372 PUACE.E. 



Var. tenuis Vnsoy. 



A very snmll plunt. 8-10 cm. high. 



Ciilil'orniji. .hiuvs 'Z'iOl. 



'ill. (15S). Trisetum Pors. Syn. PI. 1:97 (1808). Trichwta 

 Ik'iiuv. Agrost. 8t» (1812). Acrospelioti Pess. Triu. Mem. Acad. 

 St. Petcrsb. (VI.) 1:59 (1831). Rostraria Triu. Fuiul. Agrost. 

 U9 (18'.»0). 



Spikelets 2- rarely 3-6-flowered, in a narrow and dense or loose 

 panicle, rachilla articulate, hairy or smooth, more or less j)roduci'd 

 between the lloral ^dunies and beyond the upper one as a hairy 

 bristle or bearing a terminal empty glume or male tlower. Empty 

 glumes keeled, thiidy scarious on the sides, first 1-5-uerved, second 

 3-nerved; lloral glume more hyaline, keeled, acute or shortly bitid, 

 with a dorsal awn attached above the middle, usually twisted at 

 the base and more or less bent; palea narrow, hyaline, promi- 

 nently 2-nerved. usually 2-toothed. Stamens 3. Styles distinct, 

 stigmatic from near the base. Grain oblong, not furrowed, glabrous 

 or ])ubescent at the apex, enclosed but not adherent. 



Tufted perennial, or rarely annual, grasses with Hat blades. 



There are about 50 species; and the genus is generally distrib- 

 uted over the temperate and cooler or mountain regions of both the 

 northern and the southern hemisj)heres. 



Pentham observes: "They are all very near to the section 

 Avenmtnim of A vena, but the floral giume is decidedly toothed at 

 at the apex, the two teeth often produced into straight awns; grain 

 glabrous or slightly pubescent at the apex, with the longitudinal 

 furrow of A vena, Tlie inflorescence is also more dense, the spike- 

 lets smaller and shining." 



A. Lower floret unawned (b) 



b. First glume 1-nerved 1 



b. First glume 3-nerved 2 



B. Lower floret awned (c) 



c. Empty glumes both 1-nerved, 6-7 mm. long. ... 3 

 Empty glumes both 1-nerved, 3.5-4 mm. long. . . 4 



c. One or both empty glumes 3-nerved (d) 



d. First empty glume 3-nerved (e) 



