SMITHSONIAN CONTRIBUTIONS TO BOTANY 0 NUMBER 57 

Revision of the 

South American Genus Otachyrium 

(Poaceae: Panicoideae) 

Tatiana Sendulsky 

and Thomas R. Soderstrom 

SMITHSONIAN INSTITUTION PRESS 

City of Washington 

1984 
ABSTRACT 

Sendulsky, Tatiana, and Thomas R. Soderstrom. Revision of the South 

American Genus Otachyrium (Poaceae: Panicoideae). Smithsonian Contributions to Botany, number 57, 24 pages, 7 figures, 1984.-A review of this 

genus of seven species is provided with descriptions and illustrations of each. 

Of these species, four are described as new: 0. aquaticum, 0. grandajlorum, 0. 

piligerum, and 0. seminudum. Two, 0. pterigodium and 0. versicolor, are already 

known in the literature, and one, 0. succisum, is a new combination. In 

addition to its short, subequal glumes, remarkable peculiarities of this panicoid genus are the enlarged palea of the lower staminate floret and the 

chartaceous, dark and shining or sometimes opaque and greenish, upper 

hermaphrodite floret, both of which are united at maturity. 

OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is 

recorded in the Institution’s annual report, Smithsonian Year. SERIES COVER DESIGN: Leaf 

clearing from the katsura tree Cercidiphyllum japonicum Siebold & Zuccarini. 

Library of Congress Cataloging in Publication Data 

Sendulsky, Tatiana. 

Revision of the South American Genus Otachyrium (Poaceae: Panicoideae). 

(Smithsonian contributions to botanv ; no. 57) 

Bibliography: p. 

Sum of Docs. no.: SI 1.29:57 

1. Otachyrium-Classification. 2. Botany-South America-Classification. I. Soderstrom, 

QKlS2747 no. 57 [QK495.G74] 581s [584’.9] 84-600087 

Thomas R. 11. Title. 111. Series. 
Contents 

Page 

Introduction ............................................ 1 

2 

3 

4 

7 

9 

12 

Acknowledgments .................................... 2 

Otachyrium Nees von Esenbeck .............................. Key to the Species of Otachyrium ........................... Otachyrium aquaticum Sendulsky 8c Soderstrom, new species ...... Otachyrium grandijlorum Sendulsky 8c Soderstrom, new species .... Otachyrium piligerum Sendulsky 8c Soderstrom, new species ....... 

Otachyrium pterigodium (Trinius) Pilger ...................... Otachyrium seminudum Hackel ex Sendulsky 8c Soderstrom, new 

Otachyrium succisum (Swallen) Sendulsky 8c Soderstrom, new 

species ............................................. 14 

combination ......................................... 17 

Otachyrium versicolor (Doell) Henrard ....................... 19 

Literature Cited ......................................... 24 

... 

111 

Revision of the 

South American Genus Otachyrium 

(Poaceae: Panicoideae) 

Tatiana Sendulsky and Thomas R. Soderstrom 

Introd uction 

One of the largest and most widespread tribes 

of grasses is the Paniceae whose principal genus, 

Panicum, comprises some 600 species distributed 

throughout the world's tropics and subtropics. 

This genus and related genera are characterized 

by spikelets that contain two florets, a lower one 

that is typically more or less chartaceous and 

staminate or empty, and an upper one, which is 

hermaphrodite and usually indurate. 

In 1826 Trinius described a species of Panicum 

that had been collected in the state of Minas 

Gerais on the Serra do Espinhaco, a range that 

extends into the state of Bahia. The peculiar 

winged nature of the palea of the lower floret 

must have inspired the author to name the grass 

after the orchid, Pterygodium, whose florets have 

winglike structures and whose name is derived 

from the Greek word pteryx (wing). In this species 

the young spikelets are of a papery texture and 

light green or pale in color. As the fruit develops 

in the upper floret the palea of the lower one 

becomes expanded and appressed to the upper 

palea. At maturity the caryopsis is thus protected 

Tatiana Sendulsky, Bolsista do Conselho Nacional de Desenvolvimento Cientifico e Tecnologico, Instituto de Botanica de Sao 

Paulo, Caixa Postal 4005, 01000 Sao Paulo, SP, Brazil. 

Thomas R. Soderstrom, Department of Botany, National Museum 

of Natural History, Smithsonian Institution, Washington, D.C. 

20560. 

by a complex encasement, which consists of the 

upper lemma along with the adherent paleas of 

both florets. 

While the peculiar features of the spikelet in 

this new grass, which prompted Trinius to describe it as a new species, were quite unlike those 

of any other species of Panicum, it was Nees von 

Esenbeck who recognized the novelty as generically distinct from Panicum. Unaware that Trinius had already described the species three years 

earlier, Nees in 1829 named it Otachyrium junceum, the type of his new genus Otachyrium. He 

based the generic name on the Greek words, ous, 

otos (ear) and achyron (chaff), again in reference 

to the winged condition of the lower palea at 

maturity. By modern rules of nomenclature, a 

species must retain the earliest name, so we have 

in Otachyrium pterigodium the correct name incorporating the contributions from two early and 

renowned agrostologists, Carl Bernhard Trinius 

and Christian Nees von Esenbeck. Appropriately 

both parts of the epithet refer to the winged 

nature of the lower palea at maturity. 

While Nees accorded generic status to the new 

taxon, many investigators since his time have 

considered Otachyrium to be no more than a 

section or subgenus of Panicum. Pilger (1931) 

and Henrard (194 l), however, were' two exceptions, and both made nomenclatural changes in 

the genus. More recently, Butzin (1970) has 

1 
2 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

made the genus the basis of a separate subtribe, 

Otachyriinae, far removed in his system from the 

subtribe Panicinae. 

In addition to its short, subequal glumes, remarkable peculiarities of this panicoid genus are 

the enlarged palea of the lower staminate floret 

and the chartaceous, dark and shining or sometimes opaque and greenish, upper hermaphrodite floret, both of which are united at maturity. 

This unique combination of characters, shared 

by the seven species of the genus that we recognize in the present paper, leave little doubt that 

we are indeed dealing with a genus distinct from 

Panicum. 

The species of Otachyrium are widely distributed in South America, extending from Trinidad 

to Argentina but exhibiting their fullest diversity 

in central and northern Brazil where all are to 

be found. The plants generally inhabit wet, marshy ground or margins of streams, but sometimes 

they grow affixed to stones in running water. 

Otachyrium versicolor sometimes occurs in open 

and drier sandy habitats. 

The color of the hermaphrodite floret and 

degree of expansion of the lower palea depend 

on the state of maturity of the spikelet. At the 

time of flowering the spikelet is usually stramineous or ivory-colored, rather loose and resembling an empty shell; at this stage the paleas are 

not fully expanded. Presumably once fertilization 

has occurred, the lemma and palea of the upper 

floret become dark and rigid and the palea of 

the lower floret becomes expanded. The central, 

hyaline part of the palea frequently splits lengthwise in the middle, and its margins extend 

broadly outward from the sides of the upper 

floret. 

The species fall into two readily distinguishable morphological groups. One consists of those 

with hard, gibbous, beaklike upper lemmas that 

are generally dark and shining; in the other the 

lemmas of the upper florets are not indurate and 

are opaque, stramineous or greenish. Members 

of the former group-0. succisum, 0. piligerum, 

0. seminudum, and 0. versicolor-are generally 

medium to robust and have broad, linear leaves. 

Plants of Otachyrium aquaticum, 0. grandajlorum, 

and 0. pterigodium, which comprise the second 

group, are small in stature and have narrow, 

nearly cylindrical, inrolled or acicular leaves. 

In two species, 0. piligerum and 0. succisum, 

the enlarged paleas have no hyaline wings but do 

have large, firm, carinate margins that tightly 

embrace the hermaphrodite florets. In other species these firm margins correspond to the lateral 

nerves that form large, carinate, ribbon-like rims 

along their length. 

In the present paper we present a key to the 

seven species and a description and illustration 

of each, the latter drawn by the first author. Of 

the seven species, four are new to science (0. 

aquaticum, 0. grandajlorum, 0. piligerum, and 0. 

seminudum) and one has been transferred from 

Panicum (0. succisum). 

ACKNOWLEDGMENTS.-The first author 

wishes to thank the Office of Scientific Affairs, 

Organization of American States, and the Conselho Nacional de Desenvolvimento Cientifico e 

Tecnologico for grants that have made her part 

of this work possible. She also wishes to express 

her thanks to the staff of the U.S. National 

Herbarium, Department of Botany, National 

Museum of Natural History, Smithsonian Institution, Washington, D.C., for its assistance in 

making the collections freely available; to Mrs. 

Ruth Schallert, Botany librarian, for her help; 

and Dr. Lyman B. Smith, for the support and 

facilities offered during the course of this work 

and her stay in Washington. Her gratitude is due 

also to all colleagues of the Instituto de Botanica 

de Sao Paulo for their ever-willing cooperation. 

We both owe appreciation to Alasdair G. Burman for his revisions of the descriptions in Latin, 

to Dr. Fernando 0. Zuloaga, who gave us so 

much time and assistance during final preparation of the manuscript, and to our young colleague, Andrew Phillips, for his kindnesses and 

cheerful assistance. 

Otachyrium Nees von Esenbeck 

Otachyrium Nees von Esenbeck, 1829:273[271]. 

Spikelets two-flowered (rarely with a 3rd rudimentary, terminal floret in 0. grandzjlorum), 
NUMBER 57 3 

from ovoid and rather laterally compressed to 

strongly plano-convex, broadly ovate, orbicular 

in outline, the sides convex with a gibbous, ovate, 

dark, mostly shining, otherwise opaque, graygreenish central part (lemma of the upper floret) 

and broadly ovate to orbicular encircling, hyaline, mostly purplish or light-colored wings (palea 

of the lower floret); shape of the spikelet and 

consequently its size depending on the stage of 

development of the palea margins of the lower 

floret; spikelets falling entire from the unequal 

pedicels, generally borne in pairs at the base or 

along the branches in open or contracted panicles 

without a definite orientation toward the axis. 

