Gray horsebrush is a much-branched, unarmed shrub from 20 to 60 cm tall. The twigs, leaves, and flower involucres are notably white-tomentose. The leaves are linear or oblanceolate, measuring from 1-3 cm long and 1-4 mm wide. The leaf tips narrow abruptly to a narrow spine-like tip. The leaves are often closely ascending or appressed to the twig (See photo at right.). The leaves are deciduous in the autumn.
The flower heads are in small cymes at the ends of the numerous short branches, with 4 (occasionally 5) flowers in each head. The involucres are about 7-10 mm high and consist of 4 tomentose, oblong bracts.
Gray horsebrush is found in open, dry places in the foothills and plains.
Gray horsebrush is found from southern British Columbia east to Montana, and south through the Pacific Northwest to California, and hence eastward to New Mexico.
The photo above shows a close-up side view of the flowerheads of gray horsebrush. Note the long, narrow involucral bracts at the base of each flowerhead. Photographed in prairie and scabland along Wilson Creek, a BLM site several miles south of US Highway 2 in central Washington..........June 25, 2006.
The photo above shows a side view of the inflorescence of gray horsebrush as found along US Highway 26 through the Warm Springs Indian Reservation.........June 26, 1997.