334 MISC. PUBLICATION 243, U.S. DEPT. OF AGRICULTURE 
than half the length of the spikelet, 3- to 5-nerved; second glume and 
sterile lemma equal, or the glume shorter, several-nerved : fertile 
lemma coriaceous-indurate, smooth or rugose. Annuals or peren- 
nials with narrow terminal panicles. 
Blades narrowly elliptic, plaited; bristles below only a part of the spikelets 
(Subgenus Ptychophyllum). 
Plant annual; blades usually less than 2 em wide____________ 1. S. BARBATA. 
Plants perennial; blades usually more than 3 em wide. 
Panicle of numerous approximate, more or less 1l-sided racemes, spikelet- 
bearing to the base, 2 to 5 cm long, rarely the lower much longer. 
2. S. POIRETIANA. 
Panicle of more or less fascicled branches, not or scarcely 1-sided, some of 
them elongate and naked at base. 
Branches of panicle as mueh as 10 em long; bristles usually not more than 
twice as long as the spikelets, inconspicuous; blades as much as 6 em 
Wide. 2. We. Ss J) ee 3. S. PALMIFOLIA. 
Branches of panicle slender, finally spreading, as much as 20 cm long; 
bristles as much as 15 mm long; blades as much as 10 em wide. 
4. S. PANICULIFERA. 
Blades linear-lanceolate, narrow; bristles below all the spikelets. 
Bristles below each spikelet numerous, at least more than five. Panicles 
dense, cylindric, spikelike. 
Plants annual; spikelets 3 mm long 22. a a oe 5. S. LUTESCENS. 
Plants perennial; spikelets 2 to 2.5 mm Jong __22=_ 25.2 = 6. S. GENICULATA. 
Bristles below each spikelet 1 or by abortion of the spikelets, 2 or 3. 
Bristles more or less retrorsely scabrous. 
Plants perennial; spikelets globose or nearly so_________~- 7. S. TENAX. 
Plants annual; spikelets not globose. 
Spikelets about 2ommm Jongss—- 2. ae ee 8. S. VERTICILLATA. 
Spikelets about 1.5 mm long. 
Panicles usually green, rarely as much as 8 em long, less than 5mm 
thick, the bristles 2 to 3 mm long________ 9. S. SCANDENS. 
Panicles usually purple, as much as 15 em long and 1 em thick, the 
bristlespabout J em long. > ea 10. S. TENACISSIMA. 
Bristles antrorsely scabrous only. 
Plants annual. 
Fertile lemma at maturity finely cross-veined or nearly smooth. 
iPlanisasamuchvas 3im tall... 2 ee ee Li. 1S. MAGNA: 
‘Plants less thane matali: 2.26 3 2 a ee 12. S. VIRIDIs. 
Fertile lemma coarsely transversely rugose______ 13. S. cORRUGATA. 
Plants perennial. 
Spikelets 3 mm long. Panicle large, rather loose. 
18. S. MACROSPERMA. 
Spikelets 2 to 2.56 mm long. 
Panicle narrowed somewhat at summit but not attenuate. 
Primary panicle large and dense, as much as 25 em long, yellowish 
or brownish, the bristles 1 to 2 em long; blades as much as 
2 CM Wide. Shree Blip 5! hs te. eee 19. SS. VULPISETA. 
Primary panicle 5 to 10 em long, green, the bristles 5 to 10 mm 
long; blades 3 to 5 mm wide______~_ 14. S. MACROSTACHYA. 
Panicle attenuate at apex. 
Fertile lemma acuminate, not turgid; obscurely cross-lined. 
20. S. SUBTRANSIENS. 
Fertile lemma acute, turgid, sharply cross-ridged. 
Blades linear-lanceolate, more than 5 mm wide; panicle inter- 
rupted or branched, the branches 1 to 3 em long. 
Blades usually pubescent on one or both surfaces, thickish, 
usually less than 1 em wide____--_----_-- 15. S. SETOSA. 
Blades glabrous, thin, usually 1 to 2 em wide. 
16. S. LEIOPHYLLA. 
Blades slender, mostly less than 5 mm wide; panicle slender, 
VELY  WATTOW 2 ote eee oe ee ee 17. S. RARIFLORA. 
