MANUAL OF THE GRASSES OF THE UNITED STATES 



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29. Stipa williamsii Scribn. Williams needlegrass. (Fig. 928.) 

 Differing from S. columbiana chiefly in having more or less pubescent 

 culms, sheaths, and blades; culms 60 to 100 cm tall; panicle 10 to 20 

 cm long ; lemma about 7 mm long ; awn usually 3 to 5 cm long. % — 

 Drv hills and plains, Montana to Washington, south to Colorado and 

 California (fig. 929). 



30. Stipa pinetorum Jones. (Fig. 930.) Culms in large tufts, 30 

 to 50 cm tall; ligule very short; leaves mostly basal, the blades 5 to 



12 cm long, involute-filiform, more or less 

 flexuous, slightly scabrous ; panicle narrow, 8 to 

 10 cm long; glumes about 9 mm long; lemma 5 



Figure 929.— Distribution of 

 Stipa uilliamsii 



Figure 928.— Sti pa 

 uilliamsii. Floret, 

 X 1; lemma, X 5. 

 (Williams 2804, 

 Wyo.) 



Figure 930.— St ip a 

 pinetorum. Floret, 

 X 1; lemma, X 5. 

 (Jones 6023, Colo.) 



mm long, narrowly fusiform, clothed especially on the upper half with 

 hairs 2 mm long, forming a conspicuous tuft exceeding the body of the 

 lemma; awn about 2 cm long, twice-geniculate, nearly 

 glabrous. % — Open pine woods at high altitudes, rare, 

 Colorado, Utah, Nevada, and California (fig. 931). 



31. Stipa arida Jones. (Fig. 932.) Culms 40 to 80 

 cm tall; blades 10 to 20 cm long, 1 to 2 mm wide, flat or 

 involute, scabrous; panicle 10 to 15 cm long, narrow, 

 compact, pale or silvery; glumes 8 to 12 mm long; lemma 

 about 5 mm long, appressed-pubes- 

 cent on the lower half and along the 

 margin, slightly roughened toward 

 the summit; awn 4 to 6 cm long, 

 capillary, scaberulous, loosely 

 twisted for 1 or 2 cm, flexuous be- 

 yond. % — Rocky slopes, rare, 

 southwestern Colorado, Utah, and 

 Arizona. 

 tenuissima Trin. (Fig. 933.) Culms in 

 wiry, 30 to 70 cm tall; ligule 2 mm 



Figure 931.— Distribution of 

 Stipa pinetorum. 



32. Stipa 



large tufts, slender 



long; blades 15 to 30 cm long, sometimes longer, filiform, 

 wiry, closely involute; panicle 10 to 30 cm long, narrow, 

 soft, nodding; glumes about 1 cm long; lemma 2 to 3 mm 

 long, oblong-elliptic, glabrous, minutely papillose-rough- 

 ened, the short callus densely pilose; awn about 5 cm long, capil- 

 lary, flexuous, obscurely geniculate about the middle. 01 — Dry open 

 ground, rocky slopes, and open dry woods, Texas and New Mexico 

 to central Mexico; Argentina. 



Figure 932 — 

 Stipa arida. 

 Floret, x 1; 

 lemma, X 5. 

 (Jones 5377, 

 Ctah.) 



