blunt, almost cucullate, with a distinct line separating the chartaceous to sub- 

 coriaceous convex median portion from the flat thin margins, 1.7-2.4 mm. long; 

 lowest lemma usually microscopically cellulose-pustulate or scaberulous toward the 

 apex, 1.9-2.7 mm. long; second lemma often more scabrous than the first. 



In moist swales, in water of creeks, in seepage areas and wet soils, Okla. 

 (Waterfall), essentially throughout Tex., N.M. (Colfax, DeBaca, Eddy and 

 Guadalupe cos.) and Ariz. (Apache, Navajo, Coconino, Yavapai, Pinal, Cochise 

 and Pima cos.), spring; s. Can. and nearly all of U. S. and higher parts of Mex. 



2. Sphenopholis intermedia (Rydb.) Rydb. Fig. 101. 



Cespitose short-lived perennial, sometimes flowering as a winter annual, usually 

 3-10 dm. tall, glabrous or scabrous to pubescent; ligules 1.5-2.5 mm. long, finely 

 erose-ciliate and irregularly toothed, glabrous or sometimes scabridulous externally; 

 blades flat, 2-5 mm. wide, scabridulous; panicle 7-20 cm. long, narrow but the 

 individual crowded erect branches usually plainly distinguishable; first glume nar- 

 rowly linear, 1.6-2.5 mm. long; second glume oblanceolate, obtuse to subacute, 

 2.2-2.5 mm. long, about one fourth as wide as the first; lemmas 2.5-3 mm. long; 

 anthers about 0.6 mm. long. 



On the edge of water of lakes, ponds and along streams, in Ariz. (Navajo and 

 Cochise cos.); Nfld. to B. C, s. to Fla. and Ariz. 



22. Trisetum Pers. 



Tufted perennials with flat blades and open or usually contracted or spikelike 

 shining panicles; spikelets usually 2-flowered, sometimes 3- to 5-flowered, the 

 rachilla prolonged behind the upper floret, usually villous; glumes somewhat un- 

 equal, acute, the second usually longer than the first floret; lemmas usually short- 

 bearded at base, 2-toothed at apex with the teeth awned, bearing from the back 

 below the cleft apex a straight and included or usually bent and exserted awn 

 (rarely essentially awnless in T. IVolfii). 



A genus of 75 species in temperate regions. 



1. Awn essentially wanting, included within the glumes 1. T. Wolfii. 



1. Awn exserted (2) 



2(1). Panicle open, rather densely flowered but not spikelike 2. T. montanum. 



2. Panicle dense, spikelike, i.iore or less interrupted below 3. T. spicatum. 



1. Trisetum Wolfii Vasey. Wolf's trisetum. 



Perennial; culms erect, 5-10 dm. tall, loosely tufted, sometimes with short 

 rhizomes; sheaths scabrous, rarely with the lower pilose; blades flat, scabrous, 

 rarely pilose on the upper surface, 2-4 mm. wide; panicle erect, rather dense 

 but scarcely spikelike, green or pale, sometimes a little purplish, 8-15 cm. long; 

 spikelets 5-7 mm. long, 2-flowered or sometimes 3-flowered; glumes nearly equal, 

 acuminate, about 5 mm. long; lemmas obtusish, scaberulous, 4-5 mm. long, 

 awnless or with a minute awn below the tip, the callus hairs scant, about 0.5 mm. 

 long, the rachilla internode about 2 mm. long, rather sparingly long-villous. 



In wet meadows and wet soil along mt. streams, in N. M. {Hitchcock); Mont. 

 to Wash., s. to N. M. and Calif. 



2. Trisetum montanum Vasey. 



Perennial about 5 dm. tall, with narrow blades; sheaths from nearly glabrous to 

 softly retrorsely pubescent; panicle open, rather densely flowered but not spikelike, 

 often purple-tinged; spikelets 5-6 mm. long, disarticulating above the thinnish 

 glumes; awns delicate, 5-8 mm. long; rachilla villous. 



220 



