492 
2. R. rugosa Nutt, Culms rather robust, ereet, usually much branched above, 6 
to l2dm. high: leaves mostly conduplicate, rather thick, 3 to 5 um. wide, 2 tod dm. 
long: spikes numerous, erect, 5 to 10 ¢em, long, 3 to 5mm. thick; rachis striate: per- 
fect spikelets 4 to 5 mm. long, exceeding the short curved internode; outer glume 
acute or subacute, thickened, transversely rugose or sometimes reticulated: pedi- 
cellate spikelet 3 ium. long, neutral.—Near the coast. 
3. R. corrugata Baldw. Culmsrather robust, compressed, much branched above, 
10 to 15 dm. high: leaves flat or involute toward the points, 4 to 7 mm. wide, 3 to 6 
din. Jong, with rather broad, open, carinate sheaths: spikes numerous, erect or 
curved, 5 to 15 em. long, 3 min. thick; rachis nearly smooth: perfect spikelet 5 mm. 
long, about equaling the nearly straight internode; outer glume thickened, pitted 
or corrugated: pedicellate spikelet about 2 mim. long, neutral. 
** Joints of rachis persistent or tardily disarticulating. 
4. R. fasciculata Lam. Culms rather robust, ascending, geniculate at the nodes, 
oI D 
branched, angular or compressed, 6 to 12 dm. high: leaves numerous, fascicled, 4 to 
8 em. long: spikes numerous, somewhat fascicled, spreading, compressed, not rigid, 
© to L0 em, long; rachis striute: sessile spikelet narrow, 5 to 6 mi, long, slightly 
exceeding the straight internode; outer glume coriaceous, nervose: pedicellate 
spikelet perfect, about like the sessile one; pedicel adnate to the rachis. (Hemarthria 
fasciculata Kth.)—Along the lower Rio Grande. 
4. MANISURUS Swartz. 
Spikes single or fascicled, unilateral, somewhat compressed: spike- 
lets L-flowered, sinall, in pairs; the sessile ones perfect, globose, pitted 
externally; pedicellate spikelets staminate or neutral; pedicels adnate 
to the rachis. 
1. M. granularis Swartz. Culms 4to 8 dm. high, much branched: leaves 3 to 12 
em, long, 5 to 10 mm, wide, hirsute pubescent like the short sheaths: spikes 1 to 2 
em. long, numerous, closely flowered: sessile spikelets 1.5 mm. long; outer glume 
indurated, rather thin, pitted: pedicellate spikelet 2 mm. long; outer glumes ner- 
vose.—Near the coast or in wet places up the Rio Grande Valley. 
5. TRACHYPOGON Nees. 
Spike or spikelike raceme solitary and terminal; axis indistinetly 
articulate, not brittle: spikelets 1-flowered, in pairs; one short-pedi- 
celled, staminate, awnless; the other longer pedicelled, perfect, long- 
awned; outer glumes coriaceous, nervose; inner ones thin: stamens 3: 
styles distinet; stigmas plumose. 
1, T. polymorphus Hack. Perennial: culms 6 to 12 dim. high, simple, rather 
slender, terete, smooth: leaves tlat or involute toward the points, seabrid or pubes- 
cent, 1 to 2 din. long: spike L to 2 dim. long, slightly nodding, somewhat unilateral, 
rather loosely flowered: spikelets 6 to & min. long, pubescent; outer glume lance- 
oblong, obtuse, 9 to 13-nerved; awn pubescent, twisted and bent, 4 to 6 em. long.— 
Table-lands of western Texas. 
6. HETEROPOGON Pers. 
Spikes terminal or often lateral and fascicled, densely flowered, ap- 
pearing one-sided; axis rather brittle; spikelets t-flowered, in pairs; 
one sessile and perfect, cylindrical, awned; the other pedicellate, stam- 
inate or neutral, flat, imbricated, bent to one side, awnless; outer glume 
