonia spicata. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Kanal 012 (US-3073414); C 

modified from Hitchcock (1951).
4 6 • smithsonian contributions to botany

or tubercle-based hairs, oral hairs ciliate; ligule less than 1.5 mm 

long, a fringe of hairs; blades 6–15(–20) cm long, 0.8–3(–4) mm 

wide, curled or flexuous, flat or involute, surfaces glabrous, rarely 

scabrous and margins glabrous, apex acute. Panicles 5–10(–18) 

cm long, contracted, linear, bearing few spikelets. Spikelets 10–15 

mm long, cuneate, terete or laterally compressed; principal lemma 

awns 5–8 mm long, from a sinus, geniculate, twisted below. 

46. Dichanthelium aciculare (Desv. ex Poir.) 

Gould & C. A. Clark

Figure 54

Dichanthelium aciculare (Desv. ex Poir.) Gould & C. A. Clark, 

Ann. Missouri Bot. Gard. 65(4): 1116. 1979. 

Common names: narrow-leaf panic grass, needle-leaf rosette grass.

Caespitose perennials; butt sheaths villous with white 

hairs. Culms 15–75 cm tall; internodes distally glabrous to pilose; nodes glabrous or pubescent; lateral branches sparse; fall 

phase with erect to spreading culms, extensively branching 

from middle and upper nodes, producing flabellate clusters of 

reduced involute or flat blades. Leaves basal and cauline, heterophyllous with a basal winter rosette; sheaths glabrous or with 

soft, ascending papillose-based hairs, outer margins glabrous or 

hairy, oral hairs lacking or ciliate; ligules 0.5–2 mm long, fringe 

of hairs or absent; blades 4–16 cm long, 3–9 mm wide, stiffly 

ascending, lanceolate, flat, tapering toward tip, wider in winter 

rosette, surfaces glabrous to pilose, margins glabrous or slightly 

ciliate, hairy at bases, with prominent raised veins, apex attenuate. Panicles 2–10 cm long, 0.5–7 cm wide, open, ovate, bearing 

few spikelets. Spikelets 1.7–3.6 mm long, 1.2–1.8 mm wide, elliptic or obovate, obtuse, dorsally compressed; lemma awnless. 

47. Dichanthelium acuminatum (Sw.) 

Gould & C. A. Clark

Figure 55

Dichanthelium acuminatum (Sw.) Gould & C. A. Clark, Ann. 

Missouri Bot. Gard. 65(4): 1121. 1979. 

Common names: hairy panic grass, tapered rosette grass.

FIGURE 55. Dichanthelium acuminatum. A. Habit. B. Sheath, 

ligule, and blade. C. Spikelets. A, B drawn from Kanal 016 (DC3075122); C modified from Hitchcock (1951).

FIGURE 54. Dichanthelium aciculare. A. Habit. B. Sheath, ligule, 

and blade. C. Spikelets. A, B drawn from Steele s.n. (US-363942); C 

modified from Hitchcock (1951).
number 99 • 4 7

Caespitose perennials; butt sheaths villous with white hairs. 

Culms 15–100 cm tall, erect, ascending or decumbent, weak; internodes distally pubescent; nodes bearded; lateral branches sparse or 

ample, arising from lower culms; fall phase erect, spreading or decumbent, usually with ample branching at all except the uppermost 

nodes, forming dense fascicles of branches with reduced, flat or 

involute blade. Leaves cauline, heterophyllous with a basal winter 

rosette; sheaths glabrous on surface or pilose, with tubercle-based 

hairs; ligules 1–5 mm long, fringe of hairs; blades 2–12 cm long, 

2–12 mm wide, linear-lanceolate, flat, surfaces pubescent, hairy abaxially, margins tuberculate-ciliate, bases rounded or subcordate, 

apex acute. Panicles 3–12 cm long, 2–9 cm wide, open, oblong, 

bearing a few spikelets. Spikelets 1.1–2.1 mm long, elliptic or oblong or obovate, dorsally compressed, acute; lemmas awnless. 

48. Dichanthelium annulum (Ashe) LeBlond

Figure 56

Dichanthelium annulum (Ashe) LeBlond, Sida 19(4): 826. 2001. 

Common names: annulus panic grass, ringed panic grass.

Caespitose or solitary perennials, vernal phase usually purplish. Culms 35–60(–90) cm tall, erect or decumbent, densely 

bearded; fall phase branching from mid-culm nodes, branches 

nearly erect; autumnal phase suberect, bearing in late autumn 

a few short erect branches at the upper nodes. Leaves cauline; 

sheaths velvety pubescent or the upper nearly glabrous, tubular, 

closed most of its length, oral hairs ciliate; ligules fringe of hairs; 

blades 4.5–12 cm long, 3–10 mm wide (3–6 times longer than 

wide), lanceolate, spreading, flat, both surfaces hairy, margins 

hairy, apex acute. Panicles 4–9 cm long, open, oblong. Spikelets (1.5–)1.8–2.1 mm long, solitary, oblong or obovate, dorsally 

compressed; lemmas awnless.

49. Dichanthelium boscii (Poir.) 

Gould & C. A. Clark

Figure 57

Dichanthelium boscii (Poir.) Gould & C. A. Clark, Ann. Missouri Bot. Gard. 65(4): 1101. 1979.

Common names: Bosc’s panic grass, Bosc’s rosette grass.

FIGURE 57. Dichanthelium boscii. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelets. A, B drawn from Fleming 1286 (US-3230457); 

C modified from Barkworth et al. (2003).

FIGURE 56. Dichanthelium annulum. A. Habit. B. Sheath, ligule, 

and blade. C. Upper culm and panicle. D. Spikelets. A−C drawn from 

Hitchcock 9232 (US-733473); D modified from Hitchcock (1951).
4 8 • smithsonian contributions to botany

Caespitose perennials. Culms 25–75 cm tall from knotted 

crown, initially erect, often sprawling in the fall; internodes distally glabrous or pubescent; nodes bearded; fall phase branching 

from mid-culm nodes, branches nearly erect, sparsely rebranching; lateral branches ample, arising from mid-culm. Leaves basal 

and cauline heterophyllous with a basal winter rosette; sheath 

surface glabrous to downy-pilose; ligules 0.4–0.9 mm long, ciliate membranes; blades 3–6 times longer than wide, 15–40 mm 

wide, spreading, flat, orate-lanceolate, surfaces glabrous to puberulent, margins tuberculate-ciliate, hairy at base, bases cordate, apex acute. Panicles 6–12 cm long, 4–12 cm wide, open, 

ovate. Spikelets 3.8–5.2 mm long, 1.7–2.2 mm wide, elliptic, 

dorsally compressed; lemmas awnless.

50. Dichanthelium clandestinum (L.) Gould

Figure 58

Dichanthelium clandestinum (L.) Gould, Brittonia 26(1): 59. 1974. 

Common names: deer-tongue grass, deer-tongue rosette grass.

Caespitose perennials; rhizomes thick, short. Culms 50–140 

cm tall; internodes antrorsely scabrous, scabrous to papillose-hispid 

below the nodes; nodes glabrous or pubescent; lateral branches fastigiated; fall phase branching from the middle and upper nodes, 

with a few elongate, erect branches, sparsely rebranching. Leaves 

basal and cauline, heterophyllous with a basal winter rosette; 

sheaths hispid, with tubercle-based hairs; ligules 0.4–0.9 mm long, 

fringe of hairs; collars pubescent; blade bases cordate; blades 10–25 

cm long, 15–30 mm wide, spreading or reflexed, lanceolate, flat, 

surfaces scabrous, rough on both sides, glabrous, margins ciliate, 

hairy at base, apex acuminate. Panicles 9–16 cm long, 4–12 mm 

wide, terminal and axillary, open, elliptic. Spikelets 4–4.5 mm long, 

1.2–1.5 mm wide, elliptic, dorsally compressed; lemmas awnless. 

51. Dichanthelium columbianum

(Scribn.) Freckmann

Figure 59

Dichanthelium columbianum (Scribn.) Freckmann, Phytologia 

39(4): 270. 1978. 

Common name: American witch grass.

FIGURE 59. Dichanthelium columbianum. A. Habit. B. Sheath, ligule, and blade. C. Spikelets. A, B drawn from Leonard 21597 (US2344680); C modified from Hitchcock (1951).

FIGURE 58. Dichanthelium clandestinum. A. Base of culm. B. 

Sheath, ligule, and blade. C. Upper culm and panicle. D. Spikelets. 

A−C drawn from Leonard 10250 (US-1769828); D modified from 

Hitchcock (1951).
number 99 • 4 9

Caespitose perennials; rhizomes short butt sheaths pubescent. Culms 15–50 cm tall, without nodal roots or rooting from 

lower nodes; internodes distally hirsute; nodes black, glabrous or 

pubescent; lateral branches ample, arising from lower culm and 

upper culm. Leaves cauline, heterophyllous, narrow on older 

culms; sheaths eglandular or glandular, glabrous on surface to 

hirsute, outer margin hairy; ligules less than 0.5 mm long, ciliate 

membranes; blades 2–6(–7) cm long, 2–8 mm wide, flat, stiff or 

firm, surface glabrous adaxially, glabrous to puberulent abaxially, 

margins scabrous, ciliate, hairy at base, bases amplexicaul; apex 

acuminate. Panicles 2.5–6 cm long, about as wide as long, open, 

terminal and axillary, ovate, diffuse. Spikelets 1.5–2.6 mm long, 

obovate, asymmetrical, dorsally compressed; lemmas awnless.

52. Dichanthelium commutatum

(Schult.) Gould

Figure 60

Dichanthelium commutatum (Schult.) Gould, Brittonia 26(1): 

59. 1974. 

Common names: variable panic grass, variable rosette grass.

Caespitose perennials; with caudices or with rhizomes, 

rootstock evident. Culms 20–75 cm tall, erect or geniculately ascending; internodes distally glabrous or rarely softly puberulent; 

nodes glabrous to puberulent, often purplish; lateral branches 

clustered, arising from mid-culm; fall phase initially erect, dichotomous, rebranching. Leaves basal and cauline, heterophyllous with a basal winter rosette; sheaths glabrous, often glaucous, 

outer margins hairy; ligules 0.1–0.5 mm long, fringe of hairs or 

absent; blades 5–16 cm long, 5–25 mm wide, lanceolate, spreading or reflexed, flaccid, surfaces scabrous, margins ciliate, hairy 

and symmetrically cordate clasping at base, apex acute. Panicles 

5–12 cm long, 3–10 cm wide, terminal and axillary, open, ovate. 

Spikelets 2.2–3.2 mm long, 1.1–1.3 mm wide, elliptic, with obtuse base, dorsally compressed, subacute; lemmas awnless. 

53. Dichanthelium depauperatum (Muhl.) Gould

Figure 61

Dichanthelium depauperatum (Muhl.) Gould, Brittonia 26(1): 

59. 1974. 

Common names: starved panic grass, starved rosette grass.

FIGURE 61. Dichanthelium depauperatum. A. Habit. B. Sheath, ligule, and blade. C. Spikelets. A, B drawn from Leonard 21564 (US2382921); C modified from Hitchcock (1951).FIGURE 60. Dichanthelium commutatum. A. Habit. B. Sheath, 

ligule, and blade. C. Spikelets. A, B drawn from Allard 20578 (US2180105); C modified from Hitchcock (1951).
5 0 • smithsonian contributions to botany

Caespitose perennials. Culms 10–45 cm tall; internodes 

distally glabrous or pubescent; lateral branches sparse; nodes 

bearded; fall phase a mass of erect blades and short branches 

arising from the basal culm nodes. Leaves basal and cauline; 

sheaths pubescent, longer than internodes; ligules 0.3–1 mm 

long, fringe of hairs; blades 6–15 cm long, 1–4 mm wide, linear 

or lanceolate, flat or involute, surfaces glabrous or pilose or hispid, hairy abaxially, margins pubescent, apex attenuate. Panicles 

3–6 cm long, 1.5–3 cm wide, open, elliptic, bearing few spikelets. 

Spikelets 3.2–4.3 mm long, 1–1.7 mm wide, ovate, with obtuse 

base, dorsally compressed, acute; lemmas awnless.

54. Dichanthelium dichotomum (L.) Gould

Figure 62

Dichanthelium dichotomum (L.) Gould, Brittonia 26(1): 59. 1974. 

Common names: bushy panic grass, cypress rosette grass.

Caespitose perennials; rootstocks evident. Culms 20–60

(–100) cm tall, slender, often purplish; nodes glabrous or bearded; 

lateral branches clustered; fall phase ample branches from midculm nodes, forming dense clusters of reduced flat to involute 

blades. Leaves basal and cauline, heterophyllous with a basal 

winter rosette; sheaths longer than internodes, usually glabrous 

or densely ascending, pilose, outer margins hairy; ligules 0.2–1 

mm long, a fringe of hairs; blades 3.5–9 cm long, 5–7(–13) mm 

wide, linear, flat, sometimes involute, surfaces glabrous or pilose, 

margins glabrous or ciliate, hairy at base, apex attenuate. Panicle 

3–8(–10) cm long, open, oblong. Spikelets 1.8–2.3 mm long, 0.6–

1.1 mm wide, oblong or obovate, dorsally compressed; lemmas 

awnless. 

55. Dichanthelium ensifolium 

(Baldwin ex Elliott) Gould

Figure 63

Dichanthelium ensifolium (Baldwin ex Elliott) Gould, Brittonia 

26(1): 59. 1974.

Common name: sword-leaf panic grass.

FIGURE 63. Dichanthelium ensifolium. A. Habit. B. Sheath, ligule, 

and blade. C. Spikelets. A, B drawn from Killip 7113 (US-984197); 

C modified from Hitchcock (1951).

FIGURE 62. Dichanthelium dichotomum. A. Habit. B. Sheath, 

ligule, and blade. C. Spikelets. A, B drawn from Donald 113 (US3557139); C modified from Hitchcock (1951).
number 99 • 5 1

Caespitose perennials, with caudices. Culms 10–40 cm 

tall, weak, erect or reclining; nodes usually glabrous, sometimes sparsely bearded; internodes usually glabrous, occasionally sparsely pubescent; fall phase with spreading culms, sparsely 

branched mostly from mid-culm nodes, occasionally producing small fascicles of leafy branchlets. Leaves basal and cauline; 

sheaths prominently veined, glabrous or sparsely pilose and 

ciliate, particularly at the top; ligules 0.2–1.8 mm long, ciliate; 

blades 1.5–3.5 cm long, 1.5–4 mm wide, lanceolate to ovate, flat, 

spreading or reflexed, abaxial surfaces glabrous or sparsely pilose, 

at least basally, bases abruptly and strongly constricted, margins 

entire or fairly scaberulous, apex acute. Panicles 1.5–4 cm long, 

nearly as wide as long, open. Spikelets 1.2–1.5 mm long, 0.7–0.9 

mm wide, elliptic, dorsally compressed, obtuse; lemmas awnless. 

56. Dichanthelium latifolium (L.) Harvill

Figure 64

Dichanthelium latifolium (L.) Harvill, Castanea 42(2): 177. 1977. 

Common name: broad-leaved panic grass.

Caespitose perennials; knotty rhizomes, rootstock evident. 

Culms 45–110 cm tall, erect, robust; internodes and nodes glabrous or sparsely pubescent; fall phase lateral branches ample, 

arising from mid-culm, scarcely rebranching. Leaves cauline, 

heterophyllous with a basal winter rosette; sheaths glabrous or 

pubescent, outer margin hairy; ligules 0.4–0.7 mm long, ciliate 

membrane; blades 3.5–7 times longer than wide, 15–40 mm 

wide, ascending or spreading, ovate-lanceolate, surfaces glabrous 

or rarely sparsely pubescent, margins tuberculate-ciliate, hairy 

and cordate clasping at base, apex acute. Panicles 7–15 cm long, 

4–12 cm wide, open, ovate. Spikelets 2.9–3.9 mm long, 1.6–2 

mm wide, ovate, dorsally compressed, acute; lemmas awnless. 

57. Dichanthelium laxiflorum (Lam.) Gould

Figure 65

Dichanthelium laxiflorum (Lam.) Gould, Brittonia 26(1): 60. 

1974. 

Common names: lax-flowered panic grass, open-flowered rosette 

grass, soft-tufted panic grass.

FIGURE 65. Dichanthelium laxiflorum. A. Habit. B. Sheath, ligule, 

and blade. C. Spikelets. A, B drawn from Chase 549 (US-954337); C 

modified from Hitchcock (1951).

FIGURE 64. Dichanthelium latifolium. A. Habit. B. Sheath, ligule, 

and blade. C. Spikelets. A, B drawn from Shear s.n. (US-US-972879); 

C modified from Hitchcock (1951).
5 2 • smithsonian contributions to botany

Mat-forming or densely caespitose perennials; butt sheaths pubescent. Culms 15–55 cm tall, erect or radiating from large predominantly basal leaves; internodes distally glabrous; nodes bearded; fall 

phase branching extensively from the basal nodes, forming a dense 

cushion during the winter. Leaves cauline, heterophyllous with a 

basal winter rosette; sheaths usually longer than the internodes, 

glabrous on surface or hirsute, with simple hairs or reflexed hairs, 

outer margin hairy; ligules 0.2–1 mm long, eciliate membranes, 

erose or ciliolate membranes; blades 4–17 cm long, 4–12 mm wide, 

lanceolate, flat, yellowish green, surfaces glabrous, pubescent, or 

sparsely hairy, margins smooth or ciliate, base broadly rounded, 

apex acute. Panicles 7–12 cm long, 3–8 cm wide, open, pyramidal, 

loose. Spikelets 1.7–2.3 mm long, 1–1.2 mm wide, solitary, spreading, oblong or ovate, dorsally compressed, obtuse; lemmas awnless. 

58. Dichanthelium linearifolium (Scribn.) Gould

Figure 66

Dichanthelium linearifolium (Scribn.) Gould, Brittonia 26(1): 

60. 1974. 

Common names: low panic grass, slim-leaved panic grass, slimleaved rosette grass.

Caespitose perennials. Culms 10–50 cm tall, very slender, erect 

or drooping; internodes elongated, distally glabrous or pubescent; 

nodes bearded; lateral branches sparse; fall phase developing a dense 

mass of erect blades and short branches. Leaves basal and cauline, 

heterophyllous with a basal winter rosette; sheaths pilose, longer than 

internodes; ligules about 0.5 mm long, fringe of hairs; blades 5–20 cm 

long, 2–5 mm wide, linear or lanceolate, flat or involute, surfaces glabrous, pilose or hispid, hairy abaxially, margins sparsely hairy, apex 

attenuate. Panicles 4–10 cm long, 2–6 cm wide, open, elliptic, bearing 

few spikelets. Spikelets 2–3.2 mm long, 0.8–1.4 mm wide, elliptic, 

with obtuse base, dorsally compressed, obtuse; lemmas awnless. 

59. Dichanthelium lucidum (Ashe) LeBlond

Figure 67

Dichanthelium lucidum (Ashe) LeBlond, Sida 19(4): 831–832. 2001. 

Common name: bog panic grass.

FIGURE 66. Dichanthelium linearifolium. A. Habit. B. Sheath, ligule, 

and blade, lateral view. C. Sheath and blade, dorsal view. D. Spikelets. A, B drawn from Leonard 21139 (US-2344683); C modified 

from Barkworth et al. (2003); D modified from Hitchcock (1951).

FIGURE 67. Dichanthelium lucidum. A. Habit. B. Sheath, ligule, 

and blade. C. Spikelets. A, B drawn from Lamson-Scribner s.n. (US208289) and Kearney s.n. (US-722454); C modified from Hitchcock 

(1951).
number 99 • 5 3

Caespitose perennials. Culms 30–90 cm tall, erect but weak 

culms soon decumbent; internodes often flattened, glabrous; 

fall phase with decumbent culms and ample axillary elongated 

branches widely divergent, not forming fascicles. Leaves basal and 

cauline; sheath surface glabrous; ligules minute, ciliate membrane; 

blades 3.5–7 cm long, 3–6 mm wide, thin, lanceolate, flat, asending or widely spreading, surfaces and margins glabrous, apex 

acute. Panicles 2–6 cm long, open, lax, inconspicuous, not well 

exserted. Spikelets 1.8–2.3 mm long, ellipsoid; lemma awnless.

60. Dichanthelium mattamuskeetense 

(Ashe) Mohlenbr.

Figure 68

Dichanthelium mattamuskeetense (Ashe) Mohlenbr., Erigenia 6: 

26. 1985. 

Common name: cypress panic grass.

Sparsely caespitose perennials; butt sheaths sparsely hairy 

or pubescent. Culms 50–120 cm tall, erect; glabrous except 

lowermost nodes bearded; fall phase sparingly branched. Leaves 

cauline; sheaths velvety-pilose on upper part, sometimes glabrous; ligules 0.4–1.1 mm long, fringe of hairs; blades 6–16 cm 

long, 4–14 mm wide, horizontally spreading, lanceolate, flat, 

surface velvety-pubescent or upper blades glabrous, margins scabrous, base broadly rounded, apex acute. Panicles to 12 cm long, 

open, lance-ovoid to ovoid ellipsoid. Spikelets (2–)2.2–2.8 mm 

long; lemmas awnless.

61. Dichanthelium meridionale 

(Ashe) Freckmann

Figure 69

Dichanthelium meridionale (Ashe) Freckmann, Phytologia 39(4): 

270–271. 1978. 

Common name: southern hairy panic.

Caespitose perennials. Culms 15–40 cm tall, erect, appressed pubescent or the upper portion nearly glabrous; lateral 

branches sparse; internodes pubescent; nodes bearded; fall phase 

FIGURE 68. Dichanthelium mattamuskeetense. A. Base of culm B. 

Sheath, ligule, and blade. C. Panicle. D. Spikelets. A, C drawn from 

Chase 3791 (US-954908, US-954909); B modified from Barkworth 

et al. (2003); D modified from Hitchcock (1951).

FIGURE 69. Dichanthelium meridionale. A. Habit. B. Sheath and 

blade, dorsal view. C. Sheath, ligule, and blade. D. Spikelets. A−C 

drawn from Van Eseltine 488 (US-642961, US-642978); D modified 

from Hitchcock (1951).
5 4 • smithsonian contributions to botany

branching extensively from the lower and mid-culm nodes with 

conspicuous flabellate fascicles of branches and reduced leaves. 

Leaves mostly basal; lower internodes and sheaths pilose, upper 

minutely appressed-pubescent; ligules 2–3.4 mm long, fringe of 

hairs; blades (1.5–)3–7 cm long, 2–7 mm wide, lanceolate, flat, 

surfaces pilose, grayish-villous beneath, margins sparsely hairy, 

apex acute. Panicles 1.5–5 cm long, open, long-exserted. Spikelets 1.3–1.7 mm long; lemmas awnless.

62. Dichanthelium oligosanthes (Schult.) Gould

Figure 70

Dichanthelium oligosanthes (Schult.) Gould, Brittonia 26(1): 

60. 1974. 

Common names: few-flowered panic grass, Heller’s rosette grass.

Caespitose perennials with caudices. Culms 20–75 cm tall; 

internodes distally glabrous or pubescent or hirsute; nodes glabrous, lateral branches ample; fall phase branching from midculm nodes and rebranching, developing bushy clumps of blades. 

Leaves basal and cauline; leaves heterophyllous with a basal winter rosette; sheaths glabrous or hispid, with tubercle-based hairs, 

outer margins hairy; ligules 1–3 mm long, fringe of hairs; blades 

3.5–10 cm long, 4–9 mm wide, lanceolate, flat, surfaces glabrous 

or pubescent, bases rounded to truncate, margins cartilaginous, 

apex acute. Panicles 5–9 cm long, 3–6 cm wide, open, terminal 

and axillary, ovate. Spikelets 2.7–4.2 mm long, elliptic or obovate, 

dorsally compressed, obtuse or subacute; lemmas awnless.

63. Dichanthelium ravenelii 

(Scribn. & Merr.) Gould

Figure 71

Dichanthelium ravenelii (Scribn. & Merr.) Gould, Brittonia 

26(1): 60. 1974. 

Common names: Ravenel’s panic grass, Ravenel’s rosette grass.

Stout caespitose perennials with caudices. Culms 25–75 cm 

tall; internodes pilose; nodes densely bearded; collars densely 

pubescent; lateral branches clustered, arising from middle and 

upper culms; fall phase with nearly erect culms, branching from 

middle to upper culm nodes, branches short, ascending, and 

FIGURE 70. Dichanthelium oligosanthes. A. Habit. B. Sheath, ligule, and blade. C. Upper culm and panicle. D. Spikelets. A−C drawn 

from Lamson-Scribner s.n. (US-743743); D. modified from Hitchcock 

(1951).

FIGURE 71. Dichanthelium ravenelii. A. Habit. B. Sheath, ligule, 

and blade. C. Spikelets. D. Upper culm and panicle. A−C drawn 

from Steele s.n. (US-349739); D modified from Hitchcock (1951).
number 99 • 5 5

bushy. Leaves basal and cauline, heterophyllous with a basal 

winter rosette; sheaths pubescent, with tubercle-based hairs; collars densely pubescent; ligules 2.5–4 mm long, fringe of hairs; 

collars densely pubescent; blades 8–17 cm long, 8–25 mm wide, 

lanceolate, flat, densely short-velvety or puberulent abaxially, adaxial surfaces glabrous or sparsely pilose, margins with 

papillose-based cilia, apex acuminate. Panicles 5–11 cm long, 

almost as wide as long, open, ovate, terminal and axillary. Spikelets 3.7–4.3 mm long, oblong or obovate, with acute base, dorsally compressed, compressed slightly, obtuse; lemmas awnless.

64. Dichanthelium scabriusculum 

(Elliott) Gould & C. A. Clark

Figure 72

Dichanthelium scabriusculum (Elliott) Gould & C. A. Clark, 

Ann. Missouri Bot. Gard. 65(4): 1110. 1979. 

Common names: tall swamp panic grass, woolly rosette grass.

Caespitose perennials in large clumps; rhizomes sometimes 

present. Culms 70–150 cm tall; internodes scaberulous to almost 

glabrous; nodes glabrous; lateral branches sparse; fall phase 

branching from middle and upper nodes developing numerous, 

well-separated, dense fascicles of reduced blades and secondary 

panicles. Leaves cauline, heterophyllous with a basal winter rosette; sheaths glabrous or hirsute, with tubercle-based hairs; collars puberulent; ligules 0.5–1.2 mm long, eciliate membranes, 

usually with some small terminal cilia; blades 12–25 cm long, 

7–15 mm wide (5–9 mm wide in winter rosette), lanceolate, flat, 

surfaces glabrous or pilose, hairy abaxially, margins ciliate, hairy 

at base and somewhat cordate, apex acuminate. Panicles 10–21 

cm long, 6–13 cm wide, open, elliptic or ovate. Spikelets 2.2–2.8 

mm long, elliptic, dorsally compressed, obtuse; lemmas awnless.

65. Dichanthelium scoparium (Lam.) Gould

Figure 73

Dichanthelium scoparium (Lam.) Gould, Brittonia 26(1): 60. 

1974. 

Common names: broom rosette grass, velvety panic grass.

FIGURE 72. Dichanthelium scabriusculum. A. Habit. B. Sheath, ligule, and blade. C. Upper culm and panicle. D. Spikelets. A−C drawn 

from Sargent K-29 (US-2079685); D modified from Hitchcock (1951).

