13. Arnica ovata Greene, Pittonia. 4: 161. 1900.
Sticky leaf arnica
Arnica diversifolia Greene; A. latifolia Bongard var. viscidula A. Gray
Plants 10–50 cm. Stems (forming clumps) simple or branched among heads. Leaves 2–3(–4) pairs (basal 1–2 pairs usually withered by flowering, petiolate, petioles broadly winged, blades round-ovate, relatively small; sterile rosettes lacking), mostly cauline; petiolate (at least middle pair, petioles broadly to narrowly winged); blades broadly deltate to ovate, 4–8 × 2–6 cm (middle pair largest), margins irregularly denticulate to coarsely dentate-serrate, apices acute, faces puberulent (hairs minute) and stipitate-glandular. Heads 1–3(–5). Involucres usually narrowly turbinate, rarely narrowly campanulate. Phyllaries 9–20, linear to narrowly lanceolate. Ray florets 8–16, yellow. Disc florets: corollas yellow; anthers yellow. Cypselae brown to black, 5–7 mm, sparsely to moderately pilose and stipitate-glandular; pappi stramineous to tawny, bristles subplumose. 2n = 57, 76.
Flowering Jul–Sep. Moist meadows and conifer forests, stream banks, late snow-melt areas, montane to subalpine; 200–3600 m; Alta., B.C., Yukon; Alaska, Calif., Colo., Idaho, Mont., Oreg., Utah, Wash., Wyo.