66 GRAMINEAE (GRASS FAMILY) 



much shorter than the pedicels: glumes 1-nerved, acute, half shorter than the 

 spikelet; lemma keeled, 3-nerved (lateral nerves prominent), scabrous- 

 pubescent, erose denticulate at apex, mucronate, villous at base. Graphe- 

 phorum flexuosum. Plains of Colorado and adjacent regions. 



47. DIPLACHNE Beauv. 



Perennial grasses with abundant narrow leaves. Spikelets 2-12-flowered, 

 linear, compressed or subterete, sessile or short-pediceled, on the lower sides of 

 the rays of the racemose panicle (rarely in a simple spicate panicle) : rays hori- 

 zontal to nearly erect, spikelet-bearing to the base. Glumes 1-nerved, acute or 

 somewhat tridentate, the second larger but not exceeding the adjacent floret; 

 lemma membranaceous, rarely rigid, obtuse, truncate or acute, sometimes 

 short-awned or 3-toothed, often pubescent on the 3 nerves near the base, 

 slightly exceeding the palet. Grain translucent, amber-colored, oblong, or 

 subterete. Internodes of rachilla glabrous. 



1. Diplachne acuminata Nash, Brit. Man. 128. 1901. Culms tufted, 3-6 

 dm. high, simple or branching: leaves very rough, usually involute when dry: 

 racemes numerous, ascending: lemma 6-7 mm. long, entire and acuminate or 

 sometimes obscurely 2-toothed, the midnerve extending into an awn. D. 

 fascicularis. Colorado to Nebraska and south to Arkansas. 



48. ERAGROSTIS Beauv. 



Perennials or annuals, usually with numerous leaves somewhat pilose at the 

 ligule. Spikelets 3-30-flowered, compressed, awnless, perfect except the upper 

 floret. Panicle usually large and spreading, rarely contracted or subcapitate; 

 rachilla usually persistent with the palets. Glumes ovate, acute, or subob- 

 tuse, smooth or slightly hispid on the keel; palets arched, 2-keeled, slightly 

 shorter than the lemma. Grain oblong or globose, semitranslucent, amber- 

 colored, terete or with a shallow channel. 



Spikelets 2-3 mm. wide . . . . . . . . . .I.E. major. 



Spikelets 1-2 mm. wide . 2. E. pilosa. 



1. Eragrostis major Host. Gram. 4: t. 14. 1809. Culms 2-5 dm. high, 

 leafy: leaves flat, 4-8 mm. wide: panicles rather densely flowered, oblong, 

 1-2 dm. long: spikelets sessile or short-pediceled, 6-15 mm. long, 6-20-flowered: 

 upper glume somewhat 3-nerved; lemma obtuse, prominently nerved, one 

 fourth longer than the ciliate palet: grain subglobose, 0.8 mm. in diameter. 

 Introduced everywhere in the United States and northern Mexico. 



2. Eragrostis pilosa (L.) Beauv. Agrost. 71. 1812. Culms 2-5 dm. high, 

 rather weak: leaves usually pilose at the ligule: panicle 1-2 dm. long, diffuse; 

 branches 5 cm. long or less: spikelets 3-6 mm. long, 4-8-flowered; florets 

 rather loose on the elongated rachilla : glumes unequal, about one half as long 

 as the contiguous florets; lemma nearly smooth, subacute, slightly exceeding 

 the smooth palet: grain oblong, smooth, nearly 1 mm. long. The native form, 

 which has been called E. Purshii, does not seem to be distinct from the in- 

 troduced species here described ; one or both of the forms occur in most por- 

 tions of the United States. 



49. EATONIA Raf. 



Erect grasses with slender simple culms and usually flat puberulent leaves. 

 Spikelets usually 2-flowered, with a naked pedicel-like rudiment, compressed, 

 cuneate, awnless, perfect, numerous, short-pediceled or nearly sessile on the 

 verticillate branches of the rather slender panicles; rachilla smooth, articu- 

 lated above the thin herbaceous glumes. First glume narrowly lanceolate, 

 1-nerved; second glume broad, obovate, 3-nerved; lemma lance-oblong, her- 



