Table 1>. --Color of extract from each of seven subgroups of 

 A. tridentata under ultraviolet light 





Color of extract under 



Subgroup 



: ultraviolet light 



vaseyana la 



Bluish-white to light blue 



vaseyana lb 



Bluish-green to bluish-violet 



vaseyana I c 



Creamy -white to bluish-white 



wyomingensis Id 



Brownish-violet to greenish-violet 



tridentata II a 



Bluish-violet to greenish-violet 



tridentata lib 



Greenish -violet 



tridentata lie 



Violet to reddish-violet 



Comparisons of single-dimension, thin-layer chromatograms of the seven subgroups 

 of A. tridentata are shown in figures 26-32. 



Another rapid, but less accurate, method of separating collections of big sage- 

 brush into the previously described groups was detected during the course of the study. 

 Viewed directly under ultraviolet light, methanol extracts fluoresce in distinctive 

 colors based on the relative brilliance of the phenolic substances already described 

 in the chromatographic analysis (table 3). Young (1965), Winward (1970), and Brunner 

 (1972) have used thin- layer chromatography to distinguish Artemisia taxa. 



The chromatographic spots that exert the greatest influence on composite colora- 

 tion are 9, 5, and 6. IVhere spot 9 is large and brilliantly iridescent and 5 and 6 

 are only lightly colored {vaseyana la and vaseyana Ic) , the extract is a brilliant 

 creamy-white to bluish-white. However, when spots 5 and 6 are brilliantly colored 

 {Vaseyana lb and wyomingensis Id), much of the brilliance of 9 is masked. In such 

 cases, the composite color reflects the yellow of these spots and produces varying 

 shades of brownish- and greenish-violet. In group II, where the intensity of spot 9 

 is much reduced, a corresponding reduction in the blue coloration of the composite 

 mixture occurs that results in a strong violet background. The usefulness of this 

 technique lies in the fact that the group to which big sagebrush belongs can be 

 determined a few hours after collection. Since this determination is only qualitative, 

 extraction of the leaves can begin at the time of collection, thus eliminating the 

 drying time necessary for a more quantitative analysis. Winward and Tisdale (1969) 

 outline a similar technique. 



The same method also appears to be effective with seed. Methanol or water extract 

 of big sagebrush seed from each subgroup fluoresces in colors similar to but less 

 intense than those from corresponding foliar material. Consequently, it is a rela- 

 tively simple procedure to determine the subspecies from which seed was harvested 

 (Taylor and others 1964; Hanks and Jorgensen 1973). 



Figures 26-32. — Color photographs of representative thin-layer ahromatograms of 

 the methanol- soluble extracts from the leaves of the seven subgroups of 

 A. tridentata. The origin is on the left. The bright red band near the 

 solvent front (right) is chlorophyll A. Fig. 26, subsp. vaseyana subgroup 

 la; fig. 27, subsp. vaseyana subgroup lb; fig. 28, subsp. vaseyana subgroup 

 I<^i fig- 29, subsp. wyomingensis subgroup Id; fig. 30, subsp. tridentata 

 subgroup Ila; fig. 31, subsp. tridentata subgroup lib; fig. 32, subsp. 

 tridentata subgroup He. 



10 



