372 POACE.E. 



Var. tenuis Vasey. 



A very small plant, 8-10 cm. high. 



California, Jones 2201. 



77. (158). Trisetum Pers. Syn. PI. 1:97 (1808). Triclmta 

 Beauv. Agrost. SG (1812). Acrospelion Bess. Triu. Mem. Acad. 

 St. Petersb. (VI.) 1:59 (1831). Rostraria Trin. Fund. Agrost. 

 149 (1820). 



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

 panicle, rachilla articulate, hairy or smooth, more or less produced 

 between the floral glumes and beyond the upper one as a hairy 

 bristle or bearing a terminal empty glume or male flower. Emj)ty 

 glumes keeled, thinly scarious on the sides, first 1-5-nerved, second 

 3-nerved ; floral glume more hyaline, keeled, acute or shortly bifid, 

 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 pubescent at the apex, enclosed but not adherent. 



Tufted perennial, or rarely annual, grasses with fiat 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 hemispheres. 



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

 Avenastrum of Avena, but the floral glume 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 Avena. The inflorescence is also more dense, thesijike- 

 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 emjity glumes 3-nerved (d) 



d. First empty glume 3-uerved (e) 



