17.
Arnica cordifolia
Hooker, Fl. Bor.-Amer. 1: 331. 1834.
Heartleaf arnica
Arnica cordifolia
var.
pumila
(Rydberg) Maguire;
A. paniculata
A. Nelson;
A. whitneyi
Fernald
Plants
10—40(—70) cm.
Stems
usu-ally simple, sometimes branched.
Leaves
2—4(—6) pairs, mostly cauline (basal often persistent on sterile rosettes); petiolate; blades cordate or subcordate to ovate, 3—10 × 2—10 cm, margins dentate to coarsely dentate, apices acute to rounded, faces puberulent to sparsely villous, sometimes stipitate-glandular (especially adaxial).
Heads
1, or 3—5(—10).
Involucres
broadly campanulate.
Phyllaries
10—20, narrowly ovate to lanceolate.
Ray florets
6—13; corollas yellow.
Disc florets:
corollas yellow; anthers yellow.
Cypselae
dark gray, 5—10 mm, sparsely to densely hirsute (hairs duplex), sometimes stipitate-glandular as well;
pappi
white, bristles barbellate.
2
n
= 38, 57, 76, 95, 114.
Flowering May—Jul. Conifer forests to subalpine meadows; 500—3000 m; Alta., B.C., Man., N.W.T., Ont., Sask., Yukon; Ariz., Calif., Colo., Idaho, Mich., Mont., Nev., N.Mex., Oreg., S.Dak., Utah, Wash., Wyo.
