Sp. Pl. 2: 796. 1753.
Gen. Pl. ed. 5, 348. 1754.
Perennials, 40–150 cm; taprooted. Stems 1–6, erect or ascending, much branched, basally setose, distally glabrous. Leaves basal and cauline; petiolate (basal and proximal cauline, petioles winged); blades (at least basal) oblanceolate, pinnatifid (often runcinate) or coarsely and irregularly toothed (apices acute; distal cauline reduced, entire). Heads (terminal and axillary) usually borne singly (sometimes clustered along stems and branches). Peduncles (nearly 0) not inflated, not bracteate. Calyculi of 3–4, minute bractlets. Involucres cylindric, 2.5–5 mm diam. Phyllaries 5–9 in ± 1 series, linear-lanceolate, equal. Receptacles pitted, glabrous, epaleate. Florets 7–15; corollas (soon withering) yellow. Cypselae tan to black, nearly cylindric, beaks slender or stout, ribs 5+ (with alternating grooves), faces glabrous; pappi persistent (on expanded discs at tips of beaks), of 40–50+, distinct, white, smooth bristles in 1 series. x = 5.
Species ca. 25 (1 in the flora).