Perennials, (20-)40-80(-120) cm (caudices fibrous-rooted). Herbage usually floccose-tomentose to glabrescent, sometimes glabrous. Stems single or loosely clustered. Leaves progressively reduced distally; petiolate (proximal); blades ovate to lanceolate, 7-15 × (1-)2-5 cm, bases contracted or tapered, margins subentire or serrate to dentate (mid and distal leaves similar, sessile, bractlike, often clasping). Heads nodding (especially when young), (1-)3-12(-20) in racemiform or paniculiform arrays (terminal heads often largest). Calyculi of 4-10 linear bractlets (lengths mostly ¹ / 3 - ¹ / 2 phyllaries, sometimes 1 or 2 equaling phyllaries). Phyllaries ± 13 or ± 21, 6-12 mm, tips green. Ray florets 0. Cypselae glabrous. 2n = 40. The two varieties of Senecio bigelovii are distinguished by morphologic tendencies and by geography.