Longleaf arnica, northern arnica, arnica lonchophylle

Arnica alpina (Linnaeus) Olin & Ladau subsp. lonchophylla (Greene) G. W. Douglas & Ruyle-Douglas; A. angustifolia Vahl subsp. lonchophylla (Greene) G. W. Douglas & Ruyle-Douglas; A. arnoglossa Greene; A. chionopappa Fernald; A. gaspensis Fernald; A. lonchophylla subsp. arnoglossa (Greene) Maguire; A. lonchophylla subsp. chionopappa (Fernald) Maguire

Plants 12–50 cm. Stems usually simple, rarely branched. Leaves 3–7 pairs, mostly cauline; petiolate (petioles, at least proximal, relatively narrow, ± equaling blades); blades narrowly to broadly lanceolate or ovate, 3.5–14 × 0.5–3.7 cm, margins regularly dentate or denticulate, apices acute, faces glabrous or moderately pilose, sparsely to densely stipitate-glandular. Heads 3–8 (erect). Involucres campanulate-turbinate. Phyllaries 6–14, lanceolate (apices acute). Ray florets 6–17; corollas yellow. Disc florets: corollas yellow; anthers yellow. Cypselae gray to brown, 3–6 mm, densely hirsute, sometimes stipitate-glandular; pappi white, bristles barbellate. 2n = 38, 57, 76.

Flowering June–Aug. Dry to mesic, open montane slopes, open woodlands, stream gravels, shorelines, calcareous rocky outcrops, to lowland Arctic tundra; 0–1500 m; Alta., B.C., Man., N.B., Nfld. and Labr. (Nfld.), N.W.T., N.S., Nunavut, Ont., Que., Sask., Yukon; Alaska, S.Dak., Wyo.