264. Heliopsis Persoon, Syn. Pl. 2: 473. 1807.
Oxeye, sunflower everlasting, héliopside [Greek helios, sun, and -opsis, likeness]
Alan R. Smith
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.
Species ca. 18 (3 in the flora): North America, Mexico, Central America, South America (to Bolivia).
Most species of Heliopsis are known only from Mexico.
Fisher, T. R. 1957. Taxonomy of the genus Heliopsis (Compositae). Ohio J. Sci. 57: 171–191.