DESCRIPTIONS OF TRIBES AND GENERA. 115 



a. Spikelets strictly two-flowered, racliilla not pro- 

 longed. 



a. Empty glumes cartilaginous on the back ; keel 

 with pectinate teeth. . . . 146. Prionachne. 

 /?. Empty glumes membranaceous. 



I. Flowering glumes long ciliate-fringed on 

 the back or margins ; palea naked ; empty 

 glumes broad, many-nerved. 147. Eriachne. 



II. Flowering glumes and palea, especially 

 the latter, with a long fringe on the keels. 

 Empty glumes narrow, 1-3-nerved. 



148. Zenkeria. 

 III. Flowering glumes and palea naked. 



1. Upper flower in each spikelet on a 

 rather long pedicel, smaller than the 

 lower one, ? . . . . ISO. Coelachne. 



2. Both flowers nearly sessile, of equal 

 size, . 



* Palea many-nerved. 149. Micraira. 

 ** Palea two-nerved. 



t Empty glumes semi-globose. 

 Panicle spike-like. 151. Airopsis. 

 ft Empty glumes not semi-globose. 

 Panicle expanded. 

 O Empty glumes evidently long- 

 er than the flowering glumes. 

 < Flowering glume truncate, 

 slightly three - toothed, 

 awnless. 153. Antinoria. 

 <] < Flowering glumes two- 

 toothed, awned. 



152. Aira. 



OO Empty glume shorter than 

 the flowering glume. 



154. Molineria. 

 NOTE. Compare Isachne. 



b. Spikelets 2-oo -flowered (except Anisopogori), ra- 

 chilla prolonged beyond the upper flower. 



a. Flowering glume awnless or with a short ter- 

 minal awn. Spikelets small. . 155. Achneria. 

 ft. Awn of the floAvering glume upon the back (i.e., 



