86 Trans. Acad. Set. of St. Louis. 



torum and IS. glauca villosa from the Rocky Mts. leads to the 

 conclusion that no rigid line can be drawn between the species 

 as they are represented in that region. The extreme forms 

 are widely divergent but the numerous intermediates present 

 an almost perfect gradation between these extremes. Were it 

 not for a fact to be mentioned later the difficulty might per- 

 haps be settled by regarding the intermediate forms as 

 hybrids. The close relationship between 8. desertorum and 

 S. glauca was recognized by Hooker, and he says (I.e.): <' Yet 

 there are some varieties, as it appears, which have a different 

 aspect, with much larger, more woolly leaves, and longer and 

 looser catkins." Andersson, under S. glaucops (=8. glauca 

 villosa), says (DC. Prod. I. c.) : "Ad S. desertorum manifes- 

 tissimura praebet transitum." Under S. desertorum Bebb 

 says (Z. c. 1878): *♦ To this species should be referred Hall 

 and Harbour's No. 5^5 (very similar to Drummond's No. 657) 

 and most of the so-called 8. glauca of the Colorado Moun- 

 tains." He was certainly right in this statement. Later 

 {I. c. 1885) he quotes Hooker and then says that these forms 

 occur " toward the foothills " and present a " manifest transi- 

 tion to 8. glauca-villosa.*^ That these forms present a 

 transition to the so-called 8. glauca villosa is true but that 

 they are confined to, or more frequent in, the foothills is a 

 mistake, for numerous specimens have been collected in the 

 highest parts of the Rockies. 



From our present knowledge of this species it is apparent 

 that the original type specimens and the descriptions based 

 upon them represent not the common and normal form of 8. 

 desertorum but rather a reduced and extreme form most 

 widely divergent from 8. glauca. I have never seen the type, 

 Drummond's 657, but I have examined Hall and Harbour's 

 623, and Engelmann's 6, both from Colorado, and both said 

 by Mr. Bebb to be very near the type. The specimen of 523 

 is undoubtedly immature and it is hard to say just what the 

 dimensions of leaf, ament, etc, would have been at maturity. 

 The Engelmann specimen is an acknowledged depauperate, 

 «' 1-1^ feet high," and though the mature aments are sub 

 globose and nearly sessile, and the leaves are but 6-8 lines 

 long, the latter are anything but linear, being 3-4 lines wide. 



