93 



Fig. 69. Trisetum subspicatum (L.) Beauv. DOWNY OAT-GRASS.— a, A 

 spikelet: b and e, florets. Figs. 159 to 164, in Bui. 7, and 496 to 498, in Bui. 17, 

 illustrate other species of Trisetum. 



69. TRISETUM Pers. Syn. 1 : 97. 1805. Spikelets2- (rarely 3- to 5-) flowered; 

 rachilla hairy or naked, articulated above the empty glumes and between the 

 florets, produced beyond the upper flower as a (usually) hairy bristle. Empty 

 glumes 2, awnless, carinate, unequal, usually longer than the floral glumes: 

 flowering glumes subhyaline, carinate, cleft or 2-toothed at the apex, the teeth 

 sometimes produced into slender awns, awned between or a little below the 

 teeth; awn twisted and usually geniculate. Palea narrow, 2-toothed. Grain 

 smooth, inclosed in the fruiting glume and palea. but free from them. Csespitose 

 perennials (rarely annuals) with flat leaves and dense and spike-like, or nar- 

 row, loose panicles. 



Species 50, from the arctic regions through the temperate zone and along the 

 high mountains of the tropics to the south temperate countries. North Ameri- 

 can species about 10. 



