Senecio dimorphophyllus Greene, Pittonia 4: 109. 1900

Perennials, 10–30+ cm; fibrous-rooted (caudices horizontal to erect, relatively short and stout). Stems usually 1, rarely 2–3, clustered, glabrous. Basal leaves (relatively thick and turgid) petiolate (petioles broad-winged or narrow, delicate); blades ovate, ovate-orbiculate, oblong-lanceolate, orbiculate, suborbiculate, reniform, or subreniform, 10–50+ × 10–40 mm, bases tapering or subcordate to abruptly contracted, margins entire or crenate. Cauline leaves gradually reduced (proximal and mid sometimes as large as or larger than basal, sessile, oblanceolate to obovate, sometimes lyrate, sometimes auriculate and/or clasping, subentire to irregularly dissected; distal usually sessile, bractlike, sometimes larger). Heads 1–6+ in congested, corymbiform or subumbelliform arrays. Peduncles inconspicuously bracteate or ebracteate, glabrous. Calyculi conspicuous (bases of bractlets swollen). Phyllaries (8–)13 or 21, green (tips cyanic), 5–7+ mm, glabrous. Ray florets 8 or 13; corolla laminae (deep yellow to orange) 5–8+ mm. Disc florets 45–60+; corolla tubes 2–3 mm, limbs 2.5–3.5 mm. Cypselae 0.75–1.5 mm, glabrous, pappi 3–4 mm. 2n = 46.

Varieties 3 (3 in the flora): w United States (Rocky Mountains).