Chamisso arnica, leafy arnica, arnica de Chamisso

Arnica bernardina Greene; A. chamissonis var. bernardina (Greene) Jepson ex Maguire; A. chamissonis subsp. foliosa (Nuttall) Maguire; A. chamissonis var. foliosa (Nuttall) Maguire; A. chamissonis subsp. incana (A. Gray) Maguire; A. chamissonis var. incana (A. Gray) Hultén; A. chamissonis var. interior Maguire; A. chamissonis var. jepsoniana Maguire; A. foliosa Nuttall

Plants 20–80(–150) cm. Stems usually branched from mid heights or distally. Leaves 4–10 pairs, mostly cauline (evenly distributed; basal leaves often withered by flowering, 1–2 pairs, subsessile to short-petiolate); sessile (proximalmost with membranous connate-sheathing bases); blades lance-elliptic, broadly oblanceolate, or oblong, 5–20 × 2–6(–8) cm, margins entire or remotely denticulate to prominently dentate, apices acute, faces nearly glabrous or puberulent to sparsely or densely white-tomentose-pilose. Heads (1–)3–10(–16). Involucres campanulate (rarely hemispheric). Phyllaries 8–23, nearly linear to narrowly lanceolate (apices each with conspicuous tuft of white hairs). Ray florets 8–20; corollas yellow. Disc florets: corollas yellow; anthers yellow. Cypselae gray to brown, 3–8 mm, subglabrous to sparsely hirsutulous, stipitate-glandular; pappi stramineous, bristles barbellate to subplumose. 2n = 38, 57, 76.

Flowering Apr–Sep. Moist meadows and conifer forests, stream banks, late snow-melt areas, often montane to subalpine; 0–3500 m; Alta., B.C., Man., N.W.T., Ont., Que., Sask., Yukon; Alaska, Ariz., Calif., Colo., Idaho, Mont., Nev., N.Mex., Oreg., Utah, Wash., Wyo.