Comparison of foxtails (Setaria spp.):

	life cycle	bristles per spikelet*	direction of bristle barbs	spike aspect & L x W (includes bristles)	blade upper surface	sheath margins
yellow foxtail S. pumila	annual	4-15	point forward	erect to slightly lax 2-8 x 1-2 cm	glabrous, base w/ long hairs	glabrous
green foxtail S. viridis	annual	1-4**	point forward	erect to slightly lax 2-15 x 1-2 cm	glabrous	ciliate
giant foxtail S. faberi	annual	(1)2-3	point forward	drooping 7-18 x 1.5-3 cm	sparsely short-hairy	ciliate
bristly foxtail S. verticillata	annual	1-2(3)	point backwards	erect to slightly lax 3-15 x 0.5-1 cm	glabrous or sparsely short-hairy	glabrous or sparsely ciliate
knotroot foxtail S. gracilis	perennial w/ short, knotty rhizomes	4-12	point forward	erect 3-9 x 0.4-1 cm	glabrous	glabrous
African bristlegrass S. sphacelata	perennial w/ short rhizomes	5-15	point forward	erect 9-40 x 0.8-1.5 cm	glabrous, (base w/ few long hairs)	glabrous

* Easiest to see when spikelets have fallen or been carefully removed.

**Spikelets closely clustered; bristles may appear more numerous, especially when spikelets abort.