FIGURE 73. Dichanthelium scoparium. A. Habit. B. Sheath, ligule, 

and blade. C. Upper culm and panicle. D. Spikelets. A−C drawn 

from Strong & Simmons 1957 (US-3380566); D modified from 

Hitchcock (1951).
5 6 • smithsonian contributions to botany

Perennials, in small clumps with short, knotty rhizomes;

butt sheaths woolly. Culms 50–150 cm tall, stout, geniculately 

ascending; internodes glandular (below nodes), distally pubescent, nodes often swollen, pubescent; lateral branches ample; fall 

phase leaning or spreading, freely branching from the middle 

nodes, the branches clustered. Leaves basal and cauline, heterophyllous with a basal winter rosette; sheaths velvety, except the 

glabrous sticky summit; ligules 0.5–2 mm long, fringe of hairs; 

blades 9–20 cm long, 9–20 mm wide (13–30 mm wide in winter 

rosette), lanceolate, flat, venation distinct, surfaces puberulous or 

pubescent, hairy abaxially, margins ciliate basally, bases rounded 

to subcordate, apex acute. Panicles 6–16 cm long, open, terminal 

and axillary, ovate. Spikelets 2.2–2.8 mm long, oblong or ovate, 

with obtuse base, dorsally compressed; lemmas awnless.

66. Dichanthelium sphaerocarpon 

(Elliott) Gould

Figure 74

Dichanthelium sphaerocarpon (Elliott) Gould, Brittonia 26(1): 

60. 1974. 

Common names: round-fruited panic grass, round-seed rosette grass.

Caespitose perennials. Culms 15–50 cm long, spreading, geniculately ascending or decumbent; nodes glabrous or pubescent; 

lateral branches sparse; fall phase sparsely branching from the 

basal nodes, nodes pubescent or glabrous, internodes glabrous. 

Leaves basal and cauline, heterophyllous with a basal winter rosette; sheaths glabrous, outer margins hairy, sometimes overlapping near the bases; ligules 0–0.8 mm long, fringe of hairs or 

absent; blades 12–25 cm long, 7–15 mm wide, lanceolate, flat, 

light green, surfaces glabrous, margins white tuberculate-ciliate, 

bases hairy and cordate, apex acute. Panicles 4–14 cm long, 

nearly as wide, open, ovate or pyramidal. Spikelets 1.4–1.8 mm 

long, oblong or orbicular or obovate, with obtuse base, dorsally 

compressed, obtuse; lemmas awnless.

67. Dichanthelium villosissimum

(Nash) Freckmann

Figure 75

Dichanthelium villosissimum (Nash) Freckmann, Phytologia 

39(4): 270. 1978. 

Common names: white-haired panic grass, white-haired rosette 

grass.

FIGURE 75. Dichanthelium villosissimum. A. Habit. B. Sheath, ligule, and blade. C. Spikelets. A, B drawn from Hitchcock 1608 (US559134); C modified from Hitchcock (1951).FIGURE 74. Dichanthelium sphaerocarpon. A. Habit. B. Sheath, 

ligule, and blade. C. Spikelets. A, B drawn from Leonard 10260 (US1769836); C modified from Hitchcock (1951).
number 99 • 5 7

Densely clumped caespitose perennials; butt sheaths 

woolly. Culms 25–45 cm tall, olive green, distally hirsute, nodes 

bearded; lateral branches sparse; fall phase with decumbent to 

prostrate culms, branching and forming dense fascicles with reduced blades and secondary panicles. Leaves basal and cauline, 

heterophyllous with a basal winter rosette; sheaths glabrous or 

pilose, outer margin glabrous or hairy; ligules 2–5 mm long, ciliate membranes; blades 6–15 cm long, 6–10 mm wide (8–15 mm 

wide in winter rosette), lanceolate, flat, both surfaces pubescent, 

margins tuberculate-ciliate, bases broadly rounded and hairy, 

apex attenuate. Panicles 7–12 cm long, 5–10 cm wide, open, elliptic or ovate. Spikelets 2.1–2.5 mm long, oblong or orbicular 

or obovate, with obtuse base, dorsally compressed, obtuse; lemmas awnless.

68. Dichanthelium yadkinense 

(Ashe) Mohlenbr.

Figure 76

Dichanthelium yadkinense (Ashe) Mohlenbr., Erigenia 6: 27. 1985. 

Common name: Yadkin River panic grass.

Caespitose perennials. Culms 50–100 cm tall, weak, erect; 

internodes glabrous; nodes glabrous or sparsely pilose; fall phase 

suberect, sparsely branched from mid-culm nodes, blades are not 

greatly reduced as in the other species. Leaves cauline; sheaths 

glabrous, often with pale glandular spots between prominent 

veins, margins glabrous; ligules less than 1 mm long, ciliate 

membranes; blades 7–14 cm long, 7–12 mm wide, flat, lanceolate, surfaces glabrous, glandular spots between the prominent 

veins, margins scabrous, tapering at both ends, apex acute. Panicles 5–14 cm long, open. Spikelets 2–2.6 mm long, elliptic to 

subfusiform, apex pointed; lemmas awnless.

69. Digitaria ciliaris (Retz.) Koeler

Figure 77

Digitaria ciliaris (Retz.) Koeler, Descr. Gram. 27. 1802. 

Common name: southern crabgrass.

Mat-forming and caespitose annuals; butt sheaths pubescent. Culms 10–100 cm long, decumbent, rooting at lower nodes, 

branching. Leaves basal and cauline; sheaths with papillose-based 

FIGURE 77. Digitaria ciliaris. A. Habit. B. Sheath, ligule, and blade. 

C. Spikelets. A, B drawn from Carnes 100 (US-1724417) and Fosberg 65956 (US-3337863); C modified from Barkworth et al. (2003).

FIGURE 76. Dichanthelium yadkinense. A. Habit. B. Sheath, ligule, 

and blade. C. Upper culm and panicle. D. Spikelets. A−C drawn from 

Allard 20597 (US-2180136); D modified from Hitchcock (1951).
5 8 • smithsonian contributions to botany

hairs; ligules 2–3.5 mm long, eciliate membranes, apex erose; 

blades 1.5–14.4(–18.9) cm long, 3–9 mm wide, linear, flat, surfaces glabrous or scabrous, margins scabrous, apex acute. Spikelike racemes 6–22 cm long, 2–12, digitately arranged, unilateral. 

Spikelets (2.7–)2.8–4.1 mm long, appressed, in pairs, packing 

contiguous, oblong or orbicular or obovate, dorsally compressed, obtuse; lemmas awnless.

70. Digitaria filiformis (L.) Koeler

Figure 78

Digitaria filiformis (L.) Koeler, Descr. Gram. 26. 1802. 

Common names: finger grass, slender crabgrass.

Caespitose annuals or short-lived perennials; butt sheaths 

with white hairs. Culms (10–)25–150 cm tall, erect or decumbent, branching, sometimes rooting at lower nodes. Leaves 

mostly basal; sheaths usually with papillose-based hairs, keeled; 

ligules 0.3–1.5 mm long, eciliate membranes, apex truncate, 

subentire; blades 5–18 cm long, 1–6 mm wide, linear, flat, surfaces scabrous above, margins glabrous, apex acute. Spikelike 

racemes 7–13 cm long, single, paired, or digitately or subdigitately borne along a central axis, unilateral. Spikelets 1.3–2.8 

mm long, in pairs, elliptic, dorsally compressed; lemmas awnless.

71. Digitaria ischaemum* (Schreb.) Muhl.

Figure 79

Digitaria ischaemum* (Schreb.) Muhl., Descr. Gram. 131. 1817. 

Common names: small crabgrass, smooth crabgrass.

Caespitose annuals. Culms 20–55(–70) cm long, geniculately ascending or decumbent, rooting at lower nodes. Leaves 

mostly basal; sheaths glabrous or sparsely pubescent; ligules 

0.6–2.5 mm long, eciliate membranes, apex truncate, erose; 

blades 1.5–9 cm long, 3–5 mm wide, linear, flat, surfaces glabrous, with a few papillose-based hairs basally, margins scabrous, apex acute. Spikelike racemes 1.5–7 cm long, 2–8, 

FIGURE 79. Digitaria ischaemum. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelets. A, B drawn from Allard 20894 (US-2180034); C 

modified from Barkworth et al. (2003).

FIGURE 78. Digitaria filiformis. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelets. A, B drawn from Leonard 6117a (US-2151596); 

C modified from Barkworth et al. (2003).
number 99 • 5 9

digitately or subdigitately arranged, unilateral, rachis winged. 

Spikelets 1–2.3 mm long, in threes, elliptic, dorsally compressed, 

subacute; lemmas awnless.

72. Digitaria sanguinalis* (L.) Scop.

Figure 80

Digitaria sanguinalis* (L.) Scop., Fl. Carniol. (ed. 2) 1: 52. 1771.

Common names: crabgrass, hairy crabgrass, northern crabgrass.

Annuals. Culms 20–70(–112) cm long, decumbent or prostrate, much branched rooting from lower nodes; nodes glabrous 

or bearded. Leaves basal and cauline; sheaths pilose, keeled; ligules 0.5–2.6 mm long, eciliate membranes, apex erose, lacerate, 

truncate; blades 2–11(–14) cm long, 3–8(–12) mm wide, linear, 

flat, surfaces hairy both sides, margins scabrous, apex acute. 

Spikelike racemes 4–18 cm long, 4–10, digitately or subdigitately 

arranged, unilateral. Spikelets 1.7–3.4 mm long, in pairs, elliptic, 

dorsally compressed, acute; lemmas awnless.

73. Diplachne fusca subsp. fascicularis

(Lam.) P. M. Peterson & N. Snow

Figure 81

Diplachne fusca subsp. fascicularis (Lam.) P. M. Peterson 

& N. Snow, Ann. Bot. (Oxford) 109: 1327. 2012. [Syn.

Leptochloa fusca (L.) Kunth subsp. fascicularis (Lam.) 

N. Snow.]

Common names: bearded sprangletop, feather grass.

Annuals or short-lived perennials. Culms 5–170 cm long, decumbent, sometimes rooting from lower nodes, often branching. 

Leaves basal and cauline; sheaths glabrous or scabrous; ligules 

3–8 mm long, eciliate membrane, apex acute to attenuate; blades 

3–50 cm long, 2–7 mm wide, linear, flat or convolute, stiff, graygreen, midrib widened, surfaces glabrous or scabrous, margins 

scabrous, apex attenuate. Panicles 15–30 cm long with 10–30 

spicate primary branches (racemes) borne along a central axis, 

erect, straight. Spikelets 5–12(–14) mm long, packed broadside 

FIGURE 81. Diplachne fusca ssp. fascicularis. A. Habit. B. Sheath, 

ligule, and blade. C. Panicle. D. Spikelet. Drawn from Steury 

000902.2 (US-3376345).

FIGURE 80. Digitaria sanguinalis. A. Habit. B. Sheath, ligule, and 

blade. C. Upper culm and inflorescence. D. Spikelets. A−C drawn from 

Chase 12706 (US-3110861); D modified from Hitchcock (1951).
6 0 • smithsonian contributions to botany

to the rachis, elliptic, laterally compressed, compressed slightly; 

principal lemma awns 0.3–5 mm long, from a sinus.

74. Echinochloa crusgalli* (L.) P. Beauv.

Figure 82

Echinochloa crusgalli* (L.) P. Beauv., Ess. Agrostogr. 1: 53, 161, 

169, pl. 11, f. 2. 1812. 

Common names : barnyard grass, large barnyard grass.

Caespitose annuals. Culms 30–200 cm tall, geniculately ascending or decumbent; nodes glabrous or the lower ones puberulent. Leaves basal and cauline; sheaths compressed, glabrous; 

ligules absent; blades 8–65 cm long, 5–30 mm wide, linear, flat, 

surfaces and margins sparsely hairy, apex acute. Panicles 5–25 

cm long with 5–15 ascending primary branches borne along 

a central axis; primary branches 2–10 cm long, the spikelets 

densely packed, irregular, 2–4-rowed, unilateral. Spikelets 2.5–4 

mm long, in pairs or clustered at each node, elliptic, dorsally 

compressed, gibbous, acuminate; lemma awns 0–50 mm long on 

lower sterile floret, terminal. 

75. Echinochloa muricata (P. Beauv.) Fernald

Figure 83

Echinochloa muricata (P. Beauv.) Fernald, Rhodora 17(198): 

106. 1915. 

Common names: American barnyard grass, rough barnyard 

grass.

Annuals. Culms 80–160 cm tall, erect or geniculately ascending, sometimes rooting at the lower nodes, lower nodes 

glabrous or puberulent, upper nodes glabrous. Leaves basal and 

cauline; sheaths glabrous; ligules absent; blades 1–27 cm long, 

0.8–30 mm wide, linear, flat, surfaces glabrous, margins spinulose, apex acute. Panicles 10–35 cm long with 8–15 spreading 

primary branches borne along a central axis; primary branches 

2–8 cm long, unilateral, rachis subterete, the spikelets densely 

FIGURE 83. Echinochloa muricata. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Fosberg 23913 (US-3369205); 

D modified from Barkworth et al. (2003).

FIGURE 82. Echinochloa crusgalli. A. Base of culm. B. Sheath, 

ligule, and blade. C. Panicle. D. Spikelets. A−C drawn from Kanal 

2406 (US-3268322); D modified from Barkworth et al. (2003).
number 99 • 6 1

packed, 4-rowed. Spikelets 2.5–5 mm long, in pairs, ovate, dorsally compressed, gibbous, cuspidate; lower lemmas unawned or 

awned, the awns to16 mm long.

76. Echinochloa walteri (Pursh) A. Heller

Figure 84

Echinochloa walteri (Pursh) A. Heller, Cat. N. Amer. Pl. (ed. 2) 

21. 1900. 

Common names: coast barnyard grass, long-awned barnyard 

grass, long-awned cockspur grass.

Caespitose annuals. Culms (30–)100–200 cm tall, erect or 

geniculately ascending; internodes and nodes pubescent, occasionally glabrous. Leaves basal and cauline; sheaths hirsute or 

hispid, with tubercle-based hairs; ligules absent; blades to 55 

cm long, 10–35(–60) mm wide, linear, flat, surfaces harshly scabrous, margins scabrous, apex acute. Panicles 10–40 cm long 

with 10–25 primary branches borne along a central axis; primary 

branches 2–17 cm long, unilateral, the spikelets densely packed, 

4-rowed. Spikelets 3–5 mm long, in pairs, ovate, dorsally compressed, gibbous, cuspidate; lemmas awns 5–25(–60) mm long 

on the lower sterile floret. 

77. Eleusine indica* (L.) Gaertn.

Figure 85

Eleusine indica* (L.) Gaertn., Fruct. Sem. Pl. 1: 8. 1788. 

Common names: Indian goose grass, yard grass, wire grass.

Caespitose annuals, basal innovations flabellate. Culms 

30–90 cm tall, geniculately ascending or decumbent, slender; 

internodes elliptical in section. Leaves mostly basal; sheaths 

conspicuously keeled, outer margins hairy; ligules 0.2–1 mm 

long, eciliate membranes, apex truncate, erose; blades 15–40 cm 

long, 3–7 mm wide, conduplicate, linear, prominent white midveins, surfaces glabrous, margins scabrous, apex acute. Spikelike 

branches 3.5–15.5 cm long, single (rarely) or digitately arranged 

FIGURE 85. Eleusine indica. A. Habit. B. Sheath, ligule, and blade. 

C. Spikelet. A, B drawn from Leonard 19514 (US-1866464); C 

modified from Barkworth et al. (2003).

FIGURE 84. Echinochloa walteri. A. Base of culm. B. Sheath, ligule, 

and blade. C. Panicle. D. Spikelet. A−C drawn from Archer 7440

(US-2475637); D modified from Barkworth et al. (2003).
6 2 • smithsonian contributions to botany

in a terminal cluster, unilateral. Spikelets 3–7 mm long, 2–3 mm 

wide, elliptic, laterally compressed; lemmas awnless.

78. Elymus canadensis L.

Figure 86

Elymus canadensis L., Sp. Pl. 1: 83–84. 1753. 

Common names: Canada wildrye, great plains wildrye, nodding 

wildrye.

Caespitose perennials, rhizomes absent. Culms (40–)60–

150(–180) cm long, decumbent. Leaves mostly basal; sheath 

glabrous, auricles falcate; ligules 0.5–1 mm long, eciliate membranes, apex truncate; blades 10–25 cm long, (3–)4–15(–20) mm 

wide, linear, flat or conduplicate, surfaces glabrous or pubescent, 

margins scabrous, apex acute. Spikes 8–20 cm long, deflexed or 

drooping, bilateral, spikelets arranged broadside to the rachis. 

Spikelets 12–15 mm long, 3 per node, elliptic to oblong, laterally 

compressed; principal lemma awns 15–50 mm long, flexuous.

79. Elymus elymoides* (Raf.) Swezey

Figure 87

Elymus elymoides* (Raf.) Swezey, Doane Coll. Nat. Hist. Stud. 

1: 155. 1891. [Known from a single collection, Kearney 7 

(US-1021046) at Brookland and Terra Cotta, DC, 21 Jun 

1897.]

Common name: western bottle-brush grass.

Caespitose perennials, often glaucous. Culms 8–65 cm tall, 

erect or geniculate. Leaves mostly basal; sheaths glabrous, scabrous or villous, auricles falcate; ligules shorter than 1 mm, eciliate membrane, apex truncate or lacerate; blades 5–20 cm long, 

(1–)2–4(–6) mm wide, linear, flat, surfaces and margins glabrous, 

apex acute. Spikes 3–20 cm long, 5–15 cm wide, bilateral erect 

to subflexuous. Spikelets 10–20 mm long, packed broadside 

to the rachis, 1–3 per node, spreading, cuneate, laterally compressed; principal lemma awns 20–100 mm long, curved, spreading; sometimes split into 2–3 unequal divisions.

FIGURE 86. Elymus canadensis. A. Habit. B. Sheath, ligule, and 

blade. C. Spike. D. Spikelets. A−C drawn from Seaman s.n. (US787244); D modified from Hitchcock (1951).

FIGURE 87. Elymus elymoides. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelets. Drawn from Kearney 7 (US-1021046).
number 99 • 6 3

80. Elymus glabriflorus (Vasey ex L. H. Dewey) 

Scribn. & C. R. Ball

Figure 88

Elymus glabriflorus (Vasey ex L. H. Dewey) Scribn. & C. R. 

Ball, Bull. Div. Agrostol., U.S.D.A. 24: 49, f. 23. 1901.

Common name: southeastern wildrye.

Caespitose perennials, butt sheaths scarious. Culms 60–140 

cm tall, decumbent. Leaves basal and cauline; sheath glabrous or 

pubescent, auricles absent or to 2 mm long, falcate; ligules 0.5–1 

mm long, eciliate membranes, apex truncate; blades 15–40 cm 

long, 7–15 mm wide, linear, flat or conduplicate, surface glabrous or pubescent, margins scabrous, apex acute. Spikes 6–20 

cm long, deflexed or drooping, bilateral. Spikelets 10–20 mm 

long, packed broadside to the rachis, spikelets 2 or 3(–5) per 

node, elliptic to oblong, laterally compressed; principal lemma 

awns 20–30 mm long, straight and sometimes flexuous.

81. Elymus hystrix L.

Figure 89

Elymus hystrix L., Sp. Pl. 1: 560. 1753. 

Common name: bottle-brush grass.

Caespitose perennials. Culms 50–140 cm tall, occasionally 

glaucous, erect; internodes glabrous or pubescent; nodes glabrous. Leaves basal and cauline; sheaths smooth or scaberulous, 

glabrous on surface or pubescent, with reflexed hairs, auricles 

0.5–3 mm long, usually present; ligules 1–2(–3) mm long, eciliate membranes, apex erose; blades 4–16 mm wide, linear, flat, 

surfaces pilose or scaberulous, margins scabrous, apex attenuate. 

Spikes 7–20 cm long, 4–7 cm wide, bilateral, lax. Spikelets 10–18 

mm long, packed broadside to the rachis, 2 per node, spreading, 

lanceolate, dorsally compressed; principal lemma awns 10–40 

mm long, usually straight, rarely somewhat curved.

FIGURE 88. Elymus glabriflorus. A. Base of culm. B. Sheath, ligule, 

and blade. C. Spike. D. Spikelets. A, C drawn from Hill s.n. (US3099519); B, D modified from Barkworth et al. (2007).

FIGURE 89. Elymus hystrix. A. Habit. B. Sheath, ligule, and 

blade. C. Node with spikelets. A, B drawn from Allard 20528 (US2180078); C modified from Barkworth et al. (2007).
6 4 • smithsonian contributions to botany

82. Elymus macgregorii 

R. Brooks & J. J. N. Campb.

Figure 90

Elymus macgregorii R. Brooks & J. J. N. Campb., J. Kentucky 

Acad. Sci. 61(2): 88. 2000. 

Common name: early wildrye.

Caespitose perennials, usually glaucous. Culms 40–120 cm 

tall, erect or slightly decumbent, glabrous. Leaves mostly basal; 

sheaths usually glabrous, rarely villous, auricles 2–3 mm long, 

falcate; ligules 0.4–0.9 mm long, eciliate membrane, purple, 

apex truncate; blades 7–15 mm wide, drooping, dark green or 

glaucous, glabrous to occasionally villous, linear, flat, surfaces 

usually glabrous to occasionally villous adaxially, margins scabrous; apex acute. Spikes 4–12 cm long, (1.7–)2.2–3.4(–4) cm 

wide, packed broadside to the rachis, lax, 4–5 spikelets per centimeter. Spikelets 10–15 mm long, 2 per node, elliptic to oblong, 

dorsally compressed; principal lemma awns (15–)20–30 mm 

long, straight.

83. Elymus repens* (L.) Gould

Figure 91

Elymus repens* (L.) Gould, Madroño 9(4): 127. 1947. 

Common names: creeping wildrye, couch grass, quack grass, 

witch grass.

Caespitose perennials or culms solitary, rhizomes elongated, 

basal innovations extravaginal. Culms 50–100(–150) cm tall, 

erect. Leaves cauline; sheaths glabrous or pilose, auricles 0.3–1 

mm long, falcate; ligules 0.3–1.5 mm long, eciliate membranes, 

apex erose, truncate; blades 6–30 cm long, 6–10 mm wide, stiff 

to firm, linear, flat, surfaces smooth or scaberulous, glabrous to 

pilose, primary veins prominent, margins glabrous, apex acuminate, hardened. Spikes 5–15 cm long, erect, bilateral, packed 

FIGURE 91. Elymus repens. A. Habit. B. Sheath, ligule, and blade. 

C. Spikelet. A, B drawn from Kanal 029 (US-3073415); C modified 

from Barkworth et al. (2007).

FIGURE 90. Elymus macgregorii. A. Base of culm. B. Sheath, ligule, 

and blade. C. Spike. D. Spikelets. A−C drawn from Kanal 089 (US3075148); D modified from Barkworth et al. (2007).
number 99 • 6 5

broadside to rachis, regular. Spikelets 10–27 mm long, 1 per 

node or occasionally 2, appressed, elliptic to oblong, laterally 

compressed; principal lemma awns 0–10 mm long. 

84. Elymus riparius Wiegand

Figure 92

Elymus riparius Wiegand, Rhodora 20(233): 84. 1918. 

Common names: eastern riverbank wildrye, streambank wildrye.

Caespitose perennials, rhizomes absent, often somewhat 

glaucous. Culms 70–160 cm tall, slender, sometimes rooting at 

the lower nodes. Leaves basal and cauline; sheaths glabrous or 

scaberulous, auricles absent or to 2 mm long, brown; ligules less 

than 1 mm long, eciliate membranes, apex erose; blades (5–)

8–15(–25) mm wide, flat, lax, linear, surfaces and margins scabrous, apex acute. Spikes 7–25 cm long, 2–4 cm wide, drooping, 

bilateral, packed broadside to the rachis. Spikelets 10–20 mm 

long, 2 per node, elliptic to oblong, laterally compressed; principal lemma awns 20–30(–45) mm long, straight, subterete below.

85. Elymus villosus Muhl. ex Willd.

Figure 93

Elymus villosus Muhl. ex Willd., Enum. Pl. 1: 131. 1809. 

Common names: downy wildrye, hairy wildrye, slender wildrye.

Caespitose perennials, butt sheaths pubescent. Culms 40–

130 cm tall, geniculately ascending. Leaves basal and cauline; 

sheaths pilose, occasionally glabrate, auricles 1–3 mm long; 

ligules less than 1 mm long, eciliate membranes, apex entire 

or erose, brownish; blades 10–20 cm long, 4–12 mm wide, linear, flat, surface pubescent, hairy adaxially, margins pubescent 

or sparsely hairy, apex acute. Spikes 4–12 cm long, 1.5–3.5 

cm wide, long exserted, arcuate, bilateral, packed broadside to 

rachis. Spikelets 7–12 mm long, usually 2 per node, cuneate, 

FIGURE 93. Elymus villosus. A. Habit. B. Sheath, ligule, and blade. 

C. Spikelet. A, B drawn from Smith 5060 (US-2151140); C modified 

from Barkworth et al. (2007).

FIGURE 92. Elymus riparius. A. Base of culm. B. Sheath, ligule, 

and blade. C. Spike. D. Spikelet. A−C drawn from Kanal 183 (US3279014); D modified from Barkworth et al. (2007).
6 6 • smithsonian contributions to botany

laterally compressed; principal lemma awns 10–30 mm long, 

straight. 

86. Elymus virginicus L.

Figure 94

Elymus virginicus L., Sp. Pl. 1: 84. 1753. 

Common names: Terrell grass, Virginia wildrye grass.

Densely caespitose perennials, sometimes glaucous. Culms 

30–130 cm tall, erect or geniculately ascending. Leaves basal and 

cauline; sheaths glabrous, rarely pubescent, auricles falcate; ligules less than 1 mm long, eciliate membranes, truncate; blades 

5–15 mm wide, linear, flat, surfaces scabrous, glabrous or pubescent, margins scabrous; apex acute. Spikes (3–)4–16(–22) 

cm long, 1–2.2(–2.5) cm wide, exserted or embraced at base by 

subtending leaf, bilateral; spikelet packed broadside to rachis. 

Spikelets 10–15 mm long, usually 2 per node, elliptic to oblong, 

laterally compressed; principal lemma awns 5–25 mm long, 

straight.

87. Eragrostis capillaris (L.) Nees

Figure 95

Eragrostis capillaris (L.) Nees, Fl. Bras. Enum. Pl. 2(1): 505. 1829. 

Common name: lace grass.

Caespitose annuals. Culms (15–)20–50(–60) cm tall, erect 

or geniculately ascending, glabrous, branched at the base. Leaves 

mostly basal; sheath surface glabrous, outer margins hairy, oral 

hairs ciliate; ligules 0.2–0.5 mm long, fringe of hairs; blades 

(6–)8–20(–30) cm long, 2–5 mm wide, linear, flat or conduplicate, abaxial surfaces smooth, glabrous, adaxial surfaces with 

tubercle-based hairs, margins glabrous, apex acute. Panicles (10–)

15–45(–55) cm long, (7–)10–25 cm wide, open, ovate, diffuse. 

Spikelets (1.4–)2–5 mm long, 1–1.4 mm wide, 2–5(–7)-flowered, 

FIGURE 94. Elymus virginicus. A. Base of culm. B. Sheath, ligule, 

and blade. C. Spike. D. Spikelet. A−C drawn from Kanal 645 (US3268301); D modified from Barkworth et al. (2007).

FIGURE 95. Eragrostis capillaris. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Holm s.n. (US-2380775); C 

modified from Barkworth et al. (2003).
number 99 • 6 7

lanceolate or ovate, laterally compressed; lemmas awnless. Caryopses 0.4–0.7 mm long, ovoid to rectangular-prismatic, deeply 

grooved adaxially, striate.

88. Eragrostis cilianensis*

(All.) Vignolo ex Janch.

Figure 96

Eragrostis cilianensis* (All.) Vignolo ex Janch., Mitt. Naturwiss. 