Glumes short, subequal, l/s to l/4 the length of the 

spikelet, membranous, 1-7-nerved. 

Lowerfloret staminate, ovoid-lanceolate, inconspicuously greenish or light-colored, as long as 

or sometimes longer than the upper floret. 

Lemma oblong-ovate, boat-shaped, membranous, 

opaque, 3-nerved. Palea broad, hyaline, purplish 

or light-colored, at maturity widely expanding 

beyond the spikelet and adhering to the upper 

hermaphrodite floret, otherwise folded. The 

central, generally hyaline part of a palea frequently splits lengthwise in the middle and its 

margins extend broadly at the sides of the upper 

floret, increasing the spikelet in size and changing its shape; nerves 2, forming ribbon-like, 

opaque, rather dark, firm, alate-carinate rims, 

mostly finely denticulate or ciliate at the keels. 

Lodicules 2, broadly cuneate, with thinner, generally slightly raised median and distal margins. 

Stamens 3. 

Upper floret hermaphrodite (probably only female or cleistogamous in 0. pterigodium and in 

0. aquaticum), ovoid-lanceolate or oblong, 

strongly plano-convex, sometimes gibbous, from 

papery to strongly crustaceous, shining, smooth 

or opaque, rarely finely papillose, pale yellow or 

greenish or dark purplish brown, nearly black. 

Lemma convex or gibbous, obscurely 3-5-nerved, 

acute, loosely embracing the margins of the palea. Palea flat, rather concave, more or less similar in texture and color to the lemma. Lodicules 

2, broadly cuneate, mostly with a wide, concave 

apical area and with median and distal margins 

expanded into fine wings. Stamens 3, styles distinct, stigmas feathery. Caryopsis ovoid, rather 

compressed; embryo about half the size of the 

caryopsis; hilum ovate, subbasal. 

Rhizomatous perennials (except 0. succisum 

and 0. piligerum) of various habits and sizes. Leaf 

blades from long-lanceolate or linear to rather 

convolute, filiform or acicular. Ligule membranous, truncate with a ciliolate apex (incomplete 

in 0. piligerum). 

Chromosome number 2n = -18, reported 

only once for the genus Otachyrium from Brazilian material cited as Panicum versicolor Doell, 

Irwin & Soderstrom 5796 (Gould and Soderstrom, 

1967). 

TYPE SPECIES.-otachyrium pterigodium (Trinius) Pilger. 

Key to the Species of Otachyrium 

1. Spikelets 4.5-8.5 mm long, panicles few-flowered, with 5-15 spikelets .......................... 0. grandiflorum, new species 

Spikelets 2-4 mm long, panicles many-flowered, with 50 or more 

spikelets ........................................... 2 

2. Spikelets with the upper floret strongly crustaceous, shining, dark 

brownorblack ...................................... 3 

Spikelets with the upper floret not crustaceous, stramineous or greenish, generally opaque, sometimes finely papillose (if slightly shining 

then only on the lower half of the lemma) ................. 6 

3. One pedicel of the paired spikelets 5-10 times longer than the other 

.................................................. 4 
4 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

One pedicel of the paired spikelets 1.5-2 (2.5) times longer than the 

other .............................................. 5 

4. Plants leafless at the base and slightly decumbent, strongly rooting at 

the 2nd to 4th nodes, branching at all subsequent upper nodes; axis 

of the inflorescence pilose. ........... 0. piligerum, new species 

Plants with a leafy, more or less semi-rosette type of base, never 

rooting at the nodes, if branching, at the base only; axis of the 

inflorescence glabrous .......... 0. succisum, new combination 

5. Panicles open with spreading branches .............. 0. versicolor 

Panicles narrowly contracted with the branches adherent to the 

main axis ....................... 0. seminudum, new species 

6. Leaf-blades acicular, almost cylindrical . . 0. aquaticum, new species 

Leaf-blades flat, narrow, convolute .............. 0. pterigodium 

Otachyrium aquaticum 

Sendulsky 8c Soderstrom, new species 

FIGURE 1 

TYPE COLLECTION.-BRAZIL. BAHIA: Serra 

do Rio de Contas, -2 km N of the town of Rio 

de Contas, in flood plain of the Rio Brumado. 

Alt. -980 m. Approx. 41"50'W, 13"35'S, 25 

January 1974, R.M. Harley, S.A. Renvoize, S.M. 

Erskine, S.A. Brighton €+ R. Pinheiro 15498 [holotype, US, sheet no. 2777098; isotypes, CEPEC, 

K, NY]. 

Gramen perenne, culmis gracilibus, erectis, 

30-40 cm altis. Foliorum laminae aciculatae vel 

cylindricae, adscendentiae, 8- 16 cm longae, 1 

mm latae, glabrae. Paniculae oblongae, 6-14 cm 

longae, sparsim ramosae, ramis effusis, adscendentibus vel appressis, ad apicem brevissimis vel 

absentibus, spiculis per K superiores longitudinis 

ramorum congestis. Spiculae ovatae oblongae, 

hiantes, 2.2-2.4 mm longae, glabrae; gluma 

prima ovata, lh, longitudinis spiculae aequans, 1- 

nervia; gluma segunda ovata, Ih longitudinis spiculae aequans, 1 -3-nervia. Flosculus inferus d; 

lemma ovato oblongum, spiculum aequans, 3- 

nervium; palea evoluta, binervia, bicarinata; carinis scaberulis vel puberulis et firmis, marginibus 

membranaceis, latissimis, reflexis. Flosculus superus probabiliter 9 vel cleistogamus, oblong0 

convexus, opacus; lemma et palea obscure papillosa. 

Erect, slender, light green, tufted, aquatic perennials, 30-40 cm tall, with scales covering the 

basal internodes, rather shiny and variable in 

size; basal internodes 3 or 4, short, the nodes 

closely approximate with salient, dark, sharp, 

encircling rims sometimes growing into rigid, 

long, wiry, glabrous, rather angular, ascending 

stolons -2.5 cm long, each consisting of a single 

long internode, these again growing into a series 

of approximate nodes similar to those from 

which they first developed, the last short nodes 

subsequently giving rise to the culms and 

branches. Roots long, strong, densely covered 

with root-hairs. Culms filiform, terete, simple, 

glabrous, sulcate, 1-2 mm in diameter. Nodes 

dark, constricted, glabrous. Leafsheaths of the 

lower nodes open, wide, loose, with wide hyaline 

margins, those of the uppermost nodes strongly 

carinate with the keel area half as wide as the 

sheath; margins less hyaline; auricles small with 

a few hairs on the margins; adaxial surface of the 

sheath bearing numerous, conspicuous transverse veins. Ligule with a short, truncate, membranous base, up to 0.25 mm long, long-ciliate 

at the apex. Leafblades ascending, acicular, glabrous, sulcate, 8-16 cm long, -1 mm wide, almost cylindrical in transverse section, the adaxial 
FIGURE 1 .--Otachyrium aquaticum: a, habit of plant; b, leaf midregion, showing ligule and part 

of acicular leaf; c, branch of the panicle; d, upper floret, lemma side; e, upper floret, palea side; 

f; hermaphrodite flower of upper floret, showing reduced anthers; g, lodicules of upper floret; 

h, lemma of lower floret; i, broad palea of lower floret;j, andrecium of lower floret; k, lodicules 

of lower floret; 1, transverse section of the blade; m, caryopsis, embryo side; n, caryopsis, hilum 

side. All drawings based on Harley et al. 15498 (US). 

NUMBER 57 5 
6 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

surface with only a shallow groove, the basal part 

rather constricted, sometimes with long cilia 

along the margins. 

Panicles 6-14 cm long, 3-4 cm wide, oblong, 

more or less pyramidal in outline, with sparse, 

rather few, raceme-like, contracted or spreading, 

many-flowered branches, the axis sulcate, glabrous; lower branches 2.5-3.5 mm long, diminishing upwards into short clusters of spikelets, 

bearing no spikelets near the base nor on the 

lower '1'3. Pedicels unequal, mostly borne in pairs 

along the branches, with cup-shaped tips. 

Spikelets ovoid to oblong-ovoid, 2.2-2.4 mm 

long, 1.2 mm wide, often somewhat gaping and 

with a rather truncate apex, gray-greenish or 

dark purplish, glabrous, opaque, crowded on the 

racemes. Glumes subequal, short, keeled, finely 

denticulate along the keels. Lower glume Ih the 

length of the spikelet, l-nerved. Upper glume 

the length of the spikelet, l-3-nerved. 

Lower jloret staminate. Lemma ovate-oblong, 

navicular, convex and rounded on the back, papery, 1.8 mm long, -1 mm wide, 3-nerved, the 

margins rather hyaline. Palea -2 mm long, 1.5 

mni wide, broadly ovate, roundly navicular, with 

wide, hyaline, undulate, reflexed margins, embracing its flower, at maturity adhering only to 

the upper floret and not expanding throughout, 

2-keeled, producing greenish or purplish, firm 

longitudinal lines along the keels; keels finely 

denticulate, the median hyaline area not splitting 

lengthwise in the middle. Lodicules cuneate, truncate, with a wide, concave, horizontal area, the 

distal margins wing-like and protruding behind 

the rather swollen adaxial sides. 

Upper jloret female or cleistogamous? (andrecium reduced to 3 tiny, transparent anthers), 

narrowly ovoid, 1.8-2 mni long, 0.8 mm wide, 

plano-convex, acute. Lemma ovate, plano-convex, 

acute, papery or finely crustaceous, opaque, 

finely papillose, not tightly embracing the palea, 

firmer in texture than the lemma of the lower 

floret, nerveless or finely 3-nerved. Palea rather 

flat, of the same texture as the lemma, with 

narrow hyaline margins and apex, nerveless or 

finely 2-nerved. Lodicules smaller but similar to 

those of the staminate floret. Caryopsis 1.5 mm 

long, narrowly ovoid, light brown; embryo half 

the length of the caryopsis; hiluni oblong-ovate, 

subbasal. 

