126 THE TRUE GRASSES. 



ft The axis bordered by a narrow 

 membrane ; flowering glumes 

 many times shorter than the 

 empty ones. 



180. Craspedorhachis. 

 II. Spikelets distinctly awned. 



1°. Spikes terminal, one to four in number. 



171. Sehoenefeldia. 



2°. Spikes numerous, approximate at the end 



of the culm 178. Monoehsete. 



Note.— Compare Nardus with one spike, one 

 pistil, one indistinct empty glume. 



fi. One to several empty glumes above the £ 



flower ; these are often small or awn-like, rarely 



with a $ flower in their axils. 



I. Empty glumes four, the two upper often 



having a palea in the axil but bearing no 



flower 173. Ctenium. 



II. Empty glumes two. 



1°. Spike one, terminal. 



* Spikelets awnless. 172. Harpeehloa. 

 ** Spikelets awned. 174. Enteropogon. 



2°. Spikes two to many (occasionally re- 

 sembling short fascicles). 



* Spikes in false whorls or at least 

 closely approximate. 



t Flowering glume of the § flower 

 with one awn, or awnless. 



175. Chloris. 



ft Flowering glume of £ flower 



with three awns. 176. Trichloris. 



** Spikes remote or the lowest only 



approximate. 



t Spikelets scattered or remote. 



177. Gymnopogon. 

 ft Spikelets crowded. 



O Flowering glume plumose- 

 ciliate. 182. Melanocenchris. 

 O O Flowering glume not plu- 

 mose. . . 181. Bouteloua. 

 Note. — Compare the one-flowered Leptochloa species. 



