The most obvious chromatographic characteristic of collections that were selected 

 by deer and livestock was the presence of a large and highly iridescent spot 9. This 

 marker is particularly obvious in subgroups la, lb, and Ic where its brilliance is 



unpalatable subgroups; however, this distinction is 

 Ila. Since subgroups Id and Ila are found in close 

 additional characters is frequently necessary. Other 

 indicators of palatability for deer and livestock are the presence of spots 16 and 22 

 in subgroups la, lb, and Ic; the presence of 22 in Id; and the absence of 26 in all 

 groups . 



Discussion 



considerably greater than in the 

 not so clear in regard to Id and 

 physical association, the use of 



At this point in our study of the big sagebrush complex, we believe it is signifi- 

 cant that chromatograms of the various collections allow rather well-defined groupings. 

 The existence of these groups not only supports our initial hypothesis regarding the 

 occurrence of genetic divergence within subspecies of big sagebrush, but provides 

 evidence that this genetic change is following quite discrete lines. However, we must 

 point out that some of the collections do not fall into any of the designated groupings 

 but appear to occupy positions intermediate between them. Chromatograms of these inter- 

 mediates most commonly contain both spot 22, found primarily in group I, and 26 occur- 

 ring in group II; but such chromatograms lack spot 16 found in group I, and spot 9 is 

 usually intermediate in brilliancy. This combination suggests hybridization between 

 groups I and II and the retention by the progeny of some characteristics from each 

 parent. Nevertheless, the majority of collections can be readily separated into the 

 previously described groupings by the methods given. 



In regard to the ecological distribution of the major groups and subgroups, the 

 following observations have been made. Collections of group I were obtained primarily 

 in mountain habitats. Those of subgroup Ic were obtained in the lower mountains and 

 higher foothill areas. Individuals from subgroups la and lb of the lower foothills 

 area have come from areas extending from the lower limits of Ic to the base of the 

 foothills where they overlap with subgroup lib, the prevalent big sagebrush (A. 

 tridentata tridentatd) of the more extensive lowlands. 



The two subgroups la an 

 la predominates in the upper 

 lower part. However, specim 

 range . 



d lb occupy the lower foothi 

 portion while most collecti 

 ens of each have been collec 



11 areas, and it appears that 

 ons of lb have come from the 

 ted throughout this entire 



Subgroups Id and Ila have only been collected from areas on the Jackson and Pine 

 Forest mountains in northwest Nevada where they occupy similar habitats. 



Chromatograms of the tall bushes commonly observed growing along such places as 

 fencerows and arroyos differ slightly from those of lib, among which they are frequently 

 found. However, too few collections have been analyzed to vvarrant the formation of a 

 separate subgroup at this time, although it appears likely that this may be advisable 

 following a more thorough study. In the present paper, this tall fencerow type is 

 included in lib. Thus, on the basis of source material, it seems significant that the 

 distribution pattern fits fairly close to the chromatographic divisions, especially 

 between highland and lowland sources. 



There is little likelihood that phenols observed in the big sagebrush of this 

 study are responsible for the relative palatability of these plants. However, the 

 strong association that has been found between chromatographic variation and palatability 

 suggests that this laboratory procedure may be utilized to quickly evaluate the grazing 

 potential of any collection of big sagebrush. Consequently, chromatography can be a 

 useful tool in selecting strains of big sagebrush for specific purposes. 



S 



