Annuals [perennials], (10–)30–60(–180+)[–250] cm. Leaves: petioles 10–30(–70) mm; blades either ovate to lanceolate, 30–70(–120) × 12–18(–45) mm, or 1-pinnately lobed, primary lobes 3–7, ovate to lanceolate [linear], (10–)25–80+ × (5–)10–40+ mm [blades 2(–3)-pinnatisect], bases truncate to cuneate, ultimate margins serrate or entire, usually ciliate, apices acute to attenuate, faces pilosulous to sparsely hirtellous or glabrate. Heads usually borne singly, sometimes in open, ± corymbiform arrays. Peduncles 10–20(–90) mm. Calyculi (6–)7–9(–13) ± appressed, spatulate to linear bractlets (3–)4–5 mm, margins ciliate, abaxial faces usually hispidulous to puberulent. Involucres turbinate to campanulate, 5–6 × (6–)7–8 mm. Phyllaries (7–)8–9(–13), lanceolate to oblanceolate, 4–6 mm. Ray florets 0 or (3–)5–8+; laminae whitish to pinkish [yellowish], 2–3 or 7–15+ mm. Disc florets 20–40(–80+); corollas yellowish, (2–)3–5 mm. Cypselae: outer red-brown, ± flat, linear to narrowly cuneate, (3–)4–5+ mm, margins antrorsely hispidulous, apices ± truncate or somewhat attenuate, faces obscurely 2-grooved, sometimes tuberculate-hispidulous; inner blackish, ± equally 4-angled, linear-fusiform, 7–16 mm, margins antrorsely hispidulous, apices ± attenuate, faces 2-grooved, tuberculate-hispidulous to sparsely strigillose; pappi 0, or of 2–3(–5), erect to divergent, retrorsely barbed awns (0.5–)2–4 mm. 2n = 24, 36, 48, 72.
