Helianthus strumosus L.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Rhizomatous perennial; stems 1–2 m, glabrous below the infl or with a few long hairs, often glaucous; lvs opposite or the uppermost alternate, relatively thick and firm, scabrous-hispid above, green and moderately short-hairy to more often glaucous and subglabrous beneath, mostly broadly lanceolate to ovate and 8–20 × 2.5–10 cm (sometimes narrower), long-acuminate, shallowly toothed or subentire, commonly decurrent onto the 0.5–3 cm petiole; disk yellow, 1.2–2.5 cm wide; invol bracts subequal, lanceolate, somewhat loose, especially the long-acuminate tips, which commonly equal or slightly surpass the disk; rays 8–15, 1.5–4 cm; 2n=68, 102. Woods and open places; Me. to Fla., w. to Minn., e. Kans., and e. Tex. July–Sept.