Eupatorium altissimum L.

Plants stout, 8–20 dm; stems arising singly or in pairs from a system of stout, branching rhizomes, softly villous-puberulent, or glabrate below; lvs numerous, opposite, hairy like the stem, strongly trinerved to the base, lance-elliptic, gradually and narrowly acute or acuminate, and gradually narrowed to a sessile or shortly petioliform base, serrate above the middle or subentire, mostly 5–12 cm × 8–30 mm; invol 4.5–7 mm, short-hairy like the herbage, its bracts imbricate, broadly rounded or obtuse; fls 5; cor white, 4–5 mm; 2n=20, 30, 40. Woods, thickets, savannas, glades, and clearings; N.J. and Pa. to s. Minn. and e. Neb., s. to S.C., Miss., and Tex.; casually intr. elsewhere, as in Conn. E. saltuense Fernald, from se. Va., with triplinerved lvs, may reflect hybridization with some other sp. such as E. album.