270 Bulletin No. 205 [March, 



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ff. Panicle not wooly, joints more or less short pubescent; 

 lacemes of 1 to 5 joints, pediceled spikelet staminate 

 or reduced to the pedicel, 

 g. Pediceled spikclets staminate; panicle open; awns 

 deciduous. 5. Holous 



gg. Pediceled spikelets reduced to a hairy pedicel; pani- 

 cle narrow ; awns persistent. 4. Sorghastrum 

 dd. Spikelets not in pairs, or if so, the two alike; axis not disjointing, 

 e. Spikelets sessile in 1-sided spikes, these digitate or racemose 

 on a common axis (as in Bermuda grass, Fig. 193), 

 f. Spikes digitate (Fig. 201). 



g. Spikes slender; spikelets 1-flowered; plants peren- 

 nial. 40. Capriola 

 gg. Spikes stout; spikelets 3- or 4-flowered ; plant'-', annual. 

 h. Kachis of spike prolonged into a point beyond 

 the spikelets; lower lemmas awn-tipped. 



43. Bactyloctenium 

 hh. Eachis of spike not prolonged beyond the spike- 

 lets; lemmas awnless. 44. Eleusine 

 ff. Spikes racemose (Figs. 194, 195, 196). 



g. Spikes very slender; spikelets remote, closely ap- 

 pressed; plants annual. 41. Schedonnardus 



gg. Spikes thick; spikelets densely imbricated. 



h. Plants robust, 4 to 6 foot tall ; spikelets 1-flow- 

 ered; first glume exceeding the floret, stiffly 

 ciliate on the keel; spikelets falling entire. 



39. Spartina 

 hh. Plants not robust, not over 3 feet tall; spikelets 

 with 1 perfect floret and 1 or 2 sterile lemmas; 

 first glume shorter than the floret, persistent 

 after the fall of the floret. 42. Bouteloua 



ee. Spikelets pediceled, in open (Fig. 118) or spike-like (Fig. 

 117) panicles, or in racemes (Fig. 29). 

 f . Spikelets 1-flowered or with 1 perfect terminal floret and 

 1 or 2 sterile or staminate florets below it. 

 g. Spikelets without staminate or rudimentary florets 

 below the jjerfect one; spikelets laterally com- 

 pressed, glumes keeled. 

 h. Glumes wanting; spikelets strongly flattened, im- 

 bricate on the slender branches of an open pan- 

 icle; lemmas awnless. 14. Homalocenchrus 

 hh. Glumes present, if minute the lemmas awned. 

 i. Lemmas more or less indurate, at least firmer 

 than the glumes, terete or subterete, not 

 keeled, 

 j. Lemma not sharp-pointed, strongly indu- 

 rate; panicle branches spreading or 

 drooping. 17. Milium 

 jj. Lemma sharp-pointed or awned; panicle 

 branches ascending or erect. 

 k. Awn 3-parted; lemma with a sharp- 

 pointed callus at base. 



20. Aristida 

 kk. Awn simple. 



1. Awn 4 to 8 inches long, twisted 

 and bent ; leniniawitha needle- 

 pointed callus. 19. Stipa 

 11. Awn not over 2 inches long; 

 callus not sharp-pointed. 

 m. Awn deciduous, bent; lem- 

 ma broad, elliptical or 

 ovate. 18. Orysopsis 



