366 Bulletin No. 205 [March, 



35. DESCHAMPSIA Beauv. 



This genus belongs to cold climates; only one species has been 

 found in Illinois. The plants are perennial with short, very narrow 

 or involute leaves clustered at the base, and, borne far above them, a 

 loose, open panicle with shining spikelets, which are brown, tinged 

 with purple. The spikelets are mostly 2- rarely 3-flowered, the glumes 

 and lemmas thin, the lemma bearing an awn from near its base. 



Deschampsia caespitosa (L.) Beauv. 

 Tufted Hair Grass (Figs. 183 and 185) 



Aira caespitosa, Vasey '61, 671; Flagg 78, 284. 



Culms in tufts 2 to 4 feet tall, smooth ; sheaths smooth ; ligulc 

 membranous, transparent, 3 to 5 mm. long ; blades usually flat, becom- 

 ing involute when dry, rough on the upper surface, 1 to 6 inches long, 

 2 to 3 mm. wide ; panicle 4 to 8 inches long, usually half as wide, the 

 branches not numerous, slender, rough and spikelet-bearing at the 

 ends; spikelets 3.5 to 4 mm. long, the glumes usually as long as the 

 lemma, the awn extending slightly beyond the glumes. This species 

 is found in moist soil, usually along streams. 



ILLINOIS SPECIMENS: Without locality, Vasey in 1861; northern Illinois, 

 Vasey. kane co. Elgin, Vasey. 



36. AVENA (Tonrn.) L. 

 Oat 



Two species of oat, both annuals, may be found in Illinois — the 

 wild and the cultivated. The latter often escapes from cultivation 

 and may be found in waste places, but it seldom establishes itself. The 

 genus is distinguished by its large, open panicles with spikelets from 

 half an inch to an inch long. The spikelets are 2- to 4-flowered, the 

 many-nerved glumes longer than the lemmas, which usually bear a 

 dorsal awn. The leaves are long and flat, the ligule membranous, 1 to 

 4 mm. long. 



Lemmas pubescent; awn well developed, twisted at the base. A. fatua 



Lemmas smooth; awn, if present, small, usually straight. A. sativa 



Avena fatua L. 



Wild Oat (Fig. 186) 



Culms stout, 1 to 4 feet tall, smooth ; sheaths usually smooth, some- 

 times slightly roughened near the blade, occasionally hairy; blades 

 slightly roughened,' 3 to 12 inches long, 4 to 14 mm. wide ; panicle 4 

 to 12 inches long, usually narrow, the branches ascending; spikelets 

 22 to 25 mm. long, excluding the awns, the lemmas sparsely covered 

 with long brown hairs, which are more numerous near the base ; awn 

 arising from near the middle of the lemma, twisted at base. 



