Plants 80-200+ cm (perennating bases ± erect, internodes winged). Leaves all or mostly opposite (distal sometimes alternate); blades ± ovate or lance-deltate to lanceolate, 6-12(-16+) × 3-6(-10+) cm, bases ± cuneate, margins coarsely toothed to subentire, apices usually acute to attenuate, sometimes rounded, faces scabrellous. Heads 20-100+ in corymbiform-paniculiform arrays. Involucres campanulate to turbinate, 3-5+ mm diam. Phyllaries 8-12+ in 2 series, ± erect, spatulate to oblanceolate, 3-7+ mm. Ray florets (0-)1-3(-5); laminae 10-15(-20+) mm. Disc florets 8-15+; corollas yellow. Cypselae dark brown to black, oblanceolate, 5 mm, faces strigose; pappi 3-4 mm. 2n = 34. Flowering Aug-Oct. Bottomlands, margins of thickets, waste places; 10-300 m; Ala., Del., D.C., Fla., Ga., Ill., Ky., Md., Miss., Mo., N.C., Ohio, Okla., S.C., Tenn., Tex., Va., W.Va.
Coarse perennial 1-2 m, the stem leafy, glabrous below, puberulent above; lvs opposite, ovate, serrate, 7-17 נ4-11 cm, strigillose to scabrous, the petioles ±winged, decurrent on the stem; heads small, numerous, 20-100+ in a congested or rather open infl, the disk 3-7 mm wide in fl; invol bracts erect, the tips loose, often imbricate, commonly sparsely puberulent; receptacle small, convex; rays 2-5, yellow, usually pistillate and fertile, 0.5-2 cm; achenes wingless; 2n=34. Bottomlands, thickets, woods, and waste places; Md. to O. and Mo., s. to Fla. and Tex. Aug.-Oct. (Phaethusa o.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.