Vereins Univ. Wien, n.s., 5: 110. 1907. 

Common name: stink grass.

Densely caespitose annuals; sometimes with crateriform 

glands wartlike below the nodes. Culms 15–45(–65) cm tall, erect 

or geniculately ascending. Leaves basal and cauline; sheaths glabrous, occasionally glandular; ligules 0.4–0.8 mm long, fringe of 

hairs; blades (1–)5–20 cm long, (1–)3–5(–10) mm wide, linear, 

flat, surfaces glabrous, sometimes glandular, scaberulous, margins 

glandular or eglandular. Panicles (3–)5–20 cm long, 2–8.5 cm 

wide, open or somewhat contracted, ovate, dense or loose; panicle 

branches stiff, glandular. Spikelets 6–20 mm long, 2–4 mm wide, 

10–40-flowered, oblong or ovate, laterally compressed; lemma 

keels with 1–3 crateriform glands, awnless. Caryopses 0.5–0.7 

mm long, globose to broadly ellipsoid, smooth to faintly striate.

89. Eragrostis frankii (Fisch., C. A. Mey. 

& Avé-Lall.) C. A. Mey. ex Steud.

Figure 97

Eragrostis frankii (Fisch., C. A. Mey. & Avé-Lall.) C. A. Mey. ex 

Steud., Syn. Pl. Glumac. 1: 273. 1854. 

Common names: Frank’s lovegrass, sandbar lovegrass.

Caespitose annuals. Culms 10–50 cm tall, decumbent, erect 

to geniculate, glabrous, often with glandular pits below the 

nodes; lateral branches ample. Leaves basal and cauline; sheaths 

FIGURE 96. Eragrostis cilianensis. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Kanal 670 (US-3205467) and 

Kanal 307 (US-3214590); C modified from Barkworth et al. (2003).

FIGURE 97. Eragrostis frankii. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. Drawn from Kearney 197 (US-640360).
6 8 • smithsonian contributions to botany

longer than adjacent culm internodes, glabrous, oral hairs ciliate; 

ligules 0.2–0.5 mm long, fringe of hairs; blades (2–)4–10(–21) 

cm long, 1–4 mm wide, linear, flat to involute, surfaces scabrous, rough adaxially, glabrous, margins glabrous, apex acute. 

Panicles 4–20 cm long, less than 1/2 the height of the plants, 

2–10(–14) cm wide, open, oblong. Spikelets (1.7–)2–4(–5.6) mm 

long, 1–2.5 mm wide, 3–6-flowered, lanceolate, laterally compressed; lemmas awnless. Caryopses 0.4–0.7 mm long, ovoid to 

rectangular-prismatic, striate.

90. Eragrostis hypnoides 

(Lam.) Britton, Sterns & Poggenb.

Figure 98

Eragrostis hypnoides (Lam.) Britton, Sterns & Poggenb., Prelim. 

Cat. 69. 1888. 

Common name: teal lovegrass.

Mat-forming annuals, stolons present. Culms (2–)5–12(–20) 

cm long, decumbent, the erect portion often branched, rooting 

from lower nodes; internodes glabrous or pubescent; nodes glabrous. Leaves basal and cauline; sheaths glabrous, outer margins 

pilose; ligules 0.3–0.6 mm long, fringe of hairs; blades 0.5–2.5 

cm long, 1–2 mm wide, linear, flat or conduplicate, surfaces puberulous, hairy adaxially, margins glabrous, apex acute. Panicles 

1–3.5 cm long, 0.7–2.5 cm wide, open, ovate, terminal and axillary. Spikelets 4–13 mm long, 1–1.5 mm wide, 12–35-flowered, 

lanceolate, laterally compressed; lemmas awnless. Caryospese 

0.3–0.5 mm long, ellipsoid, somewhat translucent.

91. Eragrostis minor* Host

Figure 99

Eragrostis minor* Host, Icon. Descr. Gram. Austriac. 4: 15. 1809. 

Common name: little lovegrass.

Caespitose annuals; glands wartlike below the nodes. Culms 

10–45 cm tall, geniculately ascending. Leaves cauline; sheath 

sometimes glandular on midveins, hairy at the apices; ligules 

0.2–0.5 mm, fringe of hairs; blades 1.5–10 cm long, 1–3(–4) mm 

FIGURE 99. Eragrostis minor. A. Habit. B. Sheath, ligule, and blade. 

C. Spikelet. Drawn from Baltars 3427 (US-2577113A).

FIGURE 98. Eragrostis hypnoides. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Leonard 3512 (US-3150974); C 

modified from Barkworth et al. (2003).
number 99 • 6 9

wide, linear, flat, surfaces scabrous, glandular, margins glandular or eglandular, apex acute. Panicles 4–20 cm long, 2.2–8(–10) 

cm wide, open, ovate, dense or loose; branches stiff, eglandular 

or glandular. Spikelets 4–7(–11) mm long, 1.1–2.2 mm wide, 

7–12(–20)-flowered, oblong, laterally compressed; lemmas occasionally with 1 or 2 crateriform glands, awnless. Caryopses 

0.4–0.7 mm long, ellipsoid, striate.

92. Eragrostis pectinacea (Michx.) Nees

Figure 100

Eragrostis pectinacea (Michx.) Nees, Fl. Afr. Austral. Ill. 406. 

1841. 

Common names: Carolina lovegrass, pink grass, purple lovegrass.

Densely caespitose annuals; butt sheaths green or purple. 

Culms 10–50 cm tall, geniculately ascending or decumbent. Leaf 

sheath glabrous below, hairy at the summit, oral hairs bearded; 

ligules 0.2–0.5 mm long, fringe of hairs; blades 2–20 cm long, 

1–4.5 mm wide, linear, flat to involute, surfaces scaberulous, 

rough adaxially, margins glabrous, apex acute. Panicles 5–25 

cm long, 3–12(–15) cm wide, open, ovate. Spikelets 3.5–11 mm 

long, 1.2–2.5 mm wide, 6–22-flowered, appressed, laterally compressed; lemmas awnless. Caryopses 0.5–1.1 mm long, pyriform, 

slightly laterally compressed, surface smooth to faintly striate.

93. Eragrostis pilosa* (L.) P. Beauv.

Figure 101

Eragrostis pilosa* (L.) P. Beauv., Ess. Agrostogr. 71, 162, 175. 

1812. 

Common name : India lovegrass.

Caespitose annuals. Culms 8–45(–70) cm tall, slender, erect 

or geniculately ascending. Leaves basal and cauline; sheath 

mostly glabrous, occasionally glandular; ligules 0.1–0.3 mm, 

fringe of hairs; blades 2–15(–20) cm long and 1–2.5(–4) mm 

wide, linear, flat, surfaces and margins glabrous; occasionally 

FIGURE 101. Eragrostis pilosa. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Allard 21862 (US-2236901); C 

modified from Barkworth et al. (2003).

FIGURE 100. Eragrostis pectinacea. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Fosberg 55104 (US-2681659); 

C modified from Barkworth et al. (2003).
7 0 • smithsonian contributions to botany

with glandular pits along midrib, apex acute. Panicles 4–20(–28) 

cm long, 2–15(–18) cm wide, open, elliptic or ovate; primary 

panicle branches whorled at lower nodes. Spikelets (2–)3.5–6

(–10) mm long, 0.6–1.4 mm wide, 5–17-flowered, oblong, laterally compressed; lemmas awnless. Caryopses 0.5–1 mm long, 

obovate to prism shaped, surface smooth to faintly striate.

94. Eragrostis spectabilis (Pursh) Steud.

Figure 102

Eragrostis spectabilis (Pursh) Steud., Nomencl. Bot. (ed. 2) 1: 

564. 1840. 

Common names: petticoat-climber, purple lovegrass, troublegrass, tumble grass.

Caespitose perennials, rhizomes short, knotty. Culms 30–

70(–85) cm tall, erect or geniculately ascending. Leaves basal 

and cauline; sheaths glabrous or pilose, outer margins hairy, 

oral hairs ciliate; ligules 0.1–0.2 mm long, fringe of hairs; blades 

10–32 cm long, 3–8 mm wide, linear, flat or folded, surfaces glabrous or pilose adaxially, margins glabrous, apex acute. Panicles 

(15–)25–45(–60) cm long, 15–35 cm wide, open, oblong or 

ovate, diffuse, deciduous as a whole, exserted or embraced at 

base by subtending leaf. Spikelets 3–7.5 mm long, 1–2 mm wide, 

6–12-flowered, oblong, laterally compressed; lemmas awnless. 

Caryopses 0.6–0.8 mm long, ellipsoid, strongly flattened.

95. Erianthus giganteus (Walter) P. Beauv.

Figure 103

Erianthus giganteus (Walter) P. Beauv., Ess. Agrostogr. 14, 151, 

177. 1812. [Syn. Saccharum giganteum (Walter) Pers.]

Common names: giant plume grass, sugarcane plume grass.

Caespitose perennials; rhizomatous, rootstock evident. Culms 

130–250 cm tall, erect, robust; nodes bearded. Leaves cauline; 

FIGURE 102. Eragrostis spectabilis. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Oakland s.n. (US-2382837); C 

modified from Barkworth et al. (2003).

FIGURE 103. Erianthus giganteus. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Pollard 597 (US-260003); C 

modified from Barkworth et al. (2003).
number 99 • 7 1

sheaths glabrate or glabrous, oral hairs bearded; ligules 2–6 mm 

long, ciliolate membranes; blades 35–70 cm long, 8–30 mm wide, 

linear, flat, surfaces glabrous or hispid on both sides, margins scabrous, apex acute. Panicles 15–50 cm long, 6–15 cm wide, open, 

oblong, dense. Spikelets 6–8 mm long, in pairs; fertile spikelets 

sessile, lanceolate, dorsally compressed; callus hairs 6–10(–20) 

mm long, longer than the spikelets; principal lemma awns 12–26 

mm long, straight or curved, subterete below; anthers 2. 

96. Eriochloa contracta* Hitchc.

Figure 104

Eriochloa contracta* Hitchc., Proc. Biol. Soc. Wash. 4: 163. 1928 

Common name: prairie cupgrass.

Caespitose annuals. Culms 20–100 cm tall, erect or geniculately ascending, sometimes branching rooting at the lower nodes; 

internodes sparingly pilose; pubescent to puberulent. Leaves 

basal and cauline; sheaths sparsely to densely pubescent; ligules 

0.4–1.1 mm long, fringe of hairs; blades 6–12(−22) cm long, 2–8 

mm wide, linear, flat, folded to convolute, surfaces sparsely to 

densely pubescent, margins pubescent, apex attenuate. Panicles 

6–20 cm long, 0.3–1.2 cm wide; dense, somewhat contracted, 

erect. Spikelets (3.1−)3.5–4.5(−5) mm long, lanceolate, dorsally 

compressed; lower glumes fused with the glabrous callus to form 

a cuplike structure; upper lemmas 2−2.5 mm long, indurate, 

elliptic, 5−7-veined, apex acute to obtuse, mucronate to shortawned, the awns 0.4−1.1 mm long.

97. Festuca filiformis* Pourr.

Figure 105

Festuca filiformis* Pourr., Hist. & Mém. Acad. Roy. Sci. Toulouse 3: 319. 1788. 

Common names: fine-leaved sheep fescue, hair fescue.

Densely caespitose perennials. Culms 18–40(–60) cm tall, 

erect, mostly scabrous or puberulent below the inflorescence. 

Leaves basal and cauline; sheaths 0.5 mm long, closed for less 

than 1/3 their length, glabrous or finely puberulent, auricles erect; 

collars glabrous; ligules 0.1–0.4 mm long, eciliate membrane, 

FIGURE 104. Eriochloa contracta. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. D. Upper floret. Modified from Barkworth et al. 

(2003).

FIGURE 105. Festuca filiformis. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Fleming 494 (US-3117631); C 

modified from Barkworth et al. (2007).
7 2 • smithsonian contributions to botany

apex truncate; blades 0.2–0.4(–0.6) mm in diameter, flat, conduplicate, surface smooth or scabrous, margins glabrous, apex 

obtuse or acute. Panicles 1–6(–14) cm long, contracted, linear 

or lanceolate or oblong. Spikelets 3–6(–6.5) mm long, oblong, 

laterally compressed; lemma awnless, sometimes mucronate. 

98. Festuca myuros* L.

Figure 106

Festuca myuros* L., Sp. Pl. 1: 74–75. 1753. [Syn. Vulpia myuros

(L.) C.C. Gmel.]

Common names: rat-tail fescue, rat-tail six-weeks grass.

Solitary or caespitose annuals. Culms 10–70 cm tall, erect 

or decumbent, branched or unbranched. Leaves mostly basal; 

sheaths smooth, glabrous; ligules 0.3–0.5 mm long, eciliate 

membrane, apex truncate; blades 2–10(–17) cm long, 0.5–3 mm 

wide, linear, flat or involute, firm or flaccid, usually glabrous, 

sometimes hairy adaxially, margins scaberulous, apex attenuate. 

Panicles 3–25 cm long, 0.5–1.5(–2) cm wide, contracted, linear, 

nodding, curved. Spikelets 5–12 mm long, oblong or cuneate, 

laterally compressed, exserted or embraced at base by subtending leaf; lower glumes 1/5–1/2 the length of the upper glumes; 

principal lemma awns 5–15 mm long.

99. Festuca octoflora Walter

Figure 107

Festuca octoflora Walter, Fl. Carol. 81. 1788. [Syn. Vulpia octoflora (Walter) Rydb.] 

Common names: eight-flowered six-weeks grass, six-weeks fescue, six-weeks grass.

Solitary or loosely caespitose annuals. Culms 5–60 cm tall, 

geniculately ascending or decumbent, glabrous. Leaves mostly 

basal; sheaths glabrous or pubescent; ligules 0.5–1 mm long, 

FIGURE 107. Festuca octoflora. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. Drawn from Kanal 620 (US-3205491) and Smith 

5049 (US-2151137).

FIGURE 106. Festuca myuros. A. Base of culm. B. Sheath, ligule, 

and blade. C. Spikelet. A, B drawn from Hermann 10533 (US2146187); C modified from Hitchcock (1951).
number 99 • 7 3

eciliate membranes, apex truncate, sometimes ovate; blades 2–10 

cm long, 0.5–1 mm wide, linear, flat or involute, glabrous or 

pubescent. Panicles 1–20 cm long, 0.5–1.5 cm wide, contracted, 

linear, nodding. Spikelets 4–10(–13) mm long, oblong, laterally compressed; lower glumes 1/2–2/3 the length of the upper 

glumes; principal lemma awns 0.3–6 mm long.

100. Festuca paradoxa Desv.

Figure 108

Festuca paradoxa Desv., Mém. Soc. Agric. Angers 1: 209. 1831. 

Common name: clustered fescue.

Loosely caespitose perennials. Culms 50–120 cm tall, geniculately ascending. Leaves basal and cauline; sheaths glabrous 

on surface, closed for less 1/3 their length; ligules (0.2–)0.5–1.5 

mm long, eciliate membranes; blades 2–8 mm wide, linear, flat 

or loosely convolute, surfaces smooth or scabrous, margins 

scabrous, apex acute. Panicles 12–20 cm long, open, ovate. 

Spikelets 4–7(–7.5) mm long, clustered toward branch tips, oblong, laterally compressed; lemmas awnless. 

101. Festuca rubra L.

Figure 109

Festuca rubra L., Sp. Pl. 1: 74. 1753. 

Common name: red fescue.

Loosely caespitose perennials; rhizomes absent or elongated; 

basal innovations extravaginal or intravaginal. Culms (8–)10–

120(–130) cm tall, erect or geniculately ascending, sometimes 

single and widely spaced. Leaves basal and cauline; sheaths tubular for about 3/4 of their length, without keel, glabrous or pubescent, lowest sheaths brown or reddish, fibrous; ligules 0.1–0.5 

mm long, eciliate membranes, apex truncate; blades 0.3–2.5 mm 

in diameter, 1.5–7 mm wide, filiform, conduplicate or convolute, 

FIGURE 108. Festuca paradoxa. A. Base of culm. B. Sheath, ligule, 

and blade. C. Panicle. D. Spikelet. A−C drawn from Steury 020626.1

(US-3433353); D modified from Barkworth et al. (2007).

FIGURE 109. Festuca rubra. A. Base of culm. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelet. A−C drawn from Kearney 92 (US986738); D modified from Barkworth et al. (2007).
7 4 • smithsonian contributions to botany

sometimes flat and stiff, surfaces smooth or scabrous, glabrous, 

margins scabrous, apex obtuse or abruptly acute. Panicles 3–20 

cm long, open or contracted, lanceolate or oblong. Spikelets 

(6–)7–17 mm long, elliptic or oblong, laterally compressed; principal lemma awns 0.5–3 mm long.

102. Festuca subverticillata 

(Pers.) E. B. Alexeev

Figure 110

Festuca subverticillata (Pers.) E. B. Alexeev, Novosti Sist. Vyssh. 

Rast. 17: 52. 1980. 

Common name: nodding fescue.

Solitary or caespitose perennials. Culms (40–)50–100(–150) 

cm tall, glabrous, erect or decumbent at the base; basal innovations usually extravaginal. Leaves basal and cauline; sheaths glabrous on surface or hirsute, closed for less than 1/3 their length; 

ligules (0.2–)0.5–1(–2) mm long, eciliate membranes, apex erose; 

blades (3–)5–10 mm wide, linear, flat, or loosely convolute, surfaces glabrous or pubescent, sparsely hairy, hairy adaxially, margins glabrous, apex acute. Panicles 13–25 cm long, open, ovate, 

diffuse. Spikelets 4–5(–7) mm long, elliptic, laterally compressed; 

lemmas awnless. 

103. Festuca trachyphylla* (Hack.) Krajina

Figure 111

Festuca trachyphylla* (Hack.) Krajina, Acta Bot. Bohem. 9: 190. 

1930. 

Common names: hard fescue, sheep fescue.

Densely caespitose perennials; butt sheaths persistent and 

investing base of culm, with compacted dead sheaths, fibrous; 

basal innovations intravaginal. Culms (15–)20–75 cm tall; internodes glabrous or with spare hairs. Leaves mostly basal; sheaths 

closed for less than 1/3 their length, with persistent margins, 

not becoming fibrous, pubescent, auricles erect, obtuse; collars 

FIGURE 111. Festuca trachyphylla. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Fleming 300 (US-3117582); C 

modified from Barkworth et al. (2007).

FIGURE 110. Festuca subverticillata. A. Base of culm. B. Sheath, 

ligule, and blade. C. Panicle. D. Spikelet. A−C drawn from Fosberg 

65463 (US-3343452); D modified from Barkworth et al. (2007).
number 99 • 7 5

glabrous; ligules 0.1–0.5 mm long, eciliate membranes, apex obtuse; blades (0.5–)0.8–1.2 mm wide, conduplicate, rarely flat, elliptic in section, surfaces scabrous, glabrous or pubescent, hairy 

on both sides, margins glabrous, apex acute. Panicles 4.5–13 cm 

long, open, interrupted. Spikelets 5–9 mm long, oblong, laterally 

compressed; principal lemma awns (0.5–)2–2.5 mm long. 

104. Glyceria canadensis (Michx.) Trin.

Figure 112

Glyceria canadensis (Michx.) Trin., Mém. Acad. Imp. Sci. St.-

Pétersbourg, Sér. 6, Sci. Math. 1(4): 366. 1830. 

Common names: rattlesnake grass, rattlesnake manna grass.

Solitary or caespitose perennials with short rhizomes. 

Culms 60–150 cm tall, thick, erect or bases decumbent; internodes smooth or scaberulous. Leaves basal and cauline; sheaths 

scaberulous; ligules 0.5–6 mm long, eciliate membranes, apex 

lacerate; blades 8–40(–60) cm long, 3–8(–10) mm wide, linear, 

flat, surfaces scabrous, rough adaxially, margins scabrous, apex 

acute. Panicles 10–40 cm long, 8–20 cm wide, open, ovate; primary branches spreading to drooping. Spikelets 5–8 mm long, 

(4–)5–10-flowered, ovate, laterally compressed; lemmas 2.4–4 

mm long, projecting conspicuously beyond the palea, awnless. 

105. Glyceria laxa (Scribn.) Scribn.

Figure 113

Glyceria laxa (Scribn.) Scribn., Fl. Mt. Desert Isl. 180. 1894. 

[Syn. Glyceria canadensis var. laxa (Scribn.) Hitchc.] 

Common names: lax manna grass, lax rattlesnake manna grass, 

limp manna grass.

Solitary or caespitose perennials with short rhizomes; butt 

sheaths sparsely hairy. Culms 60–160 cm tall, erect; internodes 

smooth or scaberulous. Leaves basal and cauline; sheaths scaberulous; ligules 1–6 mm long, eciliate membranes, apex erose; blades 

8–40(–60) cm long, 3–8(–10) wide, linear, flat, surface scabrous, 

FIGURE 113. Glyceria laxa. A. Base of culm. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelet. A−C drawn from Leonard 21203 (US2378644); D modified from Barkworth et al. (2007).

FIGURE 112. Glyceria canadensis. A. Base of culm. B. Sheath, ligule, and blade. C. Panicle. D. Spikelet. A−C drawn from Steele s.n.

(US-279330); D modified from Barkworth et al. (2007).
7 6 • smithsonian contributions to botany

rough adaxially, margins scabrous, apex acute. Panicles 15–40 cm 

long, 8–18 cm wide, ovate; primary branches drooping. Spikelets 

3–5 mm long, 2–5-flowered, ovate, laterally compressed; lemmas 

1.8–2.5 mm long, about as long as the palea, awnless. 

106. Glyceria septentrionalis Hitchc.

Figure 114

Glyceria septentrionalis Hitchc., Rhodora 8(95): 211. 1906.

Common names: floating manna grass, northern manna grass.

Caespitose perennials. Culms 73–182 cm tall, to 8 mm thick; 

rooting from lower nodes. Leaves basal and cauline; sheaths tubular for much of their length, keeled or strongly compressed, glabrous; ligules 5–16 mm long, eciliate membrane, apex acuminate; 

blades 18–32 cm long, 2–15 mm wide, linear, flat, abaxial surfaces 

scabrous, adaxial surfaces scaberulous, margins glabrous, apex 

acute. Panicles 15–60 cm long, 1–3.5 cm wide, open, lanceolate; 

primary branches equilateral spreading or nodding. Spikelets 

(6.5–)10–23 mm long, 8–16-flowered, linear, laterally compressed, 

compressed slightly; lemmas 2.4–4.8 mm long, awnless. 

107. Glyceria striata (Lam.) Hitchc.

Figure 115

Glyceria striata (Lam.) Hitchc., Proc. Biol. Soc. Wash. 41: 157. 

1928. 

Common names: fowl manna grass, nerved manna grass, ridged 

glyceria.

Caespitose perennials, rhizomes absent or short. Culms 20–

80(–100) cm tall, erect. Leaves basal and cauline; sheaths tubular 

for much of their length, smooth, glabrous, keeled, sometimes 

weakly so; ligules 1.5–4 mm long, eciliate membranes, apex 

usually rounded, sometimes acute to mucronate, erose-lacerate; 

blades 12–30 cm long, 2–8 mm wide, linear, flat or conduplicate, 

FIGURE 114. Glyceria septentrionalis. A. Base of culm. B. Sheath, 

ligule, and blade. C. Panicle. D. Spikelet. A−C drawn from Hitchcock 

12927 (US-1063142); D modified from Barkworth et al. (2007).

FIGURE 115. Glyceria striata. A. Base of culm. B. Sheath, ligule, 

and blade. C. Panicle. D. Spikelet. A−C drawn from Strong 2381

(US-3409634); D modified from Barkworth et al. (2007).
number 99 • 7 7

surfaces smooth, glabrous, margins glabrous, apex acute. Panicles 6–25 cm long, 2.5–21 cm wide, open, ovate to pyramidal; 

primary branches nodding. Spikelets 1.8–4 mm long, 1.2–2.9 

mm wide, 3–7-flowered, oblong or ovate, laterally compressed; 

lemmas 1.2–2 mm long, awnless. 

108. Gymnopogon ambiguus 

(Michx.) Britton, Sterns & Poggenb.

Figure 116

Gymnopogon ambiguus (Michx.) Britton, Sterns & Poggenb., 

Prelim. Cat. 69. 1888. 

Common names: beard grass, bearded skeleton grass.

Caespitose perennials; rhizomes short, with a knotty base; 

butt sheath glabrous. Culms 20–100 cm tall, erect or geniculately ascending, sparingly branched. Leaves distichous, basal 

and cauline; sheaths overlapping, glabrous; collars conspicuously 

pubescent; ligules 0.2 mm long, ciliate membrane; blades 

(1.5–)2.5–12 cm long, (2–)5–10(–18) mm wide, bases broadly 

rounded, linear-lanceolate, flat or conduplicate, stiff or firm, surfaces mostly glabrous, margins glabrous, apex acute. Panicles (6–)

11.5–30(–35) cm long; primary branches 7–24 cm long, borne 

along a central axis, spreading or deflexed, straight, unilateral. 

Spikelets 4.1–6.9 mm long, appressed, lanceolate, laterally compressed, packed broadside to the rachis; principal lemma awns 

4–12.2 mm long, subapical, flexuous. 

109. Holcus lanatus* L.

Figure 117

Holcus lanatus* L., Sp. Pl. 2: 1048. 1753. 

Common names: common velvet grass, Yorkshire fog.

Caespitose perennials; butt sheaths pubescent. Culms 

20–100 cm tall, grayish, erect or geniculately ascending; lower 

FIGURE 117. Holcus lanatus. A. Habit. B. Sheath, ligule, and 

blade. C. Glumes. D. Florets. A, B drawn from Leonard 20965 (US2164473); C, D modified from Barkworth et al. (2007).

FIGURE 116. Gymnopogon ambiguus. A. Habit. B. Sheath, ligule, 

and blade. C. Spikelet. A, B drawn from Swallen s.n. (US-1646134); 

C modified from Barkworth et al. (2003).
7 8 • smithsonian contributions to botany

internodes densely pilose, upper internodes often glabrous; nodes 

pubescent. Leaves mostly basal; sheaths densely pubescent, with 

reflexed hairs; ligules 1–4 mm long, eciliate membrane, apex 

truncate, erose-ciliolate; blades 4–20 cm long, (3–)5–10 mm 

wide, green or gray green, linear, flat, surfaces densely pubescent, 

soft pubescent on both sides, margins pubescent, apex acute. 

Panicles 3–15(–20) cm long, 1–8 cm wide, open, lanceolate or 

oblong or ovate, dense or loose. Spikelets 3–6 mm long, elliptic, 

laterally compressed; apical sterile lemma awns 1–2 mm long 

(enclosed by glumes), subapical, twisted and forming a hook.

110. Hordeum jubatum L.

Figure 118

Hordeum jubatum L., Sp. Pl. 1: 85. 1753. 

Common names: foxtail grass, squirrel-tail grass.

Densely caespitose perennials, short-lived, sometimes appearing annuals. Culms 20–80 cm tall, erect or geniculately 

ascending; nodes brown, glabrous. Leaves basal and cauline; 

sheaths glabrous or pubescent; ligules 0.2–0.8 mm long, eciliate 

membranes, apex truncate; blades 6–15 cm long, 2–5 mm wide, 

linear, flat, surface scabrous, sometimes pubescent, margins scabrous, apex acute. Spikes 3–15 cm long, 4–6 mm wide, linear, 

bilateral. Spikelets 4–7 mm long, 3 per node, packed broadside 

to the rachis, lanceolate, dorsally compressed; lemmas 4–8.5 mm 

long, awns 2–15 mm long, straight to divergent, ascending. 

