Arnica sororia is a North American species of flowering plant known by the common name twin arnica.[1] It is native to Western Canada (British Columbia, Alberta, Saskatchewan) and the Western United States (Washington, Oregon, California, Nevada, Utah, Idaho, Montana, Wyoming, South Dakota).[2] It grows in grasslands and in conifer forests,[3] as well as the sagebrush steppe.[4]

Arnica sororia
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Asterales
Family: Asteraceae
Genus: Arnica
Species:
A. sororia
Binomial name
Arnica sororia

Arnica sororia is a rhizomatous perennial herb producing one or more hairy, glandular stems 10 to 50 centimeters (4 to 19+12 in) tall. There are a few to several pairs of broadly lance-shaped leaves along the stem,[4] the lower ones borne on petioles. Leaves may reach up to 14 cm long.[5]

The inflorescence consists of a daisy-like flower head, rarely more than one per stem.[4] These are lined with phyllaries coated in glandular hairs. The flower head has a center of glandular yellow disc florets and a fringe of yellow ray florets. The fruit is an achene a few millimeters long with a white pappus.[5]

References

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  1. ^ Calflora taxon report, University of California, Arnica sororia E. Greene, twin arnica
  2. ^ Biota of North America Program 2014 county distribution map
  3. ^ Flora of North America Vol. 21 Page 370 Twin arnica Arnica sororia Greene
  4. ^ a b c Taylor, Ronald J. (1994) [1992]. Sagebrush Country: A Wildflower Sanctuary (rev. ed.). Missoula, MT: Mountain Press Pub. Co. p. 158. ISBN 0-87842-280-3. OCLC 25708726.
  5. ^ a b Greene, Edward Lee 1910. Ottawa Naturalist 23(12): 213
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