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). 2n = 38, 57, 76, 95, 114, 133, 152.

Arnica mollis Hook. Fl. Bor. Am. 1: 331. 1834
Arnica subplumosa Greene, Pittonia 3: 104. 1896.
Arnica Ckamissonis longinodosa A. Nels. Bot. Gaz. 30: 199. 1910.
Rootstock rather stout; stem 3-6 dm. high, sulcate, sparingly crisp-hairy, glandularhirsute in the inflorescence; leaves of the offsets with petioles 5-8 cm. long, the blades broadly oblanceolate or elliptic, acute at each end, 6-10 cm. long, sparingly crisp-hairy on both sides, ciliolate on the margins, entire or denticulate ; stem-leaves 3 or 4 pairs, the lower ones shortpetioled, the blades broadly oblanceolate or lance-oval, 6-12 cm. long, the upper leaves lanceolate, sessile, smaller and with shorter and coarser hairs; heads 1-3; peduncles 5-15 cm. long, glandular-hirsute; involucre hemispheric, 12-14 mm. high, lS-20 mm. broad, glandularhirsute; bracts 15-18, from broadly oblanceolate and abruptly acuminate to narrowly lanceolate and more attenuate (A. subplumosa); ray-flowers 10-12, the ligules 12-15 mm. long, about 4 mm. wide; disk-corollas 5 mm. long; achenes 5 mm. long, sparingly hirsute; pappusbristles 6 mm. long, light-brown, short-plumose.
Type locality: [Canadian] Rocky Mountains. Distribution: Alberta to Colorado, California, and Alaska.

Arnica silvatica Greene, PI. Baker. 3: 27. 1901
Arnica subphimosa silvatica A. Nels.; Coult. & Nets. Man. 573. 1909.
Rootstock horizontal; stem 3-5 dm. high, striate, puberulent and glandular on the upper part; leaves of the offsets long-peduncled, the peduncles 3-6 dm. long, the blades ovate, dentate with mucronate-tipped teeth, acute, 3-7 cm. long, thin, puberulent above, glabrous or nearly so and paler beneath; stem-leaves 3-5 pairs, the lower ones with winged petioles sheathing at the base, the blades ovate, 6-10 cm. long, sharply dentate, acute or the lowermost obtuse, the upper stem-leaves ovate, sessile; heads 3-5 cymose; involucre nearly hemispheric, 12-13 mm. high and 15-18 mm. broad, glandular-puberulent; bracts 12-16, lance-linear, acuminate; ray-flowers 12-15, the ligules about 15 mm. long, 3 mm. wide, 7-9-veined; diskcorollas 6-8 mm. long; achenes 5 mm. long, sulcate, hirsute; pappus-bristles tawny, 6 mm. long, short-plumose.
Type locality : Ruby, Colorado.
Distribution: Spruce woods and rocky hillsides, western Colorado and Wyoming.

Arnica mollis is a North American species of arnica in the sunflower family, known by the common name soft arnica,: 113  or hairy arnica. It is native to Canada (British Columbia, Alberta, Quebec, and all 3 Arctic territories) and the United States (Alaska and the western mountains as far south as San Bernardino County, California and Rio Arriba County, New Mexico. There are also isolated populations in the White Mountains of Coos County, New Hampshire. The species grows in subalpine mountain habitat such as meadows and streambanks.

Arnica mollis is a perennial herb producing one or more hairy, glandular, mostly naked stems 20 to 60 centimeters tall. There are 3 to 5 pairs of leaves along mainly the lower half of the stem, each oblong in shape and 4 to 20 centimeters in length.

The inflorescence holds one to a few daisylike flower heads with centers of yellow disc florets and fringes of yellow ray florets. The fruit is an achene with a brownish pappus.

"Mollis" means "soft", referring to the soft hairs on the leaves.: 113