The photo
at right of the leaves and tomentose stem of catclaw horsebrush found in the Alvord
Desert, SE Oregon.....May 28, 2000.
Catclaw horsebrush is a much-branched shrub from 50 -120 cm tall. The twigs are densely white-tomentose. The primary leaves are transformed into spreading or recurved spines frokm 0.5-5 cm long. These subtend clusters of linear, green and glabrous leaves up to 1 cm long (See photo at right.).
The flower heads are borne from leaf axils either singly or in pairs along the stems, with 5-9 flowers in each head. The flowers are all disk flowers. No ray flowers are present. The involucre consists of 4-6 glabrous to loosely tomentose bracts from 7-10 mm long.
variety spinosa: Spines 0.5-1.5 cm long, reecurved. The variety found in southeastern Oregon.
variety longispina: Spines 1.5-5 cm in length, nearly straight. Found at the southern extent of the range of the species.
Catclaw horsebrush may be found in open, dry places in the foothills and plains between the elevations of 800-2000 meters.
Catclaw horsebrush is found from southeastern Oregon south to southern California and east to southwestern Montana, Wyoming, western Colorado, southern Utah, northwestern New Mexico, and southern Nevada,
