Plants not rhizomatous. Culms 70-190 cm tall, 1.2-2.4 mm thick;
internodes glabrous. Sheaths mostly glabrous, throats pubescent;
ligules 2-5 mm, decurrent, ciliate; blades 20-55 cm long, 2.5-5.5(8)
mm wide, mostly glabrous. Panicles 10-35 cm, open, straight to arching,
dark purple; rachises 0.3-0.8 mm thick 1-2 mm above the lowest node,
sometimes with a ring of hairs; branches capillary, flexuous, longest
branches 19.5-34.5 cm. Spikelets 6-7.5 mm long, 1.1-1.4 mm wide, dark
chestnut brown at maturity. Calluses 1-1.3 mm, blunt; lower glumes
5.5-7.3 mm, glabrous, 5-veined; upper glumes 6.2-7.5 mm; awns
25-40 mm, 5 times longer than the spikelets, twice-geniculate; anthers
2-3 mm. Caryopses 2-2.5 mm. Pedicels 3-6.5 mm, flexuous. 2n
Sorghastrum elliottii usually grows in dry, open woods on sandy terraces
of the lowlands in the southeastern United States, often over a clay subsoil.
Plants with straight panicles and sessile spikelets that are 1.3-1.8 mm wide
are sometimes called S. apalachicolense
D.W. Hall, but the variation appears to be continuous and such plants are included
here in S. elliottii.
Much like no. 1 [Sorghastrum nutans (L.) Nash], but without rhizomes and with narrower lvs and more open, less hairy (not golden) panicle; stems slender, often glabrous throughout; sheaths usually glabrous; spikelets 5-7 mm, chestnut-brown to nearly black, sparsely white-villous; awn 20-35 mm, bent twice and twisted below the second bend, its margins white-ciliate toward the base; 2n=20. Dry or sandy soil, chiefly on the coastal plain; Md. to Fla. and Tex., inland to Tenn. and Ark.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.