[Arnicas and Leopardbanes: The Genus Arnica East of the Cascade Mountains of Oregon and Washington]
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.
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.
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Foothills arnica blooming in a vernally moist swale along the Eagle Trail, Waikiki Springs Nature Preserve, Spokane County, WA......June 24, 2022. Arnica fulgens is also in the county, so there's a possibility this could be that very similar species.
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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.
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..
The photo above shows a basal leaf of foothills arnica as seen from Wilson Creek in central Washington.
Habitat view of foothills arnica as seen at Brooks Memorial State Park off US 97 near Satus Pass........June 1, 2019.
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Additional photos of foothills arnica as seen in Logan Valley just west of the Big Creek Campground, Malheur National Forest............July 1, 2010.
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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.
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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.
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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