1046 



ANALYTICAL KEY 



i Rudiment of 4th or 5th glume present; e.g. = spk. 



j Spikes dense; lateral teeth of fi. gl. awn-pointed or awned . Bouteloua. 

 jj Spikes very slender, interrupted; lateral teeth of fi. gl. minute, not 



awn-pointed Gymnopogon. 



(Atheropogon sometimes has secund spikes.) 

 ii Rudiment of 4th glume absent. 

 j Spikes very slender, almost filiform; spikelets distant; e.g.<spk. 



SCHEDONARDUS. 



jj Spikes more dense; spikelets overlapping; e.g. = spk Spartina. 



ff None of the glumes long-pointed or awned, nor distinctly 3-toothed. 

 g Spikelets almost circular, i.e. very broad, strongly imbricated; e.g. = spk. 



Beckmannia. 

 gg Spikelets narrower; glumes narrow; e.g.<spk. 



h Spikelets i-fld.; spikes digitate Capriola. 



hh Spikelets 2- or more-fid.; spikes racemose. 



i Spikes filiform, alternately fid Leptochloa. 



ii Spikes dense Elusine. 



ee Spikelets not laterally compressed; glumes rounded. 

 f Glumes or some of them awn-pointed or awned; e.g. = spk. or none. 

 g Leaves setaceous; well-developed glumes only 1; spikelets distant, in 



solitary true spike Nardus. 



gg Leaves broad; glumes more than 1; one glume indurated; spikelets in 

 spikes or spike-like panicles, which are racemose. 



h Glumes 3 Eriochloa. 



hh Glumes 4. 



i First glume awned; creeping grasses (Oplismenus.) 



ii First glume usually awnless; glumes coarsely hairy; erect grasses. 



Echinochloa. 

 ff Glumes not awn-pointed. 

 g Peculiar extensively creeping grasses with monoecious inf., only the stam. 

 secund, pist. very different, clustered in the upper sheaths; e.g. <spk. 



in stam. spk. . . r . . Bulbilis. 



gg Ordinary grasses with hermaphrodite inf., all spikelets alike; one glume 

 indurated. 

 h Glumes 4. 



i Second glume shorter than spk.. 3-nerved Syntherism; 



ii Second glume equaling the spk., or nearly so, 5-nerved. . Brachiari/ 

 hh Glumes 3; e.g. = spk. 



i First glume 3-nerved, 2d 7-nerved Syntherism/ 



ii First and 2d glume 3-5 -nerved. 



j Back of indurated glume turned toward rachis Paspalum. 



jj Back of indurated glume turned away from rachis Anastrophus. 



dd Spikelets not in distinctly 1 -sided spikes. 



e Hairs or bristles forming a tuft or whorl at base of fl. gl., or on the rachis, 

 or on sterile pedicels, or forming an involucre around the spikelet: hairs 

 on the rl. gls., if present, are abruptly different (shorter or appressed) 

 and do not grade gradually over into the others. 



(The pedicels of the ordinary spikelets are very villous in Lamarckia.) 

 f Glumes 4, the 3d gl. with stamens only or empty, and usually of thinner 

 texture than the 4th gl.; spikelets surrounded by an involucre of bristles 

 or hairs. 

 g Involucre of rigid barbed persistent bristles; e.g.= or <spk. 



CaETOCHLOA. 

 gg Involucre of unequal softer bristles or hairs which are often plumose; 



4th gl. stand} coriaceous; e.g. = spk (PennisetuM.} 



ff Glumes similar in texture or else the 3d firmer than the 1st and 2d or the 

 outer gls. firmer. 



g Spikelets in pairs or threes, all but one often sterile and reduced; hair 

 outside of empty gls.; fl. gl. of perfect spikelet long-awned except some 

 times in Sorghum; 1st e.g. larger than 2d and = spk. 



