Stems 5-20 dm from a short caudex, glabrous below the rough-puberulent infl, angular at least below; lvs basally disposed, glabrous beneath, strongly scabrous on the upper surface, the lower with somewhat sheathing petiole and elliptic, elliptic-ovate, or elliptic-obovate, sharply toothed blade 8-30 נ4-10 cm, the middle and upper gradually reduced but still generally toothed; infl paniculiform, generally with widely spreading, recurved-secund branches, in smaller plants sometimes narrower, denser, and elongate, but still secund; invol 3-4.5 mm, its bracts acute (especially the outer) to obtuse (especially the inner); rays 5-12; disk-fls 8-23; achenes sparsely hairy; 2n=18. Swamps and wet meadows; Vt. to Wis., s. to Ga., Miss., and Tex. Most of our plants, as described above, belong to var. patula. Southward, from Va. to Ga. and Tex., this gives way to var. strictula Torr. & A. Gray, a smaller plant with smaller, narrower (to 5 or 6 cm wide), less strongly toothed lvs, the upper notably numerous, much reduced, and commonly entire. (S. salicina)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.