[Greek korios, bedbug, and -opsis, resembling, alluding to cypselae of original species]

John L. Strother

Annuals, perennials, subshrubs, or shrubs, 10–80(–200+) cm (often rhizomatous or with cormiform bases, stoloniferous in C. auriculata). Stems usually 1, erect, branched distally or ± throughout. Leaves basal, basal and cauline, or cauline; opposite or alternate or both; petiolate or sessile; blades simple and entire (dentate in C. latifolia), or ± pinnately or pedately lobed, faces glabrous or hairy. Heads radiate, borne singly or in open, ± corymbiform arrays. Calyculi of (3–)8+, distinct, ± herbaceous bractlets. Involucres ± globose to cylindric, 4–25+ mm diam. Phyllaries usually ± 8 in ± 2 series (usually distinct, rarely connate ± ¹/10 their lengths, mostly oblong to linear, ± membranous, margins ± scarious). Receptacles flat to convex, paleate; paleae falling, ovate to linear or subulate, ± flat, ± scarious (not adnate to and not falling with cypselae except in C. bigelovii). Ray florets mostly (5–)8(–12+, more in "double" cultivars), neuter, or styliferous and sterile, or pistillate and fertile; corollas usually yellow, sometimes red-brown to purple proximally, sometimes wholly purple or pink to white. Disc florets 8–150+, bisexual, fertile; corollas usually yellow, sometimes red-brown to purple at tips or throughout, tubes equaling or shorter than narrowly funnelform throats, lobes 4 or 5 (adaxial sinus seldom deeper than others). Cypselae obcompressed, ± orbiculate to ovate, oblong, or linear, usually thin-margined or winged, wings membranous to chartaceous or corky, entire or lobed to toothed, sometimes ciliolate; faces smooth or ± papillate to tuberculate; pappi 0, or persistent, of 2 bristly cusps or scales (sometimes pappi 0 and shoulders of cypsela wings ± bristly, pappus-like). x = 14.

Species ca. 35 (28 in the flora): mostly temperate North America, also tropical New World and Old World. Early leaves of some coreopsises often differ from later leaves on individual plants.

In such plants, early (proximal) leaves may be 1–3-pinnately or pedately lobed and 12–25+ cm long with 9–15+ orbiculate to lanceolate, linear, or filiform lobes and contrast markedly with later (distal) leaves 1–3 cm that are undivided or have 3–5+ lanceolate to linear or filiform lobes. Cultivars (often "doubles" with multiple series of "ray" florets) derived from Coreopsis auriculata, C. grandiflora, C. lanceolata, and C. tinctoria are grown in public and residential gardens and are grown commercially for cut flowers.

SELECTED REFERENCES

Jansen, R. K., E. B. Smith, and D. J. Crawford. 1987. A cladistic study of North American Coreopsis (Asteraceae: Heliantheae). Pl. Syst. Evol. 157: 73–84. Smith, E. B. 1976. A biosystematic survey of Coreopsis in eastern United States and Canada. Sida 6: 123–215. Smith, E. B. 1984. Biosystematic study and typification of the Californian Coreopsis (Compositae) sections Tuckermannia, Pugiopappus, and Euleptosyne. Sida 10: 276–289.