CXLVII. GRAMINE/E, 075 



fragile ; joints 1 or few, filiform, truncate, with ciliate margins ; sessile 

 .s))ikelets dorsally compressed. 



Perennial ; stems up to 15 ft. high; leares 1-2 ft. by |- 



2 in. ; joints 3-7 15, A. halepeJisis. 



Annual ; stems less than 5 ft. long ; leaves 8-10 by ^-^ in. ; 

 joints rarely 3 16. A. purpurea- sericeus. 



Subgenus 6, Chbysopogon. Eaceme solitary, 1-jointed («'. e. reduced 

 to 1 sessile, 2-sexual, and 2 pedicellate male or neuter spikelets), on the 

 bearded tips of the branches of the panicle; sessile spikelets laterally 

 compressed. 



Pedicels of the upper spikelets J as long as the sessile 

 spikelets or longer. 



Pedicels of upper spikelets glabrous or nearly so 17. A. aciculattis. 



Pedicels ef upper spikelets ciliate with long reddish- 

 brown hairs 18. A. lancearius. 



Pedicels of upper spikelets not \ as long as the sessile 

 spikelets. 



Stems reaching 4 ft. high ; leaves up to 18 in. long ; 



callus 3V, in. long, bearded on one side only 19. A. Monticola. 



Steins reaching 18 in. high ; loaves up to 4 in. long ; 



callus iV in. long, villous all over 20. A. Aucheri. 



SECT, B. HETEROZYGI. Lowest one or more sessile spikelets 

 in all racemes, or at least in one or two, differing from those above it in 

 sex and form. 



(Subgenus 7. DiCHANTiiiUM. Eacemes digitate Crarely solitary or 

 paniculate) ; spikelets all alike in form, but differing in sex ; lower 1-4 

 pairs of spikelets usually homogamous. 



Raceme solitary, less than 1 in. long 21. A. Cooled. 



Racemes digitate (sometimes solitary in A. caricosus), 1 in. 

 or more long. 



Lower invol.-glumes of the pedicellate spikelets armed 

 with submarginal tubercular-based bristles ^ in. 



long 22. A. armatus. 



Lower invol.-glume not armed with marginal bristles. 



Pedicels \ as long as the sessile spikelets ; nodes of 



stem glabrous ; ligule a sliortly ciliate small 



membrane 23. A. caricosus. 



Pedicels ^ as long as the sessile spikelets; nodes of 

 stem bearded ; ligule large, oblong, obtuse, 

 membranous 24. A. anmda/u.i. 



Subgenus 8. Heteeopogon. Eaceme solitary, terminal on the stems 

 and branches; lower sessile spikelets very unlike the upper, which are 

 cylindric. 



A dwarf erect grass not 1 ft. high 25, A. jiolystachyos. 



Tall gras.ses reaching several feet high. 



Lower invol.-glume dorsally deeply grooved ; ligule a 



rounded membrane 20. A. triticeus. 



Lower invol.-glume not dorsally grooved. 



Margins of lower invol. -glume of pedicellate spikelets 

 equally winged, the keels studded with long yellow 

 bristles ; ligule of several narrow membranous 



segments 27. A. Ritchiei. 



Margins of lower invol.-glume of pedicellate spikelets 

 unequally winged, the keels not studded with 

 bristles; ligule truncate, ciliohite 28. A. coiitorlits. 



