Helianthus laevigatus Torr. & A.Gray

Perennials, 100–220 cm (rhizomatous). Stems erect, usually glabrous, sometimes proximally hirsute (glaucous). Leaves cauline; opposite (proximal) or alternate ; sessile or subsessile; blades (grayish green or bluish green) lanceolate, 8–15 × 1.5–3.5 cm, bases ± cuneate, margins serrate to subentire, abaxial faces glabrous or glabrate (smooth or slightly rough to touch, glaucous). Heads 1–6. Peduncles 2–8 cm. cm. Involucres cylindric, 10–15 mm diam. Phyllaries 23–28, lanceolate, 6–13 × 2–3 mm, (margins sometimes ciliate) apices acuminate, abaxial faces glabrous, not gland-dotted. Paleae 8.5–10 mm, 3-toothed to subentire. Ray florets 5–10; laminae 15–20 mm. Disc florets 35+; corollas 5.5–6.5 mm, lobes yellow; anthers dark, appendages dark. Cypselae 4–5.5 mm, glabrous; pappi of 2 aristate scales 3.2–4.1 mm plus 0–1 deltate scales 0.5–1.1 mm. 2n = 68.