Senecio castoreus S. L. Welsh, Rhodora 95: 399, fig. 6. 1993

Perennials, 3–9+ cm; usually fibrous-rooted, sometimes rhizomatous (bases erect or ascending, branched). Stems 1 or 2–3, (white) woolly-tomentose. Basal leaves (and proximal cauline) petiolate; blades obovate to oblanceolate or spatulate, 10–20+ × 5–18 mm, bases tapering, margins entire or crenate (abaxial faces densely tomentose, adaxial glabrescent). Cauline leaves gradually reduced (becoming sessile and bractlike). Heads 1–4+, in corymbiform arrays. Peduncles ebracteate. Calyculi inconspicuous. Phyllaries purple-tinged, 7–10 mm, tomentose (ciliate distally, apices with dense tufts of hairs). Ray florets 0. Disc florets not seen. Cypselae not seen (reported to be glabrous).

Flowering late Jul–late Sep. Ridges, spruce-fir communities, igneous soils; of conservation concern; 3300–3900 m; Utah.

Packera castoreus is known only from relatively few collections from the Tushar Mountains in Beaver and Piute counties. Welsh speculated that it may have some affinities with P. cana and P. werneriifolia.