12.
Arnica mollis
Hooker, Fl. Bor.-Amer. 1: 331. 1834.
Hairy arnica
Plants
15—70 cm.
Stems
(forming clumps) simple or branched among heads.
Leaves
(2—)3(—4) pairs, mostly cauline (basal sometimes present); petiolate (petioles relatively short, broad-winged) or subsessile; blades broadly elliptic, lance-elliptic, or narrowly to broadly lanceolate, 4—20 × 1—4 cm, margins entire or irregularly denticulate, apices acute, faces sparsely to moderately hairy (hairs relatively short to long, stipitate glands or soft, silky).
Heads
1 or 3—7.
Involucres
hemispheric to campanulate.
Phyllaries
10—22, usually broadly lanceolate, rarely narrowly lanceolate or oblanceolate.
Ray florets
10—22; corollas yellow.
Disc florets:
corollas yellow; anthers yellow.
Cypselae
grayish brown to black, 4—8 mm, mostly stipitate-glandular, sparsely hirsutulous (hairs white to brownish, simple or bifid);
pappi
tawny, bristles plumose (with deep, amberlike deposits).
2
n
= 38, 57, 76, 95, 114, 133, 152.
Flowering Jun—Sep. Moist meadows and conifer forests, stream banks, late snow-melt areas, montane to subalpine; 1000—4000 m; Alta., B.C., N.W.T., Yukon; Alaska, Calif., Colo., Idaho, Mont., Nev., Oreg., Utah, Wash., Wyo.
