44 THE TRUE GRASSES. 



articulate racliis, one sessile and one pedicellate, often 

 apparently three at the terminal joint. Raceme some- 

 times reduced to the terminal joint. Spikelets generally 

 one-flowered with three empty glumes, rarely a flowering 

 glume with a $ flower instead of the third empty glume ; 

 first empty glume always more indurated than the flow- 

 ering glume, the latter often hyaline, usually bearing a 

 bent or twisted awn. Palea usually shorter than its 

 glume, sometimes 0. Stamens three, rarely two or one. 

 Style free, stigma plumose. Grain uniiirrowed, embryo 

 nearly half as large as the fruit. Starch-grains simple, 

 polyhedral to roundish. Mainly natives of elevated 

 plains within the tropics, forming an important part of 

 the grasses of the savannas. 

 A. Spikelets homogamoiis, $ ; joints of the rachis not much 



thickened, nor excavated for the reception of the spikelet. 



(Saccharece.) 



a. Axis of racemes continuous. 

 a. Spikelets solitary. 



I. Spikelets on very short pedicels, disposed 

 in one to several slender unilateral racemes. 



8. Dimeria. 



II. Spikelets pedicellate, forming a narrow, 

 symmetrical, and much-branched panicle. 



36. Cleistachne. 



ft. Spikelets in pairs, rarely in threes, upon each 

 joint of the rachis. 

 I. Eacemes in a narrow spike-like panicle, 



spikelets awnless 9. Imperata. 



II. Racemes in broad often fan-shaped pani- 

 cles, spikelets usually awned. 



10. Miscanthus. 



b. Axis of racemes articulate. 



a. Racemes solitary, terminal. 



I. Spikelets in pairs at each joint of the rachis. 

 16. Pogonatherum. 



II. Spikelets in threes at each joint of the axis. 



15. Polytrias. 



ft. Racemes two to many, digitate or approximate 

 on a shortened main axis. 

 I. Spikelets one-, rarely two-flowered ; when 