111. Hordeum murinum* L.

Figure 119

Hordeum murinum* L., Sp. Pl. 1: 85. 1753.

Common name: wall barley.

Caespitose annuals. Culms 6–60 cm tall, erect. Leaves basal 

and cauline; basal sheaths somewhat hairy; auricles to 8 mm 

long, falcate; ligules 1–4 mm long, eciliate membranes, apex 

erose; blades to 28 cm long, 2–8 mm wide, linear, flat, surfaces 

FIGURE 119. Hordeum murinum. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelets. A, B drawn from Reed s.n. (US-3049731); C 

modified from Barkworth et al. (2007).

FIGURE 118. Hordeum jubatum. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelets. A, B drawn from Ward s.n. (US-1885285); C 

modified from Barkworth et al. (2007).
number 99 • 7 9

and margins sparsely hairy, apex acute. Spikes 3–8 cm long, 7–16 

mm wide, linear or oblong, bilateral; rachis internodes oblong. 

Spikelets 7–12 mm long, 3 per node, packed broadside to the 

rachis, lanceolate, dorsally compressed; lemmas 8–14 mm long, 

awns 20–40 mm long.

112. Hordeum pusillum Nutt.

Figure 120

Hordeum pusillum Nutt., Gen. N. Amer. Pl. 1: 87. 1818.

Common name: little barley.

Caespitose annuals. Culms 10–60 cm tall, geniculately 

ascending; nodes brown, glabrous. Leaves basal and cauline; 

sheaths scabrous or pubescent; auricles absent or falcate; ligules 

0.2–0.8 mm long, eciliate membrane, apex truncate; blades to 

10.5 cm long, to 4.5 mm wide, surfaces sparsely to densely pubescent on both sides, linear, flat, margins glabrous or sparsely 

hairy, apex acute. Spikes 2–9 cm long, 4–8 mm wide, linear, bilateral. Spikelets 4–6 mm long, 3 per node, packed broadside to 

the rachis, lanceolate, dorsally compressed; lemmas 5–8.5 mm 

long, awns 3.5–9.5 mm long.

113. Hordeum vulgare* L.

Figure 121

Hordeum vulgare* L., Sp. Pl. 1: 84–85. 1753. 

Common name: barley.

Caespitose annuals. Culms to 100(–150) cm tall, erect. 

Leaves basal and cauline; lower sheaths pilose, upper sheaths 

glabrous; auricles to 6 mm long, falcate; ligules 1–2 mm long, 

eciliate membranes, apex truncate; blades 10–30 cm long, 6–15 

mm wide, linear, flat, surfaces scabrous, sometimes glabrous, 

margins glabrous, apex acute. Spikes 5–10 cm long, bilateral. 

Spikelets 10–15 mm long, 3 per node, packed broadside to the 

FIGURE 120. Hordeum pusillum. A. Habit. B. Sheath, ligule, 

and blade. C. Portion of the spike. D. Spikelets. A−C drawn from 

Herman 10327 (US-2479306); D modified from Barkworth et al. 

(2007).

FIGURE 121. Hordeum vulgare. A. Habit. B. Sheath, ligule, and 

blade. C. Spike. D. Spikelets. A−C drawn from Fleming 795 (US3193000) and Steele s.n. (US-364260); D modified from Barkworth 

et al. (2007).
8 0 • smithsonian contributions to botany

rachis, cuneate, dorsally compressed; lemmas 6–12 mm long, 

awns 6–15 mm long, straight, scabrous. 

114. Leersia oryzoides (L.) Sw.

Figure 122

Leersia oryzoides (L.) Sw., Prodr. 21. 1788.

Common name: rice cut grass.

Caespitose perennials; rhizomes elongated, not scaly. Culms 

35–150 cm long, erect or geniculately ascending, branching, 

nodes pubescent, rooting at the lower nodes. Leaves basal and 

cauline; sheaths conspicuously retrorse-scabrous; ligules 0.5–1 

mm long, eciliate membranes, apex truncate; blades 7–30 cm 

long, 5–15 mm wide, linear, flat, ascending, surfaces scaberulous, 

margins spinulose, apex acute. Panicles 10–30 cm long, 5–14 cm 

wide, open, elliptic or oblong, exserted or embraced at base by 

subtending leaf or enclosed, usually with 2 or more branches at 

the lowest node. Spikelets (4–)4.2–6.5 mm long, solitary, elliptic, 

strongly laterally compressed; lemmas awnless; anthers 3.

115. Leersia virginica Willd.

Figure 123

Leersia virginica Willd., Sp. Pl. 1(1): 325. 1797. 

Common name: white grass.

Caespitose perennials; rhizomes short, scaly giving rhizome 

“braided” appearance. Culms 30–140 cm long, decumbent, 

sometimes rooting from lower nodes, nodes pubescent. Leaves 

basal and cauline; sheaths smooth or scaberulous; ligules 1–3 

mm long, eciliate membranes, apex truncate; blades 4–20 cm 

long, (1–)6–15 mm wide, flaccid, linear, flat, surfaces glabrous 

or scaberulous or the abaxial surfaces sometimes densely pilose, 

margins hispid, apex acute. Panicles 10–25 cm long, open, exserted or embraced at base by subtending leaf, ovate, contracted 

FIGURE 123. Leersia virginica. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. Drawn from Kanal 695 (US-3268388).

FIGURE 122. Leersia oryzoides. A. Base of culm. B. Sheath, ligule, 

and blade. C. Panicle. D. Spikelet. A−C drawn from Leonard 1941

(US-1873998); D modified from Hitchcock (1951).
number 99 • 8 1

about secondary branches, bearing congested spikelets, 1 branch 

per node. Spikelets 2.5–3.6 mm long, ovate, strongly laterally 

compressed; lemmas awnless; anthers 2. 

116. Lolium arundinaceum* (Schreb.) Darbysh.

Figure 124

Lolium arundinaceum* (Schreb.) Darbysh., Novon 3(3): 241. 

1993. [Festuca arundinacea Schreb.; Schedonorus arundinaceus (Schreb.) Dumort.] 

Common names: alta fescue, tall fescue.

Caespitose perennials, sometimes rhizomatous. Culms to 

2 m tall. Leaves basal and cauline; sheaths glabrous on surface, oral hairs ciliate, auricles falcate, ciliate; ligules 1–2 mm 

long, eciliate membranes, apex lacerate; blades 10–60 cm long, 

4–12 mm wide, linear, flat, convolute in young shoots, surfaces 

smooth, margins scabrous, apex attenuate. Panicles 10–35 cm 

long, open, lanceolate or ovate, dense or loose. Spikelets 8–15.5 

mm long, elliptic or oblong, laterally compressed; lemmas 5–9 

mm long, awns 0–4 mm long.

117. Lolium multiflorum* Lam.

Figure 125

Lolium multiflorum* Lam., Fl. Franç. 3: 621. 1778. 

Common names: annual rye grass, Italian rye grass.

Caespitose annual or short-lived perennials. Culms 30–150 

cm tall, erect or decumbent. Leaves basal and cauline; sheath 

surface glabrous, auricles falcate; ligules 1–2 mm long, eciliate 

membranes, apex truncate, entire; blades 10–30 cm long, (2–)

3–8(–13) mm wide, linear, flat, surfaces and margins scabrous, 

apex acute. Spikes 15–45 cm long, bilateral. Spikelets 8–31 mm 

long, packed edgewise (adaxially) to rachis, oblong, laterally 

compressed; principal lemma awns to 15 mm long. 

FIGURE 125. Lolium multiflorum. Base of culm. B. Sheath, ligule, 

and blade. C. Spike. D. Spikelet. A−C drawn from Kanal 260 (US3214594); D modified from Hitchcock (1951).

FIGURE 124. Lolium arundinaceum. A. Base of culm. B. Sheath, 

ligule, and blade. C. Panicle. D. Spikelet. A−C drawn from Kanal 

129 (US-3117694); D modified from Barkworth et al. (2007).
8 2 • smithsonian contributions to botany

118. Lolium perenne* L.

Figure 126

Lolium perenne* L., Sp. Pl. 1: 83. 1753. 

Common name: perennial rye grass.

Caespitose perennials. Culms to 100 cm tall, erect or decumbent, glabrous. Leaves basal and cauline; sheath surface glabrous, 

oral hairs lacking, auricles falcate; ligules eciliate membranes, 

apex entire; blades 10–30 cm long, (1–)2–4(–6) mm wide, linear, 

flat, surfaces and margins glabrous, apex acute. Spikes 4–30 cm 

long, bilateral; spikelets 5–22 mm long, packed edgewise (adaxially) to rachis, oblong, laterally compressed; lemmas awnless or 

with awns to about 8 mm long. 

119. Lolium pratense* (Huds.) Darbysh.

Figure 127

Lolium pratense* (Huds.) Darbysh., Novon 3(3): 242. 1993. [Festuca pratensis Huds.; Schedonorus pratensis (Huds.) P. Beauv.] 

Common name: meadow fescue.

Caespitose perennials. Culms to 1.3 m tall, erect or geniculately ascending. Leaves mostly basal; sheaths smooth, glabrous 

on surface, auricles falcate, glabrous; ligules to 0.5 mm long, 

eciliate membranes, apex entire, truncate; blades 10–25 cm long, 

2–7 mm wide, linear, folded or convolute, surfaces smooth, margins scaberulous, apex attenuate. Panicles (6–)10–25 cm long, 

open, lanceolate or ovate, diffuse, nodding. Spikelets (8.5–)12–

15.5(–17) mm long, lanceolate or oblong, laterally compressed; 

lemmas 5–8 mm long, awnless. 

FIGURE 127. Lolium pratense. A. Base of culm. B. Sheath, ligule, 

and blade. C. Panicle. D. Spikelet. Drawn from Allard 11321 (US1898154).

FIGURE 126.Lolium perenne. A. Habit. B. Sheath, ligule, and blade. 

C. Spike and rachis. A, B drawn from Smith 5091 (US-2151147); C 

modified from Barkworth et al. (2007).
number 99 • 8 3

120. Melica mutica Walter

Figure 128

Melica mutica Walter, Fl. Carol. 78. 1788. 

Common names: melic, two-flowered melic.

Caespitose perennials; rhizomes elongated, short. Culms 

45–100 cm tall, wiry; internodes sometimes scaberulous above 

the nodes. Leaves basal and cauline; sheaths tubular much of 

their length, glabrous or pilose; ligules 0.5–1 mm long, eciliate 

membranes, apex erose; blades 1.8–6 mm wide, linear, flat or 

conduplicate, abaxial surfaces glabrous scaberulous, adaxial surfaces puberulous, margins scabrous, apex acute. Panicles 4–25 

cm long, open, lanceolate. Spikelets 7–11 mm long, pendulous, 

cuneate, laterally compressed; lower glumes 6.5–10 mm long, 

oblong; lemmas awnless. 

121. Microstegium vimineum* (Trin.) A. Camus

Figure 129

Microstegium vimineum* (Trin.) A. Camus, Ann. Soc. Linn. 

Lyon, sér. 2, 68: 201. 1922. 

Common names: coverall grass, Japanese stilt grass, Nepalese 

browntop.

Mat-forming annuals. Culms 40–100 cm long, decumbent, 

branched; rooting from lower nodes; nodes glabrous or pubescent. 

Leaves basal and cauline; sheaths shorter than internodes, surfaces 

mostly or sparsely pubescent above, margins ciliate, becoming pilose at the throat; ligules 0.5–0.8 mm long, eciliate membranes, 

apex truncate; blades 3–10 cm long, 8–15 mm wide, elliptic or 

oblong, flat, surfaces glabrous or sparsely pubescent, margins scabrous or sparsely hairy, apex acute or acuminate. Rames (primary 

FIGURE 129. Microstegium vimineum. A. Habit. B. Sheath, ligule, 

and blade. C. Inflorescence with three rames. D. Spikelets. A−C 

drawn from Kanal 437 (US-32779028); D modified from Barkworth et al. (2003).

FIGURE 128. Melica mutica. A. Base of culm. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelet. A−C drawn from Terrell 3979 (US2618923); D modified from Hitchcock (1951).
8 4 • smithsonian contributions to botany

inflorescence branches) 3–7 cm long, 1–5 per culm, paired or digitately to subdigitately arranged on the rachis, spreading or erect. 

Spikelets 3.7–6.5 mm long, in pairs, dorsally compressed; lower 

florets absent or reduced and sterile; upper lemmas usually awned, 

awns 2–15 mm long, often concealed by the glumes. 

122. Miscanthus sinensis* Andersson

Figure 130

Miscanthus sinensis* Andersson, Öfvers. Förh. Kongl. Svenska 

Vetensk.-Akad. 12: 166. 1855. 

Common names: eulalia, Chinese silver grass.

Robust caespitose perennials; rhizomes short; butt sheaths 

with white hairs. Culms 60–200 cm tall, 3–7 mm thick below, 

erect. Leaves predominantly basal; sheaths glabrous, with 

oral hairs bearded near summit; ligules 1–2 mm long, ciliolate 

membranes; blades 20–70 cm long, 6–20 mm wide, linear, flat, 

midveins conspicuous abaxially, surfaces glabrous, margins 

sharply serrate, apex acute. Panicles 15–25 cm long, 8–28 cm 

wide; primary branches usually 8–15 cm long, 4–40 per culm, 

corymbosely arranged on the rachis, drooping or ascending. 

Spikelets 3.5–7 mm long, in pairs, dorsally compressed, falling 

entire; callus hairs 6–12 mm long; upper lemma awns 6–12 mm 

long, from a sinus, geniculate, with twisted column.

123. Muhlenbergia capillaris (Lam.) Trin.

Figure 131

Muhlenbergia capillaris (Lam.) Trin., Gram. Unifl. Sesquifl. 

191–192, 296, t. 5, f. 15. 1824. 

Common name: hairy-awn muhly.

Caespitose perennials; butt sheaths glabrous. Culms 60–

100(–150) cm tall, erect; internodes mostly glabrous, sometimes 

puberulent. Leaves primarily basal; sheaths rounded below, 

FIGURE 131. Muhlenbergia capillaris. A. Habit. B. Sheath, ligule, 

and blade. C. Upper culm and panicle. D. Glumes. E. Floret. Modified from Barkworth et al. (2003). 

FIGURE 130. Miscanthus sinensis. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Kanal 093 (US-3075146); C 

modified from Hitchcock (1951).
number 99 • 8 5

mostly glabrous, scaberulous below; ligules 1.8–5(–10) mm 

long, eciliate membranes, firm below, strongly decurrent, apex 

obtuse; blades 10–35(–50) cm long, 2–4 mm wide, flat or involute, glabrous, scabrous adaxially, apex acuminate. Panicles 

15–50 cm long, 5–30 cm wide, open, diffuse, terminal. Spikelets 

3–5 mm long, lanceolate, laterally compressed; glumes (0.3–)1–

1.5(–2) mm long, usually less than 1/2 as long as lemma; principal lemma awns 2–18 mm long, straight. 

124. Muhlenbergia frondosa (Poir.) Fernald

Figure 132

Muhlenbergia frondosa (Poir.) Fernald, Rhodora 45(534): 235. 

1943. 

Common name: wire-stem muhly.

Perennials not caespitose; rhizomes elongated, scaly. Culms 

40–100 cm long, 0.7–1.8 mm thick, decumbent or bushy, slender; 

internodes glabrous; lateral branches ample, arising from upper 

culm. Leaves basal and cauline; sheaths glabrous on surface, 

margins hyaline; ligules 0.7–1.7 mm long, eciliate membranes 

erose to lacerate-ciliolate, apex truncate; blades 4–18 cm long, 

2–7 mm wide, linear, flat, surfaces glabrous, margins scabrous, 

apex acute. Panicles 2–15 cm long, 0.3–2 cm wide, terminal and 

axillary, contracted, sometimes dense, linear or lanceolate, sometimes interrupted below. Spikelets 2.2–4 mm long, lanceolate, 

laterally compressed; glumes 2–4 mm long, 3/4 as long as to longer than the lemmas; principal lemma awns 0.1–13 mm long or 

unawned.

125. Muhlenbergia glomerata (Willd.) Trin.

Figure 133

Muhlenbergia glomerata (Willd.) Trin., Gram. Unifl. Sesquifl. 

191, 297, t. 5, f. 10. 1824. 

Common names: marsh muhly, spiked muhly.

FIGURE 133. Muhlenbergia glomerata. A. Habit. B. Sheath, ligule, 

and blade. C. Panicle. D. Spikelet. A−C drawn from Chickering s.n.

(US-822958); D modified from Hitchcock (1951).

FIGURE 132. Muhlenbergia frondosa. A. Habit. B. Sheath, ligule, 

and blade. C. Panicle. D. Spikelet. A−C drawn from Leonard 20980

(US-2614489); D modified from Hitchcock (1951).
8 6 • smithsonian contributions to botany

Perennials not caespitose; rhizomes elongated, scaly. Culms 

30–120 cm tall, erect; internodes distally pubescent. Leaves basal 

and cauline; sheaths keeled, scaberulous; ligules 0.2–0.6 mm 

long, eciliate membranes, erose, apex truncate; blades 2–15 cm 

long, 2–6 mm wide, flat, linear, surfaces smooth or scaberulous, 

margins scabrous, apex acute. Panicles 1.5–12 cm long, 0.3–1.8 

cm wide, spiciform, linear or lanceolate, continuous or interrupted below. Spikelets 3–8 mm long, lanceolate, laterally compressed; glumes 3–8 mm long (including the awn), about 1.3–2 

times longer than the lemmas; lemmas unawned or mucronate 

(mucro less than 1 mm long). 

126. Muhlenbergia schreberi J. F. Gmel.

figure 134

Muhlenbergia schreberi J. F. Gmel., Syst. Nat. 2: 171. 1791. 

Common name: nimblewill.

Caespitose perennials. Culms 10–45(–70) cm long, decumbent; internodes glabrous, often rooting from lower nodes. 

Leaves basal and cauline; sheath surfaces glabrous, margin pubescent; ligules 0.2–1 mm long, ciliolate membranes; blades 

3–10 cm long, 2–4.5 mm wide, linear, flat, surfaces smooth or 

scaberulous, margins glabrous or sparsely hairy, apex acute. Panicles 3–15 cm long, open, linear. Spikelets 1.8–2.8 mm long, lanceolate, slightly laterally compressed; glumes 0.1–0.4 mm long, 

upper glumes lacking or rudimentary; principal lemma awns 

1.5–5 mm long, straight or flexuous.

127. Muhlenbergia sobolifera 

(Muhl. ex Willd.) Trin.

figure 135

Muhlenbergia sobolifera (Muhl. ex Willd.) Trin., Gram. Unifl. 

Sesquifl. 189, 297, t. 5, f. 4. 1824. 

Common names: branched muhly, rock muhly.

Caespitose perennials or culms solitary; rhizomes elongated, 

scaly; butt sheaths papery. Culms 60–100 cm tall, erect or geniculately ascending; internodes distally pubescent; nodes glabrous; 

FIGURE 135. Muhlenbergia sobolifera. A. Habit. B. Sheath, ligule, 

and blade. C. Floret. A, B drawn from Steele s.n. (US-363891); C 

modified from Hitchcock (1951).

FIGURE 134. Muhlenbergia schreberi. A. Habit. B. Sheath, ligule, 

and blade. C. Spikelet. A, B drawn from Kanal 466 (US-3278992); 

C modified from Barkworth et al. (2003).
number 99 • 8 7

lateral branches sparse. Leaves basal and cauline; sheaths glabrous, outer margins glabrous or hairy; ligules 0.5–1 mm long, 

eciliate membranes, apex truncate, erose; blades 4–18 cm long, 

0.2–0.8 mm wide, spreading, linear, flat, surfaces scabrous, 

rough on both sides, margins scabrous, apex attenuate. Panicles 

4–18 cm long, 2–7 cm wide, contracted, linear, equilateral or 

nodding. Spikelets 1.6–3 mm long, lanceolate, laterally compressed; glumes 1–2.5 mm long, much shorter than the lemmas; 

lemmas awnless or mucronate. 

128. Muhlenbergia sylvatica 

(Torr.) Torr. ex A. Gray

figure 136

Muhlenbergia sylvatica (Torr.) Torr. ex A. Gray, N. Amer. Gram. 

1: 13. 1834. 

Common names: forest muhly, woodland muhly.

Perennials; rhizomes elongated, scaly. Culms 40–110 cm 

tall, erect, slender, wiry; internodes retrorsely scabrous, distally 

pubescent; lateral branches ample, arising from mid-culm. Leaves 

basal and cauline; sheaths glabrous, scaberulous distally, margins 

hyaline; ligules 0.4–1.2 mm long, eciliate membranes, apex erose, 

truncate, lacerate-ciliolate; blades 6–20 cm long, 4–10(–15) mm 

wide, linear, flat, surfaces scabrous to scaberulous, occasionally 

smooth, margins scabrous, apex acute. Panicles 10–33 cm long, 0.2–

0.8 cm wide, contracted, linear, interrupted, loose. Spikelets 2.6–4.5 

mm long, lanceolate, laterally compressed; glumes 1.8–3 mm long, 

nearly as long as lemmas; principal lemma awns 5–18 mm long. 

129. Muhlenbergia tenuiflora (Willd.) Britton, 

Sterns & Poggenb.

figure 137

Muhlenbergia tenuiflora (Willd.) Britton, Sterns & Poggenb.,

Prelim. Cat. 67. 1888. 

Common names: slender-flowered muhly, slender muhly.

Annuals or short-lived perennials; rhizomes elongated, 

scaly. Culms 40–120 cm tall, erect or geniculately ascending; 

FIGURE 137. Muhlenbergia tenuiflora. A. Habit. B. Sheath, ligule, 

and blade. C. Panicle. D. Floret. A−C drawn from Steele s.n. (US363892); D modified from Hitchcock (1951).

FIGURE 136. Muhlenbergia sylvatica. A. Habit. B. Sheath, ligule, 

and blade. C. Glumes. D. Floret. A, B drawn from Lamson-Scribner 

809 (US-207926); D modified from Hitchcock (1951).
8 8 • smithsonian contributions to botany

internodes distally pubescent; nodes retrorsely pubescent; lateral branches lacking or sparse. Leaves cauline; sheaths loose, 

pubescent; ligules 0.4–1.2 mm long, eciliate membranes, apex 

truncate; blades 6–20 cm long, 4–10(–15) mm wide, spreading, 

linear, flat, surfaces glabrous abaxially scaberulous adaxially, 

margins scaberulous, apex acute. Panicles 10–33 cm long, 0.2–

0.8 cm wide, contracted, linear, nodding. Spikelets 2.6–4.5 mm 

long, lanceolate, laterally compressed; glumes 1.3–3 mm long, 

shorter than lemmas; principal lemma awns 2–11 mm long. 

130. Panicum capillare L.

figure 138

Panicum capillare L., Sp. Pl. 1: 58. 1753. 

Common names: common panic grass, old-witch grass, witch grass.

Caespitose annuals, often bluish or purplish. Culms 15–130 

cm tall, erect or geniculately ascending, slender to stout, straight 

to sinuous, sparsely or freely branched; nodes densely bearded. 

Leaves basal and cauline; sheaths rounded, hispid, with tuberclebased hairs; ligules 0.5–1.5 mm, ciliate membrane; blades 5–40 

cm long, 3–18 mm wide, linear or lanceolate, flat, spreading, hispid both sides, apex attenuate. Panicles 13–50 cm long, 7–24 cm 

wide, open, oblong or ovate, diffuse. Spikelets 1.9–4 mm long, 

elliptic or oblong, often reddish purple, dorsally compressed, 

acute or acuminate; lower lemmas 1.9–3 mm long, awnless.

131. Panicum dichotomiflorum Michx.

figure 139

Panicum dichotomiflorum Michx., Fl. Bor.-Amer. 1: 48. 1803. 

Common names: fall panic grass, spreading witch grass.

Caespitose annuals or short-lived perennials. Culms 50–200 

cm tall, geniculately ascending or decumbent; rooting at the 

lower nodes; freely branching from lower to middle nodes; nodes 

glabrous, usually swollen. Leaves cauline; sheaths sparsely pubescent near the base, elsewhere glabrous, compressed; ligule 0.5–2 

FIGURE 139. Panicum dichotomiflorum. A. Habit. B. Sheath, ligule, and blade. C. Panicle. D. Spikelet. A−C drawn from Ball 2989

(US-304327); D modified from Hitchcock (1951).

FIGURE 138. Panicum capillare. A. Habit. B. Sheath, ligule, 

and blade. C. Spikelets. A, B drawn from Beyersdorfer 358 (US3047086); C modified from Hitchcock (1951).
number 99 • 8 9

mm long, ciliate membranes; blades 10–65 cm long, 3–12(–25) 

mm wide, linear, flat, midrib conspicuous, surfaces glabrous or 

puberulous, hairy adaxially, margins scabrous, apex acute. Panicles 12–40 cm long, open, ovate, diffuse, terminal and axillary, 

embraced at base by subtending leaf. Spikelets 1.8–3.8 mm long, 

elliptic or oblong, dorsally compressed, acute or acuminate; lemmas 1.8–2.8 mm long, awnless.

132. Panicum flexile (Gatt.) Scribn.

figure 140

Panicum flexile (Gatt.) Scribn., Bull. Torrey Bot. Club 20(12): 

476. 1893. 

Common name: wiry panic grass.

Caespitose annuals. Culms 10–75 cm tall, erect; much 

branched from the base; internodes solid, distally glabrous to 

hispid; nodes glabrous or pubescent or bearded. Leaves cauline; 

sheaths longer than the internodes, sometimes purplish, glabrous 

to sparsely hispid; ligules 0.5–1.5 mm long, fringe of hairs; blades 

3–23 cm long, 1–7 mm wide, linear, flat, surfaces hispid, sparsely 

hirsute or pilose (rarely glabrous), margins involute, scabrid, 

apex acute. Panicles 5–45 cm long, 1–6 cm wide, 3 times longer 

than wide, open, ovate, terminal and axillary. Spikelets 2.5–3.7 

mm long, elliptic or oblong, dorsally compressed, acute or acuminate; lower lemmas 2.2–2.7 mm long, awnless.

133. Panicum gattingeri Nash

figure 141

Panicum gattingeri Nash, Fl. S.E. U.S. 92, 1327. 1903. 

Common name: Gattinger’s panic grass.

Caespitose annuals. Culms 20–100 cm tall, slender to robust, erect or geniculately ascending; freely branching, rooting 

at the lower nodes; internodes pubescent, hirsute, tuberculatebased hairs; nodes pubescent bearded. Leaves cauline; sheaths 

hispid, with tubercle-based hairs; ligules 0.5–2 mm long, ciliate 

FIGURE 141. Panicum gattingeri. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelets. A−C drawn from Hitchcock 167 (US3048449); D modified from Hitchcock (1951).

FIGURE 140. Panicum flexile. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelets. A−C drawn from Allard 12175 (US2564070A); D modified from Hitchcock (1951).
9 0 • smithsonian contributions to botany

membranes; blades 7–30(–100) cm long, 6–10 mm wide, linear 

or lanceolate, flat, surfaces glabrous, margins tuberculate, apex 

attenuate. Panicles 7–27 cm long, 4–24 cm wide, 1/3 as long as 

the plant, open, oblong or ovate, diffuse. Spikelets 1.9–2.4 mm 

long, elliptic or oblong, dorsally compressed, acute or acuminate; lower lemmas 1.6–2 mm long, awnless. 

134. Panicum miliaceum* L.

figure 142

Panicum miliaceum* L., Sp. Pl. 1: 58. 1753. 

Common names: broom-corn millet, proso, hog millet.

