Syn. Pl. 2: 473. 1807.
Perennials [annuals], 30–150 cm. Stems erect or trailing, branched from bases or ± throughout. Leaves cauline; opposite; petiolate; blades ± 3-nerved from bases, deltate or ovate to lanceolate, bases ± cuneate to subtruncate, margins serrate or coarsely toothed, faces glabrous or hairy. Heads radiate [discoid], borne singly. Involucres turbinate to hemispheric, 8–14 mm diam. Phyllaries persistent, 12–20 in 2–3 series (ovate or oblong, ± equal, outer more foliaceous than inner). Receptacles convex to conic, paleate (paleae tardily falling, yellowish, conduplicate, becoming chartaceous). Ray florets  5–20, pistillate, fertile; corollas yellow to orange (laminae persistent, sessile, becoming papery). Disc florets 30–150+, bisexual, fertile; corollas yellow or brown to purple, tubes much shorter than narrowly cylindric throats, lobes 5, deltate. Cypselae (brown to black-brown) subterete or obscurely 3(ray)- or 4(disc)-angled (not winged); pappi 0, or persistent, coroniform (each a laciniate crown plus 1–3 toothlike scales). x = 14.
North America, Mexico, Central America, South America (to Bolivia).
Species ca. 18 (3 in the flora).
Most species of Heliopsis are known only from Mexico.
|1||Aerial stems 1–2+ (from creeping rhizomes 4–10+ cm × 1–2 mm, rhizome internodes ca. 20+ mm); heads 1–3(–5); rays 6–8(–13)||Heliopsis gracilis|
|1||Aerial stems 1–10+ (from ± erect caudices, or from creeping rhizomes to 4 cm × 2–6 mm, rhizome internodes 2–10 mm); heads 1–15+; rays 9–18||> 2|
|2||Leaf blades (1.5–)3–6 × 0.8–3 cm, faces sparsely pubescent to glabrescent; peduncles (6–)15–30 cm; cypselae rugulose to subtuberculate||Heliopsis parvifolia|
|2||Leaf blades 6–12(–15) × 2.5–6(–12) cm, faces glabrous, pubescent, or scabrous; peduncles 9–25 cm; cypselae smooth||Heliopsis helianthoides|