262. Ratibida Rafinesque, Fl. Ludov. 73. 1817.
Prairie coneflower, Mexican-hat [Derivation unknown]
Lowell E. Urbatsch, Patricia B. Cox
Perennials, 15–120 cm. Stems 1–12+, erect, branched from bases, throughout, or only among heads, strigoso-hirsute, gland-dotted. Leaves basal and cauline; alternate; petiolate (petioles relatively shorter distally); blades lanceolate to ovate or oblanceolate to obovate or oblong, pinnately lobed to 1–2-pinnatifid (lobes usually rounded), ultimate margins entire or serrate, faces usually strigoso-hirsute, usually gland-dotted. Heads radiate, borne singly or in loose, corymbiform arrays. Involucres ± rotate, 8–16 mm diam. Phyllaries persistent, 5–15 in 2 series (usually reflexed in fruit, unequal, outer longer). Receptacles subspheric to columnar, paleate (paleae conduplicate, linear to oblong-oblique, chartaceous proximally, herbaceous distally, apices truncate, usually densely strigose and gland-dotted, each margin usually with an adaxial resin gland; receptacles plus paleae and florets = discs, 5–70 × 5–18 mm). Ray florets 3–15+, neuter; corollas yellow, bicolor (maroon/yellow), or wholly maroon. Disc florets 50–400+, bisexual, fertile; corollas yellowish green, often purplish distally, tubes shorter than cylindric throats, lobes 5, obovate to triangular (gland-dotted and, sometimes, hairy abaxially). Cypselae (black) strongly compressed, linear-oblanceolate to oblong-oblique, margins (at least abaxial) usually ciliate or pectinate-fimbriate, apices truncate and, often, ciliate, faces glabrous or sparsely hairy; pappi of 1–2 toothlike projections, or coroniform, or 0. x = 16.
Species 7 (4 in flora): North America, Mexico.
Jackson, S. W. 1963. Hybridization among three species of Ratibida. Univ. Kansas Sci. Bull. 44: 3–27. Richards, E. L. 1968. A monograph of the genus Ratibida. Rhodora 70: 348–393.