Figure 44. — White rubber 

 rabbitbrush (C. 

 nauseosus ssp. albicaulisJ 

 in a thick stand of 

 grasses [ ( intermediate 

 wheatgrass fAgropyron 

 intermediumJ and crested 

 wheatgrass ( Agropyron 

 cristatumj] at Pigeon 

 Hollow 3 Sanpete Co.^ 

 Utah. 



Distribution and Habitat --Rubber rabbitbrush ranges from British Columbia and 

 Saskatchewan south to western Texas, Baja California, and eastern California. It is 

 a common plant on plains, valleys, and foothills. It grows best in openings within 

 the sagebrush, juniper-pinyon, and ponderosa pine zones in sandy, gravelly, or clay- 

 alkaline soils. This species grows at elevations ranging from 150 to 2,750 meters 

 (500 to 9,000 feet). 



Rubber rabbitbrush vigorously invades disturbed sites such as readouts and over- 

 grazed rangelands. On ranges where big sagebrush has been destroyed by fire, insects, 

 vehicular traffic, or continued heavy grazing, rabbitbrush increases and often becomes 

 the dominant vegetation (Evans and others 1973). Nevertheless, in most habitats, this 

 species is not overly competitive with herbaceous species and on some sites it does not 

 suppress grass. Production of herbaceous cover and percentage of site covered have 

 been notably greater when rabbitbrush is present than when it is not present (Plummer 

 1959; Plummer and others 1968) (fig. 44). 



J/se .- -Rubber rabbitbrush is an excellent plant for controlling erosion because of 

 its deep roots, heavy litter, and ability to establish on severe sites (USDA Forest 

 Service 1974). Once established, this species reproduces easily and spreads fast from 

 its light, plumed, wind-disseminated achene. It also grows vigorously when transplanted. 

 When cut and divided the crown readily forms basal sprouts (Hall and Clements 1923) . 



The value of C. nauseosus as browse varies greatly between subspecies and ecotypes. 

 The white to grayish subspecies such as albiaaulis and saliaifolius are more palatable 

 to livestock and big game than the green subspecies, graveolens and oonsimilis (fig. 45; 

 McArthur and others 1974; Hanks and others 1975). Throughout much of the summer range, 

 game and livestock browse the plant lightly if at all except under unusual conditions. 

 During late summer and fall when rubber rabbitbrush is in bloom, most livestock and 

 game graze the flowers, and occasionally a few leaves and the more tender stems. 

 Rubber rabbitbrush is most heavily browsed on winter ranges (fig. 46). Rubber rabbit- 

 brush was found in 48 percent of the deer stomachs examined on a portion of winter 

 range in Owens Valley, Inyo County, California, although it never amounted to more 

 than 6 percent of the total food ingested (Sampson and Jesperson 1963) . Crude protein 

 content ranged from 9 percent during the dormant months to 11.8 percent in the spring 

 after new leaves had formed (Sampson and Jesperson 1963) . 



Subspecies. — Chry sotharmus nauseosus ssp. albicaulis (white rubber rabbitbrush) 

 is a shrub from 6 to 20 dm high with erect leafy branches and leaves covered with a 



45 



