| Arnica sororia | |
|---|---|
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Asterids |
| Order: | Asterales |
| Family: | Asteraceae |
| Tribe: | Heliantheae |
| Genus: | Arnica |
| Species: | A. sororia |
| Binomial name | |
| Arnica sororia Greene |
|
Arnica sororia is a species of arnica known by the common name twin arnica. It is native to western North America from British Columbia to California to Nebraska, where it grows in many types of habitat.
It is a rhizomatous perennial herb producing one or more hairy, glandular stems 10 to 50 centimeters tall. There are several pairs of broadly lance-shaped leaves along the stem, the lower ones borne on petioles. Leaves may reach up to 14 centimeters long.
The inflorescence holds one to five daisy-like flower heads 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.