TO THE GENERA OE THE FAMILY GRAMINE^E. IO47 



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 SORGHTJM. 



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; 1st e.g. smaller than or 

 equaling the 2d (rarely slightly longer in Calamagrostis). 

 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 ludimentary 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. 



II 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. 

 [7 Leaves 8-50 mm. broad, evenly distributed up the culm (see also 



Arundo) Phragmites. 



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



stems. . . * (Gyneriuh.) 



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 glumes; sheaths 



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



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

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



