Introduction 



Common big sagebrush (Artemisia tridentata) is one of the most widely distributed 

 and abundant shrubs of the Western United States (Hall and Clements 1923; Beetle 1960; 

 Dayton 1931; and Plummer et al. (1968). It is particularly abundant over much 

 of the Great Basin and in many areas may comprise up to 90 percent of the shrubby 

 vegetation. It is an important browse for big game on their winter ranges. (The 

 nomenclature in this publication has followed Holmgren and Reveal 1966.) 



Past observations have revealed that there is considerable variation in the pala- 

 tability of big sagebrush for big game and livestock. This variation in palatability 

 is often associated with the geographical source of the sagebrush, but in some cases 

 palatable and unpalatable plants may be found growing on a common site. These obser- 

 vations indicate that there may be a real opportunity for development of improved 

 strains through selection and breeding. 



Apparently, considerable genetic diversification has occurred in the big sagebrush 

 complex as a result of hybridization and back crossing. Genetic makeup is probably 

 associated with dissimilarities in the chemistry of the plants involved; thus, if 

 chemical differences are detected in plants collected from various geographical sources, 

 this indicates that some degree of genetic divergence exists. Furthermore, the amount 

 of chemical difference may be an index of the extent to which strains have become 

 separated. Such differences in the chemistry of plants have been utilized extensively 

 in recent years to supplement morphological differences in the grouping of closely 

 related plants in some of the major taxa. For example, Hollis (1966, 1967a, 1967b, and 

 1967c) made comparative analyses of the polyphenols from leaf extracts of Eucalyptus 

 using paper chromatography. As a result of these analyses, he resolved many of the 

 problems relating to the taxonomy of this genus. The solution of these problems was 

 not possible on the basis of morphological characters alone. 



Similar studies on the genus Baptisia were conducted by Alston and Turner (1962, 

 1963) and Brehm and Alston (1964). In addition, Holbo (1965) completed a comparable 

 study of Artemisia section Tridentatae in which he readily separated the individual 

 species by chromatography. Using thin- layer chromatography, Brunner 1 showed that strain 

 variation in big sagebrush could be readily detected. Consequently, it appeared likely 

 that similar techniques could be used to separate strains of big sagebrush into pala- 

 tability classes. 



i J. Brunner. 

 Las Vegas, Nevada. 



Some observations on Artemisia in Nevada. Bureau of Land Management, 

 (Manuscript in preparation.) 