DI~TRIBuT~~N. - Besides the type collection 

from Bahia, an additional gathering at Kew (Glaziou 20113) is labeled as coming from Minas 

Gerais. This specimen, which we have not seen, 

was examined and confirmed by Stephen A. Renvoize of the Royal Botanic Gardens, Kew, England. 

PARATYPES.- BRAZIL. BAHIA: Municipio de 

Livramento do Brumado, km 5 da Rodovia Livramento do Brumado-Rio de Contas, Mori et al. 

12251 (MO); Municipio de Rio de Contas, 9-1 1 

km ao N de Rio de Contas, na estrada para o 

povoado Mato Grosso, Mori et al. 12348 (MO). 

DxscussIoN.-On~y a few plants of this species 

were available for study. It is apparently closely 

related to 0. pterigodium since both species share 

a similar overall aspect, similar type of inflorescence and spikelets, and habitat. Both species 

occur in marshy, wet ground or on the stream 

banks; but sometimes they grow attached in tufts 

to the stones in strong stream currents. A feature 

observed only in these two species is the presence 

of a reduced andrecium in the upper hermaphrodite floret (which may also be only female 

or cleistogamous). In spite of the similarity in 

several features between these species, the vegetative and the sexual organs of 0. aquaticum are 

obviously more adapted to conditions of running 

water as evidenced by the reinforcement of 

strength in the basal stolons, which show an 

alternation of a few abbreviated internodes with 

long ones. 

The increase of the plant's resistance to water 

pressure can also be observed in the transverse 

veins, which form air chambers in the tissue of 

the adaxial surface of the sheath, a feature known 

in other grasses such as Paspalum millegrana 

Schrader. The acicular leaves are filled with a 

uniform spongy parenchyma, which is also found 

in the upper part of the leaf-sheath. The adaxial 

side of the blade can be ascertained only by a 

minute groove that occurs on that surface of the 
NUMBER 57 7 

cylinder. This represents an extreme example of 

the acicular mode of specialization in grass leaves, 

according to Metcalf (1 960). 

Otachyrium grandijl orum 

Sendulsky 8c Soderstrom, new species 

FIGURE 2 

TYPE COLLECTION.-BRAZI L. GOIAS: ChaASI~ C hapada dos Veadeiros, 24 km NW of Veadeiros, 

road to Cavalcante, 14"S, 47"W, 22 October 

1965, H.S. Irwin, R. Souza €3 R. Reas dos Santos 

9515 [holotype, US, sheet no. 2528885; isotypes, 

MO, sheet no. 2400649, UB, sheet no. 10691]. 

Gramen perenne, culmis gracilibus, erectis, 

20-50 cm altis, egregie usque ad 1 m. Foliorum 

laminae involutae vel aciculatae, non cylindricae, 

adscendentiae, 3-20 cm longae, -1 mm latae, 

glabrae. Paniculae gracilae, pauciflorae, 2-5 (1 3) 

cm longae, ramulis vel pedicellis distantibus, tenuibus. Spiculae 4-7.5 (8.5) nim longae, 2-7.5 

mm latae, rotundato-ovatae, pilosae vel glabrae, 

(sub maturitatis tenipus diverso glumarum valvularumque colore plus minus palido-purpuracentes); gluma prima ovata, ]/4 longitudinis spiculae aequans, 1 -5-nervia; gluma segunda late 

ovata, semiglobosa, acuniinata, spiculae basin 

einges, 'h longitudinis spiculae aequans, irregulariter 5-7-nervia. Flosculus inferus 8; lemma 

ovatum, oblongum, spiculum aequans, irregulariter 3-7-nerviuni; palea alata, ovata, vel orbiculata, binervia, bicarinata, marginibus membranaceis, latissimis, undulatis, pallido-purpureis, pilosis vel glabris, secus carinas longeciliatis. Flosculus superus a*, plano-convexus; lemma herbaceum, pallidurn, oblongo-ovatum, acutiusculum, 

hyalinum, glabrum; palea hyalina, tenuis, plana. 

ish, thick, short hairs; adjacent prenodal zone 

rather swollen, smooth, stramineous. Leafsheaths 

shorter than the internodes, loose around the 

culms, striate, glabrous, with 2 small auricles at 

the summit; margins membranous, glabrous or 

densely ciliate; auricles with a tuft of dense, white 

hairs at the apex. Ligule membranous, truncate, 

0.4 mm long, finely denticulate at the apex, 

occasionally with a hairy line extending on the 

abaxial side of the sheath from the hairy auricle 

downwards to the niidnerve and forming a Vshaped, hairy abaxial collar. Leafblades 3-20 cm 

long, usually -1 mm wide, glabrous, with proniinent nerves, strongly infolded or acicular, with 

a narrow adaxial furrow less than half the width 

of the blade, leaving free inconspicuous margins 

only, rarely flat, up to 7 nim wide; midnerve not 

prominent. 

Panicles few-flowered, 2-5 (1 3) cm long, -2- 

3 (7) cni wide, with a few short, spreading 

branches or pedicels borne along the glabrous 

axis. Pedicels unequal, mostly in pairs, discoidal 

or shallowly cup-shaped at the apices. 

Spikelets 4-7.5 (8.5) mm long, 2-7.5 mm wide, 

mostly 2-flowered (rarely with a 3rd rudimentary 

terminal floret consisting of only 2 scales -3.5 

mm long, 0.5 mm wide), when mature, broadly 

ovate to orbicular in outline, bi- or plano-convex, 

with an ovate, salient, light-colored central part 

(lemma of the lower or of the upper floret, 

depending on the side exposed) and of broadly 

ovate, light-colored, hyaline, pilose, encircling 

wings (palea of the lower floret), otherwise ovate 

or oblong. Glumes subequal, membranous, convex, nearly subglobose, glabrous or with a few 

white hairs. Lower glume w1/4 the length of the 

spikelet, broadly ovate, acute, 1 -3(.5)-nerved. Upper glume broader and longer than the first, 

acute, irregularly 5-7-nerved. - 

Erect, slender, slightly tufted perennials, 20- Lower floret staminate. Lemma narrowly ovate, 

50 cni (exceptionally up to 1 in) tall, with short, 4-6.5 (7.5) mm long, 1-1.8 mm wide, navicular, 

syrnpodial rhizomes and small cataphylls at the convex, somewhat keeled, papery, glabrous, 

base of new shoots; roots whitish, thick. Culms greenish, opaque, irregularly 3-7-nerved, often 

simple, terete, glabrous, striate, 1-1.5 nim in longer than the lemma of the upper floret; mardiameter. Nodes constricted, yellow or sometimes gins papery. Palea broad, sometimes up to 8.5 

purplish, with dense, antrorsely appressed, whit- mm long, 7 mni wide, membranous, hyaline, 
8 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURE 2.-Otachyrium grandzjlorum: a, habit of plant; b, andrecium of upper floret; c, gynecium 

of upper floret; d, lodicules of upper floret; e, branch of the panic1e;J caryopsis, hilum side; g, 

caryopsis, embryo side; h, leaf midregion, showing ligule; i, upper floret, lateral view; j, upper 

floret, lemma side. All drawings based on Irwin et al. 9329 (US). 
NUMBER 57 9 

white or light purplish, pilose or glabrous, with 

wide, undulate margins, expanding broadly beyond the lemma; nerves 2, forming along their 

length a ribbon-like, rather dark, alate-carinate, 

densely ciliate rim, the central canaliculate part 

of the palea spliting lengthwise in the middle and 

forming two broad wings that embrace the upper 

floret. Lodicules less differentiated than those of 

the upper floret, -0.3 mm long, cuneate, truncate, with a more or less wide apical area and 

rather raised median and distal margins, otherwise a rather amorphous mass. 

Upper floret hermaphrodite, 4-7 mm long, 1 - 

2 mm wide, narrowly ovoid, plano-convex, pale 

or greenish, rather shiny. Lemma strongly convex, acute, papery, semitransparent, 3-nerved, 

not tightly embracing the margins of the palea. 

Palea flat, 2-nerved, thin, with convexly reflexed 

margins, narrowing towards the base. Lodicules 

cuneate, -0.3 mni long, with a wide, deep, funnel-shaped, horizontal area and with slightly 

raised median margins, the distal margins winglike, protruding behind the swollen ridges of the 

abaxial sides. Caryopsis 2.5 mm long, 1.5 mm 

wide, obovoid, pale; embryo half the length of 

the caryopsis; hilum prominent, dark, subbasal. 

DIsTRIBUTIoN.-Northern and central Brazil, 

Venezuela. 

PARATYPES.-BRAZIL. AMAZONAS: parte 

baixa ou pe da Serra Araca, arredores da pista 

de pouso, Rosa & Cordeiro 1603 (NY). GOIAS:ASI~ 

Chapada dos Veadeiros, -12 km NW of Veadeiros, Irwin et al. 9329 (MO, UB, US); -20 km 

N of Veadeiros, Irwin et al. 1259? (NY, US); 

Municipio Alto Paraiso, Heringer et al. 2381 

(IBGE, SP). RORAIMA: Rio Anaua, afluente do 

Rio Branco, Pires et al. 14448 (US; sheet numbers 

278 1363, 278 1364, and 2781 372). VENEZUELA. AMAZONAS (Territorio Federal): Canaripo, 

lado sur del Rio Ventuari, Steyermark et al. 

