provided by North American Flora
Arnica amplexifolia Rvdb. Mem. N. Y. Bot. Gard 1: 434. 1900.
Arnica amplexicaulis Nutt. Trans. Am. Phil. Soc. II. 7: 408. 1841. Not .4. amplexicaulis Walt. 1837.
Rootstock rather stout, branched; stem 4-8 dm. high, glabrous and with a few scattered long hairs, sulcate, leafy, branched above; stem-leaves 5 pairs or more, the lowest one or two pairs small, spatulate, tapering at the base into short petioles, which are somewhat connatesheathing, the rest ovate or broadly lanceolate, sessile, sometimes slightly clasping, 5-10 cm. long, 2-5 cm. wide, glabrous except the ciliolate margins, or with a few scattered hairs, rather prominently and sharply dentate, acute or acuminate; heads several or many in a leafy compound cyme; peduncles 3-10 cm. long, sparingly glandular-hirsute; involucre hemispheric, about 12 mm. high and 2 cm. broad, sparingly viscid-hirsute and slightly glandular-granuliferous; bracts 12-15, linear-lanceolate, acuminate; ray-flowers 10-15, the ligules 12-15 mm. long, 4—5 mm. wide, more or less deeply 3-toothed; disk-corollas 6 mm. long; achenes 5 mm. long, sparingly hispid; pappus-bristles 6 mm. long, brownish, short-plumose.
Type locality: Rocks of the Wahlamet, at the Falls. Oregon. Distribution: Western Montana to Alaska and Oregon.
- bibliographic citation
- Per Axel Rydberg. 1927. (CARDUALES); CARDUACEAE; LIABEAE, NEUROLAENEAE, SENECIONEAE (pars). North American flora. vol 34(4). New York Botanical Garden, New York, NY