Arnica sororia

Plants 15-50 cm. Stems (1 or relatively few) simple or branched. Leaves 3-6 pairs, crowded toward stem bases (axils lacking tufts of brown wool); petiolate (petioles, at least basal, narrowly winged); blades (with 3 or 5, prominent, subparallel veins) oblanceolate to narrowly oblong, 3.5-14.5 × 0.6-2.4 cm, margins usually entire, rarely denticulate, apices obtuse, faces uniformly hairy, stipitate-glandular. Heads 1-5. Involucres hemispheric. Phyllaries 13-20, usually narrowly, sometimes broadly, lanceolate. Ray florets 9-17; corollas yellow-orange. Disc florets: corollas yellow; anthers yellow. Cypselae brown, 3.5-5 mm, densely hirsute, sometimes sparingly glandular as well; pappi white, bristles barbellate. 2n = 38.

Flowering May-Jul. Prairies and grasslands to montane conifer forests; 500-1500 m; Alta., B.C., Sask.; Calif., Idaho, Mont., Nev., Oreg., Utah, Wash., Wyo.