Caespitose annuals. Culms 20–210 cm tall, stout, not woody, 

erect or geniculately ascending, sometimes branching from lower 

nodes; internodes distally glabrous or pubescent or hispid; nodes 

glabrous or pubescent or bearded. Leaves basal and cauline; 

sheaths hispid; ligules 1.5–3 mm long, ciliate membranes; blades 

15–40 cm long, 7–25 mm wide, linear, flat, surfaces glabrous 

or pubescent or hispid, margins pubescent, apex acute. Panicles 

6–20 cm long, 4–11 cm wide; dense, somewhat contracted, obovate, nodding. Spikelets 4–6 mm long, elliptic or ovate, slightly 

dorsally compressed; lower lemmas 4–4.8 mm long, awnless.

135. Panicum philadelphicum Bernh. ex Trin.

figure 143

Panicum philadelphicum Bernh. ex Trin., Gram. Panic. 216. 

1826. 

Common names: Philadelphia witch grass, wood witch grass.

Caespitose annuals. Culms 8–100 cm tall, erect, often 

slender, branched; internodes distally hirsute or hispid; nodes 

bearded. Leaves cauline; sheaths usually longer than the internodes, hispid, with tubercle-based hairs; ligules 0.5–1.5 mm 

long, fringe of hairs; blades 3–30 cm long, 2–12 mm wide, light 

FIGURE 143. Panicum philadelphicum. A. Base of culm. B. Sheath, 

ligule, and blade. C. Panicle. D. Spikelets. A−C drawn from Holm 

105 (US-2380743); D modified from Barkworth et al. (2003).

FIGURE 142. Panicum miliaceum. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelets. A−C drawn from Steele s.n. (US494805); D modified from Hitchcock (1951).
number 99 • 9 1

green, linear, flat, hirsute to sparsely pilose on both sides, margins 

tuberculate-ciliate, apex acute. Panicles 7–27 cm long, 4–24 cm 

wide, 1/4–1/3 as long as the culm, open, ovate, diffuse. Spikelets 

1.4–2.4 mm long, elliptic, dorsally compressed, clustered toward 

branch tips, acute; lower lemmas 1.6–1.9 mm long, awnless. 

136. Panicum verrucosum Muhl.

figure 144

Panicum verrucosum Muhl., Descr. Gram. 113. 1817. 

Common name: warty panic grass.

Solitary annuals. Culms 10–150 cm tall, weak, erect or 

geniculately ascending or decumbent, glabrous; rooting at the 

lower nodes; lateral branches sparse or ample. Leaves cauline; 

sheaths glabrous, outer margin hairy; ligules 0.2–0.5 mm long, 

fringe of hairs; blades 5–20 cm long, 3–10 mm wide, flaccid, 

light green, linear, flat, surfaces thin, glabrous on both sides, 

margins scaberulous, apex long-acuminate. Panicles 5–30 cm 

long, nearly as wide as long, open, ovate, diffuse, bearing few 

spikelets. Spikelets 1.7–2.2 mm long, elliptic or obovate, dorsally compressed, clustered toward branch tips; upper glumes 

and lower lemmas distinctly verrucose; upper florets 1.6–2 mm 

long; lemmas awnless.

137. Panicum virgatum L.

figure 145

Panicum virgatum L., Sp. Pl. 1: 59. 1753. 

Common names: switch grass, wand panic grass.

Caespitose or solitary perennials; rhizomes elongated, scaly. 

Culms 40–300 cm tall, erect or decumbent; nodes glabrous or 

glaucous. Leaves basal and cauline; sheaths longer than the 

lower internodes, shorter than those above, glabrous or pilose; 

ligules 2–6 mm long, ciliolate membranes; blades 10–60 cm 

FIGURE 145. Panicum virgatum. A. Base of culm. B. Sheath, ligule, 

and blade. C. Panicle. D. Spikelets. A−C drawn from Strong & Simmon 2766 (US-3434006); D modified from Hitchcock (1951).

FIGURE 144. Panicum verrucosum. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelets. A, B drawn from Chase–Amer. Gr. Nat. Herb. 

67 (US-2488443); C modified from Barkworth et al. (2003).
9 2 • smithsonian contributions to botany

long, 2–15 mm wide, ascending or spreading, linear, flat, surfaces glabrous or pilose, margins scabrous, apex acute. Panicles 

10–55 cm long, 4–20 cm wide, open, ovate. Spikelets 2.5–8 mm 

long, ovate, dorsally compressed; upper florets 2.3–3 mm long; 

lemmas awnless. 

138. Paspalum dilatatum* Poir.

figure 146

Paspalum dilatatum* Poir., Encycl. 5: 35. 1804. 

Common names: Dallis grass, golden crown grass.

Caespitose perennials; basal innovations flabellate; rhizomes 

short, forming a knotty base. Culms 50–175 cm tall, erect, nodes 

glabrous. Leaves basal and cauline; sheaths glabrous or pubescent; ligules 1.5–3.8 mm long, eciliate membrane, apex lacerate; 

blades 6–35 cm long, 2–16 mm wide, linear, flat, glabrous with 

a few long hairs near the base, margins scabrous, apex acute. 

Panicles with (2–)3–7(–11) spikelike unilateral branches racemosely arranged on a central axis; branches 1.5–12 cm long. 

Spikelets 2.3–4 mm long, 1.7–2.5 mm wide, ovate, dorsally 

compressed, paired, appressed to the branch axis; lower lemmas 

5–7-veined, awnless.

139. Paspalum dissectum (L.) L.

figure 147

Paspalum dissectum (L.) L., Sp. Pl. (ed. 2) 1: 81. 1762. 

Common names: mudbank crown grass, Walter’s paspalum.

Mat-forming perennials; rhizomatous from a creeping base. 

Culms 10–50 cm tall, decumbent or prostrate, glabrous or pubescent; lateral branches ample. Leaves basal and cauline; sheaths 

glabrous; ligules 2–2.5 mm long, eciliate membranes, apex 

slightly erose; blades 3–12 cm long, 1.3–4.8 mm wide, linear, 

flat, glabrous or pubescent to sparsely hairy, margins scabrous, 

FIGURE 146. Paspalum dilatatum. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Wells & Brown 4191 (US3418174); C modified from Hitchcock (1951).

FIGURE 147. Paspalum dissectum. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelets. A, B drawn from Ball s.n. (US-73585); C modified from Barkworth et al. (2003).
number 99 • 9 3

apex acute. Panicles with 2–4 spikelike unilateral branches racemosely arranged on a central axis; branches 1.4–7 cm long. 

Spikelets 1.7–2.1 mm long, 1–1.6 mm wide, oblong, dorsally 

compressed, usually paired, appressed to the branch axis, obtuse 

or subacute; lower lemmas 3-veined, awnless.

140. Paspalum floridanum Michx.

figure 148

Paspalum floridanum Michx., Fl. Bor.-Amer. 1: 44. 1803. 

Common names: Florida crown grass, Florida paspalum.

Stout caespitose perennials; rhizomes short. Culms 80–210 

cm tall, erect, glabrous, solitary or few; nodes glabrous or pubescent. Leaves basal and cauline; sheaths glabrous or hirsute; 

ligules 1.2–2.3 mm long, eciliate membranes, apex erose, subentire; blades 15–52 cm long, 3–18 mm wide, linear, flat or conduplicate, glabrous or hirsute, margins pubescent, apex acute. 

Panicles with 2–4 spikelike unilateral branches racemosely arranged on a central axis; branches 1–3 cm long. Spikelets 2.9–

4.1 mm long, 1.9–3.1 mm wide, oblong, dorsally compressed, 

paired, appressed to the branch axis, obtuse or subacute; lower 

lemmas 3-veined, awnless.

141. Paspalum laeve Michx.

figure 149

Paspalum laeve Michx., Fl. Bor.-Amer. 1: 44. 1803. 

Common names: field crown grass, smooth paspalum.

Caespitose perennials; butt sheaths sparsely hairy. Culms 

40–120 cm tall, erect or geniculately ascending; nodes glabrous 

or pubescent. Leaves basal and cauline; sheaths compressed, glabrous or pilose; ligules 1.5–3.8 mm long, eciliate membranes, 

apex entire to lacerate; blades 5–37 cm long, 2–9.3 mm wide, 

linear, conduplicate, glabrous or pilose, margins sparsely hairy, 

FIGURE 149. Paspalum laeve. A. Habit. B. Sheath, ligule, and blade. 

C. Panicle. D. Spikelets. A−C drawn from Kanal 691 (US-3268311); 

D modified from Hitchcock (1951).

FIGURE 148. Paspalum floridanum. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Panicle branch. E. Spikelets. A−D drawn from 

Kanal 766 (US-3278959); E modified from Hitchcock (1951).
9 4 • smithsonian contributions to botany

apex acute. Panicles with 1–6 spikelike unilateral branches racemosely arranged on a central axis; branches 4–10 cm long. 

Spikelets 2.3–3.3 mm long, ovate or orbicular, dorsally compressed, solitary; lower lemmas 5-veined, awnless.

142. Paspalum pubiflorum Rupr. ex E. Fourn.

figure 150

Paspalum pubiflorum Rupr. ex E. Fourn., Mexic. Pl. 2: 11. 1886. 

Common name: hairy-seed crown grass.

Perennials; butt sheaths fibrous. Culms 30–130 cm tall, 

geniculately ascending or decumbent; nodes rooting below, glabrous or pubescent. Leaves basal and cauline; sheaths glabrous 

or pubescent with tubercle-based hairs; ligules 1–3.2 mm long, 

eciliate membranes, apex erose; blades 10–31 cm long, 4–18 mm 

wide, lanceolate, flat, glabrous with a few hairs near base, margins 

scabrous, apex acute. Panicles with 2–5(–7) spikelike unilateral 

branches racemosely arranged on a central axis; branches 3–10 

cm long. Spikelets 2.5–3.1 mm long, 1.5–2 mm wide, elliptic 

or obovate, dorsally compressed, in pairs and forming 4 rows; 

lower lemmas 3–7-veined, awnless.

143. Paspalum setaceum Michx.

figure 151

Paspalum setaceum Michx., Fl. Bor.-Amer. 1: 43. 1803. 

Common names: slender crown grass, slender paspalum.

Caespitose perennials; rhizomes short; butt sheaths pubescent. Culms 25–110 cm long, erect, spreading or prostrate; nodes 

glabrous or pubescent. Leaves mostly basal; sheaths glabrous or 

pubescent; ligules 0.2–0.5 mm long, eciliate membranes; blades 

5–30 cm long, 2–20 mm wide, linear or lanceolate, bases broadly 

rounded or cordate, glabrous to hirsute, margins pubescent, 

apex acuminate. Panicles with 1–6 spikelike unilateral branches 

FIGURE 151. Paspalum setaceum. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelets. A−C drawn from Kanal 325 (US3214585); D modified from Hitchcock (1951).

FIGURE 150. Paspalum pubiflorum. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelets. A−C drawn from Kanal 232 (US3230410); D modified from Barkworth et al. (2003).
number 99 • 9 5

racemosely arranged on a central axis; branches 3–17 cm long, 

terminal and axillary. Spikelets 1.4–2.6 mm long, elliptic, orbicular or obovate, dorsally compressed, single or paired; lower lemmas 3-veined, awnless.

144. Phalaris arundinacea L.

figure 152

Phalaris arundinacea L., Sp. Pl. 1: 55. 1753. 

Common name: reed canary grass.

Perennial; not caespitose; rhizomes elongated, scaly; butt 

sheaths glabrous. Culms 40–230 cm tall, erect. Leaves cauline; 

ligules 4–10(–11) mm long, eciliate membranes, apex truncate, 

lacerate; blades 10–30 cm long, 5–20 mm wide, linear, flat, surfaces scabrous, margins serrate, apex acute. Panicles 5–40 cm 

long, 1–4 cm wide, contracted, linear, interrupted. Spikelets 

3.5–7.5 mm long, ovate, strongly laterally compressed; lemmas 

awnless.

145. Phalaris canariensis L.

figure 153

Phalaris canariensis L., Sp. Pl. 1: 54–55. 1753. 

Common names: birdseed grass, canary grass.

Caespitose annuals. Culms 30–100 cm tall, erect or geniculately ascending. Leaves cauline; sheath surface glabrous; 

ligules 3–6 mm long, eciliate membrane, apex rounded to obtuse, lacerate; blades 5–25 cm long, 2–10 mm wide, linear, flat, 

surfaces glabrous, margins scabrous, apex acute. Panicles 1.5–5 

cm long, 1.5–2 cm wide, spiciform or capitate, ovate. Spikelets 

6–10 mm long, obovate, strongly laterally compressed; lemmas 

awnless.

FIGURE 153. Phalaris canariensis. A. Base of culm. B. Sheath, ligule, and blade. C. Panicle. D. Spikelet. A−C drawn from Vasey s.n.

(US-979920); D modified from Hitchcock (1951).

FIGURE 152. Phalaris arundinacea. A. Base of culm. B. Sheath, ligule, and blade. C. Panicle. D. Spikelet. A−C drawn from Kanal 363

(US-3214567); D modified from Barkworth et al. (2007).
9 6 • smithsonian contributions to botany

146. Phleum pratense* L.

figure 154

Phleum pratense* L., Sp. Pl. 1: 59. 1753. 

Common name: timothy.

Caespitose perennials; butt sheaths glabrous, dark brown. 

Culms (20–)50–150 cm tall, erect or geniculately ascending, glabrous except the scabrous apex; lower internodes frequently enlarged or bulbous. Leaves cauline; sheaths glabrous, sheaths of 

the flag leaves not inflated; auricles occasionally present, inconspicuous; ligules 1–6 mm long, eciliate membranes, apex obtuse 

to acute; blades 4–20 cm long, 4–8(–10) mm wide, linear, flat, 

surface glabrous, margins scaberulous, apex acute. Panicles (2–)

6–15(–30) cm long, 0.6–2 cm wide, spiciform, linear. Spikelets 

3–3.8 mm long, oblong, laterally compressed, truncate; lemmas 

awnless. 

147. Phragmites australis (Cav.) 

Trin. ex Steud. subsp. australis

figure 155

Phragmites australis (Cav.) Trin. ex Steud., Nomencl. Bot. (ed. 

2) 1: 143. 1840. subsp. australis*. 

Common names: common reed, wild reed.

Caespitose or solitary perennials, usually forming extensive 

colonies; rhizomes elongated. Culms 1–4 m long, erect, reedlike. 

Leaves cauline; sheaths loose, glabrous; ligules 1 mm long, ciliate 

membranes; blades 15–40 cm long, 2–4 cm wide, deciduous at 

the ligule, linear, flat, surfaces and margins glabrous, apex attenuate, filiform. Panicles 15–35 cm long, 8–20 cm wide, open, 

oblong, dense. Spikelets 3–10 mm long, cuneate, laterally compressed; rachilla segments sericeous; lemmas awnless.

FIGURE 155. Phragmites australis subsp. australis. A. Base of culm. 

B. Sheath, ligule, and blade. C. Panicle. D. Spikelet. A−C drawn from 

Fosberg 24808 (US-2681778); D. modified from Barkworth et al. 

(2003).

FIGURE 154. Phleum pratense. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelet. A−C drawn from Allard 20474 (US210140); D modified from Hitchcock (1951).
number 99 • 9 7

148. Piptochaetium avenaceum (L.) Parodi

figure 156

Piptochaetium avenaceum (L.) Parodi, Revista Mus. La Plata, 

Secc. Bot. 6(25): 229. 1944.

Common names: black oatgrass, blackseed needlegrass, blackseed spear grass.

Caespitose perennials. Culms (30–)40–100 cm tall, erect, 

slender; internodes distally glabrous; nodes narrowed, yellowish to reddish, glabrous. Leaves mostly basal; sheaths glabrous 

or sparsely hairy; ligules 2–4 mm long, eciliate membranes, 

rounded, sometimes highest at the sides, apex acute; blades 8–30 

cm long, 0.6–3 mm wide, filiform, flat or involute, surfaces and 

margins scabrous; apex acute. Panicles 7–25 cm long, open, elliptic. Spikelets 10–15 mm long, lanceolate, subterete; principal 

lemma awns 35–70 mm long, geniculate or twice geniculate, 

basal segment hispid, twisted. 

149. Pleioblastus argenteostriatus* fo. glaber

(Makino) Murata

figure 157

Pleioblastus argenteostriatus* fo. glaber (Makino) Murata, Acta 

Phytotax. Geobot. 30(4–6): 147. 1979. 

Common name: dwarf bamboo.

Caespitose perennials; rhizomes elongated. Culms 40–60 cm 

tall, branched or unbranched and antrorsely fringed on branched 

culms, the branched culms (5–10) erect and often recurved at 

the apex, yellow green, nodes slightly swollen, glabrous. Leaves 

cauline; sheaths infrequently tubular, purplish at the apex, glabrous, margins ciliate; oral setae present; ligules 0.5 mm long, 

eciliate membranes or lines of hairs; blades 10–23 cm long, 8–25 

mm wide, lanceolate, flat, sometimes with cross-connecting 

veinlets, surfaces glabrous or puberulous, margins scabrous, 

bases rounded and with short pseudopetioles, apex acuminate. 

FIGURE 157. Pleioblastus argenteostriatus fo. glaber. Habit, herbarium specimen, Steury & Parrish 120229 (US-3619015).

FIGURE 156. Piptochaetium avenaceum. A. Base of culm. B. 

Sheath, ligule, and blade. C. Panicle. D. Spikelet. Drawn from Hitchcock 12572 (US-3151067).
9 8 • smithsonian contributions to botany

Panicles 5–11 cm long, open, contracted, or spikelike, terminal 

or axillary, composed of lax racemes. Spikelets 40–60 mm long, 

lanceolate, laterally compressed. 

150. Pleioblastus pygmaeus* (Miq.) Nakai

figure 158

Pleioblastus pygmaeus* (Miq.) Nakai, Sci. Educ. (Tokyo) 15(6): 

70. 1932. 

Common names: pygmy bamboo, dwarf fern-leaf bamboo.

Caespitose perennials; rhizomes elongated. Culms 10–80 cm 

tall, erect, straight, reedlike, woody, branched or unbranched, 

fastigiate; internodes glabrous. Leaves cauline; sheaths glabrous 

or puberulous; oral setae lacking or at least poorly developed; 

ligules 1 mm long, eciliate or ciliate membrane, apex obtuse; 

blades 6–18.5 cm long, 10–17 mm wide, flat, oval to lanceolate, green, not variegated in our area, pubescent on both sides, 

more densely so abaxially where cross veins are evident, midribs 

evident, margins scabrous, base wedged to rounded and with 

short pseudopetioles, apex acute to acuminate. Panicles open or 

contracted and spikelike. Spikelets about 30 mm long, laterally 

compressed, lemmas and glumes with short dorsal awns.

151. Poa annua* L.

figure 159

Poa annua* L., Sp. Pl. 1: 68. 1753. 

Common names: annual bluegrass, spear grass.

Caespitose annuals, rarely surviving for a second season. 

Culms 2–20(–45) cm long, erect or geniculately ascending or 

decumbent, sometimes rooting at the lower nodes; internodes 

terete, smooth; lateral branches lacking or sparse. Leaves mostly 

basal; sheaths weekly compressed, glabrous, closed for about 

1/3 their length; ligules 0.5–3(–5) mm long, eciliate membranes, 

apex obtuse to truncate; blades 1–14 cm long, 1–5 mm wide, 

linear, flat or weakly folded, surfaces smooth, glabrous, margins 

FIGURE 159. Poa annua. A. Habit. B. Apex of blade. C. Sheath, 

ligule, and blade. D. Panicle. E. Florets. A−D drawn from Fosberg 

55144 (US-2681617); E modified from Barkworth et al. (2007).

FIGURE 158. Pleioblastus pygmaeus. Habit, herbarium specimen, 

Steury 120308 (US-3619017).
number 99 • 9 9

scaberulous; apex obtuse or abruptly acute, hooded. Panicles 1–7

(–10) cm long, open, pyramidal or ovate. Spikelets 3–5 mm long, 

oblong or ovate, laterally compressed; callus glabrous; lemmas 

2.4–3.4 mm long, margins and lateral veins puberulent, awnless.

152. Poa autumnalis Muhl. ex Elliott

figure 160

Poa autumnalis Muhl. ex Elliott, Sketch Bot. S. Carolina 1(2): 

159. 1816.

Common name: autumn bluegrass.

Loosely caespitose. Culms 23–86 cm tall, weak; internodes 

smooth; lateral branches lacking. Leaves mostly basal; sheaths 

smooth, glabrous; ligules 0.8–1.8 mm long, eciliate membranes, 

apex lacerate; blades 5–20 cm long, 1–4.5 mm wide, flaccid, linear, flat or folded, surfaces and margins glabrous, apex mostly 

acute. Panicles 8–18 cm long, open, pyramidal. Spikelets 5–7 

mm long, oblong, laterally compressed, clustered toward the 

branch tips; callus glabrous to short-webbed; callus glabrous 

to short-webbed; lemmas 3.2–4.4 mm long, keels and marginal 

veins softly puberulent, awnless. 

153. Poa compressa* L.

figure 161

Poa compressa* L., Sp. Pl. 1: 69. 1753. 

Common names: Canada bluegrass, flat-stemmed bluegrass.

Culms solitary or loosely caespitose perennials; rhizomes elongated. Culms 15–60 cm tall, erect or geniculately ascending, wiry; 

internodes elliptical in section, smooth; butt sheaths glabrous. 

Leaves basal and cauline; sheaths closed for 1/3–1/2 their length, 

distinctly compressed, blue green, glabrous; ligules 1–3 mm long, 

eciliate membranes, apex truncate to obtuse; blades 2–12 cm long, 

1.5–4 mm wide, linear, flat or conduplicate, thin, surfaces and 

margins smooth or scaberulous, glabrous, apex abruptly acute. 

Panicles 2–10 cm long, 0.5–3 cm wide, open or contracted, oblong 

FIGURE 161. Poa compressa. A. Habit. B. Sheath, ligule, and blade. 

C. Spikelet. A, B drawn from Fosberg 42505 (US-2701175) and 

34676 (US-2681124); C modified from Barkworth et al. (2007).

FIGURE 160. Poa autumnalis. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelet. A−C drawn from Fosberg 60907 (US3343457); D modified from Barkworth et al. (2007).
100 • smithsonian contributions to botany

or ovate, dense or loose. Spikelets (2.3–)3.5–7 mm long, oblong, 

laterally compressed; callus usually webbed; lemmas 2.3–3.5 mm 

long, keels and lateral veins short-villous, awnless. 

154. Poa cuspidata Nutt.

figure 162

Poa cuspidata Nutt., Comp. Fl. Philadelph. 1: 61. 1818.

Common names: early bluegrass, short-leaved bluegrass. 

Caespitose perennials, clumped loosely; rhizomes short. 

Culms 15–60 cm tall, erect, compressed; internodes glabrous; 

basal branching mainly extravaginal. Leaves mostly basal; 

sheaths glabrous, closed for about 1/2 their length, slightly compressed, collars of proximal leaves usually retrorsely scabrid or 

pubescent distally and on the throat; ligules 0.5–4 mm long, 

eciliate membranes, apex truncate to acute; blades 30–50 cm 

long, 1–4 mm wide, linear, flat, surfaces and margins smooth, 

apex abruptly acute. Panicles 5–15 cm long, open, pyramidal, 

dense or loose, branches spreading to reflexed. Spikelets 5–8 mm 

long, ovate, laterally compressed, with hairs extending 6–8 mm 

beyond apex, clustered toward branch tips; callus webbed with 

hairs more than 1/3 as long as lemma; lemmas 3–6 mm long, keel 

and marginal veins short to long-villous, awnless. 

155. Poa palustris L.

figure 163

Poa palustris L., Syst. Nat. (ed. 10) 2: 874. 1759. 

Common names: fowl bluegrass, fowl meadow grass.

Caespitose perennials. Culms 25–120 cm tall, erect or geniculately ascending or decumbent; internodes terete or weakly 

compressed, smooth; nodes terete or slightly compressed; sometimes branching above the base. Leaves mostly basal; sheaths 

closed for 1/5 their length, slightly compressed, glabrous or 

sparsely retrorsely scabrous; ligules (1–)1.5–6 mm long, eciliate 

membranes, apex obtuse or acute, frequently lacerate; blades 

5–20 cm long, 1.5–8 mm wide, flaccid, linear, flat, steeply ascending or spreading, surfaces scaberulous, glabrous, margins 

FIGURE 163. Poa palustris. A. Habit. B. Sheath, ligule, and blade. 

C. Spikelet. A, B drawn from Steele s.n. (US-279393); C modified 

from Hitchcock (1951).

FIGURE 162. Poa cuspidata. A. Habit. B. Sheath, ligule, and blade. C. 

Panicle. D. Spikelet. A−C drawn from Dewey 188 (US-491699) and 

Degnan 99 (US-1839996); D modified from Barkworth et al. (2007).
number 99 • 101

scaberulous, apex abruptly acute. Panicles (9–)13–30(–41) cm 

long, 5–15 cm wide, open, oblong or ovate, diffuse, equilateral 

or nodding. Spikelets 3–5 mm long, oblong or ovate, laterally 

compressed; callus sparsely to moderately densely webbed; lemmas 2–3 mm long, keels and lateral veins short-villous, awnless. 

156. Poa pratensis* L.

figure 164

Poa pratensis* L., Sp. Pl. 1: 67–68. 1753. 

Common names: Kentucky bluegrass, June grass, spear grass.

Caespitose perennials; rhizomes elongated. Culms 5–70

(–100) cm tall, erect or geniculately ascending; not branching 

above the base; internodes compressed, smooth; nodes terete or 

weakly compressed. Leaves mostly basal; sheaths closed 1/4–1/2 of 

their length, slightly compressed, glabrous or infrequently sparsely 

hairy; collars smooth, glabrous; ligules 0.9–2(–3.1) mm long, eciliate membranes, apex truncate to rounded; blades 5–30 cm long, 

0.4–4.5 mm wide, linear, flat or folded, surfaces smooth or scaberulous, glabrous or pubescent (rarely) to sparsely hairy, margins 

scaberulous, apex abruptly acute, hooded. Panicles 2–15(–20) cm 

long, 1–12 cm wide, open or contracted, oblong or pyramidal or 

ovate, dense or loose. Spikelets 3.5–6(–7) mm long, oblong or 

ovate, laterally compressed; callus webbed; lemmas 2.8–4.3 mm 

long, keels and marginal veins long-villous, awnless.

157. Poa sylvestris A. Gray

figure 165

Poa sylvestris A. Gray, Manual 596. 1848. 

Common names: forest bluegrass, sylvan bluegrass, woodland 

bluegrass.

Caespitose perennials. Culms 30–120 cm tall; internodes 

slightly compressed, smooth; basal innovations usually extravaginal. Leaves mostly basal; sheaths, closed 1/20–7/8 of their length, 

smooth, glabrous or pubescent; ligules 0.5–2.7 mm long, eciliate 

FIGURE 165. Poa sylvestris. A. Habit. B. Sheath, ligule, and blade. 

C. Spikelet. D. Floret. A, B drawn from Pollard 189 (US-260122); C 

modified from Barkworth et al. (2007); D modified from Hitchcock 

(1951).

FIGURE 164. Poa pratensis. A. Habit. B. Sheath, ligule, and blade. C. 

Spikelet. D. Floret. A, B drawn from Stone 62 (US-2145953) and Hitchcock 12666 (US-3151049); C, D modified from Hitchcock (1951).
102 • smithsonian contributions to botany

membranes, apex truncate to obtuse; blades 0.7–5 mm wide, flaccid, linear, flat, thin, surfaces and margins glabrous, apex acute. 

