J. Acad. Nat. Sci. Philadelphia 7: 74. 1834
Perennials, 50–120 cm (with crown buds). Stems erect, usually hispid to ± hirsute. Leaves mostly basal; mostly opposite; petioles 0–3 cm (broadly winged); blades (3-nerved distal to bases) ovate or lanceolate to spatulate, 6–28 × 1.2–4.3 cm, bases cuneate, margins entire (often revolute), abaxial faces hispid to ± hirsute, not gland-dotted (cauline leaves relatively few, narrowly lanceolate to linear, much smaller). Heads 1–3(–5). Peduncles 10–15 cm. Involucres broadly hemispheric, 15–25 mm diam. Phyllaries 24–30, lanceolate to lance-ovate, 8–13 × 2–5 mm, (margins sometimes ciliate) apices acute to short-acuminate or acuminate, abaxial faces sparsely hispid to glabrate. Paleae 7–9 mm, 3-toothed (apices purplish). Ray florets 12–18; laminae 14–36 mm (abaxial faces not gland-dotted). Disc florets 100+; corollas 5.5–6.5 mm, lobes reddish; anthers purplish, apendages purplish (style branches usually reddish). Cypselae 4–5 mm, glabrate; pappi of 2 aristate scales 1.7–2.5 mm plus 1–3 deltate scales 0.5–1.5 mm. 2n = 34.
Phenology: Flowering late summer–fall.
Habitat: Wet sandy soils
Elevation: 0–50+ m
Ala., Fla., Ga., La., Miss., N.C., S.C., Tex.
Helianthus heterophyllus is found on the Atlantic and Gulf coastal plains. The cauline leaves are usually abruptly reduced relative to the basal leaves; individuals sometimes have relatively large cauline leaves.