258 MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



19. Elymus aristatus Merr. (Fig. 

 350.) Culms tufted, rather leafy, 

 erect, 70 to 100 cm. tall; sheaths gla- 

 brous, blades flat, 5 to 10 mm. wide; 

 spike erect, dense, 6 to 14 cm. long, 

 5 to 10 mm. thick, the rachis tardily 

 disarticulating; spikelets closely im- 

 bricate, often in threes, 1- to 2-flow- 

 ered, about 1 cm. long, excluding the 

 awns; glumes subsetaceous, scabrous, 

 10 to 20 mm. long; lemmas slightly 

 wider than in E. macounii, sparsely 

 scabrous at least on the upper half, 

 the slender straight awn 10 to 20 

 mm. long. % — Meadows and open 

 slopes, at middle altitudes, Wyoming 

 to Washington, south to Nevada 

 and California. 



Figure 349. — Elymus macounii. Disar- 

 ticulating spike, X 1. (Anderson, Mont.) 



densely tufted, erect, slender, 50 to 

 100 cm. tall; sheaths glabrous or 

 rarely pubescent; blades erect, rather 

 firm, subinvolute, usually scabrous 

 on both surfaces, 10 to 20 cm. long, 

 mostly 2 to 5 mm. wide; spike slen- 

 der, erect or somewhat nodding, 4 

 to 12 cm. long, usually about 5 mm. 

 thick (excluding awns), the slender 

 rachis tardily disarticulating; spike- 

 lets imbricate, appressed, mostly 2- 

 flowered, about 1 cm. long, excluding 

 the awns; glumes very narrow, sca- 

 brous, slightly divergent but not 

 bowed out at base, the midnerve 

 usually distinct; lemmas scabrous 

 toward the apex, extending into slen- 

 der straight awns 1 to 2 cm. long. 

 % — Meadows and open ground, 

 Minnesota to Alaska and eastern 

 Washington, south to Iowa, Kansas, 

 New Mexico, and California. (Said by 

 Stebbins to be a hybrid between 

 Agropyron trachycaulum and species 

 of Hordeum.) 



Figure 350. — Elymus aristatus, X 1. (Chase 4762, 

 Idaho.) 



20. Elymus villosus Muhl. (Fig. 

 351.) Culms in small tufts, ascending, 

 slender, 60 to 100 cm. tall; sheaths 

 glabrous to pilose; blades flat, lax, 

 pubescent on upper surface, glabrous 

 and glossy to scabrous beneath; 

 spike drooping, dense, 5 to 12 cm. 

 long; glumes subsetaceous, spreading, 

 distinctly nerved above the firm 

 cylindric nerveless divergent or some- 

 what bowed-out base, hirsute, 12 to 

 20 mm. long; lemmas nerved toward 

 the tip, hispidulous to hirsute, 7 to 

 9 mm. long, about 1.2 mm. across 

 the back, the straight slender awn 

 1 to 3 cm. long. % (E. striatus, 

 American authors, not Willd.) Moist 

 or dry woods and shaded slopes, 

 Canada and Vermont to North Da- 