113821 (MO). ATABAPO: W de la cabecera del 

Can0 Cotua (Yapacana), Huber 1801 (MO); 

alrededores de Canaripo, margen izquierda (Sur) 

del bajo Rio Ventuari, a unos 20 km al E de la 

confluencia con el Rio Orinoco, Huber 1879 

(MO); cabecera del Can0 Cotua hasta el pie occidental del Cerro Yapacana, Huber 1542 (MO), 

1680 (MYF); southeastern bank of the middle 

part of Can0 Yagua, at Cucurital de Yagua, Davidse et al. 17392 (MO), 17420 (MO); lower part 

of Can0 Yagua, Chipital, Davidse et al. 17312 

(MO); area between the western base of Cerro 

Yapacana and the headwaters of Cano Cotua, 

Davidse et al. 17212, 17234, 17254 (MO); upper 

portion of Can0 Caname, Davidse et al. 17125 

(MO); Cucurital de Caname, south bank of the 

middle part of Can0 Caname, Davidse et al. 16890 

(MO); Can0 Caname (afluente derecho [oriental] 

del medio Rio Atabapo), Huber et al. 3641 (MO). 

CASIQUIARE: al U' del medio Rio Temi, aprox. a 

unos 5 km del rio, Huber ?409 (MO). 

DIscussIoN.-This species is placed in the 

morphological group characterized by opaque, 

yellowish, not indurate lemmas, and is close to 

0. aquaticum and 0. pterigodium. Most of the 

Brazilian material examined has flowered after 

burning and the flowering culms generally arise 

from a short burnt stock. The plants are weak 

and small, with one or two fine culms. 

None of the specitnens that we have examined 

from Venezuela, except Davidse et al. 17234, 

show signs of having been burned. The plants 

are mostly all more robust, some up to 1 m tall, 

and with more developed basal parts, larger inflorescences and occasionally with some flat, wide 

leaves. In these specimens the leaves vary from 

plant to plant; even within the same individual 

there may be flat or somewhat involute or nearly 

acicular leaves. 

The size and general aspect of the spikelet 

depend considerably on its state of maturity; 

unfortunately nearly all of the material that we 

studied was immature. The few mature spikelets 

that we observed look remarkably like real petaloid flowers with their light purplish, transparent wings. 

Otachyrium piligerum 

Sendulsky 8c Soderstrom, new species 

FIGURE 3 

TYPE COLLECTION.-BRAZIL. GOA~S: Municipio Formosa, 24 km ao norte da Vila JK, no 

km 147 da RB-020, 15"02'S, 47"04'W, alt. 500 
10 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURE 3.--Otachyrium piligerum: a, habit of plant; b, section of axis with branch, showing 

papillose hairs; c, leaf niidregion, showing incomplete ligule: d, hermaphrodite flowger of upper 

floret; e, lodicules of upper floret:f; andrecium of lower floret; g, palea of lower floret, showing 

large folded margins: h, caryopsis, hilum side; i, caryopsis, embryo side. All drawings based on 

Valls et al. 6009 (CEN). 
NUMBER 57 11 

11.1, J.F.M. Valls, R.F.A. Veiga €9 G.P. Silva 6009 

[holotype, CEN; isotypes, K, RB, SP, US]. 

Gramen perenne?, 25-55 cm altum, culmis 

gracilibus, fasciculatis, erectis, laxe caespitosis; 

culmus unus inter alios geniculatus et ad nodes 

non radicans; culmi ceteri erecti, non geniculati, 

2" et 3" nodis valde radicantes et ramificantes, 

rami novi necnon ramificantes. Foliorum laminae anguste lanceolatae, (3)s-15 cm longae, 4- 

8 cm latae, acutae, glabrae vel sparsim pilosae. 

Ligula folioruin superiorum incompleta, pars 

niediana carens. Panicula multae, axillares, moderate ramosae, pauciflorae, laxa, 3-15 cm longae, 4- 12 cni latae; axis primarius dense pilosus, 

pilis tuberculatis, -1 mm longis. Spiculae 2.5-3 

mm longae, 1.8-2.2 latae, ovatae, glabrae, gibboso planiusculae, chartaceae, margine implicato 

albo cincta. Gluma prima ovata, longitudine l/4 

spiculae aequans, acuta, angusta, obscure 1-3- 

nervia; gluma segunda late ovata, truncata, obscure 5-7-nervia, longitudine '/3 spiculae aequans. Flosculus inferus 8, lemma flosculum superum aequans, ovatum, oblongum, 2.2-2.5 mm 

longuni; palea 2.8-3 mm longae, 2.2 mm latae, 

late ovata, marginibus conduplicatis, chartaceis, 

opaco-albidis, flosculum superiorem cingens. 

Flosculus superus P", plano-convexus; lemma 

chartaceuni, ovatum, gibbosum, acutiusculum, 

nigrescente castaneum, nitentum, subnervium; 

palea minus chartacea, plana. 

Erect, slender, nonrhizomatous perennials? 

(25) 42-55 cni tall, branching from the second 

or third node and all subsequent nodes and at 

each axil, giving rise to one or two branches and 

an axillary inflorescence. Roots dense, fascicled. 

Culms terete, rather grooved, sparsely pilose 

when young, afterwards glabrous, 1-3 mm in 

diameter; usually one of the culms somewhat 

geniculate at the first, never-rooting, node, the 

other culms always straight and mostly with long 

internodes and strongly rooting at the first, second, and third nodes. Nodes constricted, usually 

light-colored, glabrous to finely pilose, the adjacent prenodal zone rather swollen, pilose, the 

hairs antrorse, appressed, whitish. Leafsheaths 

generally shorter than the internodes, loose, 

striate, densely ciliate on the margin, glabrous or 

sparsely pilose, the hairs fine, simple or papillose. 

Ligule of the lower leaves a short membrane, 

-0.5 mm long, finely denticulate at the apex, 

asymmetrically arcuate; of the upper leaves incomplete and present only as two short, ciliate, 

asymmetrically situated membranes at the sides 

of the sheath, absent from middle part. Leaf 

blades lanceolate, (3) 8-15 cm long, 4-8 mm 

wide, attenuate, opaque, glabrous or sparsely 

pilose; hairs long, fine, stiff, whitish, the midnerve differentiated on the abaxial side only. 

Panicles numerous, axillary, open, sparsely 

flowered, 3-15 cm long, 4-12 cm wide, the axis 

usually sinuous, the surface finely denticulate and 

pilose; hairs persistant, - 1 mm long, white, stiff, 

papillose; branches glabrous, dark, ascending or 

spreading, distichous or somewhat verticillate, 

fascicled or solitary. Pedicels very unequal, sinuous, occurring mostly in pairs or in three's at 

the base or along the branch, the longer -20 

mm long, the shorter 2-5 mm long, with the 

apices minutely discoid. 

Spikelets ovoid, 2.5-3 mm long, 1.8-2.2 mm 

wide, glabrous, with an ivory to dark brown, 

shining, convex central part (lemma of the upper 

floret), with external, thick, light-colored, tightly 

encircling margins, -0.5 mm wide (palea of the 

lower floret). Glumes short, membranous. Lower 

glume ovate, acute, slightly keeled, -'/4 the length 

of the spikelet, much narrower than the second 

glume, obscurely 1 -3-nerved. Upper glume 

broad, truncate, -I/?, the length of the spikelet, 

with 5-7 obscure nerves. 

Lower floret staminate. Lemma equal in length 

to the upper floret, oblong-ovate, naviculate, 

2.2-2.5 mm long, 1 mm wide, crustaceous, whitish, inconspicuously 3-nerved, with two prominent, opaque, rather thick, longitudinal ridges 

and a canaliculate, membranous median part; 

margins membranous, convexly reflexed. Palea 

broad, without hyaline wings, 2.8-3 mm long, 

2.2 mm wide, 2-nerved, the nerves bearing firm, 

glabrous, strongly reflexed ribbon-like margins 

along their length, the central part hyaline. Lod- 
12 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

icules -0.5 mm long, cuneate, irregularly truncate, with a rather wide horizontal area and 

raised median and distal margins. 

Upperfloret hermaphrodite, 2.6-2.8 mm long, 

- 1.5 mm wide, crustaceous, strongly plano-convex, light or dark brown. Lemma convex, beaklike, shining, obscurely 3-nerved, embracing the 

margins of the palea. Palea thinly crustaceous, 

flat, with convexly reflexed margins narrowed 

toward the base. Lodicules similar to those of the 

staminate floret but with a wider and more concave horizontal area. Caryopsis 1.8-2 mm long, 

1 mm wide, broadly ovate, plano-convex, brownish; embryo more than half the size of the caryopsis; hilurn prominent, dark, ovate, subbasal. 

DIsTRIBuTI0N.-Known only from the type 

collection made in Goias, Brazil. 

DrscvssIoN.-Otachyrium piligerum bears a superficial resemblance to 0. succisum but is readily 

distinguished by the pilose axis of the inflorescence, the continuously branching habit, wider 

and thicker margins of the palea of the lower 

floret and unique incomplete ligule of the uppermost leaves. 

Otachyrium pterigodium (Trinius) Pilger 

FIGURE 4 

Otachyrium pterigodium (Trinius) Pilger, 193 1 :239. 

Panimm pterigodium Trinius, 1826:227 [type: Brazil, Minas 

Gerais, inter i'illa Fanado et Contendas, in campis S. 

Philippi; holotype, LE, not seen; fragment of the type, US 

ex LEI. 

Pterigodium junceum Nees ex Trinius, 1826:228 [notiien 

nudum]. 

Otachyrium junceum Nees, 1829:272 [type: presumably the 

same as that of Panicum pterigodium Trinius, above]. 

Panicum neurophyllum Spruce in Martius, 1877:254 [nomen 

nudum]. 

Erect, slightly tufted perennials with slender 

rhizomes, 30-55 cm high. Culms decumbent, 

branching and rooting at the lower nodes, terete, 

filiform, glabrous, striate, 1-2 mm in diameter. 

