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



late. % (S. minor Scribn.) — Dry 

 plains, meadows, and open woods, at 

 medium and high altitudes, South 

 Dakota to Yukon Territory, south 

 to Texas and California. Differing 

 from S. viridula in the glabrous throat 

 of the sheath and in the shape of the 

 fruit. 



STIPA COLUMBIANA Var. NELSONI 



(Scribn.) Hitchc. Differing in its 

 usually larger size, often as much as 

 1 m. tall, the broader culm blades, 

 and the larger and denser panicle; 

 lemma 6 to 7 mm. long; awn as much 

 as 3.5 cm. long, sometimes longer. 

 21 — Alberta to Washington, south 

 to Colorado and Arizona. 



Figure 664. — Stipa robusta. Panicle, X X A; lemma, 

 X 5. (Hitchcock 13280, N. Mex.) 



27. Stipa robusta (Vasey) Scribn. 

 Sleepy grass. (Fig. 664.) Culms 

 robust, mostly 1 to 1.5 m. tall; 

 sheaths villous at the throat and on 

 the margin, a strong hispidulous line 

 across the collar; ligule 2 to 4 mm. 

 long; blades elongate, flat or on the 

 innovations involute, those of the 

 culm as much as 8 mm. wide; panicle 

 narrow, compact, often more or less 

 interrupted below, as much as 30 cm. 

 long and 2 cm. thick; glumes about 

 1 cm. long, attenuate into a fine soft 

 point; lemma 6 to 8 mm. long, about 

 as in S. viridula; awn 2 to 3 cm. long, 

 rather obscurely twice-geniculate. % 

 (S. vasey i Scribn.) — Dry plains and 

 hills and dry open woods, Colorado 

 to western Texas, Arizona, and north- 

 ern Mexico. Said to act as a narcotic 

 on animals that graze upon it, 

 especially affecting horses. 



28. Stipa columbiana Macoun. 

 Columbia needlegrass. (Fig. 665.) 

 Culms mostly 30 to 60 cm. tall, 

 sometimes as much as 1 m.; sheaths 

 naked at the throat; ligule 1 to 2 

 mm. long; blades 10 to 25 cm. long, 

 1 to 3 mm. wide, mostly involute, 

 especially on the innovations, those 

 of the culm sometimes flat; panicle 

 7 to 20 cm. long, narrow, mostly 

 rather dense, often purplish; glumes 

 about 1 cm. long; lemma 6 to 7 

 mm. long, pubescent as in S. viridula, 

 the body narrower, the callus sharper; 

 awn 2 to 2.5 cm. long, twice-genicu- 



Figure 665. — Stipa colum- 

 bianai. Panicle, X H; 

 lemma, X 5. (Nelson 

 7478, Wyo.) 



29. Stipa lettermani Vasey. Letter- 

 man needlegrass. (Fig. 666.) Re- 

 sembling small forms of aS. columbi- 

 ana; culms often in large tufts, 30 

 to 60 cm. tall; blades slender, in- 

 volute; panicle slender, narrow, loose, 

 10 to 15 cm. long; glumes about 6 

 mm. long; lemma 4 to 5 mm. long, 

 slender and more copiously hairy 

 than in S. columbiana; awn 1.5 to 2 

 cm. long. 01 — Open ground or 

 open woods at upper altitudes, Wyo- 

 ming to Montana and Oregon, south 

 to New Mexico and California. 



30. Stipa williamsii Scribn. 

 Williams needlegrass. (Fig. 667.) 

 Differing from S. columbiana chiefly 

 in having more or less pubescent 

 culms, sheaths, and blades; culms 



