Arnica rhizomata

Arnica rhizomata A. Nels. Bot. Gaz. 31: 409. Je 1901
Arnica foliosa andina Nutt. Trans. Am. Phil. Soc. II. 7: 407. 1841. Arnica lanulosa Greene, PI. Baker. 3: 26. N1901.
Rootstock creeping, slender; stem 2-6 dm. high, usually rather densely white-villous or the lower part glabrate in age; stem-leaves 5-8 pairs, the lower petioled, the petioles with connate-sheathing bases, the upper sessile; blades of the lower leaves lanceolate or elliptic, obtuse or rounded at the apex, abruptly narrowed at the base, 5-10 cm. long, 2-3.5 cm. wide, 5-7-ribbed, canescent-villous with rather short hairs, mostly entire-margined, the upper leaves sessile, lanceolate, acute; heads 3-9; peduncles 3-6 cm. long; involucre broadly turbinate, 8-10 mm. high; bracts about 15, linear or linear oblong, obtusish or acute; ray-flowers 10-15, the ligules 12-15 mm. long, 4-5 mm. wide; disk-corollas 8 mm. long; achenes 5 mm. long, sparingly pilose; pappus-bristles straw-colored, 8 mm. long, barbellate. Perhaps not distinct from A. tomentulosa Rydb. (Ja 1901).
Type locality: Lincoln Gulch. Albany County. Wyoming. Distribution: Wyoming to Colorado, Utah, and Oregon.