52 Annals of the Carnegie Museum. 



Racemes naked and terminal ; spikelets awnless. 



74. Andropogon leucostachys. 

 Racemes reduced to one or two joints; all racemes more or less 



pedunculate 76. Rhaphis paucijlora. 



Lemma and palea membranaceous or indurated; sterile lemma when present like 

 the glumes in texture. 

 Spikelets unisexual; plants monoecious; blades abruptly contracted into petiole- 

 like bases 123. Olyra lalifolia. 



Spikelets all perfect. 



Spikelets 2-4 together, sunken in alternate notches of a broad thickened 



rachis; creeping grasses 122. Stenotaphrum secundum. 



Spikelets not sunken in the notches of a thickened rachis. 



Spikelets solitary or in small clusters subtended by an involucre 

 consisting of one to many bristles, these sometimes grown 

 together. 

 Involucre persistent on the rachis, spikelets deciduous. 



Inflorescence dense and spike-like; bristles of the involucre 



5 or more 117. Chceiochloa imherbis. 



Inflorescence comparatively loose; bristles 1-3. 



118. ChcEtochloa setosa. 

 Involucre deciduous with and attached to the spikelets. 

 Involucre a spiny bur enclosing 1-5 spikelets. 



119. Cenchrus echinatus. 

 Involucre of a single sterile branch produced beyond each 



spikelet 121. Paratheria prostrata. 



Spikelets not involucrate. 



Fruits not rigid, margins of lemma not inrolled. 



Inflorescence of slender racemes, divergently digitate at sum- 

 mit of culm, both glumes wanting. 



77. Reimarochloa hrasiliensis. 

 Inflorescence paniculate. 



Fruit open at the white-margined summit; spikelets 

 tuberculate-hispid between the nerves. 



92. Leplocoryphium lanatutn. 

 Fruit not open nor white-margined at the summit. 

 Spikelets clothed with long silky hairs. 



95. Valota insularis. 

 Spikelets glabrous or pubescent only. 



Spikelets 3-4 mm. long, more or less villous on the 

 nerves; rachis not pilose. 



94. Syntherisma sanguinalis. 

 Spikelets 2 mm. long, glabrous; rachis sparsely 



long-pilose 93. Syntherisma digitata. 



Fruits indurated-rigid, or if thin not open at the summit nor 

 hyaline-margined. 

 Spikelets placed with the back of the fruit turned away from 

 the main axis. 



