Perennials, (50-)100-150+ cm (rhizomes fibrous-rooted). Herb­age unevenly tomentose, glabrescent, except persistently hairy on abaxial faces of leaves. Stems single. Leaves ± evenly distributed (basal and proximal withering before flowering); mostly petiolate (proximal); blades oblong or ovate to oblong-lanceolate (pinnately or subpalmately parted, primary lobes 3-6+, lanceolate to lance-linear, 3-8+ cm), 10-20+ × 8-15+ cm, bases ± tapered, ultimate margins serrate (distal leaves similar, sessile, smaller). Heads 20-50 in corymbi­form arrays. Calyculi 0 or of 1-5+ subu­late bractlets (lengths about ¹ / 3 phyl­laries). Phyllaries ± 13, 4-6 mm, tips green. Ray florets ± 5; corolla laminae ca. 10 mm. Cypselae glabrous. 2n = 40.

Flowering summer. Open meadows and slopes; 0-100 m; Alaska; Eurasia.

Senecio cannabifolius barely enters the flora from far-eastern Asia. Infraspecific taxa are recognized within S. cannabifolius in some floras of Asiatic regions; our plants are referable to var. cannabifolius.

Senecio cannabifolius has been treated in Jacobaea by E. Wiebe (2000); see discussion under 53. S. jacobaea.