Twin Arnica - Arnica sororia
MNPS Threat Rank
Stems solitary, 20–40 cm. Herbage glandular, pubescent, sometimes with tufts of white hair among leaf bases. Leaves: basal blades short-petiolate, narrowly lanceolate, entire, 3–10 cm long; cauline 2 to 4 pairs, similar, sessile above. Heads 1 to 5; involucre hemispheric, 10–15 mm high. Rays 9 to 16; ligules 1–2 cm long. Pappus short-barbed, white. Achenes hirsute, 3–7 mm long (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX)
BC to SK south to CA, NV, UT and WY (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
Observations in Montana Natural Heritage Program Database
Number of Observations:
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(Observations spanning multiple months or years are excluded from time charts)
The following animal species have been reported as pollinators of this species or genera where their geographic ranges overlap: Bombus bifarius
, Bombus mixtus
, and Bombus occidentalis
(Mayer et al. 2000, Wilson et al. 2010).
- Literature Cited AboveLegend: View Online Publication
- Mayer, D.F., E.R. Miliczky, B.F. Finnigan, and C.A. Johnson. 2000. The bee fauna (Hymenoptera: Apoidea) of southeastern Washington. Journal of the Entomological Society of British Columbia 97: 25-31.
- Wilson, J.S., L.E. Wilson, L.D. Loftis, and T. Griswold. 2010. The montane bee fauna of north central Washington, USA, with floral associations. Western North American Naturalist 70(2): 198-207.
- Additional ReferencesLegend: View Online Publication
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- Aradottir, A.L. 1984. Ammonia volatilization from native grasslands and forests of SW Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 48 p.
- Cope, M.G. 1992. Distribution, habitat selection and survival of transplanted Columbian Sharp-tailed Grouse (Tympanuchus phasianellus columbianus) in the Tobacco Valley, Montana. M.Sc. Thesis. Bozeman, Montana: Montana State University. 60 p.
- Grove, A.J. 1998. Effects of Douglas fir establishment in southwestern Montana mountain big sagebrush communities. M. Sc.Thesis. Bozeman, MT: Montana State University. 150 p.
- Hodgson, J.R. 1970. Ecological distribution of Microtus montanus and Microtus pennsylvanicus in an area of geographic sympatry in southwestern Montana. Ph.D. Dissertation. Bozeman, Montana: Montana State University. 65 p.
- Husby, P.O. 1982. Effects of grazing on vegetation in the Artemisia tridentata-Festuca idahoensis habitat type. M.Sc. Thesis. Bozeman, MT: Montana State University. 76 p.
- Johnson, T. W. 1982. An analysis of pack and saddle stock grazing areas in the Bob Marshall Wilderness. M.Sc.Thesis. Bozeman, MT: Montana State University. 105 p.
- Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
- Martinka, R.R. 1970. Structural characteristics and ecological relationships of male blue grouse (Dendragapus obscurus (Say)) territories in southwestern Montana. Ph.D Dissertation. Bozeman, MT: Montana State University. 73 p.
- Quire, R.L. 2013. The sagebrush steppe of Montana and southeastern Idaho shows evidence of high native plant diversity, stability, and resistance to the detrimental effects of nonnative plant species. M.Sc. Thesis. Bozeman, MT: Montana State University. 124 p.
- Rundquist, V.M. 1973. Avian ecology on stock ponds in two vegetational types in north-central Montana. Ph.D. Dissertation. Bozeman, MT: Montana State University. 112 p.
- Seipel, T.F. 2006. Plant species diversity in the sagebrush steppe of Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 87 p.
- Williams, K.L. 2012. Classification of the grasslands, shrublands, woodlands, forests and alpine vegetation associations of the Custer National Forest portion of the Beartooth Mountains in southcentral Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 376 p.