Eupatorium serotinum Michx.

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.