Plants not rhizomatous. Culms 90-180 cm tall, 1.5-3 mm wide; internodes
glabrous or pubescent beneath the nodes. Sheaths usually glabrous, occasionally
pubescent in young plants; ligules 2.5-4(5.7) mm; blades 20-50 cm
long, (1.8)3-6 mm wide, scabrous, particularly on the adaxial surfaces. Panicles
15-40 cm, straight to slightly arching, secund, somewhat open; nodes glabrous
or almost so; branches erect or nearly so. Spikelets 6-8 mm long,
0.8-1.2 mm wide, lanceolate, dark brown to golden brown at maturity. Calluses
1-1.2 mm, blunt, densely bearded; lower glumes 6-7.5 mm, pubescent, truncate,
7-9-veined; upper glumes 6.5-8 mm, glabrous, acuminate, 5-veined; awns
30-40 mm, 4-5 times longer than the spikelets, twice-geniculate, dark brown; anthers
2.5-4.5 mm. Caryopses 2-3 mm. Pedicels 4-7.5 mm, pubescent, sharply
curved to recurved. 2n = 20.
Sorghastrum secundum grows in woodlands, sandy soils, and occasionally
at the edges of marshes, at elevations below 1000 m. Its native range extends
north and west from Florida to the Appalachian Mountains; other records probably
reflect introductions. The mountains may have effectively prevented its further
spread to the northwest.
Sorghastrum secundum may be confused with plants of S.
elliottii that are not at anthesis because both species may have straight
to slightly arching panicles with ascending branches. They sometimes differ with
respect to their rachis nodes, those of S. secundum being glabrous or almost
glabrous whereas those of S. elliottii often have a ring of hairs.