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broadleaf arnica, mountain arnica

cordilleran arnica, hairy arnica

Habit Plants 1–5 dm; strongly rhizomatous. Plants 2–6 dm; rhizomatous.
Stems

usually simple, sometimes branched, glabrous to puberulent or villous.

simple or branched, tomentose to lightly or densely villous, usually stipitate-glandular, sometimes glabrate proximally.

Basal leaves

withering early, usually in separate sterile rosettes, petiolate.

well developed, petiolate.

Cauline leaves

2–4 pairs;

blades ovate, lanceolate, or elliptic, 1.5–14 cm, bases rounded to attenuate, rarely truncate or cordate;

margins entire to denticulate, dentate, or serrate;

veins branching laterally;

tips acute;

surfaces glabrous to puberulent or strigose;

adaxial surfaces sometimes densely and minutely strigillose; most sessile; lower pair sometimes subsessile.

2–4 pairs;

distal pairs more developed than proximal;

blades ovate to broadly or narrowly lanceolate, 3–15 cm, bases attenuate to cordate;

margins entire or denticulate;

veins branching laterally;

tips usually acute;

surfaces glabrous or villous, often glandular-puberulent, sessile or lower pair short-petiolate.

Peduncles

glabrate or villous, sometimes glandular-puberulent at apex.

glandular-puberulent, often pilose or villous.

Involucres

cylindric to campanulate or hemispheric, 8–15 mm.

broadly campanulate or hemispheric, 12–14 mm.

Ray florets

5–15;

rays 10–28 mm, yellow.

10–22;

rays 14–24 mm, yellow.

Disc florets

20–90;

corollas 6–10 mm, yellow.

20–100;

corollas 7–10.5 mm, yellow.

Phyllaries

broadly or narrowly lanceolate to oblanceolate, elliptic, or linear;

tips acute or acuminate;

surfaces glabrous to pilose or villous, sometimes tomentulose or glandular-puberulent at bases.

lanceolate or elliptic-lanceolate to linear;

tips acute or acuminate;

surfaces pilose or scabridulous, stipitate-glandular.

Fruits

columnar-fusiform, 5–9 mm, dark brown, glabrous to glandular-puberulent;

pappus bristles 5–7 mm, white, barbellate.

columnar-fusiform, 5–8 mm; brownish black; hirsute;

pappus bristles 3–6 mm; brownish, plumose.

Heads

radiate.

radiate.

2n

=38, 76.

=38, 57, 76, 95, 114, 133, 152.

Arnica latifolia

Arnica mollis

Distribution
[WildflowerSearch map]
[BONAP county map]
[WildflowerSearch map]
[BONAP county map]
Discussion

Coniferous forests, meadows, shrublands, cliffs, rocky talus, clearcuts, roadsides. Flowering May–Sep. 300–2300 m. BW, Casc, CR, ECas, Owy, Sisk. CA, ID, WA; north to AK, northeast to Alberta, east to WY, southeast to NM. Native.

Moist coniferous forests, meadows, streambanks, bogs, cliffs, rocky slopes. Flowering Jun–Sep. 1000–3000 m. BR, BW, Casc, ECas, Lava, Owy. CA, ID, NV, WA; north to British Columbia, AK, northeast to Alberta, east to WY, southeast to CO. Native.

Source Flora of Oregon, volume 2, page 185
Kenton Chambers
Flora of Oregon, volume 2, page 185
Kenton Chambers
Sibling taxa
A. cernua, A. chamissonis, A. cordifolia, A. discoidea, A. diversifolia, A. fulgens, A. gracilis, A. lanceolata, A. longifolia, A. mollis, A. nevadensis, A. parryi, A. rydbergii, A. sororia, A. spathulata, A. viscosa
A. cernua, A. chamissonis, A. cordifolia, A. discoidea, A. diversifolia, A. fulgens, A. gracilis, A. lanceolata, A. latifolia, A. longifolia, A. nevadensis, A. parryi, A. rydbergii, A. sororia, A. spathulata, A. viscosa
Synonyms Arnica latifolia var. latifolia
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