DESCRIPTIONS OF TRIBES AND GENERA. 47 



a. Axis of racemes indistinctly articulate, not 

 brittle ; spikelets all pedicellate. 



29. Trachypogon. 



/3. Axis of racemes distinctly articulate ; spikelets 

 both sessile and pedicellate. 

 I. First empty glume with a balsam-bearing 

 line within the side keels. Racemes soli- 

 tary ; spikelets awnless. 30. Elionurus. 

 II. First empty glume without balsam lines. 

 Racemes when solitary almost always 

 awned. 



1. A false whorl of four or more staminate 

 or empty spikelets at the base of each 

 raceme. Racemes solitary, short, usu- 

 ally subtended by a sheathing leaf. 



* False whorl composed of four $ , one-^ 

 flowered or empty spikelets. 



t $ spikelets with a pointed callus, 



readily separating from the false 



whorl. . . . 33. Themeda. 



ft $ spikelets without a callus, falling 



off together with the false whorl. 



35. Iseilema. 



** False whorl composed of 6-9 $ 

 two-flowered spikelets. 



34. Germainia. 



2. No distinct false whorl of $ spikelets at 

 the base of the racemes, or where an im- 

 perfect one occurs, the racemes in pairs, 

 subtended by a leaf-sheath. 



* Fertile glume awned from the back 

 or base ; leaves cordate at base. 



31. Arthraxon. 



** Fertile glumes awned from the point 

 or from a more or less deep cleft, or 

 awnless ; leaves not cordate at the 

 base 32. Andropogon. 



1. SUB-TRIBE Dimerieae. 



8. (82) Dimeria R. Brown. (Haplacline Presl., Didactylon 

 Zoll., Psilostachys Steud., Pterygostachyum Nees). Spike- 



