Perennials, (50-)60-100(-120) cm (caudices fibrous-rooted). Herbage sparsely floccose­­-to­me­ntose, unevenly glabrescent. Stems single. Leaves evenly distributed; petiolate; well-developed mid leaves: blades lanceolate to oblong,(8-)10-15(-18) × (2-)3-5(-9) cm overall, margins deeply dentate or irregularly pinnate-lobed to laciniate; distal leaves sessile, weakly clasping. Heads 8-20 in corymbiform arrays. Calyculi of 3-8+ linear to filiform bractlets (lengths ¹ / 2 - ³ / 4 + phyllaries). Phyllaries ± 13 or ± 21, 5-8 mm, tips green. Ray florets ± 8 or ± 13; corolla laminae 8-12(-20) mm. Cypselae glabrous.

Flowering late summer. Moist meadows, conifer-dominated sites; 1400-2700 m; Calif.

Senecio clarkianus grows on west slopes of the central and southern Sierra Nevada.