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sticky arnica

Rydberg's arnica, subalpine arnica

Habit Plants 1.5–4 dm; rhizomatous. Plants 0.8–3 dm; rhizomatous.
Stems

single or branched, usually glandular-puberulent, sometimes glabrate proximally or sparsely scabrous-pilose.

simple, strigose or villous, usually stipitate-glandular.

Basal leaves

usually much reduced, withering early; round-ovate;

petioles broadly winged.

usually in separate sterile rosettes;

petioles winged or not.

Cauline leaves

2–3(4) pairs;

distal 1–2 pairs reduced and bract-like;

blades ovate to lanceolate, 2–8 cm, bases truncate or attenuate;

margins denticulate or serrate-dentate, rarely entire;

veins branching laterally;

tips acute or obtuse;

surfaces glabrous to glandular-puberulent, often gland-dotted; short-petiolate or sessile.

2–4 pairs;

blades lanceolate or elliptic, 2–6 cm, bases attenuate or rounded;

margins entire or denticulate distally;

veins parallel from bases;

tips acute;

surfaces sparsely to moderately pubescent; short-petiolate or sessile.

Peduncles

glandular-puberulent.

stipitate-glandular, usually also villous.

Involucres

turbinate, 10–15 mm.

campanulate-turbinate, 7–22 mm.

Ray florets

8–15;

rays 10–20 mm, yellow.

6–10;

rays 14–30 mm, yellow

Disc florets

15–40;

corollas 7–10 mm, yellow.

Phyllaries

lanceolate to elliptic or linear;

tips acute;

surfaces pilose and stipitate-glandular.

narrowly lanceolate to oblanceolate or elliptic;

tips acute;

surfaces ± pilose or tomentose at base or throughout, stipitate-glandular.

Fruits

columnar-fusiform, 5–6.5 mm, brown or blackish, hispidulous;

pappus bristles 7–10 mm; brownish, subplumose.

columnar-fusiform, 4–7 mm, brown or blackish; hirsute;

pappus bristles 5–7 mm, white, barbellate.

Heads

radiate.

radiate.

. disc florets

20–60;

corollas 6–9 mm, yellow.

2n

=57, 76.

=38, 76.

Arnica diversifolia

Arnica rydbergii

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

Open pine forests, grasslands, bogs, subalpine talus, cliffs, ridges. Flowering Jul–Sep. 1700–3000 m. BW, Casc. CA, ID, WA; north to AK, northeast to MT, southeast to UT. Native.

Alpine meadows, rocky slopes and ridges. Flowering Jul–Aug. 2200–2700 m. BW. ID, WA; north to British Columbia, northeast to Alberta, east to SD, southeast to CO. Native.

Source Flora of Oregon, volume 2, page 184
Kenton Chambers
Flora of Oregon, volume 2, page 186
Kenton Chambers
Sibling taxa
A. cernua, A. chamissonis, A. cordifolia, A. discoidea, A. diversifolia, A. fulgens, A. gracilis, A. lanceolata, A. latifolia, 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. mollis, A. nevadensis, A. parryi, A. sororia, A. spathulata, A. viscosa
Synonyms Arnica ovata
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