Panicles (6.7–)9–20 cm long, open, ovate. Spikelets 2.5–4.4 mm 

long, oblong, laterally compressed; callus webbed; lemmas 2.1–

3.1 mm long, keel, marginal, and lateral veins short-villous, usually sparsely soft puberulent between the veins, awnless.

158. Poa trivialis* L.

figure 166

Poa trivialis* L., Sp. Pl. 1: 67. 1753. 

Common names: meadow grass, rough bluegrass, rough-stemmed 

bluegrass.

Caespitose perennials, short-lived; stolons present. Culms 

25–120 cm tall, erect, weak or geniculately ascending or decumbent, sometimes trailing and rooting at nodes; internodes 

terete or slightly compressed, smooth. Leaves mostly basal; 

sheaths compressed, antrorsely scabrous, closed 1/3–1/2 of their 

length; collars glabrous or scabrous; ligules 3–10 mm long, eciliate membranes, apex acute to acuminate; blades 3–20 cm long, 

1.5–6 mm wide, linear, flat, surfaces smooth or scaberulous, 

glabrous, lax, margins scabrous, apex abruptly acute, hardened. 

Panicles 8–25 cm long, 1–15 cm wide, open or contracted, oblong or ovate, dense or loose or diffuse, equilateral or nodding. 

Spikelets 2.3–3.5 mm long, elliptic or oblong or ovate, laterally 

compressed; callus webbed with hairs more than 2/3 as long as 

lemma; lemmas 2–3.5 mm long, keels sparsely puberulent, marginal veins usually glabrous, awnless. 

159. Schizachyrium scoparium (Michx.) Nash

figure 167

Schizachyrium scoparium (Michx.) Nash, Fl. S.E. U.S. 59. 1903.

Common names: little bluestem, little false bluestem.

Loosely or densely caespitose perennials; rhizomes absent 

or short. Culms 50–210 cm tall; lateral branches ample. Leaves 

FIGURE 167. Schizachyrium scoparium. A. Habit. B. Sheath, ligule, 

and blade. C. Inflorescence. D. Spikelet pair. A−C drawn from Chase 

2748 (US-740522); D modified from Barkworth et al. (2003).

FIGURE 166. Poa trivialis. A. Base of culm. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelet. E. Floret. A−C drawn from Morton 

1658 (US-1870605) and Kearney s.n. (US-36144081); D modified 

from Barkworth et al. (2007).
number 99 • 103

mostly basal; sheaths keeled or rounded, glabrous to villous, 

sometimes glaucous; ligules 0.5–2 mm long, eciliate membranes, 

apex erose; blades 7–105 cm long, 1.5–9 mm wide, linear, flat, 

green or glaucous, surfaces glabrous to hirsute, margins scabrous, 

apex acute. Rames solitary, occasionally 2 on each peduncle; each 

rame 2.5–8 cm long, partially to completely exserted, subtended 

by a spatheole 4–6 cm long. Fertile sessile spikelets 3–11 mm 

long, lanceolate, dorsally compressed; pedicelled spikelets 0.7–10 

mm long, sterile or staminate; principal lemma awns 6–11(–17) 

mm long, from a sinus, geniculate, with twisted column.

160. Secale cereale* L.

figure 168

Secale cereale* L., Sp. Pl. 1: 84. 1753. 

Common name: rye.

Caespitose annuals or biennial. Culms (35–)50–120(–300) 

cm tall, 6–7-noded. Leaves basal and cauline; sheaths glabrous or 

hirsute, auricles falcate; ligules 1 mm long, eciliate membranes, 

apex truncate; blades 10–20 cm long, (3–)4–12 mm wide, linear, 

flat, surfaces glabrous or sparsely pilose, margins glabrous, apex 

acute. Spikes (2–)4.5–12(–19) cm long, single, bilateral. Spikelets 

12–15 mm long, cuneate, laterally compressed, packed broadside to the rachis; lemmas 12–18 mm long, pectinate-ciliate on 

the keels, awns 20–50 mm long. 

161. Setaria faberi* R. A. W. Herrm.

figure 169

Setaria faberi* R. A. W. Herrm., Beitr. Biol. Pflanzen 10(1): 51. 

1910. 

Common names: Japanese bristle grass, giant foxtail grass, nodding foxtail grass.

Solitary annuals. Culms 50–200 cm tall, geniculately ascending, rooting from lower nodes; lateral branches ample. Leaves 

cauline; sheaths glabrous, outer margins hairy; ligules 1–2 mm 

long, fringe of hairs; blades 15–30 cm long, 10–20 mm wide, 

linear, flat, surfaces strigose above, puberulent below, margins 

FIGURE 169. Setaria faberi. A. Habit. B. Sheath, ligule, and blade. 

C. Panicle. D. Spikelet. A−C drawn from Beyersdorfer 220 (US3047080); D modified from Barkworth et al. (2003).

FIGURE 168. Secale cereale. A. Base of culm. B. Sheath, ligule, and 

blade. C. Spike. D. Spikelet. A−C drawn from Kearney s.n. (US1018252); D modified from Hitchcock (1951).
104 • smithsonian contributions to botany

scabrous, apex attenuate. Panicles 6–20 cm long, 1–2.5 cm wide, 

spiciform, linear, nodding. Spikelets 2.5–3 mm long, subsessile, 

ovate, dorsally compressed, each spikelet subtended by (1–)3(–6) 

bristles; bristles about 10 mm long; lemmas awnless. 

162. Setaria italica* (L.) P. Beauv.

figure 170

Setaria italica* (L.) P. Beauv., Ess. Agrostogr. 51, 170, 178. 1812.

Common names: foxtail millet, Italian bristle grass.

Caespitose annuals. Culms 10–100 cm tall, erect or geniculately ascending, robust. Leaves basal and cauline; sheaths mostly 

glabrous, outer margins hairy; ligules 1–2 mm long, fringe of 

hairs; blades to 20 cm long, 1–3 cm wide, flaccid, linear, flat, 

surfaces scaberulous, rough adaxially, margins cartilaginous, 

scaberulous, apex attenuate. Panicles 8–30 cm long, 0.8–2.4 cm 

wide, spiciform, linear or oblong, continuous or interrupted, 

equilateral or nodding. Spikelets 2–3 mm long, subsessile, elliptic, dorsally compressed, each spikelet subtended by 1–3 bristles; 

bristles to 13 mm long; lemmas awnless.

163. Setaria parviflora (Poir.) Kerguelen

figure 171

Setaria parviflora (Poir.) Kerguelen, Lejeunia, n.s. 120: 161. 1987. 

Common names: knotroot bristle grass, knotroot foxtail grass, 

perennial foxtail grass.

Caespitose perennials; rhizomes absent or short, knotty. 

Culms 30–120 cm tall, erect or geniculately ascending; internodes thin walled; nodes glabrous. Leaves basal and cauline; 

sheaths glabrous, outer margin glabrous, oral hairs ciliate; ligules to 1 mm long, fringe of hairs; blades to 25 cm long, 2–8 

mm wide, linear, flat, surface scabrous, rough adaxially, margins scabrous to scaberulous, apex acuminate. Panicles 3–8 cm 

FIGURE 171. Setaria parviflora. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Leonard 607 (US-2612432); C 

modified from Barkworth et al. (2003).

FIGURE 170. Setaria italica. A. Habit. B. Sheath, ligule, and blade. 

C. Panicle. D. Spikelet. A−C drawn from Fosberg 36170 (US2669792); D modified from Barkworth et al. (2003).
number 99 • 105

long, 0.8–1.4 cm wide, spiciform, linear. Spikelets 2–2.8 mm 

long, pedicelled, lanceolate, dorsally compressed, each spikelet 

subtended by 4–12 bristles; bristles 2–12 mm long, antrorsely 

scabrous; lemmas awnless. 

164. Setaria pumila* (Poir.) Roem. & Schult.

figure 172

Setaria pumila* (Poir.) Roem. & Schult., Syst. Veg. 2: 891. 1817. 

Common name: yellow foxtail grass.

Caespitose annuals. Culms 5–130 cm tall, geniculately ascending; nodes glabrous. Leaves basal and cauline; sheaths glabrous; ligules 1.5 mm long, ciliolate membranes or a fringe of 

hairs; blades 3–30 cm long, 4–10 mm wide, loosely twisted, linear, flat, upper surfaces sparsely hairy, margins scabrous, apex 

acute. Panicles 3–15 cm long, 9–19 mm wide, spiciform, linear. 

Spikelets 2–3.4 mm long, pedicelled, ovate, dorsally gibbous, 

dorsally compressed, each spikelet subtended by 4–12 bristles; 

bristles 3–8 mm long, antrorsely scabrous; lemmas awnless.

165. Setaria verticillata* (L.) P. Beauv.

figure 173

Setaria verticillata* (L.) P. Beauv., Ess. Agrostogr. 51, 171, 178. 

1812. 

Common names: bur bristle grass, bur foxtail grass, rough bristle grass, rough foxtail grass.

Caespitose annuals. Culms 30–100 cm tall, decumbent; 

nodes glabrous. Leaves mostly basal; sheath surface glabrous, 

outer margins glabrous or hairy; ligules to 1mm long, densely 

ciliate membranes; blades 5–30 cm long, 5–15 mm wide, flaccid, 

linear, flat, abaxial surfaces scabrous, margins scabrous, apex 

acute. Panicles 5–15 cm long, 0.5–1.5 cm wide, spiciform, linear, 

continuous or interrupted. Spikelets 2–2.3 mm long, pedicelled, 

FIGURE 173. Setaria verticillata. A. Lower culm with adventitious 

roots. B. Habit. C. Sheath, ligule, and blade. D. Spikelet. Drawn 

from Ward s.n. (US-825057).

FIGURE 172. Setaria pumila. A. Habit. B. Sheath, ligule, and blade. 

C. Spikelet. A, B drawn from Kanal 753 (US-3268326); C modified 

from Barkworth et al. (2003).
106 • smithsonian contributions to botany

elliptic, dorsally compressed, each spikelet subtended by a solitary bristle; bristles 4–7 mm long, retrorsely scabrous; lemmas 

awnless.

166. Setaria viridis* (L.) P. Beauv.

figure 174

Setaria viridis* (L.) P. Beauv., Ess. Agrostogr. 51, 171, 178. 1812. 

Common names: green bristle grass, green foxtail grass.

Caespitose annuals. Culms 20–250 cm tall, erect or geniculately ascending; nodes glabrous. Leaves basal and cauline; 

sheaths glabrous, sometimes scaberulous, outer margins hairy; 

ligules 1–2 mm long, fringe of hairs; blades to 20 cm long, 4–25 

mm wide, linear, flat, scaberulous or glabrous, margins scabrous, 

apex acute. Panicles 3–20 cm long, 0.4–1 cm wide, spiciform, 

linear. Spikelets 1.8–2.2 mm long, pedicelled, elliptic, dorsally 

compressed, obtuse, each spikelet subtended by 1–3 bristles; 

bristles 5–10 mm long, antrorsely scabrous; lemmas awnless.

167. Sorghastrum nutans (L.) Nash

figure 175

Sorghastrum nutans (L.) Nash, Fl. S.E. U.S. 66, 1326. 1903. 

Common names: Indian grass, yellow Indian grass.

Stout caespitose perennials; rhizomes short, stout, scaly. 

Culms 50–240 cm tall, 1.5–4.5 mm thick, erect; internodes glabrous. Leaves mostly basal; sheaths glabrous to pilose, auricles 

erect; ligules 2–6 mm long, eciliate membranes, apex lacerate; 

blades 10–70 cm long, 1–4 mm wide, linear, flat, glaucous, glabrous or pubescent, margins scabrous, apex attenuate. Panicles 

20–75 cm long, open, oblong, loosely contracted; branches 

tipped by a few spikelets. Fertile spikelets 5–8.7 mm long, lanceolate, sessile, dorsally compressed; pedicelled spikelets absent; 

principal lemma awns 10–22 mm long overall, from a sinus; geniculate, twisted below. 

FIGURE 175. Sorghastrum nutans. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelet. A−C drawn from Smith 4925 (US2181313); D modified from Hitchcock (1951).

FIGURE 174. Setaria viridis. A. Habit. B. Sheath, ligule, and blade. 

C. Panicle. D. Spikelet. Drawn from Kanal 764 (US-3268329).
number 99 • 107

168. Sorghum bicolor* (L.) Moench

figure 176

Sorghum bicolor* (L.) Moench, Methodus 207. 1794. 

Common names: milo, broom-corn, kafir corn, sorghum, Sudan 

grass.

Solitary annuals or short-lived perennials. Culms 50–500 

cm tall, 1–5 cm thick, sometimes branching at the base, erect, 

robust; nodes glabrous or appressed pubescent; internodes glabrous. Leaves cauline; sheaths glabrous; ligules 1–4 mm long, 

ciliate membranes; blades 5–100 cm long, 0.5–10 cm wide, linear, flat, glabrous, margins scabrous, apex acute. Panicles 5–60 

cm long, 3–30 cm wide, open or contracted, lanceolate or ovate 

or globose, equilateral or nodding; branches (rames) tipped by 

2–7 spikelet pairs. Fertile spikelets 3–10 mm long, sessile, oblong 

or ovate or obovate or orbicular, dorsally compressed; pedicelled 

spikelets staminate or sterile; lemmas unawned or with awns 

5–30 mm long from a sinus, geniculate, twisted below.

169. Sorghum halepense* (L.) Pers.

figure 177

Sorghum halepense* (L.) Pers., Syn. Pl. 1: 101. 1805. 

Common name: Johnson grass.

Solitary perennials; rhizomes elongated, scaly. Culms 50–

200 cm tall, 0.4–2 cm thick, erect or geniculately ascending or 

decumbent; nodes appressed pubescent; internodes glabrous. 

Leaves cauline; sheaths glabrous, ribbed; ligules 2–6 mm long, 

ciliolate membranes; blades 10–90 cm long, 8–40 mm wide, surfaces smooth, lanceolate, linear, flat, margins scaberulous, apex 

acute. Panicles 10–55 cm long, 3–25 cm wide open, lanceolate 

or pyramidal; branches (rames) tipped by 1–5 spikelet pairs. 

Fertile spikelets 4.5–5(–5.5) mm long, sessile, elliptic, dorsally 

compressed; pedicelled spikelets staminate; lemmas unawned 

or with awns 10–16 mm long from a sinus, geniculate, twisted 

below.

FIGURE 177. Sorghum halepense. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelet pair. A−C drawn from Fleming 616

(US-3117621); D modified from Barkworth et al. (2003).

FIGURE 176. Sorghum bicolor. A. Panicle. B. Sheath, ligule, and 

blade. C. Spikelet pair. A, B drawn from Dewey 161 (US-431586); 

C modified from Barkworth et al. (2003).
108 • smithsonian contributions to botany

170. Spartina cynosuroides (L.) Roth

figure 178

Spartina cynosuroides (L.) Roth, Catal. Bot. 3: 10. 1806. 

Common names: big cordgrass, salt reed grass.

Solitary perennials; rhizomes elongated, scales closely imbricate. Culms 100–350 cm tall, 1–2 cm thick, erect. Leaves cauline; sheaths smooth or straight, mostly glabrous, lower sheaths 

often wrinkled; oral hairs lacking or ciliate; ligules 1–3 mm long, 

fringe of hairs; blades 60–45 cm long, 6–20 mm wide, sometimes involute, linear, flat, glabrous, margins strongly scabrous, 

apex acuminate. Panicles 15–40 cm long with 5–67 unilateral 

branches borne along a central axis; branches 6–15 cm long each 

with 10–70 fertile spikelets; central axis 15–40 cm long. Spikelets 

9–14 mm long, 1-flowered, oblong, laterally compressed, packed 

broadside to the rachis, pectinate and 2-rowed; lower glumes 

1/2–2/3 as long as lemma; upper glumes unawned or with awns 

up to 2 mm long; lemmas awnless.

171. Spartina pectinata Link

figure 179

Spartina pectinata Link, Jahrb. Gewächsk. 1(3): 92–93. 1820. 

Common names: cordgrass, freshwater cordgrass, prairie cordgrass.

Solitary perennials; rhizomes elongated, scaly. Culms 100–

250 cm tall, 2.5–11 mm thick, erect. Leaves cauline; sheath mostly 

glabrous, oral hairs lacking or ciliate; ligules 1–3 mm long, fringe 

of hairs; blades 20–96 cm long, 5–15 mm wide, linear, flat to involute, glabrous, margins strongly scabrous, apex acuminate. Panicles 10–50 cm long with 5–25 unilateral branches borne along a 

central axis; branches 1.5–15 cm long, each with 10–80 fertile 

spikelets; central inflorescence axis 10–50 cm long; spikelet packing broadside to rachis, regular, 2-rowed. Spikelets 10–25 mm 

long, 1-flowered, pectinate, oblong, laterally compressed, packed 

broadside to the rachis, 2-rowed; lower glumes 3/4 to as long as 

lemmas; upper glumes with awns 4–8 mm long; lemmas awnless.

FIGURE 179. Spartina pectinata. A. Base of culm. B. Sheath, ligule, 

and blade. C. Panicle. D. Spikelet. A−C drawn from Steele s.n. (US349803); D modified from Hitchcock (1951).

FIGURE 178. Spartina cynosuroides. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Spikelet. A−C drawn from Fosberg 34809 (US2681776, US-2681777); D modified from Barkworth et al. (2003).
number 99 • 109

172. Sphenopholis intermedia (Rydb.) Rydb.

figure 180

Sphenopholis intermedia (Rydb.) Rydb., Bull. Torrey Bot. Club 

36: 533. 1909. 

Common names: slender wedge grass, slender wedgescale.

Caespitose perennials. Culms 30–120 cm tall, erect. Leaves 

basal and cauline; sheaths glabrous or scaberulous, sometimes 

pubescent; ligules 1.5–2.5 mm long, erose-ciliate membranes; 

blades 8–15 cm long, (1–)2–6 mm wide, linear, flat to slightly involute, glabrous to sparsely pilose, margins scabrous, apex acute. 

Panicles (2–)7–20 cm long, (0.5–)1–3 cm wide, open, lanceolate 

or ovate, dense or loose, nodding. Spikelets 2.1–4 mm long, obovate, laterally compressed; lemmas 2.1–3 mm long, awnless. 

173. Sphenopholis nitida (Biehler) Scribn.

figure 181

Sphenopholis nitida (Biehler) Scribn., Rhodora 8(92): 144. 1906. 

Common names: shiny wedge grass, shiny wedgescale.

Caespitose perennials. Culms 30–80 cm tall. Leaves cauline; 

sheaths pubescent at the upper sheaths, otherwise glabrous; ligules 1–2 mm long, eciliate membranes, lacerate; blades 2–15 cm 

long, (1–)2–5(–7) mm wide, linear, flat to slightly involute, glabrous or pubescent, margins scabrous, apex acute. Panicles 7–20 

cm long, 1–5 cm wide, open, oblong, diffuse. Spikelets 2.5–5 mm 

long, obovate, laterally compressed; lemmas 2.1–3.8 mm long, 

usually unawned, rarely mucronate.

FIGURE 181. Sphenopholis nitida. A. Habit. B. Sheath, ligule, and 

blade. C. Panicle. D. Glumes. E. Florets. A−C drawn from Allard 

8579 (US-1874749) and Norton 1695 (US-1870617); D, E modified 

from Hitchcock (1951).

FIGURE 180. Sphenopholis intermedia. A. Habit. B. Sheath, ligule, 

and blade. C. Panicle. D. Spikelet. A−C drawn from Donald 133

(US-3557152) and Swallen 9648 (US-2181188); D modified from 

Barkworth et al. (2007).
110 • smithsonian contributions to botany

174. Sphenopholis obtusata (Michx.) Scribn.

figure 182

Sphenopholis obtusata (Michx.) Scribn., Rhodora 8(92): 144. 

1906. 

Common names: prairie wedge grass, prairie wedgescale.

Caespitose annuals or perennials; butt sheaths sparsely 

hairy. Culms (9–)20–130 cm tall. Leaves cauline; sheaths glabrous or hairy, sometimes scaberulous; ligules (1–)1.5–2.5 mm 

long, erose-ciliate membranes, apex more or less lacerate; basal 

blades 5–14 cm long, (1–)2–8 mm wide, linear, usually flat, 

rarely slightly involute, surfaces scabrous or pubescent, margins 

pubescent, apex acute. Panicles (2–)5–15(–25) cm long, 0.5–2 

cm wide, open or contracted, lanceolate. Spikelets 2.2–3.6 mm 

long, obovate, laterally compressed; lemmas 1.9–2.8 mm long, 

awnless.

175. Sporobolus compositus (Poir.) Merr.

figure 183

Sporobolus compositus (Poir.) Merr., Circ. Div. Agrostol. 

U.S.D.A. 35: 6. 1901.

Common names: headlike dropseed, tall dropseed, rough dropseed.

Solitary or caespitose perennials; rhizomes absent or elongated, scaly. Culms (20–)30–130(–150) cm tall, erect. Leaves 

basal and cauline; sheaths glabrous with hairy apices; ligules 

0.1–0.5 mm long, fringe of hairs; blades 5–70 cm long, 0.5–10 

mm wide, not conspicuously distichous, linear, flat, conduplicate 

or involute, glabrous or pilose, margins glabrous, apex acute. 

Panicles 5–30 cm long, 0.4–1.6 cm wide, spiciform, linear, dense 

or loose, terminal and axillary, partially included in the uppermost sheath. Spikelets 4–6(–10) mm long, lanceolate, subterete, 

FIGURE 183. Sporobolus compositus. A. Habit. B. Sheath, ligule, 

and blade. C. Spikelet. A, B drawn from Dewey 402 (US-431575); 

C modified from Barkworth et al. (2003).

FIGURE 182. Sphenopholis obtusata. A. Habit. B. Sheath, ligule, 

and blade. C. Spikelet. A, B drawn from Hotchkiss 7291 (US2043989); C modified from Barkworth et al. (2007).
number 99 • 111

1-flowered; lemmas glabrous and smooth, awnless; caryopsis 

outer wall gelatinous when wet.

176. Sporobolus neglectus Nash

figure 184

Sporobolus neglectus Nash, Bull. Torrey Bot. Club 22(11): 464. 

1895. 

Common name: small dropseed.

Caespitose annuals. Culms 10–45 cm tall, erect or geniculately ascending, delicate, slender, wiry. Leaves mostly basal; 

sheaths inflated, glabrous; ligules 0.1–0.3 mm long, fringe of 

hairs; blades 1–12 cm long, 0.6–2 mm wide, linear, flat, involute 

at the tip, glabrous abaxially, scaberulous adaxially, margins glabrous or scaberulous, apex attenuate. Panicles 2–5 cm long, 0.2–

0.5 cm wide, contracted, linear, terminal and axillary, included 

in the uppermost sheaths. Spikelets 1.6–3 mm long, lanceolate, 

subterete, 1-flowered; lemmas glabrous, awnless. 

177. Sporobolus vaginiflorus (Torr. ex A. Gray) 

Alph. Wood

figure 185

Sporobolus vaginiflorus (Torr. ex A. Gray) Alph. Wood, Classbook Bot. (ed. 1861) 775. 1861. 

Common names: poverty dropseed, poverty grass.

Caespitose annuals, delicate. Culms 15–60(–70) cm tall, 

erect, wiry, scabrous. Leaves basal and cauline; sheaths often inflated, sometimes sparsely hairy at summit; ligules to 3 mm long, 

fringe of hairs; blades 2–12(–25) cm long, 1–2 mm wide, linear, 

flat or involute at the tips, glabrous or pilose, margins scaberulous or glabrous, apex acute. Panicles 1–5 cm long, 0.2–0.5 cm 

FIGURE 185. Sporobolus vaginiflorus. A. Habit. B. Sheath, ligule, 

and blade. C. Panicle. D. Spikelet. A−C drawn from Kanal 077 (US3075178) and Leonard 5711 (US-2160824); D modified from Barkworth et al. (2003).

FIGURE 184. Sporobolus neglectus. A. Habit. B. Sheath, ligule, and 

blade. C. Spikelet. A, B drawn from Steele s.n. (US-431580); C modified from Barkworth et al. (2003).
112 • smithsonian contributions to botany

wide, contracted, linear, terminal and axillary, enclosed in the 

uppermost sheath. Spikelets 2.3–6 mm long, lanceolate, laterally 

compressed; lemmas strigose, awnless.

178. Tridens flavus (L.) Hitchc. var. flavus

figure 186

Tridens flavus (L.) Hitchc. var. flavus, Rhodora 8(95): 210. 

1906.

Common names: purpletop, tall redtop.

Caespitose perennials; rhizomes short, knotty. Culms 60–

180 cm tall, erect. Leaves basal and cauline; sheaths keeled, glabrous below, pubescent near summit; collars pubescent; ligules 

to 0.5 mm long, fringe of hairs; blades 10–50 cm long, 3–10 mm 

wide, linear, flat, glabrous or sparsely hispid, margins scabrous, 

apex attenuate and involute. Panicles 15–40 cm long, 3–30 cm 

wide, open, ovate; branches divergent to drooping. Spikelets 

5–10 mm long, oblong, laterally compressed; lemmas awnless.

179. Tripidium ravennae* (L.) H. Scholz

figure 187

Tripidium ravennae* (L.) H. Scholz, Willdenowia 36(2): 664. 

2006. [Syn. Saccharum ravennae (L.) L.] 

Common names: plume grass, Ravenna grass.

Caespitose perennials; butt sheaths glabrous. Culms 100–

450 cm tall, erect; internodes solid. Leaves cauline; sheaths 

glabrous; ligules 0.6–1.1 mm long, ciliate membranes; blades 50–

100 cm long, 4–14 mm wide, linear, flat, surfaces glabrous, margins scabrous, bases tapering to the midrib, apex acute. Panicles 

25–70 cm long, open, elliptic, primary branches (rames) 6–20 

cm long. Spikelets 3–6(–6.5) mm long, in pairs; fertile spikelets 

elliptic, dorsally compressed, acuminate; principal lemma awns 

FIGURE 187. Tripidium ravennae. A. Base of culm. B. Sheath, 

ligule, and blade. C. Panicle. D. Spikelet. A−C drawn from Steury 

001016.1 (US-3376334); D modified from Barkworth et al. (2003).

FIGURE 186. Tridens flavus var. flavus. A. Habit. B. Sheath, ligule, 

and blade. C. Panicle. D. Spikelet. A−C drawn from Fosberg 55972

(US-2773636) and Allard 22297 (US-2919277); D modified from 

Hitchcock (1951).
number 99 • 113

2.5–5 mm long, apical, straight or curved at the base, clearly 

exserted from spikelet; anthers 3. 

180. Tripsacum dactyloides (L.) L.

figure 188

Tripsacum dactyloides (L.) L., Syst. Nat. (ed. 10) 1261. 1759. 

Common name: eastern gama grass.

Caespitose perennials; plants monoecious; rhizomes short, 

knotty; butt sheaths, sparsely hairy or pilose. Culms 150–400 

cm tall, erect or geniculately ascending, robust or of moderate 

stature, with prop roots; internodes solid. Leaves basal and cauline; sheaths glabrous, occasionally pilose; ligules 1 mm long, 

ciliolate membranes; blades 30–75(–120) cm long, 18–60 mm 

wide, scaberulous, rough adaxially, glabrous, margins scabrous, 

apex attenuate. Panicles with 1–6 branches, subdigitate to racemosely arranged, terminal and axillary; rames 12–25 cm long. 

Pistillate spikelets 6–8 mm long, 3–5.5 mm wide, sessile, sunken, 

and embedded in the indurate rame, dorsally compressed; lemmas awnless.

181. Triticum aestivum* L.

figure 189

Triticum aestivum* L., Sp. Pl. 1: 85. 1753. 

Common name: wheat.

