116 THE TRUE GRASSES. 



rising from below the teeth of the point, not 

 betiveen them). 



I. Spikelets in an open (rarely spike-like) 

 panicle, not in a true spike. 



1. Flowers all $ or the upper ones $ , or 

 sterile. 



* Grain free, unfurrowed. Spikelets 



usually small (less than 1 cm. long). 



O Flowering glumes finely erose- 



dentate, or two-lobed, or with the 



edges entire. 



<] Awns not articulated, the point 

 fine. . . 157. Deschampsia. 



< < Awns articulated, the point 



club-shaped. 



156. Corynephorus. 



OO Flowering glume cleft or two- 

 toothed with the teeth sometimes 

 produced into awns. 

 < Lower flower awnless, spike- 

 lets narrowly oblong. 



159. Ventenata. 



< < Lower flower awned. Spikelets 



elliptical-lanceolate. 



158. Trisetum. 



** Grain furrowed, usually adherent to 

 the glumes ; spikelets over 1 cm. long. 

 O Only two nerves of the flowering 

 glume reach the point ; grain hairy 

 at the apex. . . . 160. Avena. 

 O O Nerves five, prominent, all extend- 

 ing to the point ; grain naked. 



161. Amphibromus. 



2. Upper flower , the lower $ and strongly 

 awned 162. Arrhenatherum. 



II. Spikelets in a trua, two-ranked, simple 



spike 163. Gaudinia. 



y. Awns from between the lobes or teeth of the 

 flowering glume; the teeth also frequently 

 awned. 