Nodes constricted, brown or nearly black, glabrous or pilose, the adjacent prenodal zone 

slightly swollen, smooth, glabrous, stramineous 

or purplish below; hairs, when present, dense, 

whitish, rather long, antrorsely appressed. Leafsheaths longer or shorter than the internodes, 

striate, glabrous, loose around the culms, ciliate 

along the upper margins, slightly auriculate; auricles with dense tufts of long hairs on the niargins, the hairs -5 nim long. Ligules papery, -0.5 

mm long, truncate, irregularly denticulate and 

finely ciliate at the apex, with dense, long, white 

hairs behind. Leafblades flat, narrow, convolute, 

8- 17 cm long, 2 mm wide, glabrous, sulcate. 

Panicles narrowly contracted, many-flowered, 

6-7 cm long, -0.8 cm wide, the axis glabrous or 

scaberulous, striate; branches rather long, ascending, adherent to the main axis, the first 

branch sometimes distant below. Pedicels unequal, mostly in pairs, occurring densely at the 

base of the main branches and more sparsely 

toward the summit. 

Spikelets ovoid, -2 nini long, 1.3 mni wide, 

yelloivish green or purplish, glabrous, rather 

opaque. Glumes subequal, membranous, -'I3 the 

length of the spikelet. Lower glume ovate, keeled, 

acute, 1 -nerved, finely denticulate along the 

keels, smaller than the second glunie. Upper 

glume broader, keeled, acute, 3-nerved, finely 

denticulate along the keels. 

Lower floret staminate, more or less laterally 

compressed. Lemma ovate, navicular, -2 mm 

long, 0.7 mm wide, keeled, acute, yellowish 

green, obscurely 3-nerved, finely denticulate on 

the keels, the margins papery. Palea broad, 

winged, up to 2 nini wide, 2-nerved, keeled along 

the nerves, the keels slightly firmer and ribbonlike, opaque, finely ciliate, the central part hyaline, canaliculate, sometimes splitting lengthwise 

at maturity and embracing the margins of the 

upper floret. Lodicules cuneate, -0.25 mm long, 

with a rather wide, concave, horizontal area and 

slightly raised, thin, lateral margins. 

Upper floret probably female (anthers present 

as tiny, open structures less than 0.1 mm long), 

-2 mm long, 0.6 mm wide, thinly crustaceous, 

ovoid, acute, yellow or greenish, nearly equal in 

length to the lower floret. Lemma convex, a little 

smaller than the lower floret, obscurely 3-nerved, 
NUMBER 57 13 

FIGURE 4.--Otachyrzum pterzgodium: a, habit of plant; b, branch of the panicle; c, upper floret, 

lemma side; d, upper floret, palea side; e, hermaphrodite flower of upper floret, showing tiny 

anthers;J lodicules of upper floret; g, lemma of lower floret; h, palea of lower floret, showing 

enlarged margins; i, andrecium of lower floret; j, lodicules of lower floret; k, leaf midregion, 

showing ligule; 1, caryopsis, hilum side; m, caryopsis, embryo side. All drawings based on E. 

Pereira 1464 (US). 
14 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

not tightly embracing the sides of the palea, with 

a rather shiny basal part, the upper part covered 

by short, sometimes dark-colored tubercles, the 

margins membranous. Palea membranous, flat, 

nerveless, the margins reflexed. Lodicules similar 

to those of the lower floret. Caryopsis - 1.5 mm 

long, 0.6 mm wide, ovoid, light brown; embryo 

-*/z as long as the caryopsis; hilum oblong, dark, 

subbasal. 

DIsTRIBuTI0N.-Brazil: Minas Gerais; Amazonas (?). 

ADDITIONAL SPECIMENS SEEN.-BRAZIL: 

AMAZONAS: Rio Negro, inter S. Gabriel et Barcellos, Spruce 2050 (fragment, US). MINAS GERAIS: Diamantina, Romariz 01 18 (US); Diamantina, Tombador, Glaziou 201 13 (US, sheet numbers 1 162988, 1 126870, 1715299, 1341 373, 

1280006); Diamantina, Serra do Rio Grande, 

Mexia 5812 (US); Diamantina, Agua Limpa, E. 

Pereira 1463 (R, US); 2 km depois de Soupa na 

estrada para Sao Joao de Chapada, Burman 61 1 

(SP); 5 km de Diamantina, 2 km ao sul da linha 

ferroviaria a Conselheiro Mata, Burman 554 (SP); 

Serra de Santo Antonio, 2-5 km ao leste da 

cidade de Diamantina, Burman €3 Sendulsky 719, 

720, 721B, 723 (SP); Serra do Espinhaco, Serra 

do Cipo, km 120, - 145 km N of Belo Horizonte, 

Irwin et al. 20290, 20291 (NY). 

DIscuss1oN.-The flowering of 0. pterzgodium 

has been observed in situ by the first author 

when innumerable purplish, feathery stigmas 

exserted laterally near the tips of the florets at 

anthesis gave a light purple coloration to dense 

tufts of this grass. The plant mostly occupies wet, 

marshy grounds and margins of streamlets. It 

also occurs in strong water currents in large tufts 

affixed to stones. 

As all specimens of 0. pterigodium come from 

the state of Minas Gerais within a habitat of 

highland streams and "campos rupestres," the 

single collection of Spruce 2050 from Amazonas 

is noteworthy. 

Brown (1977) reported a non-Kranz type of 

leaf anatomy for this species, with a 13C/'2C ratio 

of -27.2. 

Otachyrium seminudum Hackel 

ex Sendulsky 8c Soderstrom, new species 

FIGURE 5 

TYPE COLLECTION.-BRAZIL: GOIAS: Serra

dos Cristais, 2 km N of Cristalina, 17"S, 48"W, 

elev. 1250 m, 2 March 1966, H.S. Irwin, J.W. 

Grear Jr., R. Souza €3 R. Reis dos Santos 13321 

(holotype, US, sheet no. 2529147; isotype, NY). 

Gramen perenne, robustum, 80-150 cm altum, Foliorum laminae lineares, acutae, firmae, 

scabriusculae. Panicula lineari-contracta, multiflora, 12-30 cm longa, 3-5 cm lata, ramis adscendentibus vel appressis, ad basin ramulis instructis, spiculis ad basin ramorum congestis. Spiculae 2.4-2.7 (3) mni longae, 1-3 mm latae, 

ovate-alatae vel ovatae, gibboso-planiusculae, sub 

maturitatis tempus diverso glumarum valvularumque colore plus minus violascentes. Gluma 

prima ovata, Ih longitudinis spiculae aequans, 

acuta, 1 -3-nervia; gluma segunda late ovata, 

truncata, 5-nervia, lh longitudinis spiculae aequans. Flosculus inferus $, lemma oblongo-ovatum, spiculum aequans, membranaceo-papyraceum, 3-nerviuni, palea 3 mm longa, 3 mm lata, 

rotundado-ovata, latissima, binervia, marginibus 

membranaceis, undulatis, glabris, pallido-purpureis, carinis inflexis, scaberulis vel puberulis 

firmisque. Flosculus superus EF, lemma chartaceum, ovatuni, gibbosuni, acutiusculum, nigrescenti-castaneum vel fusco-purpureum, nitentum, 

subnervium, apice pallido; palea minus chartacea, plana. 

Erect, robust perennials, 80-1 50 cm tall, with 

a well-developed rhizomatous base. Young extravaginal shoots enclosed in short, obtuse, glabrous, aphyllous, yellowish scales arising from 

the upper part of curved, scaly rhizomes; roots 

whitish, extremely thick. Culms simple or sometimes branching at the nodes, terete, rigid, rather 

stout, glabrous, striate, up to 1 cm in diameter. 

Nodes with a swollen, shining, yellow to brown, 

glabrate adjacent prenodal zone grading upward 

into a wide, densely pubescent ring; the hairs 
NUMBER 57 15 

FIGURE 5.--Otachyrium seminudum: a, habit of plant; 6, andrecium of lower floret; c, lodicules 

of lower floret; d, palea of lower floret, showing enlarged margins; e, part of branch of the 

panicle (enlarged, not to scale);f; upper floret, lemma side (enlarged, not to scale); g, upper 

floret, palea side (enlarged, not to scale); h, andrecium of upper floret; i, gynecium of upper 

floret; j, lodicules of upper floret with schematic transverse section; k, caryopsis, embryo side; 

I, caryopsis, hilum side; m, leaf midregion, showing ligule. All drawings based on Inuin et al. 

13321 (US). 
16 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

long, white, antrorsely appressed, often papillose, mostly straight or sometimes flexuous on 

the lower part of the node. Leafsheaths generally 

shorter than the internodes, loose around the 

culms, striate, mostly densely pilose at the base; 

hairs long, sometimes sparse, borne between the 

nerves, generally antrorsely appressed; margins 

densely ciliate; adaxial area near the ligule sometimes with dark, brown spots. Ligules papery, -1 

mm long, truncate, irregularly denticulate at the 

apex, split longitudinally, dark yellowish, shining 

and sometimes with brown spots similar to those 

of the inner surface of the sheath. Leafblades 

linear, (5) 20-40 cm long, 5-10 mm wide, firm, 

rigid, with inrolled margins, gradually narrowing 

toward the sharp, hard point, slightly scabrid, 

with a few long hairs scattered between the 

nerves and along the margins; midnerve not 

prominent. 

Panicles narrowly contracted, 12-30 cm long, 

3-5 cm wide, the axis finely and mostly retrorsely 

scabrid; branches ascending, fascicled, flexuous, 

adherent to the axis and held at a more or less 

uniform angle; each branch consisting of the 

stout main branch, invariably containing at its 

base two pairs of shorter, half as thick, sometimes 

dark-colored, many-flowered supplementary 

branchlets, one pair on each side, the pair sometimes also consisting of one branchlet and a pair 

(rarely 3) of short pedicels, arising in place of 

another supplementary branchlet, the base of the 

branches thus with many approximate spikelets 

appearing densely crowded, the first branch 

sometimes distant below. Pedicels unequal, 

mostly in pairs, borne at the base or along the 

branch, shallowly cup-shaped at the apices. 

