Silphium asteriscus L.

Fibrous-rooted from a short rhizome or caudex, 5–12 dm; herbage sparsely to densely spreading-hispid, or the lvs merely hispid-scabrous, many of the hairs of the stem ca 1 mm or more; stem leafy, the lvs opposite or alternate, coarsely toothed or entire, mostly 6–15 × 1.5–5 cm, (2–)2.5–5 times as long as wide, the lower often rather large and evidently long-petiolate, the others variously sessile or short-petiolate, rounded or tapering at base; heads several or many in a ± leafy-bracteate infl, with mostly ca 8 or ca 13(–21) rays 1.5–3 cm, the disk mostly 1–2 cm wide; 2n=14. Open woods, glades, and clearings; Va. to n. Fla., w. to Mo. and Tex. June–Sept. Our plants, with the stem lacking under-pubescence and with the receptacular bracts blunt and neither densely white-hairy nor glandular-hairy toward the tip, are var. asteriscus.