Caespitose annuals. Culms 14–150 cm tall; internodes thin 

walled. Leaves cauline; sheaths glabrous or pubescent, oral hairs 

ciliate, auricles falcate; ligules 1 mm long, eciliate membranes 

apex erose; blades 10–60 cm long, 0–15(–20) mm wide, linear, 

flat, pubescent, margins scabrous, apex acute. Spikes (3.5–)6–18 

cm long, linear or oblong, bilateral. Spikelets 10–15 mm long, ascending, 1 per node, solitary, ovate, laterally compressed, packed 

broadside to rachis; principal lemma awns 4–150 mm long. 

FIGURE 189. Triticum aestivum. A. Habit. B. Sheath, ligule, and 

blade. C. Spike. D. Spikelet. A, B drawn from Smith s.n. (US1963579); C, D modified from Hitchcock (1951).

FIGURE 188. Tripsacum dactyloides. A. Base of culm. B. Sheath, 

ligule, and blade. C. Panicle with three branches. D. Pistillate spikelet. E. Staminate spikelets. A−C drawn from Van Eseltine 424 (US642955); D, E modified from Barkworth et al. (2003).
114 • smithsonian contributions to botany

182. Zizania aquatica L.

figure 190

Zizania aquatica L., Sp. Pl. 2: 991. 1753. 

Common names: Indian wild rice, wild rice.

Solitary annuals or short-lived perennials; plants monoecious. Culms 90–300 cm tall, erect or decumbent at base, reedlike, spongy. Leaves basal and cauline; sheaths glabrous or 

pubescent; ligules 0.3–20 mm long, eciliate membranes, apex 

truncate to acute, entire or usually somewhat lacerate; blades 

to 1.5 m long, (3–)10–55(–75) mm wide, linear, flat, scaberulous, glabrous, margins scabrous, apex acute. Panicles 20–120 

cm long, (5–)10–50 cm wide, open, ovate; branches unisexual. 

Pistillate spikelets 5–24 mm long, 1–2.5 mm wide, lanceolate, 

laterally compressed; staminate spikelets 5–12.5 mm long; principal lemma awns 10–20 mm long. 

FIGURE 190. Zizania aquatica. A. Base of culm. B. Sheath, ligule, 

and blade. C. Panicle. D. Pistillate spikelet. A, B, D drawn from 

Kanal 663 (US-3205460); C modified from Barkworth et al. (2007).
Glossary of Terms

adaxial. The side of an organ toward the axis, e.g., upper surface of a leaf. Opposite: 

abaxial.

adventitious root. A root that arises from any plant part other than the primary root. 

ample. Large, copious; usually referring to a panicle.

amplexicaul. Used to describe a leaf blade where the base clasps the stem.

annual. A plant that completes its life cycle from seed to maturity in one year.

apex. The tip or end point of a structure. Opposite: base.

apical. Located at the apex.

apiculate. Ending abruptly in a short, sharp point.

appressed. Keeping close to or lying flat against another organ. Compare: adnate.

aquatic. Living in water.

aristate. With a bristle at the end; stiff awned or stiff bristled.

aristulate. Bearing or terminating in a small awn or sharp bristle.

aromatic. Fragrant due to essential oils in the plant tissues.

articulate. Jointed; provided with joints or nodes where separation may naturally take 

place.

ascending. Rising upward and approaching erect; often used to describe branches that 

form an angle from the culm of less than 90°.

asymmetrical. With both sides of an organ not equal.

attenuate. Gradually tapering to a slender base or tip, long pointed.

auricle. A small earlike appendage of the collar.

auriculate. Having an auricle; with earlike structures.

awn. A slender bristle-like appendage ending in an organ, borne on the glume or lemma 

of grasses.

axil. The upper angle between a stem and its branch (or leaf).

axillary. Used in reference to structures attached in the axil.

axis. The main stem or culm, especially of an inflorescence.

barbed. With rigid points or short bristles pointing backward.

basal. At or toward the base. Opposite: apical.

bearded. With long or stiff hairs.

biennial. Taking two years of growth from seedling to maturity, usually producing only 

vegetative growth in the first season and flowering in the second.

bifid. Two clefts or two lobes at the tip; deeply divided into two parts.

bilateral. Two-sided, usually referring to the placement of spikelets along two sides of 

a branch.
116 • smithsonian contributions to botany

blade. The final segment of grass leaf, above the sheath where 

the leaf clasps the stem.

bloom. Whitish waxy or powdery coating on a surface; see 

glaucous.

bract. A small modified leaf subtending pedicels or flowers; in 

grasses this includes the glumes, lemma, and palea.

branch. Lateral growth from the axis.

bristle. A fine, stiff, hairlike structure; these are found subtending the spikelets of Setaria.

bulbous. A swollen, thickened structure often made of fleshy 

scales, usually at the base of a culm resembling a bulb.

bur. A spiny cluster of spikelets or fascicle that falls as a single 

unit.

butt sheath. The thick basal remnant parts of leaves.

caducous. Falling off soon after formation, not persistent.

caespitose. Growing in low, tight groups or clumped; forming 

a tussock or tufted.

callus. A hard or firm structure; in grasses, the thick, hardened 

portion just below the lemma on the rachilla.

capitate. Forming headlike clusters, aggregated into a very 

dense or compact cluster.

cartilaginous. Hard and tough, gristly, but elastic, like a cartilage.

caryopsis. A one-seeded, dry, indehiscent fruit with the seed 

coat adherent to the fruit wall; the grain of most grasses.

cataphyll. A scale leaf, usually on a rhizome at the base of the 

plant.

caudices. Short, thickened, verticillate or branched stems, usually subterranean or at ground level; in grasses, found at the 

base of the culm.

cauline. Borne on or arising along the stem, compared to basal, 

where leaves are mainly near the base.

chartaceous. Of papery or tissue-like texture.

ciliate. Fringed with spreading stiff hairs on the margin.

ciliolate. Fringed with very small hairs, minutely ciliate.

clasping. Leaf base surrounding and touching the stem closely 

on two sides; see amplexicaul.

clavate. Club shaped, the wider portion at the apex.

clumped. Growing in a tight group, or caespitose.

collar. A band of tissue situated at the junction of the blade and 

sheath, often lighter in color than the rest of the leaf.

column. The lower twisted part of a geniculate awn, or the 

portion below the awn branching point in Aristida.

compound. Referring to inflorescences made up of a number 

small constituent inflorescences (as in some Andropogonodae) or raceme or spike with some secondary branching.

compressed. Flattened, either laterally or dorsally.

concave. Hollowed out, curving inward. Opposite: convex.

conduplicate. Folded lengthwise down the middle, used when 

referring to a leaf blade.

confluent. Structure merging in one, or fusing.

connate. Union or fusion of like parts or organs.

constricted. Abruptly narrowed, tightened or drawn together.

contracted. A narrow, dense inflorescence, usually with appressed branches.

convex. Having a more or less rounded surface.

convolute. Rolled longitudinally; leaf blades having one edge 

rolled inside the other.

cordate. Shaped like a heart at the base of the leaf blades, these 

often deeply notched, with rounded lobes.

coriaceous. Leathery in texture.

corymbose. A flat-topped, open inflorescence where the lower 

branches are longer than the upper branches, used to describe the panicles of Miscanthus.

cosmopolitan. Found throughout the world.

crateriform. Saucer or cup shaped, used to describe gland 

shape in Eragrostis. 

crested. With an elevated and irregular-toothed ridge.

crown. The persistent basal portion of a tufted, herbaceous, perennial grass; the region from which the culm and roots grow.

crustaceous. Of hard, thin, and brittle texture.

culm. The grass stem that will eventually bare the spikelets; 

also applies to sedges and rushes.

cuneate. Wedge shaped; with the acute angle at the attachment 

point.

cupule. An involucre composed of bracts usually adherent at 

the base.

cuspidate. Abruptly tipped with a sharp, rigid point, usually in 

reference to the apex of a leaf blade.

decumbent. Stems or culms having the basal part flat along the 

ground, then curving upward; reclining.

decurrent. A structure adnate to the stem with its margins extending down the stem or axis below the point of insertion, 

usually used to describe the sheath.

deflexed. Bent or turned abruptly outward or downward, but 

not to 180° (see reflexed).

dentate. With a sharp-toothed margin, with teeth perpendicular to the margin. Compare: serrate.

depressed. More or less flattened from above.

dichotomous. With forked, paired branches or divisions of approximately equal size.

digitate. Arranged like the fingers of a hand; with the members 

arising from the same point, same as palmate.

disarticulate. The separation of a structure usually at a node 

or joint.

distant. Farther from the point of attachment. Opposite: 

proximal.

distichous. Two-ranked on the opposite sides of a stem or culm.

divaricate. Spreading wide apart and in different directions.

divergent. Spreading broadly, but less so than divaricate.

dorsal. The back; the face turned away from the culm axis (the 

term abaxial is preferable). Opposite: ventral.

eglandular. Without glands.

ellipsoid. An elliptical three-dimensional shape, more or less 

with identical ends.

elliptic. Shaped like an ellipse; the broadest point midway between the ends and the width about one-half the length.

emarginate. Having a shallow notch at the apex, usually in reference to a leaf blade.

entire. With an even margin without teeth.
number 99 • 117

ephemeral. A short-lived structure or organism.

erect. A plant that is quite upright, growing perpendicular to 

the ground.

erose. Having an irregular-toothed margin.

excurrent. Extending beyond the margin or tip.

exserted. Protruding; sticking out; projecting beyond the edge. 

Opposite: included.

extravaginal branching. Growth of the shoot initial when the 

tip emerges or breaks through or ruptures the enveloping 

sheath; this is usually distinguished by the occurrence of bladeless leaves found directly above the indistinct prophyllum. Opposite: intravaginal.

falcate. Sickle shaped; curved on distal end.

false spike. A very narrow panicle with spikelets borne in tight 

clusters on much reduced side branches as in some species 

of Setaria and Pennisetum.

fascicle. A fairly tight cluster.

fascicles. Spikelike panicles of highly reduced branches forming a “bur” in Cenchrus and cluster of bristles in Setaria.

fasciculate. Leaves or branches in a cluster or tight bundle.

feathery. Resembling a feather.

fibrous. Furnished with fibers, often found in basal leaf sheaths.

filiform. Threadlike, long, slender, and cylindrical.

fimbriate. Fringed with long slender hairs coarser than ciliate.

flabellate. Fanlike, applied to flattened basal leaf sheaths.

flaccid. Soft or weak, limp, wilted. Opposite: firm or stiff.

flexuous. A zigzag or wavy form; bent alternately one way then 

the other.

floret. A portion of a spikelet (grass inflorescence) that includes 

the lemma, palea, and reproductive structures.

foliaceous. Leaflike.

fulvous. Tawny, orange-like, or dull yellowish brown to nearly 

chestnut.

geniculate. Abruptly bent like a knee joint.

gibbous. Slightly pouched or swollen on one side.

glabrous. Without hairs or glands, but not necessarily smooth. 

Opposite: hairy.

gland. A secreting structure on the surface, but often used in 

the sense of a gland-like body, any protuberance of like nature which may not secrete.

glandular. Covered with glands.

glaucous. Covered with a grayish, whitish, or bluish waxy 

coating that readily rubs off.

globose. Spherical, nearly or quite globular.

globular. Spherical.

glomerate. In a compact cluster or group of clusters.

glossy. Refers to a surface that is lustrous or shinny.

glume. The bract, usually occurring in pairs, at the base of a 

grass spikelet.

granular. Covered in little knobs or tubercles, less pronounced 

than tuberculate.

habit. The general appearance of a plant.

habitat. The surroundings in which a plant grows.

hair. A cylindrical cell or a row of cells, often very fine and 

transparent. Synonym: trichome.

head. An inflorescence of closely packed spikelets that is more 

or less round.

herb. A nonwoody plant whose stem dies back to the ground 

level at the end of the growing season.

herbaceous. Not woody, but soft and green.

heterophyllous. Having leaf blades of different sizes and 

shapes; see Dichanthelium.

hirsute. With straight, long, coarse, and stiff hairs.

hirtellous. Minutely hirsute.

hispid. Beset with stiff hairs, often strong enough to penetrate 

the skin.

hooded. Shaped like a hood or boat shaped, used to describe 

the leaf blade apex in most species of Poa.

hook. A curved or bent part at the apex of a leaf blade.

hyaline. Colorless, thin and translucent or transparent.

imbricate. Partly overlapping, like the tiles of a roof.

incurved. Curving inward or bent inward.

indument. Any hairy covering or pubescence.

indumentum. A cover of hairs, scales, or bristles.

indurated. Hardened at maturity.

inflexed. Turned sharply inward.

inflorescence. The flowing part of a plant, categorized by the 

arrangements of flowers on the floral axis.

inflorescence unit. Term used to describe pairs of spikelets in 

the supertribe Andropogonodae, usually consisting of one 

sessile and one or two pedicellate spikelets.

innovation. A new vegetative shoot in a perennial grass.

inserted. Growing upon or attached to.

internode. The portion of the stem or culm between two nodes.

interrupted. When continuity is broken, particularly in dense 

inflorescence whose form is not continuous.

intravaginal branching. Growth of the shoot initial within the 

sheath that envelops the node, usually distinguished by the 

absence of bladeless leaves and development of an obvious, 

often palea-like prophyllum. Opposite: extravaginal.

involute. Rolled from both margins toward the middle, the 

upper surface within, especially common in leaf blades.

joint. Node of the culm or internode of an inflorescence.

keel. The adaxial ridge or fold of a compressed sheath, blade, 

glume, lemma, or palea.

keeled. Ridged along the middle of a flat or convex surface.

key. An ordered series of alternatives used to facilitate the identification of organisms.

knee. An abrupt bend in a stem or culm.

lacerate. Torn at the margin or irregularly lobed, as if torn.

lamina. The flat part of a leaf. Synonym: leaf blade.

lanate. With a very dense, wooly indumentum of hairs.

lanceolate. Lance shaped; narrow, tapering at both ends with 

the broadest part below the middle, approximately three 

times longer than wide.

lateral. Relating to the side of an organ or structure.

lax. Loose, distant, and not crowded together. Opposite: 

congested.

leaf blade. The upper expanded part of the leaf beyond the leaf 

sheath.
118 • smithsonian contributions to botany

leaf sheath. The lower part of the leaf clasping the adjacent 

part of the grass stem and terminating at a node below.

lemma. The lower (outer) of two bracts enclosing the grass 

flower; together with palea constitutes a floret.

ligule. An appendage (membrane) or ring of hairs on the adaxial leaf surface at the junction of the sheath and blade.

limb. The distant untwisted part of a geniculate awn above the 

column.

linear. Long and narrow with parallel margins, more than 10 

times longer than wide; usually refers to the shape of the 

leaf blade.

lobed. A flat organ split in two or more subdivisions.

lobule. A small lobe.

loose. Refers to the branching pattern of inflorescences that are 

often open, but not dense or compact.

marginal. At or near the edge.

membranous. Thin, soft tissue, usually green or translucent; 

similar to a thin membrane.

midrib. The central vascular trace or vein in the leaf blade.

mucronate. A short, small, abrupt point or minute awn less 

than 1 mm in length.

muricate. Rough, with short, hard points.

muticous. Blunt and without a mucro or awn.

nerve. A vein or vascular trace, often raised, usually running 

longitudinally on blades, glumes, and lemmas.

node. Point on the stem or culm axis at which leaves or 

branches originate; usually, these are swollen or knob-like.

notched. V-shaped cut from an entire edge.

oblique. Pertains to base of leaf blades where two sides of the 

lamina are unequal.

oblong. Longer than broad, with the margins nearly parallel. 

obovate. Reversed ovate, inverted ovate, the broadest part near 

the apex and the narrow side near the base.

obovoid. Egg shaped, but with the broadest part near the apex 

and the narrowest part near the base.

obtuse. With a blunt or rounded apex.

oral hairs or setae. Hairs on the margin of the distal end of leaf 

sheath; hairs adjacent to the ligule auricular region.

orbicular. Disk shaped, flat with a circular outline.

ovate. The shape of a longitudinal section of an egg, the broader 

end below the middle.

ovoid. Egg shaped.

palea. The inner or upper bract enclosing the pistil and stamens 

of a grass.

pallid. Pale in color.

panicle. An inflorescence in which the main axis has several 

divided or subdivided branches.

paniculate. Resembling a panicle.

papillose. Bearing minute nipple-like projections.

pectinate. Comb-like, with very close narrow divisions or parts.

pedicel. The stalk of an individual flower in an inflorescence; in 

grasses the stalk of a spikelet.

pedicellate. Borne on a pedicel.

peduncle. The stalk of an inflorescence or cluster of spikelets.

pedunculate. With a foot-stalk or peduncle.

perennial. A plant living for more than two years.

perfect. A floret (flower) with functional stamens and pistil.

persistent. Remaining attached, not falling off.

petiole. The stalk of a leaf blade.

pilose. Covered with loose, soft, long, straight hairs, not dense 

but somewhat shaggy.

pleated. Folded; see plicate.

plicate. Folded into pleats lengthwise several times like a 

closed fan.

pit glands. Small glandular depressions common on some species of Eragrostis.

plane. Level, flat surface.

plicate. Folded on several ribs in the manner of a closed fan.

plumose. Covered with long, spreading, soft hairs, each hair 

with side hairs along the main axis like the plume of a 

feather.

procumbent. Prostrate, trailing or lying flat, usually not rooting at nodes. Compare: stolon.

prophyllum. An initial, usually two-keeled, bladeless, adaxial, 

protective bract surrounding an axillary vegetative or floral bud; usually well developed in intravaginal branching 

shoots.

prostrate. Lying flat on the ground.

puberulent. Minutely pubescent, with very short hairs barely 

visible to the eye.

pubescent. A generalized term for hairy, lacking definition of 

the type of hairs, but sometimes referring to fine short hairs.

punctate. With transparent or colored dots, depressions, or 

pits.

pungent. Ending in a rigid sharp point.

pyriform. Pear shaped, used to describe grains of Eragrostis 

pectinacea.

raceme. A portion of an inflorescence with the spikelets borne 

on pedicels directly on the axis or peduncle; racemes may be 

solitary, digitate, or scattered.

racemose. Arranged like a raceme.

rachilla. The branching axis of the spikelet that bear florets.

rachis. The axis of an inflorescence that bares spikelets.

rame. A compound inflorescence in the supertribe Andropogonodae consisting of one to many units (branches) of 

one sessile and one or two pedicellate spikelets.

rectangular-prismatic. Having six more or less flat surfaces, i.e., 

shaped like a brick; used to describe the grain in Eragrostis.

reedlike. A semipersistent, aboveground stem that is not woody 

and is generally unbranched except in the inflorescence; in 

grasses this refers to stems that are large, usually more than 

2 m tall. 

reflexed. Abruptly curved or bent downward or backward to 

about 180°; see deflexed.

retrorse. Marginal spines or barbs bent abruptly downward or 

backward (away from the apex). Opposite: antrorse.

revolute. Rolled or curled toward the abaxial (lower) surface. 

Opposite: involute.
number 99 • 119

rib. A prominent vein, usually on a leaf.

ridged. Having raised veins.

rhizome. An underground stem, differing from a true root in 

the presence of buds or scalelike leaves.

rootstock. A short, vertical, subterranean stem, bearing roots.

rosette. A spreading and radiating basal cluster of leaves at 

ground level.

rostrate. With a beak, narrowed into a slender tip or point.

rounded. Smoothly curved without sharp angles. Synonym: 

obtuse.

rudimentary. Imperfectly or incompletely developed; vestigial 

and usually nonfunctional.

rufous. Rusty or brownish red.

rugose. Covered with wrinkles or creased surface.

rugulose. Finely wrinkled; diminutive of rugose.

runner. A creeping or prostrate lateral shoot; a very slender or 

filiform stolon.

sagittate. Shaped like an arrowhead; used to describe the base 

of a leaf blade that has two acute lobes that point backward.

scaberulous. Minutely scabrous, slightly rough.

scabrid. Rough to touch, usually caused by the presence of 

minute teeth or scattered short, stiff, broad-based hairs.

scabrous. Rough or harsh to touch, usually from short, stiff, 

broad-based hairs.

scales. Thin, dry, flat, almost leaflike structure protecting the 

rhizome or shoots.

scarious. Small, thin, dry, and shriveled, not green.

secund. One-sided; as when all branches or spikelets are borne 

to the same side of the axis.

sensu lato. A Latin phrase meaning “in a broad sense” (abbreviated s.l.). 

sensu stricto. A Latin phrase meaning “in a narrow sense” (abbreviated s.s.).

sericeous. Silky, with closely appressed, soft, straight hairs.

serrate. Sharp toothed and angled like a saw edge, the teeth 

directed toward the apex.

serrulate. Serrate with minute teeth.

sessile. Without stalk or pedicel.

seta. A bristle or stiff hair (pl. setae).

setaceous. Stiff and narrow, bristle-like.

setose. Bristly, beset with bristles.

sheath. A more or less tubular structure surrounding an organ 

or part, as the lower part of a grass leaf that wraps around 

the stem.

silky. A condition produced by a cover of soft, long, straight, 

fine hairs.

simple. Composed of not more than one anatomically or morphologically identical unit; not compound.

sinuous. Strongly wavy. Compare: undulate.

sinus. The notch between two lobes of a leaf or apex of a 

lemma.

slender. Slim, thin.

Smooth. Referring to surfaces that are not rough, sometimes 

loosely used for the absence of hairs.

solitary. Borne singly or alone.

spathe. A leafy bract that supports the branches of a spatheate 

inflorescence.

spatheate. With spathes or spatheoles.

spatheolate. Having spatheoles.

spatheole. A small leafy bract (spathe) enclosing part of an inflorescence.

spatulate. Spoon or spatula shaped.

spicate. With spikes, spikelike, or disposed in a spike.

spiciform. Spikelike, in the form of a spike.

spike. An inflorescence or branch with sessile spikelets on an 

axis; spikes may be solitary, digitate, or scattered.

spikelet. The unit of the inflorescence in grasses, consisting of 

two glumes and one or more florets; a diminutive of spike.

spine. A hard, sharp-pointed structure, often long and narrow.

spinose. Spiny or spine-like.

spinulose. With small spine; diminutive of spinose.

spreading. Referring to branches of an inflorescence having an 

outward direction at about right angles to the main axis.

stipe. A stalk to an organ that is part of the organ itself and not 

a separate branch.

stilt-root. Adventitious roots from the lower nodes of the 

culms.

stolon. A modified stem above ground (runner) that creeps and 

roots at the nodes and can give rise to new plants.

stoloniferous. Bearing stolons.

striate. With numerous longitudinal and parallel fine grooves, 

ridges, or lines of color.

strigose. With appressed, stiff, rather short hairs.

sub–. A prefix to denote somewhat, slightly, or to a lesser degree; as in subacute, subdigitate, suberect, subglabrous, subsessile, subspicate, subobtuse.

subdigitate. With inflorescence branches arising predominantly 

at the one point (apex), but with one or a few branches 

clearly arising below these.

subtend. To be below and yet close to, to extend under another 

structure.

subulate. Awl shaped, very narrow and tapering to a fine tip 

from a broader base.

tapering. Gradually narrowing in width toward one end, not 

abrupt.

taxon. Any taxonomic unit into which living organisms are 

classified, e.g., species, genus, tribe, subfamily, family, etc.

terete. Circular in cross section, lacking grooves or ridges.

terminal. At the end of a branch, stem, or culm axis.

ternate. Arranged in a cluster of three.

tiller. A leafy, nonflowering shoot initiating from the base of 

the plant.

tomentose. Densely covered with matted soft wool-like hairs.

toothed. Having teeth-like protrusions.

tough. Not disarticulating. Opposite: fragile.

truncate. Ending abruptly; cut squarely; with the apex flat as if 

cut across at the top.

tubercle. A small rounded protruding body; a little tuber.
120 • smithsonian contributions to botany

tuberculate. Furnished with small projections or tubercles.

tufted. Clustered, or clumped. Synonym: caespitose.

turgid. Swollen, inflated.

tussock. A tough, dense tuft of basal leaves found in perennial 

grasses (see caespitose).

undulate. Gently wavy. Compare: sinuous.

unilateral. One-sided, usually referring to the placement of 

spikelets along one side of a branch.

vein. A strand of vascular tissue (a vascular bundle) usually 

found in leaves, glumes, lemmas, and paleae.

venation. The arrangement of the vascular bundles or veins in 

a leaf.

vernal. Occurring in the spring. 

verrucose. Having a wartlike or nodular surface.

verticillate. Arranged in whorls.

villous. Densely covered with long, weak, silky, often curly 

hairs.

viscid. Sticky or glue-like.

viscous. Glutinous, or very sticky.

wanting. Lacking.

wart. A hard or firm excrescence.

webbed. A tuft of cotton-like hairs found just below the lemma 

in some species of Poa.

whorl. Three or more structures arranged in a circular manner 

around a common insertion point.

whorled. Having whorls.

winged. With a thin projection or border resembling a wing.

wiry. Like a wire, thin and cylindrical.

woolly. Hairy with dense, long, soft, entangled, curled hairs 

not appressed to the surface. Synonym: lanate.
References

Barkworth, M. E., K. M. Capels, S. Long, L. K. Anderton, and M. B. Peip, eds. 2007. 

Magnoliophyta: Commelinidae (In Part): Poaceae, Part 1. Flora of North America 

North of Mexico, Vol. 24. Oxford University Press, New York.

Barkworth, M. E., K. M. Capels, S. Long, and M. B. Peip, eds. 2003. Magnoliophyta: 

Commelinidae (In Part): Poaceae, Part 2. Flora of North America North of Mexico, 

Vol. 25. Oxford University Press, New York.

Brown, M. L., and R. G. Brown. 1984. Herbaceous Plants of Maryland. The Book Center, University of Maryland, College Park.

Clayton, W. D., M. S. Vorontsova, K. T. Harman, and H. Williamson. 2006–. GrassBase—The Online World Grass Flora. http://www.kew.org/data/grasses-db.html (accessed 5 January 2013).

Gleason, H. A., and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern 

United States and Adjacent Canada. New York Botanical Garden, New York.

Hitchcock, A. S. 1951. Manual of the grasses of the United States, edition 2, revised by 

A. Chase. United States Department of Agriculture Miscellaneous Publication 200: 

1−1051.

Shetler, S. G., and S. S. Orli. 2002. Annotated Checklist of the Vascular Plants of the 

Washington-Baltimore Area. Part II. Monocotyledons. Botany Section, Department 

of Systematic Biology, National Museum of Natural History, Smithsonian Institution, Washington, D.C.

Soreng, R. J., G. Davidse, P. M. Peterson, F. O. Zuloaga, E. J. Judziewicz, T. S. Filgueiras, 

and O. Morrone. 2013. Catalogue of New World Grasses (Poaceae). http://www

.tropicos.org/Project/CNWG (accessed 5 August 2013). [Includes suprageneric classification.]

Steury, B. W. 2004. Noteworthy Collections from the District of Columbia and Maryland. Castanea 69(2): 154−157. http://dx.doi.org/10.2179/0008-7475(2004)069

<0154:DOC>2.0.CO;2 

Steury, B. W., J. K. Triplett, and J. Parrish. 2013. Noteworthy Collections. Virginia, 

Maryland, and District of Columbia. Castanea 78(2): 138–139. http://dx.doi.org

/10.2179/12-045 

Terrell, E. E., and P. M. Peterson. 2009. Annotated List of Maryland Grasses (Poaceae). 

Journal of the Botanical Research Institute of Texas 3(2): 905–919.

Tropicos. 2013. http://www.tropicos.org (accessed 5 January 2013).

Weakley, A. S., J. C. Ludwig, and J. F. Townsend. 2012. Flora of Virginia, B. Crowder, 

ed. Botanical Research Institute of Texas, Fort Worth.

