TO THE GENERA OF THE FAMILY GRAMINE&. 1047 



h Both spikelets of the cluster perfect, one longer pediceled than the 



other; large ornamental grasses. 

 i Axis of spike continuous; panicle somewhat fan-shaped. (MISCANTHUS.) 



ii Axis of spike articulate; panicle denser ERIANTHUS. 



hh Spikelets of the cluster unlike, one or two sterile and more slender or 



much reduced (often to a mere pedicel). 

 i Clusters of spikelets in irregular panicles. 



j Lateral spikelets reduced to mere plumose pedicels, two with each 

 fertile spikelet, all sessile at apex of a long common pedicel. 



SORGHASTRUM. 



jj Lateral spikelets with glumes; ultimate branches of inf. dichotomously 

 sympodial, two branches at base of each fertile spikelet, one bearing 

 a sterile spikelet, the other a continuation of the inf., terminal 



spikelet with two sterile ones . SORGHUM. 



ii Clusters of spikelets in false spikes. 



j Spikes in pairs or digitate; rachilla-internodes and pedicels opaque. 



ANDROPOGON. 

 jj Spikes panicled; rachilla-internodes and pedicels thickened on margins, 



intervening portion thin and translucent AMPHILOPHIS. 



gg Spikelets not in small definite clusters as above; ist e.g. smaller than or 



equaling the 2d (rarely slightly longer in Calama grostis) . 

 h Spikelets i-fld. or with rudiment of 2d fl. 



i Empty glumes shorter than the fl. gls., nearly equal REDFIELDIA. 



ii Empty glumes as long as or longer than the fl. gls., or if shorter then 



very unequal. 



j Flowering glume awned; e.g. = spk. 

 k Fl. gl. with a terminal awn. 

 / Awn twisted, very long; fl. gl. 4 mm. or more long, firmer than 



empty gls STIPA. 



// Awn straight; fl. gl. less than 4 mm. long, about as firm as empty 



glumes MUHLENBERGIA. 



kk Fl. gl awned on back; rachilla extending beyond the palet; empty 



gls. nearly equal ' CALAMAGROSTIS. 



kkk Fl. gls. awned between 2 teeth; spikelets spiked on slender branches 



of inflorescence GYMNOPOGON. 



jj Flowering glume not awned. 



k A small tuft of hair on either side of base of fl. gl., each borne on a 

 minute scale representing the very udimentary 3d and 4th glumes; 



e.g. = spk PHALARIS. 



kk Hairs at base of fl. gl. in a ring, not borne as above. 



/ Panicle dense, spike-like; e.g. = spk AMMOPHILA. 



// Panicle open; e.g.= or <spk CALAMOVILFA. 



hh Spikelets 2-many-flowered. 



i Very tall reed-like grasses (1.5-6 m. high); e.g.<spk. 

 [/ Leaves 8-50 mm. broad, evenly distri uted up the culm (see also 



Arundo) PHRAGMITES. 



jj Leaves very long and narrow, recurved, densely clustered at base of 



stems (GYNERIUM.) 



ii Lower ordinary grasses. 

 j Flowering glume with a dorsal awn. 



k Spikelets more than 7 mm. long; e.g.= or <spk AVENA. 



kk Spikelets 7 mm. or less long. 



/ Fl. gl. acutely 2-toothed at apex; e.g.<spk TRISETUM. 



// Fl. glume blunt or bluntly 2-lobed at apex; e.g. = or <spk. 



DESCHAMPSIA. 



jj Flowering glume awnless or 3-toothed or mucronate. 

 k Fl. glume 3-toothed, broad, shorter than empty glunies; sheaths 



villous at summit; ligule a ring of hairs; e.g. = spk SIEGLINGIA. 



kk Fl. glume not 3-toothed, broad or narrow. 

 / Ligule a ring of hairs; e.g.<spk. 



