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



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 nun 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. % — Mountain 

 meadows, moist ravines and along 

 streams, Montana to British Columbia, 

 south to central California (fig, 561). 



Figure 560.— Distribution of 

 Trisetum spicatum. 



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^ to 8 mm long. 91 — 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. Panicle, X 1; 

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



