15b. Arnica lanceolata Nuttall subsp. prima (Maguire) Strother & S. J. Wolf in Flora of North America Editorial Committee, Fl. N. Amer. N. Mexico. 21: 373. 2006.
Clasping arnica
Arnica amplexifolia Rydberg subsp. prima Maguire, Madroño 6: 154. 1942; A. amplexicaulis Nuttall; A. amplexicaulis var. piperi H. St. John & F. A. Warren; A. amplexicaulis subsp. prima (Maguire) Maguire; A. amplexicaulis var. prima (Maguire) B. Boivin
Leaves: basal commonly withered by flowering, sessile or subsessile to petiolate, blades usually oblong to narrowly lanceolate or oblanceolate, rarely ovate, margins subentire to prominently dentate-serrate; cauline sessile (bases sometimes partly connate-sheathing), blades narrowly to broadly lance-elliptic or ovate, margins subentire to serrate-dentate, faces sparsely to densely pilose. Phyllaries narrowly lanceolate. 2n = 38, 57, 76.
Flowering May–Sep. Moist areas, along stream banks, snow-melt areas, montane to alpine meadows; 0–3000 m; Alta., B.C., N.W.T., Yukon; Alaska, Calif., Idaho, Mont., Nev., Oreg., Utah, Wash., Wyo.
The name Arnica amplexifolia Rydberg (1900c) was a superfluous (illegitimate) substitution for A. amplexicaulis Nuttall (1841).
