I05O ANALtilLAL KEY 



t Empty glumes nearly or quite equaling the spikelet. 



u Fl. gl. with long bent awn; spk. 2-fld DANTHONIA. 



uu Fl. gl. 3-toothed; spk. 3-5 -fld. . " SIEGLINGIA. 



// Empty glumes much shorter than the spikelet. 



Fl. glume 5~9-nerved. BROMUS. 



uu Fl. glume i-3-nerved, margin and nerves pilose. 

 v Internodes in the spikelets long (| length of glume); 



callus long-pointed pilose TRIPLASIS. 



w Internodes very short; callus short. 



iv Spikelets irregularly paniculate TRICUSPIS. 



ww Spikelets distantly spicate on branches of the open 



inflorescence DIPLACHNE. 



00 Flowering glume awnless, or sometimes narrowed into a terminal 



cusp or awn, the latter not borne between two teeth. 

 p Glume i (empty glumes absent); spikelets flattened laterally, 

 i -fld. 



(See also Muhlenbergia and Brachyelytrum.') 

 q Lowest glume awned, at least in the pist. spikelets; spikelets 



unisexual, monoecious. 

 r Pistillate spikelets ovate, borne at the apex of each branch of 



the panicle ZIZANIOPSIS. 



rr Pistillate spikelets linear, borne on the upper branches of 



the panicle ZIZANIA. 



qq Lowest glume not awned; spikelets hermaphrodite. 



HOMALOCENCHRUS. 



PP Glumes 2 (ist empty glume absent) Abnormal conditions 



in Muhlenberg^a, Brachyelytrum, and Phippsia. 

 ppp Glumes more than 2. 



q Glumes 5, the 3d and 4th reduced to minute, often hairy 

 scales; outer glumes large and keeled, equaling the spikelet. 



PHALARIS. 



qq Glumes 3; spikelets i -fld. (See also qqq.} 

 r Fl. gl. awned at tip (awn in one genus soon deciduous). 

 s Awn twisted; glume 4 mm. or more long; e.g. = spk. . STIPA. 

 ss Awn straight; glume short or long. 



/ Fl. gl. broad, oval or elliptical, much firmer than empty glume; 

 e.g. -spk. 



u Fl. gl. short-hairy or glabrous ORYZOPSIS. 



uu Fl. gl. silky, hairs longer than spikelet ERIOCOMA. 



U Fl. gl. narrow, elliptical to linear, not conspicuously firmer 



than empty glumes. 

 u Leaves 6-18 mm. wide; e. gls. very minute. 



BRACHYELYTRUM. 



uu Leaves less than 6 mm. wide; e. gls. long or short. 

 v Fl. gl. 3-nerved; grain inclosed by glume . MUHLENBERGIA. 



w Fl. gl. i-nerved; grain and seed free SPOROBOLIS. 



rr Fl. gl. awnless. 

 s Fl. gls. distinctly coriaceous and firmer than the empty glumes; 



e.g. = spk. 

 t Sheaths papillose-hirsute; both aerial and subterranean 



spikelets present AMPHICARPON. 



// Sheaths glabrous; no subterranean spikelets MILIUM. 



ss FJ. gls. not distinctly different in texture from the empty 



glumes. 



t Spikelets truly spiked, alternately arranged, appressed, acute; 

 plant decumbent, much branched; e.g. = spk.. .LEPTURUS. 

 // Spikelets paniculate, panicle contracted or open. 

 u Empty glumes cuspidately awn-pointed, equaling the spike- 

 let; panicle very densely spike-like; e.g. = spk. .PHLEUM. 

 uu Empty glumes gradually acute, or obtuse. 



