Stem erect, 1-2 m, pubescent with hooked hairs, commonly with a single long terminal raceme or few-branched panicle; stipules ovate, acuminate, 10-15 mm; petioles much longer than the stalk of the terminal lfl; lfls lance-ovate, rough on both sides with hooked hairs, strongly reticulate beneath, the terminal one 6-10 cm; axis of the infl softly spreading-hairy as well as commonly with some hooked hairs; fls 8-10 mm, white, on pedicels 12-23 mm; stipe 2.5-5 mm; articles 2-5, 4.5-7 mm, with rounded margins. Rich prairie soil; s. Ont. to Wis. and Neb., s. to O., Okla., and n. Tex. July, Aug.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.