Dioecious. Plants 3–20 cm (caudices branching or rhizomes stout). Stolons none. Basal leaves 3-nerved, narrowly oblanceolate, 10–60(–100) × 3–12 mm, tips acute, faces gray-woolly or tomentose. Cauline leaves linear, 5–40 mm, mid and distal flagged. Heads 3–9 in corymbiform arrays. Involucres: staminate 4.5–6 mm; pistillate 5–8 mm. Phyllaries (proximally light brown, dark brown, or olivaceous) distally whitish or light brown. Corollas: staminate 3–4.5 mm; pistillate 2.5–4 mm. Cypselae 1–1.6 mm, glabrous; pappi: staminate 4–5 mm; pistillate 3.5–5 mm. 2n = 28 (under A. neodioica).
Phenology: Flowering summer.
Habitat: Protected alpine and subalpine sites, gravelly or sandy soils near conifers at timberline
Elevation: 1400–3400 m
Alta., B.C., Calif., Idaho, Mont., Oreg., Utah, Wash., Wyo.