Spikelets 2.4-2.7 (3) mm long, 1-3 mm wide, 

the convex side with a dark brown, almost black, 

shining, gibbous, ovate-lanceolate central part 

(lemma of the upper floret) and broadly ovate or 

recurved, encircling, light-colored, hyaline wings 

(palea of the lower floret); the opposite side with 

a papery, whitish scale (lemma of the upper 

floret). Glumes short, subequal. Lower glume -'/3 

the length of the spikelet, broad, slightly acute, 

1 -3-nerved, keeled, finely denticulate along the 

keels. Upper glume broader and a little longer 

than the first, truncate, 5-nerved, keeled, finely 

denticulate along the keels. 

Lower jloret staminate. Lemma oblong-ovate, 

1.7-2.5 mm long, 0.8-1 mm wide, navicular, 

papery, whitish, opaque, 3-nerved, sometimes 

longer than the upper floret; margins papery. 

Palea broad, up to 3 mm long, 3 mm wide, with 

membranous, hyaline, white or light purplish 

margins; nerves 2, forming ribbon-like, rather 

dark, alate-carinate, finely denticulate rims; the 

central canaliculate part of the palea at maturity 

splitting lengthwise in the middle, the margins 

extending broadly to the sides of the upper 

floret. Lodicules cuneate, truncate, with a wide 

horizontal area and thin, slightly raised distal 

margins. 

Upperfloret hermaphrodite, 1.6-2.2 mm long, 

0.8- 1 mm wide, ovate, crustaceous, strongly 

plano-convex, light or dark to almost black. 

Lemma gibbous, smooth, shining, obscurely 3- 

nerved, loosely embracing the margins of the 

palea, the apex attenuate to a whitish beaklike 

point. Palea thinly crustaceous, flat or slightly 

concave, with convexly reflexed margins, narrowed toward the base. Lodicules broadly cuneate, truncate, with a wide irregular, horizontal 

apical area and thin wing-like, adaxial distal lobes 

protruding behind the swollen abaxial side. Caryopsis 1.7 mm long, 1.2 mm wide, ovoid, pale; 

embryo rather indistinguishable, -'/2 the length 

of the caryopsis; hilum prominent, dark, obovate, 

subbasal. 

DIsTRIBUTroN.-Brazi~: Goias and Mato 

Grosso. 

PARATYPES.-BRAZIL: locality unknown, 

Glariou 22587 [must be 225371 (US). DISTRITO 

FEDERAL: Parque Municipal do Gama, -20 km 

S of Brasilia, Irwin €3 Soderstrom 5796 (NY); -25 

km SW of Brasilia, Irwin et al. 12993 (NY, SP, 

US); Brasilia, 3 km SE da Reserva Ecologica do 

IBGE, Heringer et al. 1873 (IBGE); Bacia do Rio 

Sao Bartolomeu, Heringer et al. 4329, 4637, 

5117, 6134 (IBGE). GOIAS: locality unknown, 

1894-1 895, Glaziou 22497, 22537 (fragments, 

US sheet no. 1126933); Fazenda de Lamarao, 
NUMBER 57 17 

Glariou s.n. (US sheet no. 1160498); Serra dos 

Cristais: -6 km from Cristalina, Irwin et al. 9753 

(US), 9887 (NY, SP, US); Chapada dos Veadeiros, -40 km N of Alto do Paraiso, Irwin et al. 

331 11 (SP); Mun. Rio Verde, BR-060, km 172, 

entre Rio Verde e Acreuna, Valls et al. 5144 

(CEN, K, SI, SP, US). MATO GROSSO: Rio do 

Sangue, Linha Teleg., Kuhlmann 1753 (US); 

Margin of Rio Ibo, NW of Sao Lourcngo, Chase 

11958 (US). 

 DISCUSSION.-^. seminudum is the most robust 

of all species in the genus except for the unusually 

large form of 0. versicolor, known only from 

Paraguay. This species resembles, and has often 

been confused with, 0. versicolor but differs 

mainly in the narrowly contracted panicle, which 

may sometimes be spike-like, in the rather short 

upwardly appressed branches and the somewhat 

crowded disposition of the spikelets along the 

main axis. When fresh, the mature spikelets are 

funnel-shaped and flower-like as a result of the 

fine, transparent and mostly purplish, large paleas of the lower florets. 

The earlier herbarium sheets of this species 

(Glariou 22497 and 22537), of which fragments 

were examined at US, bear the specific epithet, 

seminudum, given by Dr. E. Hackel to this species 

for which, however, he never published a description. 

In a note on the herbarium sheet of Irwin et 

al. 12993 (US), Brown noted that the leaves have 

a ''C/''C ratio of -25.1 and non-Kranz type of 

anatomy. 

Otachyrium succisum (Swallen) 

Sendulsky & Soderstrom, new combination 

FIGURE 6 

Panicum succisurn Swallen, 1952:391 [type: the same as that 

of P. inaequale Pilger]. 

Panicum inaequale Pilger, 1902:133 [type: Brazil, Mato 

Grosso, Piava, April 1899, H. Meyer 499; holotype, B, not 

seen; fragment of the type, UB ex B; not P. inequale 

Mueller, 1874: 1891. 

Otachyrium inaequale (Pilger) Pilger, 1931:239. 

Erect, stout annuals, leafy at the base, of a 

somewhat semirosette type with one terminal 

inflorescence, rarely with one or two small panicles on the basal lateral branches, lO(45)-60(85) 

cm tall; roots dense, fascicled. Culms rather flat, 

glabrous, striate, 3-8 mm in diameter, sparingly 

branching from the lower nodes. Nodes constricted, stramineous, pilose; hairs white, rigid, 

antrorsely appressed. Leafsheaths generally 

longer than the internodes, the lower usually 

dark purplish, loose, striate, prominently nerved, 

densely pilose; hairs white or dark purplish, 

thick, sparse, papillose, the margins not differentiated, the inner sometimes thinner and hyaline. Ligules papery, -0.5 mm long, truncate, 

finely denticulate at the apex. Leafblades longlanceolate to linear, (2)lO-30 cm long, 5-1 5 mm 

wide, gradually attenuate toward the apex, glabrous to densely pilose on both surfaces; hairs 

long, stiff, white, papillose, the midnerve white 

or sometimes not prominently differentiated. 

Panicles open, sparsely flowered, 5-30 cm 

long, 5- 10 cm wide, the axis glabrous, sometimes 

sinuous, finely denticulate, the branches ascending or spreading, distichous or somewhat verticillate, fascicled or solitary. Pedicels very unequal, 

borne mostly in pairs at the base or along the 

branch, the longer -20 mm long, the shorter 2- 

5 mm long, the apices minutely discoid. 

Spikelets ovoid, 2.2-2.5 mm long, 1.2-1.5 mm 

wide, glabrous, with an ivory to dark brown, 

shining, gibbous central part (lemma of the upper 

floret) and with pale external, narrow, encircling 

margins -0.2 mm wide (palea of the lower 

floret). Glumes short, membranous, -l/3 the 

length of the spikelet, usually dark purple. Lower 

glume ovate, acute, slightly keeled, much narrower than the second glume, obscurely 1-3- 

nerved. Upper glume broad, nearly embracing the 

base of the spikelet, nerves obscure, 5-7, distally 

anastomosing. 

Lower floret staminate. Lemma equal in length 

to the upper floret, oblong-ovate, navicular, 2.2 

mm long, 0.8 mm wide, crustaceous, whitish, 

inconspicuously 3-nerved, with two prominent, 

opaque longitudinal ridges and a canaliculate, 

hyaline central part; margins membranous, re- 
18 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURE 6.-Otachyrium succisum: a, habit of plant; b, part of branch of the panicle, showing 

long and short pedicels; c, upper floret, lemma side (enlarged, not to scale); d, upper floret, 

palea side (enlarged, not to scale); e, gynecium of upper floret with 1odicules;J lodicules of 

upper floret; g, andrecium of upper floret; h, palea of lower floret, showing ribbon-like margins; 

i, lemma of lower floret; j, lodicules of lower floret; k, andrecium of lower floret; I, leaf 

midregion, showing ligule; m, caryopsis, embryo side; n, caryopsis, hilum side. All drawings 

based on Swallen 4944 (US). 
NUMBER 57 19 

curved. Palea broad, without hyaline wings, up 

to 2 mm long, 1.5-1.8 mm wide, 2-nerved, the 

nerves bearing firm, glabrous, reflexed, ribbonlike margins, the central hyaline part at maturity 

splitting lengthwise in the middle, with its margins adhering to the upper floret. Lodicules 0.3 

mm long, cuneate, irregularly truncate, with a 

broad, concave horizontal area and slightly raised 

median and distal margins. 

Upperfloret hermaphrodite, 2.1-2.2 mm long, 

1.2 mm wide, crustaceous, strongly plano-convex, light or dark brown. Lemma gibbous on the 

back, beaklike, shining, obscurely 3-nerved, embracing the margins of the palea. Palea thinly 

crustaceous, flat or slightly concave, with convexly reflexed margins narrowed toward the 

base. Lodicules similar to those of the staminate 

floret. Caryopsis 1.5 mm long, 1 mm wide, 

broadly ovoid, plano-convex, brownish; embryo 

half the size of the caryopsis; hilum prominent, 

dark, ovate, subbasal. 

DIsTRIBuTI0N.-Guyana, French Guiana, 

Surinam, northern and central Brazil. 

ADDITIONAL SPECIMENS SEEN. -BRAZI L. 

