Arnica chamissonis

Arnica chamissonis is native to western North America, including Alaska, and most of Canada including Yukon and Northwest Territories.[5][6] Arnica chamissonis is perennial. It has a temperature minimum of −33 °F (−36 °C).[5] They are adapted to both coarse and medium textured soils with a pH between 6.0–7.2.[5] Since this plant uses a lot of moisture, it has a precipitation requirement of between 14–24 inches (36–61 cm).[5] It generally prefers moist meadows and conifer forests and often grows in montane to subalpine zones, 0–3,500 metres (0–11,483 ft).[7] Seeds are easily available and the plant can be grown in a home garden. It prefers full sun exposure and an average soil temperature of 65–75 °F (18–24 °C).[8]

Arnica chamissonis has yellow flowers with green medium textured foliage.[5] The leaves of the Arnica chamissonis are grouped in 4–10 pairs.[7] It produces brown seeds and has an active growth period of the spring and summer. It has rhizomatous growth and grows at a moderate rate.[5] Rhizomatous plants have an underground stem with small fiber-like adventitious roots. A. chamissonis has a mature height of roughly 2.5 feet (76 cm).

Arnica chamissonis has an active bloom period throughout the summer.[5] There are approximately 400,000 seeds per pound. These individuals have a medium seedling vigor and a moderate vegetative spread rate.[5] Seedling vigor refers to "the expected seedling survival percentage of the plant compared to other species with the same growth habit." A vegetative spread rate refers to how quickly a plant can spread through a given area. In general, A. chamissonis can be grown in a container, by using seeds or sprigs.[5]

Both A. montana and A. chamissonis contain the toxin helenalin.

The species is named for German poet and botanist Adelbert von Chamisso, 1781–1838.[9][10]

• Arnica chamissonis in the CalPhotos photo database, University of California, Berkeley