B54 

 RABBITBRUSHES 



Chrysotham'nus spp. 



Eabbitbrush is the name most commonly applied to this genus of 

 shrubby plants, including approximately 70 species and about a 

 dozen subspecies, all of which are distinctly confined to western 

 North America. These plants belong to the aster, or composite 

 family (Asteraceae, or Compositae) and are frequently called rabbit- 

 sage, rayless-goldenrod, and yellowbrush. 



The northern limit of this genus is in British Columbia, Alberta, 

 and Saskatchewan ; it extends to South Dakota and western Nebraska 

 on the east; and southward to Texas, southern New Mexico, and 

 southern Arizona, with extensions of a few species into Mexico and 

 Lower California. A few species have been found as far west as 

 the Coast Range Mountains in California. These shrubs are most 

 abundant within the Great Basin, and here they often dominate large 

 tracts. The rabbitbrushes are characteristic shrubs or undershrubs 

 of the open plains and foothills from sea level to 10,000 feet in eleva- 

 tion. They are frequently a conspicuous component of the vegeta- 

 tion on alkaline plains and stream banks throughout the semiarid 

 regions of the West. Most of the species grow at comparatively low 

 altitudes on fairly deep, heavy soils. On moderately alkaline flats, 

 C. graveolens, C. nauseosus and C. pinifoliiis appear in dense, exten- 

 sive stands and are often the dominant plants on many areas, asso- 

 ciated with saltgrass (Distichlis spicata), greasewood (Sarcobatus 

 vermiculaiiis) , and poverty weed (Ivai aoffittaris). A few members, 

 including C. tcmceolatus, &. parryi, and C. viscidiflorus serrulatus, 

 occur in mixed types of the foothills and mountains. 



Most species of C hrysothamnus have little or no forage value, but 

 a few, such a lanceleaf yellowbrush (C. lanceolatus} and twistleaf 

 rabbitbrush (C. viscidiftorus tortifolius') , rank as fair to good forage 

 for sheep and cattle (see B55). Small rabbitbrush (C. steno- 

 pJiyllus] often grows abundantly in desert areas and furnishes 

 considerable forage for sheep during the winter. 



Under certain circumstances several of the species are useful indi- 

 cators of range deterioration. Rubber rabbitbrush (C. nauseosus), 

 for example, now grows abundantly on depleted areas that formerly 

 supported a good stand of giant wild-rye (Elynws condensatus) . 

 Small rabbitbrush has become the dominant plant on many depleted 

 winterfat (Eurotia lanata) ranges in western Utah and central 

 Nevada. Sampson 2 states that, in the Wasatch Mountains of Utah, 

 lanceleaf yellowbrush "is the most characteristic forerunner of other 

 aggressive perennial plants which gain a foothold as the wheat- 

 grasses are killed out by overgrazing or other adverse factors." 

 Rabbitbrushes grow profusely over many of the arid lands and 

 stream channels of the West, and by virtue of their deep and extensive 

 root systems serve as impediments to wind and water erosion. 



The possibility of utilizing certain species of rabbitbrushes as 

 sources of raw rubber has been investigated by Hall and Goodspeed 3 



3 Sampson, A. W. PLANT SUCCESSION IN RELATION TO RANGE MANAGEMENT. U. S. Dept. 

 Agr. Bull. 791, 76 pp., illus. 1919. 



8 Hall, H. M., and Goodspeed, T. H. A RUBBER PLANT SURVEY OP WESTERN NOETH 

 AMERICA. Calif. Univ. Pubs., Bot. 7: [159]-278, illus. 1919. 



