Perennials, (20–)40–80(–140) cm (caudices branched, fibrous-rooted). Herbage glabrous or glabrate. Stems single or loosely clustered. Leaves ± evenly distributed (proximal often withering before flowering); petiolate or sessile; blades ovate or lanceolate to narrowly lanceolate, (3–)6–12(–20) × (1–)1.5–5(–7) cm, bases tapered, margins usually pinnate to lacerate, sometimes dentate. Heads 10–60+ in compound corymbiform arrays. Calyculi of 3–5+ (prominent or inconspicuous) bractlets (lengths to ³ / 4 phyllaries). Phyllaries (± 8) ± 13, 3–8+ mm, tips green or black. Ray florets ± 8; corolla laminae 5–10 mm. Cypselae usually glabrous, sometimes hirtellous. 2n = 38, 40, 44.

Varieties 3 (3 in the flora): mostly n, w North America.

Varieties of Senecio eremophilus are distinguished by head size and distribution. Varieties eremophilus and macdougalii are notably different; var. kingii is intermediate in both morphology and distribution.