Perennials, 50-150+ cm (with crown buds, rhizomes absent or poorly developed).
Stems erect, usually ± hairy.
Leaves mostly cauline; opposite or alternate; sessile or subsessile; blades (3-nerved near bases) narrowly lanceolate to linear, 8-15 × 0.15-0.5(-1) cm, bases cuneate , margins entire (revolute, abaxial face sometimes obscured by rolled margins), abaxial faces strigose to hispid or hirsute, sometimes (adaxial not) gland-dotted.
Heads 3-16.
Peduncles 5-15 cm.
Involucres shallowly hemispheric, 10-20 mm diam.
Phyllaries 25-32 (loose), lanceolate, 4-9 × 1-2 mm, apices acute to slightly acuminate, abaxial faces usually scabrous, rarely glabrous, usually gland-dotted.
Paleae (oblanceolate) 5.5-6.5 mm, entire or ± 3-toothed (apices purplish, mucronate, gland-dotted).
Ray florets 10-20; laminae 10-20 mm (abaxial faces gland-dotted).
Disc florets 75+; corollas 4-4.5 mm, lobes yellow; anthers dark brown or black, appendages dark (style branches usually yellow).
Cypselae 2-3 mm, glabrate;
pappi of 2 aristate scales 1.5-2.1 mm.
2n = 34. Flowering late summer-fall. Open to shaded, usually moist places; 10-700 m; Ala., Ark., Fla., Ga., Ind., Iowa, Ky., La., Md., Miss., Mo., N.J., N.C., Ohio, Okla., Pa., S.C., Tenn., Tex., Va., W.Va. The distal parts of
Helianthus angustifolius are identical in appearance to those of
H. simulans; plants of the latter are taller (200+ cm) and more robust. The leaves are not only narrower in
H. angustifolius but also tend to be more strongly revolute (abaxial faces sometimes scarcely visible).