Perennials, 50–150+ cm. Stems (from short caudices) single, sparsely to densely branched distally, pubescent throughout (sometimes reddish to purplish). Leaves opposite; petiolate (petioles 10–25 mm); blades ± 3-nerved, lanceolate, 20–90+ × 5–40 mm, bases rounded to slightly oblique, margins entire or serrate, apices acute, faces puberulent, gland-dotted. Heads in corymbiform arrays. Phyllaries 8–12 in 1–2 series, elliptic to oblong, 1–3 × 0.5–1 mm, apices slightly rounded to acute, abaxial faces puberulent, gland-dotted. Florets 9–15; corollas 2.5–3 mm. Cypselae 1–1.5 mm; pappi of 20–30 bristles 2–2.5 mm. 2n = 20.
"Stems 4–20 dm, puberulent especially above; lvs opposite, with an evident petiole 1 cm or more, the blade lanceolate to ovate, serrate, mostly acuminate, 5–20 × 1.5–10 cm, 3–5-nerved or -plinerved, commonly less hairy than the stem, the upper surface often subglabrous; heads numerous; invol 3–4 mm, densely villous-puberulent, its bracts broadly rounded to merely obtuse, evidently imbricate in ca 3 series; fls 9–15 per head, white; 2n=20. Mostly in bottomlands and moist woods, sometimes in drier or more open places; s. N.Y. to Ill. and reputedly Minn., s. to Fla. and Tex.; casually intr. elsewhere, as in Conn. Aug.–Oct. E. serotinum var. polyneuron F. J. Herm. is a hybrid with E. perfoliatum."