Index of Common Names

The description number and scientific name are included in parentheses for reference.

Alleghany flyback (44, Danthonia compressa), 45

alta fescue (116, Lolium arundinaceum), 81

American barnyard grass (75, Echinochloa muricata), 60

American witch grass (51, Dichanthelium columbianum), 48

annual bluegrass (151, Poa annua), 98

annual rye grass (117, Lolium multiflorum), 81

annulus panic grass (48, Dichanthelium annulum), 47

arrowfeather threeawn (19, Aristida purpurascens), 32

arthraxon (21, Arthraxon hispidus), 33

autumn bent (5, Agrostis perennans), 25

autumn bluegrass (152, Poa autumnalis), 99

awnless brome (28, Bromus inermis), 37

bald brome (31, Bromus racemosus), 38

barley (113, Hordeum vulgare), 79

barnyard grass (74, Echinochloa crusgalli), 60

barren brome (33, Bromus sterilis), 39

beaked panic grass (40, Coleataenia anceps), 43

beard grass (108, Gymnopogon ambiguus), 77

bearded skeleton grass (108, Gymnopogon ambiguus), 77

bearded sprangletop (73, Diplachne fusca subsp. fascicularis), 59

Bermuda grass (42, Cynodon dactylon), 44

big bluestem (9, Andropogon gerardii), 27

big cordgrass (170, Spartina cynosuroides), 108

birdseed grass (145, Phalaris canariensis), 95

black oatgrass (148, Piptochaetium avenaceum), 97

blackseed needlegrass (148, Piptochaetium avenaceum), 97

black-seed spear grass (148, Piptochaetium avenaceum), 97

bluejoint turkeyfoot (9, Andropogon gerardii), 27

bog panic grass (59, Dichanthelium lucidum), 52

Bosc’s panic grass (49, Dichanthelium boscii), 47

Bosc’s rosette grass (49, Dichanthelium boscii), 47

bottle-brush grass (81, Elymus hystrix), 63

branched muhly (127, Muhlenbergia sobolifera), 86

broadleaf chasmanthium (37, Chasmanthium latifolium), 41

broad-leaved panic grass (56, Dichanthelium latifolium), 51

broom-corn (168, Sorghum bicolor), 107

broom-corn millet (134, Panicum miliaceum), 90

broom rosette grass (65, Dichanthelium scoparium), 55
124 • smithsonian contributions to botany

broomsedge (13, Andropogon virginicus), 29

browntop (1, Agrostis capillaris), 23

bur bristle grass (165, Setaria verticillata), 105

bur foxtail grass (165, Setaria verticillata), 105

bushy beard grass (10, Andropogon 

glomeratus), 27

bushy bluestem (10, Andropogon 

glomeratus), 27

bushy panic grass (54, Dichanthelium 

dichotomum), 50

Canada bluegrass (153, Poa compressa), 99

Canada brome (30, Bromus pubescens), 38

Canada wildrye (78, Elymus canadensis), 62

canary grass (145, Phalaris canariensis), 95

Carolina lovegrass (92, Eragrostis pectinacea), 

69

cheat (32, Bromus secalinus), 39

cheatgrass (34, Bromus tectorum), 40

chess (32, Bromus secalinus), 39

Chinese silver grass (122, Miscanthus 

sinensis), 84

churchmouse threeawn (16, Aristida 

dichotoma), 31

clustered fescue (100, Festuca paradoxa), 73

coast barnyard grass (76, Echinochloa 

walteri), 61

colonial bent (1, Agrostis capillaris), 23

common brome (28, Bromus inermis), 37

common hair grass (23, Avenella flexuosa), 34

common panic grass (130, Panicum 

capillare), 88

common reed (147, Phragmites australis), 96

common silver hair grass (6, Aira 

caryophyllea), 25

common velvet grass (109, Holcus lanatus), 77

common woodreed (39, Cinna arundinacea), 

42

cordgrass (171, Spartina pectinata), 108

couch grass (83, Elymus repens), 64

coverall grass (121, Microstegium vimineum), 

83

crabgrass (72, Digitaria sanguinalis), 59

creeping wildrye (83, Elymus repens), 64

crinkled hair grass (23, Avenella flexuosa), 34

cypress panic grass (60, Dichanthelium 

mattamuskeetense), 53

cypress rosette grass (54, Dichanthelium 

dichotomum), 50

Dallis grass (138, Paspalum dilatatum), 92

deer-tongue grass (50, Dichanthelium 

clandestinum), 48

deer-tongue rosette grass (50, Dichanthelium 

clandestinum), 48

downy brome (34, Bromus tectorum), 40

downy chess (34, Bromus tectorum), 40

downy wildrye (85, Elymus villosus), 66

dwarf bamboo (149, Pleioblastus argenteostriatus fo. glaber), 97

dwarf fern-leaf bamboo (150, Pleioblastus 

pygmaeus), 98

early bluegrass (154, Poa cuspidata), 100

early wildrye (82, Elymus macgregorii), 64

eastern gama grass (180, Tripsacum 

dactyloides), 113

eastern riverbank wildrye (84, Elymus 

riparius), 65

eight-flowered six-weeks grass (99, Festuca 

octoflora), 72

Elliott’s beard grass (11, Andropogon 

gyrans), 28

Elliott’s bent (2, Agrostis elliottiana), 23

Elliott’s bluestem (11, Andropogon gyrans), 

28

eulalia (122, Miscanthus sinensis), 84

fall panic grass (131, Panicum 

dichotomiflorum), 88

feather grass (73, Diplachne fusca subsp. 

fascicularis), 59

few-flowered panic grass (62, Dichanthelium 

oligosanthes), 54

field crown grass (141, Paspalum laeve), 93

fine-leaved sheep fescue (97, Festuca 

filiformis), 71

finger grass (70, Digitaria filiformis), 58

flat-stemmed bluegrass (153, Poa compressa), 

99

flat-stemmed panic grass (40, Coleataenia 

anceps), 43

flattened poverty grass (44, Danthonia 

compressa), 45

flattened wild oatgrass (44, Danthonia 

compressa), 45

floating manna grass (106, Glyceria 

septentrionalis), 76

Florida crown grass (140, Paspalum 

floridanum), 93

Florida paspalum (140, Paspalum 

floridanum), 93

forest bluegrass (157, Poa sylvestris), 101

forest muhly (128, Muhlenbergia sylvatica), 

87

fowl bluegrass (155, Poa palustris), 100

fowl manna grass (107, Glyceria striata), 76

fowl meadow grass (155, Poa palustris), 100

foxtail grass (110, Hordeum jubatum), 78

foxtail millet (162, Setaria italica), 104

Frank’s lovegrass (89, Eragrostis frankii), 67

freshwater cordgrass (171, Spartina pectinata), 

108

Gattinger’s panic grass (133, Panicum 

gattingeri), 89

giant foxtail grass (161, Setaria faberi), 103

giant plume grass (95, Erianthus giganteus), 

70

golden crown grass (138, Paspalum 

dilatatum), 92

great plains wildrye (78, Elymus canadensis), 

62

green bristle grass (166, Setaria viridis), 106

green foxtail grass (166, Setaria viridis), 106

hair fescue (97, Festuca filiformis), 71

hair grass (4, Agrostis hyemalis), 24

hairy-awn muhly (123, Muhlenbergia 

capillaris), 84

hairy chess (26, Bromus commutatus), 36

hairy crabgrass (72, Digitaria sanguinalis), 59

hairy panic grass (47, Dichanthelium 

acuminatum), 46

hairy-seed crown grass (142, Paspalum 

pubiflorum), 94

hairy wildrye (85, Elymus villosus), 65

hairy woodland brome (30, Bromus 

pubescens), 38

hard fescue (103, Festuca trachyphylla), 74

headlike dropseed (175, Sporobolus 

compositus), 110

Heller’s rosette grass (62, Dichanthelium 

oligosanthes), 54

hog millet (134, Panicum miliaceum), 90

India lovegrass (93, Eragrostis pilosa), 69

Indian goose grass (77, Eleusine indica), 61

Indian grass (167, Sorghastrum nutans), 106

Indian reed (39, Cinna arundinacea), 42

Indian wild rice (182, Zizania aquatica), 114

Indian wood-oats (37, Chasmanthium 

latifolium), 41

Italian bristle grass (162, Setaria italica), 104

Italian rye grass (117, Lolium multiflorum), 81

Japanese bristle grass (161, Setaria faberi), 

103

Japanese brome (29, Bromus japonicus), 37

Japanese chess (29, Bromus japonicus), 37

Japanese stilt grass (121, Microstegium 

vimineum), 83

Johnson grass (169, Sorghum halepense), 107

June grass (34, Bromus tectorum), 40

June grass (156, Poa pratensis), 101

kafir corn (168, Sorghum bicolor), 107

Kentucky bluegrass (156, Poa pratensis), 101

knotroot bristle grass (163, Setaria 

parviflora), 104

knotroot foxtail grass (163, Setaria 

parviflora), 104

lace grass (87, Eragrostis capillaris), 66

large barnyard grass (74, Echinochloa 

crusgalli), 60

lax-flowered panic grass (57, Dichanthelium 

laxiflorum), 51

lax manna grass (105, Glyceria laxa), 75

lax rattlesnake manna grass (105, Glyceria 

laxa), 75

limp manna grass (105, Glyceria laxa), 75

little barley (112, Hordeum pusillum), 79

little bluestem (159, Schizachyrium 

scoparium), 102

little false bluestem (159, Schizachyrium 

scoparium), 102

little lovegrass (91, Eragrostis minor), 68

long-awned barnyard grass (76, Echinochloa 

walteri), 61

long-awned cockspur grass (76, Echinochloa 

walteri), 61
number 99 • 125

longspine sandbur (36, Cenchrus 

longispinus), 41

loose silkybent grass (15, Apera spica-venti), 

30

low panic grass (58, Dichanthelium 

linearifolium), 52

marsh muhly (125, Muhlenbergia glomerata), 

85

mat sandbur (36, Cenchrus longispinus), 41

meadow brome (26, Bromus commutatus), 36

meadow fescue (119, Lolium pratense), 82

meadow grass (158, Poa trivialis), 102

melic (120, Melica mutica), 83

milo (168, Sorghum bicolor), 107

mountain oatgrass (44, Danthonia 

compressa), 45

mudbank crown grass (139, Paspalum 

dissectum), 92

narrow-leaf panic grass (46, Dichanthelium 

aciculare), 46

needle-leaf rosette grass (46, Dichanthelium 

aciculare), 46

Nepalese browntop (121, Microstegium 

vimineum), 83

nerved manna grass (107, Glyceria striata), 

76

nimblewill (126, Muhlenbergia schreberi), 86

nodding fescue (102, Festuca subverticillata), 

74

nodding foxtail grass (161, Setaria faberi), 

103

nodding wildrye (78, Elymus canadensis), 62

northern crabgrass (72, Digitaria 

sanguinalis), 59

northern manna grass (106, Glyceria 

septentrionalis), 76

oats (22, Avena sativa), 34

old-witch grass (130, Panicum capillare), 88

open-flowered rosette grass (57, Dichanthelium laxiflorum), 51

orchard grass (43, Dactylis glomerata), 44

perennial foxtail grass (163, Setaria 

parviflora), 104

perennial rye grass (118, Lolium perenne), 82

petticoat-climber (94, Eragrostis spectabilis), 

70

Philadelphia witch grass (135, Panicum 

philadelphicum), 90

pink grass (92, Eragrostis pectinacea), 69

plume grass (179, Tripidium ravennae), 112

poverty brome (33, Bromus sterilis), 39

poverty dropseed (177, Sporobolus 

vaginiflorus), 111

poverty grass (16, Aristida dichotoma), 31

poverty grass (45, Danthonia spicata), 45

poverty grass (177, Sporobolus vaginiflorus), 

111

poverty oatgrass (45, Danthonia spicata), 45

poverty wild oatgrass (45, Danthonia 

spicata), 45

prairie cordgrass (171, Spartina pectinata), 

108

prairie cupgrass (96, Eriochloa contracta), 71

prairie threeawn (18, Aristida oligantha), 32

prairie wedge grass (174, Sphenopholis 

obtusata), 110

prairie wedgescale (174, Sphenopholis 

obtusata), 110

proso (134, Panicum miliaceum), 90

purple lovegrass (92, Eragrostis pectinacea), 

69

purple lovegrass (94, Eragrostis spectabilis), 

70

purpletop (178, Tridens flavus var. flavus), 112

pygmy bamboo (150, Pleioblastus pygmaeus), 

98

quack grass (83, Elymus repens), 64

rat-tail fescue (98, Festuca myuros), 72

rat-tail six-weeks grass (98, Festuca myuros), 

72

rattlesnake grass (104, Glyceria canadensis), 

75

rattlesnake manna grass (104, Glyceria 

canadensis), 75

Ravenel’s panic grass (63, Dichanthelium 

ravenelii), 54

Ravenel’s rosette grass (63, Dichanthelium 

ravenelii), 54

Ravenna grass (179, Tripidium ravennae), 

112

red fescue (101, Festuca rubra), 73

red threeawn (17, Aristida longespica), 31

redtop (3, Agrostis gigantea), 24

red-top panic grass (41, Coleataenia 

rigidula), 43

reed canary grass (144, Phalaris 

arundinacea), 95

rescue grass (25, Bromus catharticus), 35

Rhode Island bent (1, Agrostis capillaris), 23

rice cut grass (114, Leersia oryzoides), 80

ridged glyceria (107, Glyceria striata), 76

ringed panic grass (48, Dichanthelium 

annulum), 47

rock muhly (127, Muhlenbergia sobolifera), 

86

rough barnyard grass (75, Echinochloa 

muricata), 60

rough bluegrass (158, Poa trivialis), 102

rough bristle grass (165, Setaria verticillata), 

105

rough dropseed (175, Sporobolus 

compositus), 110

rough foxtail grass (165, Setaria verticillata), 

105

rough-stemmed bluegrass (158, Poa trivialis), 

102

round-fruited panic grass (66, Dichanthelium 

sphaerocarpon), 56

round-seed rosette grass (66, Dichanthelium 

sphaerocarpon), 56

rye (609, Secale cereale), 103

rye brome (32, Bromus secalinus), 39

salt reed grass (170, Spartina cynosuroides), 

108

sandbar lovegrass (89, Eragrostis frankii), 67

scutch grass (42, Cynodon dactylon), 44

sheep fescue (103, Festuca trachyphylla), 74

shiny wedge grass (173, Sphenopholis nitida), 

109

shiny wedgescale (173, Sphenopholis nitida), 

109

short-leaved bluegrass (154, Poa cuspidata), 

100

silver hair grass (6, Aira caryophyllea), 25

silvery hair grass (6, Aira caryophyllea), 25

six-weeks fescue (99, Festuca octoflora), 72

six-weeks grass (99, Festuca octoflora), 72

slender alopecurus (8, Alopecurus 

myosuroides), 26

slender chasmanthium (38, Chasmanthium 

laxum), 42

slender crabgrass (70, Digitaria filiformis), 58

slender crown grass (143, Paspalum 

setaceum), 94

slender foxtail (8, Alopecurus myosuroides), 

26

slender meadow foxtail (8, Alopecurus 

myosuroides), 26

slender muhly (129, Muhlenbergia 

tenuiflora), 87

slender paspalum (143, Paspalum setaceum), 

94

slender wedge grass (172, Sphenopholis 

intermedia), 109

slender wedgescale (172, Sphenopholis 

intermedia), 109

slender wildrye (85, Elymus villosus), 65

slender wood-oats (38, Chasmanthium 

laxum), 42

slender-flowered muhly (128, Muhlenbergia 

tenuiflora), 87

slim-leaved panic grass (58, Dichanthelium 

linearifolium), 52

slim-leaved rosette grass (58, Dichanthelium 

linearifolium), 52

slim-spike threeawn (17, Aristida longespica), 

31

small carp grass (21, Arthraxon hispidus), 33

small crabgrass (71, Digitaria ischaemum), 58

small dropseed (176, Sporobolus neglectus), 

111

small reedgrass (35, Calamagrostis 

cinnoides), 40

smooth brome (28, Bromus inermis), 37

smooth brome (31, Bromus racemosus), 38

smooth cheat (31, Bromus racemosus), 38

smooth crabgrass (71, Digitaria ischaemum), 

58

smooth paspalum (141, Paspalum laeve), 93

soft brome (27, Bromus hordeaceus), 36

soft chess (27, Bromus hordeaceus), 36

soft-tufted panic grass (57, Dichanthelium 

laxiflorum), 52

sorghum (168, Sorghum bicolor), 107

southeastern wildrye (80, Elymus 

glabriflorus), 63
126 • smithsonian contributions to botany

southern crabgrass (69, Digitaria ciliaris), 57

southern hairy panic (61, Dichanthelium 

meridionale), 53

southern shorthusk (24, Brachyelytrum 

erectum), 35

spear grass (151, Poa annua), 98

spear grass (156, Poa pratensis), 101

spiked muhly (125, Muhlenbergia glomerata), 

85

split-beard bluestem (12, Andropogon 

ternarius), 28

split-beard little bluestem (12, Andropogon 

ternarius), 28

spreading witch grass (131, Panicum 

dichotomiflorum), 88

squirrel-tail grass (110, Hordeum jubatum), 

78

starved panic grass (53, Dichanthelium 

depauperatum), 49

starved rosette grass (53, Dichanthelium 

depauperatum), 49

stink grass (88, Eragrostis cilianensis), 67

stout woodreed (39, Cinna arundinacea), 42

streambank wildrye (84, Elymus riparius), 65

Sudan grass (168, Sorghum bicolor), 107

sugarcane plume grass (95, Erianthus 

giganteus), 70

sweet vernal grass (14, Anthoxanthum 

odoratum), 30

sweet woodreed (39, Cinna arundinacea), 42

switch grass (137, Panicum virgatum), 91

sword-leaf panic grass (55, Dichanthelium 

ensifolium), 50

sylvan bluegrass (157, Poa sylvestris), 101

tall dropseed (175, Sporobolus compositus), 

110

tall fescue (116, Lolium arundinaceum), 81

tall oatgrass (20, Arrhenatherum elatius), 33

tall redtop (178, Tridens flavus var. flavus), 

112

tall swamp panic grass (64, Dichanthelium 

scabriusculum), 55

tapered rosette grass (47, Dichanthelium 

acuminatum), 46

teal lovegrass (90, Eragrostis hypnoides), 68

Terrell grass (86, Elymus virginicus), 66

tickle grass (4, Agrostis hyemalis), 24

timothy (146, Phleum pratense), 96

trouble-grass (94, Eragrostis spectabilis), 70

tufted alopecurus (7, Alopecurus 

carolinianus), 26

tufted foxtail (7, Alopecurus carolinianus), 26

tufted meadow foxtail (7, Alopecurus 

carolinianus), 26

tumble grass (94, Eragrostis spectabilis), 70

two-flowered melic (120, Melica mutica), 83

upland bent grass (5, Agrostis hyemalis), 24

upland bent grass (5, Agrostis perennans), 25

upright chess (26, Bromus commutatus), 36

variable panic grass (52, Dichanthelium 

commutatum), 49

variable rosette grass (52, Dichanthelium 

commutatum), 49

velvety panic grass (65, Dichanthelium 

scoparium), 55

Virginia wildrye grass (86, Elymus 

virginicus), 66

wall barley (111, Hordeum murinum), 78

Walter’s paspalum (139, Paspalum 

dissectum), 92

wand panic grass (137, Panicum virgatum), 

91

warty panic grass (136, Panicum 

verrucosum), 91

wavy hair grass (23, Avenella flexuosa), 34

western bottle-brush grass (79, Elymus 

elymoides), 62

wheat (181, Triticum aestivum), 113

white grass (115, Leersia virginica), 80

white-haired panic grass (67, Dichanthelium 

villosissimum), 56

white-haired rosette grass (67, Dichanthelium 

villosissimum), 56

wild oats (37, Chasmanthium latifolium), 41

wild reed (147, Phragmites australis subsp. 

australis), 96

wild rice (182, Zizania aquatica), 114

wire grass (77, Eleusine indica), 61

wire-stem muhly (124, Muhlenbergia 

frondosa), 85

wiry panic grass (132, Panicum flexile), 89

witch grass (83, Elymus repens), 64

witch grass (130, Panicum capillare), 88

wood witch grass (135, Panicum 

philadelphicum), 90

woodland bluegrass (157, Poa sylvestris), 

101

woodland muhly (128, Muhlenbergia 

sylvatica), 87

woolly rosette grass (64, Dichanthelium 

scabriusculum), 55

Yadkin River panic grass (68, Dichanthelium 

yadkinense), 57

yard grass (77, Eleusine indica), 61

yellow foxtail grass (164, Setaria pumila), 

105

yellow Indian grass (167, Sorghastrum 

nutans), 106

Yorkshire fog (109, Holcus lanatus), 77
Index of Scientific Names

Names without an asterisk are accepted; those with an asterisk are synonyms. Page numbers in 

bold italics denote account description.

Agrostis capillaris, 18, 23

elliottiana, 20, 23, 24

gigantea, 16, 18, 24

hyemalis, 21, 24, 25

perennans, 16, 21, 25

Aira caryophyllea, 13, 25, 26

Alopecurus carolinianus, 17, 26

myosuroides, 19, 26, 27

Andropogon gerardii, 17, 27

glomeratus, ii, 15, 27, 28

gyrans, 17, 28

ternarius, 17, 28, 29

virginicus, 15, 29

Anthoxanthum odoratum, 13, 20, 30

Apera spica-venti, 17, 30

Aristida dichotoma, 13, 17, 31

longespica, 17, 31

oligantha, 14, 20, 32

purpurascens, 17, 32

Arrhenatherum elatius, 18, 21, 33

Arthraxon hispidus, 12, 33

Arundo canadensis*, 40

Avena sativa, 20, 34

Avenella flexuosa, 13, 34

Brachyelytrum erectum, 16, 18, 35

Bromus catharticus, 21, 35

commutatus, 20, 36

hordeaceus, 19, 36

inermis, 19, 37

japonicus, 19, 37

pubescens, 16, 19, 20, 38

racemosus, 20, 38

secalinus, 20, 39

sterilis, 20, 39

tectorum, 20, 40

Calamagrostis canadensis*, 40

cinnoides, 18, 40

nuttalliana*, 40
128 • smithsonian contributions to botany

Cenchrus longispinus, 14, 41

Chasmanthium latifolium, 17, 18, 41

laxum, 16, 18, 42

Cinna arundinacea, ii, 20, 42

Coleataenia anceps, 15, 18, 43

rigidula, 14, 43

Cynodon dactylon, 12, 44

Dactylis glomerata, 15, 21, 44

Danthonia compressa, 13, 45

spicata, 16, 45

Deschampsia flexuosa*, 34

Dichanthelium aciculare, 14, 46

acuminatum, 15, 46

annulum, 16, 47

boscii, 15, 47

clandestinum, 15, 48

columbianum, 15, 17, 48

commutatum, 15, 49

depauperatum, 14, 49

dichotomum, 14, 50

ensifolium, 16, 50

latifolium, 15, 51

laxiflorum, 12, 51

linearifolium, 14, 52

lucidum, 16, 52

mattamuskeetense, 15, 53

meridionale, 16, 53

oligosanthes, 15, 16, 54

ravenelii, 16, 54

scabriusculum, 15, 55

scoparium, 15, 55

sphaerocarpon, 15, 56

villosissimum, 14, 56

yadkinense, 16, 57

Digitaria ciliaris, 12, 57

filiformis, 15, 58

ischaemum, 17, 58

sanguinalis, 15, 59

Diplachne fusca subsp. fascicularis, 14, 59

Echinochloa crusgalli, 14, 60

muricata, 12, 16, 20, 60

walteri, 19, 21, 61

Eleusine indica, 14, 61

Elymus canadensis, 13, 62

elymoides, 13, 62

glabriflorus, 13, 21, 63

hystrix, 12, 14, 63

macgregorii, 13, 64

repens, 12, 64

riparius, 13, 17, 21, 65

villosus, 13, 65

virginicus, 13, 66

Eragrostis capillaris, 16, 66

cilianensis, 19, 67

frankii, 16, 67

hypnoides, 12, 68

minor, 19, 68

pectinacea, 16, 69, 120

pilosa, 19, 69

spectabilis, 16, 70

Erianthus giganteus, 15, 70

Eriochloa contracta, 14, 71

Festuca arundinacea*, 81

filiformis, 13, 71

myuros, 14, 72

octoflora, 17, 20, 72

paradoxa, 20, 73

pratensis*, 82

rubra, 13, 73

subverticillata, 20, 74

trachyphylla, 13, 20, 74

Glyceria canadensis, 18, 75

canadensis var. laxa*, 75

laxa, 21, 75

septentrionalis, 16, 76

striata, 18, 20, 76

Gymnopogon ambiguus, 15, 77

Holcus lanatus, 19, 77

Hordeum jubatum, 21, 78

murinum, 13, 78

pusillum, 13, 20, 79

vulgare, 13, 79

Leersia oryzoides, 17, 80

virginica, 16, 18, 80

Leptochloa fusca subsp. fascicularis*, 59

Lolium arundinaceum, 12, 81

multiflorum, 13, 81

perenne, 13, 82

pratense, 12, 82

Melica mutica, 18, 20, 83

Microstegium vimineum, 12, 83

Miscanthus sinensis, 16, 84

Muhlenbergia capillaris, 20, 84

frondosa, 18, 85

glomerata, 15, 85

schreberi, 17, 19, 86

sobolifera, 14, 86

sylvatica, 18, 87

tenuiflora, 19, 87

Panicum anceps*, 43

capillare, 14, 88

dichotomiflorum, 17, 88

flexile, 12, 89

gattingeri, 16, 17, 89

miliaceum, 17, 19, 90

philadelphicum, 17, 90

rigidulum*, 43

verrucosum, 17, 91

virgatum, 18, 91

Paspalum dilatatum, 18, 92

dissectum, 12, 92

floridanum, 18, 93

laeve, 15, 93

pubiflorum, 16, 94

setaceum, 15, 94

Phalaris arundinacea, 18, 95

canariensis, 20, 95

Phleum pratense, 13, 21, 96

Phragmites australis subsp. australis, 12, 96

Piptochaetium avenaceum, 13, 97

Pleioblastus argenteostriatus fo. glaber, ii, 

12, 97

pygmaeus, 12, 98

Poa annua, 14, 17, 20, 98

autumnalis, 21, 99

compressa, 14, 99

cuspidata, 17, 18, 100

palustris, 14, 17, 20, 100

pratensis, 14, 18, 101

sylvestris, 20, 101

trivialis, 14, 16, 20, 102

Saccharum giganteum*, 70

ravennae*, 112

Schedonorus arundinaceus*, 81

pratensis*, 82

Schizachyrium scoparium, 15, 17, 102

Secale cereale, 13, 103

Setaria faberi, ii, 14, 103

italica, 14, 104

parviflora, 16, 104

pumila, 19, 105

verticillata, 19, 105

viridis, 19, 106

Sorghastrum nutans, 13, 106

Sorghum bicolor, 19, 107

halepense, 16, 107

Spartina cynosuroides, 18, 108

pectinata, 18, 108

Sphenopholis intermedia, 19, 21, 109

nitida, 21, 109

obtusata, 19, 20, 110

Sporobolus compositus, 18, 19, 110

neglectus, 14, 111

vaginiflorus, 19, 111

Tridens flavus var. flavus, ii, 14, 112

Tripidium ravennae, 12, 112

Tripsacum dactyloides, 12, 113

Triticum aestivum, 13, 113

Vulpia myuros*, 72

octoflora*, 72

Zizania aquatica, 12, 114
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