Arnica gracilis Rydb.
Annotated by Charles F. Williams, 2010. Sources: USDA-NRCS Plants Database. Remarks: taxonomic update

Idaho: Caribou County: Caribou Mountain. Camp at junction of Barnes Creek Road & Willow Creek Road 0.2 miles North of Monte Cristo Mine. Climbed roughly straight up from cabin to ridge. Grassy, fairly moist, open hillside.Elevation: 9400 ft. Elev. 9400 ft.
43.0919578° N, 111.3199138° W; T4S R44E S8 NE1/4
Datum: WGS84. Uncertainty: 500 meters. Coordinate Source: BioGeomancer. Invalid coordinates (located outside county bounds).
Rock slide, from boulders to medium rocks with lichens at margin of slide in little soil. Found species below. Almost at ridge crest, large rocks. In soil between large rocks near summit of west ridge. Associated with white geranium, Rudbeckia, Agastache, Solidago, Scrophularia lance, and yellow Mimulus. Some conifers: parrots beak, pink geranium, Potentilla, tobacco, yarrow, Senecio, Carex gayophytum, Eriogonum. Also columbine, Arnica, and a bramble (Rubus idaeus var. gracilipes). Achenes glabrous below. Involucres with some long hairs, not as much as A. cordifolia. Heads 3-9. Involucres 7-13 mm high. Phenology: Flowers.

Thomas Dieffenbach 00349, Jul 27, 1977
IDS, Accession: 2012.010, Barcode: IDS0054131