GOIAS: Serra do Morcego, Corrego Estrema, ~38 Serra do Morcego, Corrego Estrema, -38 

km NE of Formosa, Irwin et al. 15176 (NY, US), 

Municipio Natividade, proximo a Natividade, a 

3 km ao norte, na estrada para Dianopolis, Valls 

et al. 6641 (K, RB, SI, SP, US). MARANHAO: 

Porto Franco, Swallen 3869 (US); Carolina, Swallen 3872 (US), Pires & Black 2550 (US); Carolina 

to Sao Antonio de Balsas, Swallen 3991 (US), s.n. 

(US, sheet no. 1817712). MATO GROSSO: Barra 

de Garcas, Xavantina road, 25 km from Xavantina, Hunt 5935 (K, NY, SP, US); 25 km S of 

Xavantina, Irwin et al. 17072 (US). PARA: E of 

Para, Meseiaria?, Huber? 2330 (US); Curralinho, 

Pires 1227 (US, sheet numbers 2205585, 

2487500); Marajo Island: Swallen 6966 (US), 

Estate Gavinho, Goeldi 226 (US); Fazenda Camburupy, near Soure, Swallen 4944 (US), Soure, 

Swallen 4991 (US), Rio Camara, Fazenda Curupatuba, Black 50-9886 (US), Rio Arari, Fazenda 

Tuiniu, Black et al. 52-14241 (US). GUYANA: 

Rupununi, Dirven 220 (US). FRENCH 

GUIANA: Route de Sinnomary, Chemin Marosipetit pont, Hood s.n. (K); Route de Sinnomary, 

Pariacobo a Cote, Montayne Carapa, s.coll. (NY). 

SURINAM: Sapaliwini, on Brazilian frontier, 

Oldenburger et al. ON 287 (NY). 

DIscussIoN.-P~ants of 0. succisum inhabit wet 

grounds, flooded fields and margins of ponds 

and streams. The species most resembles 0. piligerum but can be distinguished from it and all 

other species by its annual habit, lack of rooting 

on the lower nodes, absence of rhizomes or stolons, semirosette habit with a leafy basal part and 

usually one terminal inflorescence, and the glabrous axis of the panicle. The striking difference 

in length between the pedicels of each pair is a 

further characteristic that differentiates 0. succisum from all species except from 0. piligerum. 

Brown (1 977: 17) reported this species (as 0. 

inaequale) to have a non-Kranz anatomy with a 

13C/12C ratio of -26.8. This was based on a 

study of Goeldi 226. 

Otachyriurn versicolor (Doell) Henrard 

FIGURE 7 

Otachyriurn versicolor (Doell) Henrard, 194 1 :5 1 1. 

Panicum versicolor Doell in Martius, 1877:254 [new name; 

type: the same as that of P. truncatum Nees]. 

Panicum truncatum Nees, 1829:2 15 [type: Brazil, Minas Geraes, fluminis (Rio) Jequitinhonha; holotype M, not seen; 

fragment of the type, US ex M; not Panicum truncatum 

Trinius, 18261. 

Erect, slender to rather robust, variable perennials, usually 20-65, but as much as 195 cm 

tall, with creeping, well-developed, shiny, scaly 

rhizomes and strong, thick, spongy roots. Culms 

rigid, terete, striate, glabrous, mostly simple, 

rarely branching at the second or third node. 

Nodes dark, constricted, glabrous or with white, 

sinuous, tightly appressed hairs. Leaf-sheaths generally shorter than the internodes, open to the 

base, loosely rolled around the culms, overlapping only at the very base, striate, scabrous, 

sometimes purplish, from glabrous to slightly 

hirsute or pilose, with rather long, sparse hairs, 

the margins glabrous or ciliate. Leafblades linear, 

4-40 cm long, 2-24 mm wide, flat, narrow at 

the base, gradually tapering above the middle 

toward the attenuate tip, obscurely nerved, with 
20 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURE 7.--Otachyrium uersicolor: a, habit of plant; b, upper floret, lemma side; c, upper floret, 

palea side; d, gynecium of upper floret with lodicules; e, andrecium of upper floret;f, lodicules 

of upper floret; g, lemma of lower floret (enlarged, not to scale); h, andrecium of lower floret; 

i, lodicules of lower floret; j, palea of lower floret, showing enlarged margins and schematic 

transverse section (enlarged, not to scale); k, leaf midregion, showing ligule; 1, palea of lower 

floret, opposite side from that shown in j; m, part of branch of the panicle; n, caryopsis, embryo 

side; 0, caryopsis, hilum side. All drawings based on Hussler 12430 (US). 
NUMBER 57 

the midnerve not clearly differentiated, slightly 

scabrid above and between the nerves, the margins finely denticulate. 

Panicles open, many-flowered, 2-30 cm long, 

2-15 (24) cm wide, the branches ascending or 

spreading, flexuous, stramineous or dark purplish, distichous, fascicled or verticillate, the axis 

light green, sulcate, glabrous, finely denticulate, 

sparsely pilose, each branch consisting of the 

stout main branch and invariably bearing at its 

base two pairs of smaller, half as thick, sometimes 

dark-colored, supplementary branchlets, one 

pair on each side, the pair sometimes consisting 

also of one branchlet and a pair (rarely 3) of 

pedicels, arising in place of another supplementary branchlet, the lower branch sometimes subtended by a few hairs and a rather long scale on 

the semi-oval scar. Pedicels unequal, mostly in 

pairs, shallowly cup-shaped at the apices. 

Spikelets ovoid, plano-convex, (1.8) 2-3.5 (4) 

rnm long, (2) 2.5-3 mm wide (when immature 

rather laterally compressed, -1 mm wide), the 

convex side with a dark brown, almost black, 

shining, gibbous, narrowly ovate central part 

(lemma of the upper floret), and with broadly 

ovate to rounded, pale, hyaline, encircling wings 

(palea of the lower floret), the opposite side with 

a pale, opaque, central part (lemma of the lower 

floret). Glumes short, subequal, sometimes purplish, glabrous, rarely with rather thick, white 

apical hairs. Lower glume -'/s the length of the 

spikelet, ovate, acute, keeled, 1 (5)-nerved, denticulate or with a few hairs along the keel. Upper 

glume broader and a little longer than the lower, 

truncate at the apex, suborbicular, 5-nerved, 

keeled. 

Lowerfloret staminate. Lemma ovate-lanceolate, 

navicular, narrowing to the base, membranous, 

whitish, opaque, sometimes purple, 3-nerved, 2- 

3.5 mm long, 0.8-1 mm wide, longer than the 

upper floret, when mature, with firm, brown, 

wide lines extending from the base to the middle 

of the lateral nerves, the margins papery. Palea 

membranous, hyaline, white or light purplish, 2- 

4 mm long, -2.5 mm wide, with 2 nerves, forming ribbon-like, rather dark, alate-carinate, inflexed rims with finely ciliate margins, the can21 

aliculate, hyaline central part of the palea, when 

mature, splitting in the middle, the halves extending broadly to the sides of the hermaphrodite floret, increasing the size of the spikelet. 

Lodicules cuneate, -1 mm long, with wide, concave, deep, somewhat funnel-shaped apical areas 

and with slightly raised median margins, the distal margins wing-like, behind the thicker abaxial 

sides. 

Upper floret hermaphrodite, narrowly ovoid, 

2-3.5 mm long, 1.5 mm wide, strongly planoconvex. Lemma gibbous, keeled, shining, light to 

dark brown, almost black, whitish toward the 

apex, obscurely 5-nerved, loosely embracing the 

sides of the palea. Palea thinly crustaceous, shining, flat or slightly concave, light to brown, with 

convexly reflexed margins, narrowing toward 

the base. Lodicules similar to those of the lower 

floret but a little smaller. Caryopsis 1.5-2 mm 

long, 1.2 mm wide, ovoid, dark yellow; embryo 

manifest, -'/z the length of caryopsis; hilum oblong, dark, subbasal. 

DISTRIBUTION.-Trinidad, Venezuela, Colombia, Bolivia, Brazil, Paraguay, and Argentina. 

ADDITIONAL SPECIMENS SEEN.-ARGENTINA. MISIONES: Posadas, inter Santa Ana et 

Loreto Municip., Ekman 644? (US); Posadas, Establecimiento Santa Ines, Parodi 4188 (US). CORRIENTES: Dep. Santo-Tome, Cuay Grande, Zbarrola 1600 (NY); Dep. San Martin, San Martin, 

Zbarrola 1675 (NY). 

BOLIVIA. SANTA CRUZ: Buenavista, Steinbach 

6643 (US), 6656 (US). 

BRAZIL. AMAZONAS: Mun. of Humaita: Rio 

Madeira, road Humaita to Labrea, km 20, Prance 

et al. 3382 (US); 6 km pela estrada 319 para 

Porto Velho, Gemtchujnicov €+ JansSen 35 (IBGE, 

SP); Gemtchujnicov 1 (SP); 500 m ao sul da BR 

230, km 4, Janssen €+ Gemtchujnicov 511 (SP). 

DISTRITO FEDERAL: east of Lagoa Paranoa, Zrwin 

et al. 11212 (NY). GOA~S: West of Rio Verde, 

near Rio Doce, Chase 12074 (US); Chapada dos 

Veadeiros, -40 km N of Alto do Paraiso, Zrwin 

et al. 33141 (NY). MATO GROSSO: between Bonito 

and Rondonopolis, Chase 11907 (US). MINAS 

GERAIS: 1845, Widgren 907, 1209 (US); Pouso 

Alegre, Hoenhe s.n. (SP, US); Diamantina, Serra 
22 

de Sao Antonio, Chase 10386 (SP, US); 5-10 km 

west of Diamantina, Serra de Sao Antonio, Chase 

10435 (US); Pocos de Caldas, Chase 10676 (US); 

S.S. Paraiso; Bau, Brade 17682 &' Barbosa (US); 

estrada Serro-Datas, 12 km depois de erro, Burman 580 (SP); Soupa, na estrada Diamantina-Sao 

Joa0 da Chapada, Burman 550; estrada para Conselheiro Mata, perto de Guinda, Burman 544 and 

570 (SP); entre km 996-997.5 da antiga linha 

ferrovia Diamantina-Corinto, Burman 761 €3 

Sendulsky (SP). PARA: Serra do Cachimbo, Pires 

et al. 6105 (US). PARANA: without locality, Dusen 

3250 (US); Pinhaes, Dusen 7778 (US); Curitiba, 

Banhado, Estacao Experimental, Swallen 8533 

(US); Ponta Grossa, Faz. Cambijoan, Brade 

19637 (US); Mun. Senges, Rio do Funil, Fazenda 

Morungava, Hatschbach €3 Lunge 5332 (US); 

Mun. Tibagi, estrada Castro-Tibagi, Fazenda 

Palmito, Hatschbach 5460 (US); Mun. Tibagi, 

Fazenda lngrata, Hatschbach 5464 (US); Mun. 

