[The Genus Arnica East of the Cascade Mts. of Oregon and Washington]

Bunch Arnica, Foothills Arnica, Twin Arnica, Twin Leopardbane

Arnica sororia

Synonym: Arnica fulgens var. sororia

Flower head of Bunch Arnica, Foothills Arnica, Twin Arnica, Twin Leopardbane: Arnica sororia (Synonym: Arnica fulgens var. sororia)

The photo above shows a close-up of the flower head of foothills arnica as seen from prairie above Wilson Creek, a BLM site several miles south of US Highway 2 in central Washington........June 25, 2006.

Bunch Arnica, Foothills Arnica, Twin Arnica, Twin Leopardbane: Arnica sororia (Synonym: Arnica fulgens var. sororia)The photo at right shows foothills arnica as seen in prairie at Big Summit Prairie, Ochoco N.F...........June 23, 1998.
Characteristics:

Foothills Arnica is an upright perennial to about 50 cm in height. The stems are solitary. It generally has two to three pairs of opposite leaves, which are narrow and long, mostly three to ten times as long as wide. The basal leaves measure 3-12 cm long and 1-4 cm wide and have prominent parallel venation with 3-5 veins (See photo at bottom of page.). The leaves are reduced in size upwards on the stem, and the basal leaves of Arnica fulgens are similar, but has conspicuous tufts of brown, woolly axillary hairs compared to the white or non-existent axillary hairs of Arnica sororia.

The flower heads are sunflower-like, with both ray and disk flowers. The ray and disc flowers are both yellow. There are typically 13 ray flowers, although they can range from 8-23. Individual rays measure 1.5-2.5 cm long. The involucral bracts are broadest at the base, tapering gradually to an acute tip.


Habitat:

Foothills Arnica is found in dry, open places in the foothills and high plains to moderate altitude in the mountains.


Range:

Foothills arnica is found from British Colombia and Alberta south to Wyoming, Utah, and California.


Involucre of Bunch Arnica, Foothills Arnica, Twin Arnica, Twin Leopardbane: Arnica sororia (Synonym: Arnica fulgens var. sororia) - Upper stem leaves of Bunch Arnica, Foothills Arnica, Twin Arnica, Twin Leopardbane: Arnica sororia (Synonym: Arnica fulgens var. sororia)

The photo above left shows a closeup of the involucral bracts of foothills arnica as seen from Wilson Creek in central Washington...........June 25, 2006. The photo at upper fith shows the upper pair of stem leaves of foothills arnica as seen from the location on the same date.

Fruits of Bunch Arnica, Foothills Arnica, Twin Arnica, Twin Leopardbane: Arnica sororia (Synonym: Arnica fulgens var. sororia)

A close-up of the mature fruits of foothills arnica as seen on a potted representative of this species found in the webmaster's garden in Gresham, OR........June 17, 2016..

Basal leaf of Bunch Arnica, Foothills Arnica, Twin Arnica, Twin Leopardbane: Arnica sororia (Synonym: Arnica fulgens var. sororia)

The photo above shows a basal leaf of foothills arnica as seen from Wilson Creek in central Washington.

Involucral bracts of Bunch Arnica, Foothills Arnica, Twin Arnica, Twin Leopardbane: Arnica sororia (Synonym: Arnica fulgens var. sororia) - Pappus of Bunch Arnica, Foothills Arnica, Twin Arnica, Twin Leopardbane: Arnica sororia (Synonym: Arnica fulgens var. sororia)

Bunch Arnica, Foothills Arnica, Twin Arnica, Twin Leopardbane: Arnica sororia (Synonym: Arnica fulgens var. sororia) - Bunch Arnica, Foothills Arnica, Twin Arnica, Twin Leopardbane: Arnica sororia (Synonym: Arnica fulgens var. sororia)

Additional photos of foothills arnica as seen in Logan Valley just west of the Big Creek Campground, Malheur National Forest............July 1, 2010.

Basal leaf of Bunch Arnica, Foothills Arnica, Twin Arnica, Twin Leopardbane: Arnica sororia (Synonym: Arnica fulgens var. sororia) - Basal leaves of Bunch Arnica, Foothills Arnica, Twin Arnica, Twin Leopardbane: Arnica sororia (Synonym: Arnica fulgens var. sororia)

Leaf details for foothills arnica as seen in scablands (a moist drainage) between Long Prairie and FS Road 4230-050, Ochoco National Forest........April 30, 2016.

Flower head of Bunch Arnica, Foothills Arnica, Twin Arnica, Twin Leopardbane: Arnica sororia (Synonym: Arnica fulgens var. sororia) - Bunch Arnica, Foothills Arnica, Twin Arnica, Twin Leopardbane: Arnica sororia (Synonym: Arnica fulgens var. sororia)

The photo at left shows a close-up of the flower head of foothills arnica from Big Summit Prairie, Ochoco N.F...........June 23, 1998. The photo at right shows foothills arnica in bloom on vernally moist scablands at the south rim of Umtanum canyon above Umtanum Falls, Yakima County, WA......May 25, 2019.

Basal leaf of Bunch Arnica, Foothills Arnica, Twin Arnica, Twin Leopardbane: Arnica sororia (Synonym: Arnica fulgens var. sororia) - Bunch Arnica, Foothills Arnica, Twin Arnica, Twin Leopardbane: Arnica sororia (Synonym: Arnica fulgens var. sororia)

The photo at left shows a view of the lowest leaf of foothills arnica as seen from Big Summit Prairie, Ochoco N.F...........June 23, 1998. The photo at right shows foothills arnica as seen atop Lookout Mountain, Ochoco National Forest.........June 15, 2015.
Paul Slichter