Perennials, 150-250+ cm (rhi-zomatous). Stems (green or purplish) erect, glabrous (glaucous). Leaves cauline; alternate; sessile or subsessile; blades linear to lance-linear, 8-21 × 0.2-1.2 cm, bases ± attenuate, margins slightly serrulate to subentire (flat), abaxial faces glabrate, gland-dotted. Heads 6-15+. Peduncles 2-6 cm. Involucres campanulate, 10-18 mm diam. Phyllaries 40-50, linear to lance-linear, 12-20 × 1.8-2 mm, (margins ciliate) apices long-attenuate, abaxial faces glabrous or glabrate, not gland-dotted. Paleae 8-10 mm, entire or weakly 3-toothed (apices greenish, ± hirsute). Ray florets 10-20; laminae 28-35 mm (apices often bifid). Disc florets 50+; corollas 5.5-6 mm, lobes reddish; anthers dark, appendages dark (style branches yellow). Cypselae 4-6 mm, glabrous; pappi of 2 aristate scales 3-3.6 mm plus 2-8 lacerate scales 0.3-0.5 mm. 2n = 34. Flowering late summer-fall. Limestone prairies; 100-300 m; Kans., Mo., Nebr., Okla., Tex. Helianthus salicifolius is found chiefly in the region of the Ozark Plateau. It is cultivated and may occasionally escape. It was recorded from a single site in Chicago, Illinois, where it has now been extirpated.
Perennial with coarse roots and long stout rhizomes; stems 1.5-3 m, glabrous, sometimes glaucous; lvs numerous, commonly alternate except near the base, subglabrous or sparsely hairy, linear or nearly so, long-acuminate, to 20+ cm, seldom over 5(-10) mm wide, about the same color on both sides; disk red-purple (yellow), 1-2 cm wide; invol bracts loose, all subulate or lance-subulate, caudate, usually some of the inner exceeding the disk, glabrous or slightly hairy, often ciliolate; rays 10-20, 1.5-3 cm; 2n=34. Prairies and dry places, especially on calcareous substrate; Mo. to Kans. and Tex., and intr. into O. and n. Ill. Aug.-Oct. (H. orgyalis)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.