Perennials, (5-)10-60 cm (rhi­zomatous or with branched caudices). Herbage (often purplish-tinged) glabrous or sparsely and unevenly hairy, especially near leaf axils and among heads, usually glabrescent. Stems single or loosely clustered. Leaves usually progressively reduced distally (basal sometimes smaller than proximal or mid leaves); petiolate (petioles shorter than to equaling blades, often clasping); blades broadly lanceolate or lanceolate to oblanceolate, (5-)10-20+ × 2-4(-5+) cm, bases tapered, margins dentate to denticulate (distal leaves smaller, bractlike). Heads nodding, 1-5(-10). Calyculi of 2-5+ linear to filiform bractlets (lengths to ¹ / 2 phyllaries). Phyllaries ± 13 or ± 21, tips often black or brownish (sometimes with scattered black hairs). Ray florets usually ± 13, sometimes fewer; corolla laminae (10-)15-25 mm. Cypselae glabrous. 2n = 40, ca. 175-180.

The varieties of Senecio amplectens are distinguished by morphologic tendencies and habitat preferences; there are many intermediates. Where the ranges of the two overlap, var. amplectens occurs at slightly lower elevations than var. holmii.