7.
Arnica sororia
Greene, Ottawa Naturalist. 23: 213. 1910.
Twin arnica
Arnica fulgens
Pursh var.
sororia
(Greene) G. W. Douglas & Ruyle-Douglas
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.
2
n
= 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.
