1	"Bristles retrorsely scabrous"	"Setaria verticillata"
1	"Bristles antrorsely scabrous"	2
2	"Lemma of upper floret smooth or granular but not boldly ridged, quite blunt"	3
2	"Lemma of upper floret boldly transversely ridged, tapered to a minute apical point"	4
3	"Panicle thicker than 1 cm (not including bristles), with branches of panicle developed, mostly 10–20 mm long; fertile floret separating from remainder of spikelet at maturity"	"Setaria italica"
3	"Panicle thinner than 1 cm (bristles excluded), with branches not or hardly developed; spikelet falling entire at maturity"	"Setaria viridis"
4	"Perennial; leaves firm, mostly narrower than 4 mm; bristles generally about as long as spikelets"	"Setaria parviflora"
4	"Annual; leaves flaccid, mostly wider than 5 mm; bristles generally considerably longer than spikelets"	"Setaria pumila"