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



Figure 560.— Distribution of 

 Trisetum spicatum. 



6. Trisetum canescens Buckl. Tall trisetum. (Fig. 559, B.) 

 Culms erect, or decumbent at base, 60 to 120 cm tall; sheaths, at least 

 the lower, sparsely to densely and softly 

 retrorse-pilose, rarely scabrous only; blades 

 flat, scabrous or canescent, sometimes sparsely 

 pilose, mostly 2 to 7 mm wide; panicle narrow, 

 usually loose, sometimes interrupted and spike- 

 like, 10 to 25 cm long; spikelets about 8 mm 

 long, 2- or 3-flowered, the florets not so distant 

 as in T. cernuum; glumes smooth, except the 

 keel, the first narrow, acuminate, the second 

 broad, acute, 3-nerved, 5 to 7 mm long; lemmas rather firm, scaberu- 

 lous, the upper exceeding the glumes, 5 to 6 mm long, the teeth 



aristate, the callus hairs rather scant, 

 the rachilla hairs copious ; awn genicu- 

 late, spreading, loosely twisted below, 

 attached one-third below the tip, usually 

 about 12 mm long. Qi — Mountain 

 meadows, moist ravines and along 

 streams, Montana to British Columbia, 

 south to central California (fig, 561). 



Figure 562. — Trisetum montanum. Pani- 

 cle, X 1; glumes and floret, X 5. (Type.) 



Figure 561.— Distribution of 

 Trisetum canescens. 



Plants with less pubescent sheaths and looser panicles resemble T. 

 cernuum in that the spikelets are commonly 3-flowered, the florets 

 distant. Plants with more velvety 

 foliage and narrow panicles with 

 short densely flowered branches, 

 the lower in distant fascicles, have 

 been differentiated as T. projectum 

 Louis-Marie. Intergrading speci- 

 mens are more numerous than the 

 extreme described. 



7. Trisetum montanum Vasey. 

 (Fig. 562.) Resembling T. canes- 

 cens, on the average smaller, the 

 blades narrower; sheaths from 

 nearly glabrous to softly retrorsely 

 pubescent; panicles smaller than 

 usual in T. canescens, more uni- 

 formly rather dense, often purple- 

 tinged ; spikelets 5 to 6 mm long, the 

 glumes and lemmas thinner than 

 in T. canescens, the awn more deli- 

 cate, 5 to 8 mm long. % — Moun- 

 tain meadows, gulches and moist places on mountain slopes, between 

 2,000 and 3,300 m, Colorado, Utah, and New Mexico. A form. 



Figure 563.— Trisetum flavescens 



floret, X 5. (Grant 26, Wash.) 



Panicle, X 1; 



