; 517 
28. ORYZOPSIS Michx. 
Spikelets 1-flowered, rather short oblong: empty glumes persistent, 
membranaceous, acuminate, slightly longer than the floret; floral 
glume pubescent, broad, indurate at maturity; awn somewhat excen- - 
tric, 2 cm. long or less: perennials, growing in small tufts, with 
numerous involute radical leaves. 
* Kinpty qghones pubescent. 
1. O. membranacea (Pursh) Vasey. (MOUNTAIN RICE.) Culins erect, 3 to 5 dm, 
high: lower leaves nearly reaching the panicle; upper leaf witha broad inflated sheath 
and narrow blade usually overtopping the panicle: panicle open and diffusely 
spreading at maturity; branches dichotomously subdivided, bearing solitary spike- 
lets on long pedicels: empty glumes ventricose below, attenuate above; floret 
prominvently white-bearded, becoming glabrate, dark and shining at maturity. 
(Stipa membranacea Pursh.)—Mountain regions of western Texas and northward, 
~* Empty qlimes smooth, 
2. O. fimbriata (HBK.) Hems]. Culms slender, 3 to5dm. high: radical leaves invo- 
lute-filiform, one-half as long as the culm or more; culm leaves shorter: panicle 
usually exserted, 1 to 2 dm. long, with few spreading branches, bearing few scattered 
spikelets near the extremities: spikelets about 5 mim. long, obovate; empty glumes 
slightly exceeding the pubescent floret. (Stipa fimbriata HBK.)—Mountains, west- 
ern Texas and westward to California. 
3. O. micrantha (Trin. & Rupt.) Thurb. Culms slender, 5 to 8 dm. high: leaves 
narrow, flat or involute: panicle 1 to 2 dm, long; branches spreading, with short 
appressed subdivisions bearing the spikelets somewhat clustered near the extrem- 
ities: spikelets about 4mm. long; empty glumes thin, nearly twice as long as the 
brown finely pubescent floret; awn 5 to 10 mm. long, tardily deciduous. ( Urachne 
micrantha Trin. & Rupt.)—Mountains and high plains, western Texas to Colorado. 
29. CINNA L. 
Spikelets 1-flowered, rarely with a rudiment of a second, narrow, 
flattened laterally, pedicellate in rather close or spreading panicles: 
empty glumes acute, carinate, hispid on the keel, the second longer, 
about equaling the floret; floret raised on a distinct stipe; floral glume 
3-nerved, herbaceous, emarginate with a short awn in the sinus; palet 
nearly as long as the tloral glume, 1-nerved. 
1. C. arundinacea L. (SWEET REED-GRASS.) Culms 1 to 21m. high, ratherrobust, 
leafy to the top: panicle 2 to3dm, long, rather dense: spikelets 4 to 6 mm. long; 
empty glumes scabrous throughout; floret about equaling the second glume; awn 
seldom exceeding the lobes of the emarginate floral glume,—Northern Texas to 
Maine and Minnesota. 
2. C. latifolia (Trev.) Griseb, (SLENDER REED Grass.) Culmsslender, about 1 m. 
high, leafy throughout: panicle usually flexuous, loose and spreading: spikelets 3 to 4 
mm. long; empty glumes smooth except the hispid keel; awn of the floral glume 
often t to 2 mm. long. (Agrostis latifolia Trev. C. pendula Trin.)—Cold bogs, 
northern Texas and northward. 
30. POLYPOGON Desf. 
Spiklets 1-flowered, compressed laterally, nearly sessile on the short 
branches of a dense oblong spikelike panicle: empty glumes equal, 
11874—No. 3 12 