Jaguariaiva, Lageado 5 Reis, Hatschbach 9076 

(US); Mun. Castro, Carambei by Rio Sao Joa0, 

L.B. Smith et al. 14495 (US); Mun. Jaguariaiva, 

Barra do Rio das Mortes, Rio Jaguariaiva, L.B. 

Smith et al. 14751 (US); Quatro Barras, Clayton 

4328 (SP, US); Mun. Imbituva, rodovia BR, km 

277, Hatschbach €3 Ravenna 23070 (US); Mun. 

de Sao Jose dos Pinhaes, Rio Pequeno, Hatschbach 23465 (US); 6 km N of Mandirituba along 

Highway BR 116 to Curitiba, Davidse €3 D'Arcy 

11004 (SP). SANTA CATARINA: Lages, Swallen 

8112 (US); Mafra, Reitz 5340 (US), Mun. Campo 

Alegre, Campo Alegre, lower fazenda of Ernest 

Scheide, L.B. Smith &' Klein 10540 (US); Mun. 

Mafra, 2-4 km south of Mafra by the Estrada de 

Rodagem Federal, L.B. Smith €3 Klein 10674 

(US); Mun. Porto Uniao, between Matos Costa 

and Calmon (22 km), L.B. Smith €3 Klein 10856 

(US); Campo Alegre, Morro do Iquererim, Reitz 

& Klein 6374 (US); Sao Francisco do Sul, Morro 

do Campo Alegre, Reitz €3 Klein 10945 (US); 

Santa Cecilia, Banhado, Reitz €3 Klein 11352 

(US); Ireneopolis, Valoes, Reitz €3 Klein 11554 

(US); Mafra, Klein 3921 (US); Mun. Mafra, 

Campo Novo, 7 km from Mafra, L.B. Smith €3 

Klein 15759 (NY, US); Mun. Lages, Serra dos 

SMITHSONIAN CONTRIBUTIONS TO BOTANY 

Ilheus, L.B. Smith €3 Klein 16053 (US). SAO 

PAULO: Cantareira, Horto Botahico, Usteri s.n. 

(SP); Sao Jose dos Campos, Logren 3848 (US); 

Sao Paulo, Pickel 5215 (US); Sao Paulo, Alto da 

Boa Vista, Pickel 5813 (US); Jeriguara, Fazenda 

da Estiva, Mattos 11679 €3 Bicalho (SP); Estacao 

Florestal de Paraguacu Paulista, 6 km N of city, 

Clayton 4636 (SP, US); Sao Paulo, Agua Funda, 

Bordo 17 (SP). 

COLOMBIA: CUNDINAMARCA: Bogota, between Rio Guejar & Rio Ariari, Uribe sen. (US 

sheet no. 888782); San Martin, Ih km NE, Hermann 11 170 (US sheet numbers 1879784 and 

2487601); Savanna of San Martin, 100 miles 

(161 km) southeast of Bogoai, Shaw s.n. (US); 

META: Meta, Cabuyano, Garcia Barriga 5191 

(US); -20 km southeast of Villavicencio, Killip 

34310 (US); 20 km southeast of Villavicencio, 

Alston 7567 (US); Rio Meta, Maria, Cuatrecasas 

3750 (US). Los LLANOS: Rio Casanare, Esmeralda, Cuatrecasas 3888 (US sheet numbers 

1773359 and 2780374). 

PARAGUAY: locality unknown, Balansa 25 

(fragment, US); cursus superioris fluminis Apa, 

Hassler 11446 (US). ALTO PARANA: Nacunday, 

Montes 10919 (US sheet numbers 2183621, 

2594564), 11016 (US sheet numbers 2 18364 1, 

2594589). CORDILLERA: Valenzuela, Rojas 9501 

(US); San Bernardino, Rojas 10365 (US). 

GUAIRA: Cordillera de Villa-Rica, Hassler 8690, 

8690a (fragments, US). MISIONES: Santiago, Estancia La Soledad, Pedersen 3182 (US). PARAGUARI: Yaguaron, Balansa 4364 (US). PARAGUARIA CENTRALIS: Regio lacus Ypacaray, Hassler 12430; prope Sapucay, Hassler 13017 (US), 

12902 (US); Caapucu, Barrerito, Jaguary, Rosengurtt B-5386 (US); Caapucu, Estancia Barrerito, 

Potero de Paiva, Ramirez 164 (US). SAN PEDRO: 

Alto Paraguay, Primavera, Woolston G-97 (SP). 

TRINIDAD: Piarco Savanna, Soderstrom, Bhorai €3 Goodland 994 (US). 

VENEZUELA. AMAZONAS: Esmeralda, Alto 

Orinoco, Williams 15474 (US); Guapuchana, Rio 

Orinoco, orilla izquierda, -20 km por arriba de 

su confluencia con el Ventuari, Foldats 214-A 

(US). ANZOATEGUI: Vicinity of San Tome (San- 
NUMBER 57 

tame), Rio Guara Guara, Chase 12509 (US); margen del morichal, cabeceras del [Rio] Guanipa, 

Pittier 14877 (US); cabecera del Rio Guanipa, 

Pittier 14639 (US); orillas del morichal del Rio 

Laisme, Pittier 15013 (US). APURE: Alto-Apure, 

Jahn 1 99a (US). BOLIVAR: Cuayapo, Williams 

12004 (US); El Tigre, cerca del Rio Cuchivero, 

Williams 13334 (US); Parguara, Velez 2366 (US). 

MONAGAS: 7.5 km SW of Santa Barbara, Purse11 

9305, Curry &3 Kramer (US); Rio Purgatorio, 

Chase 12597 (US). 

 DISCUSSION.-^. versicolor is extremely variable in its height as well as in the size of its leaves, 

inflorescences, and spikelets. The smallest specimens found are no more than about 20 cm tall, 

with inflorescences -4-6 cm long and spikelets 

-2 mm long. The largest plants reach 2 m in 

height and have panicles up to 30 cm long. In 

the larger plants, the spikelets also may be twice 

23 

as long and twice as wide as in the smaller plants. 

In between are plants that present the entire 

range of diversity in size in both vegetative and 

spikelet features. Plants at either extreme are 

strikingly different and could easily be judged as 

two distinct species, but apart from the difference 

in size, no basic morphological difference can be 

found to separate them. 

The smallest plants occur only in the northern 

part of Brazil, Venezuela, Bolivia, and Colombia. 

In the central part of Brazil the plants become 

larger and reach medium size; further south, in 

the states of Santa Catarina and in Parana, they 

become larger, attaining maximum size in Paraguay. 

Brown (1 977: 17) reported this species to have 

a non-Krantz anatomy with a 13C/12C ratio of 

-25.3. This was based on a study of Chase 10435. 
Literature Cited 

Brown, W.V. 

1977. The Kranz Syndrome and Its Subtypes in Grass 

Systematics. Memoirs of the Torrey Botanical Club, 

23(3):ii + 97 pages. 

Die systematische Gliederung der Paniceae. Willdenowia, 6(1):179-192. 

Butzin, F. 

1970. 

Could, F.W., and T.R. Soderstrom 

1967. Chromosome Numbers of Tropical American 

Grasses. American Journal of Botany, 54(6):676- 

683. 

Henrard, J.Th. 

Notes on the Nomenclature of Some Grasses, 11. 

Blumea, 4:5 10-5 1 1. 

Tribe 3, Paniceae. In Flora Brasiliensis, 2(2):33- 

342, plates 12-49 (fascicle 72). Munich and Vienna. [This consists of 14 volumes (in 40) published in 130 fascicles between 1840-1 906.1 

Anatomy of the Monocotyledons, I: Gramineae. 1 xi + 

73 1 pages. London: Oxford University Press. 

1941. 

Martius, C.F.P. von, editor 

1877. 

Metcalfe, C.R. 

1960. 

Mueller, F.J.H. von 

1854- 1882. Fragmenta Phytographiae Australiae, 8: 189. 

Melbourne. 

Agrostologza Brasiliensis. 608 pages. Stuttgart and 

Tubingen. [This represents volume 2, part 1, Gramineae, of Flora Brasiliensis seu Enumeratio, edited 

by C.F.P. von Martius.] 

Beitrag zur Flora von Mattogrosso. Botanische 

Jahrbiucher furr Systematik, Pflanrengeschichte und 

Pflanzengeographie, 30: 127-238. 

Bemerkungen zu Panicum und verwandten Gattungen. h’otizblatt des Botanischen Gartens Museums 

zu Berlin-Dahlem, 104(11):239. 

Plant Explorations in British Guiana. Brittonia, 

Nees von Esenbeck, C.G.D. 

1829. 

Pilger, R. 

1902. 

193 1. 

Swgallen, J.R. 

1952. 

7:39 1-4 14. 

Trinius, C.B. 

1826. De Graminibus Paniceis: Dissertatio botanica altera. 

29 1 pages. St. Petersburg: Impensis Academiae 

Imperialis Scientiarum. 

24