JOURNAL 



OF THE 



ARNOLD ARBORETUM 



Volume II JULY, 1920 Numdeu 1 



NOTES ON AJVIERICAN WILLOWS. IX. 



Camillo Schneider 



In this article I shall discuss the species of two sections which were be- 

 lieved to be well known. If we, however, make a close examination of these 

 species we find that our present knowledge of them is still superficial and only 

 an attempt can be made to elucidate the synonymy, variability and the re- 

 lationship of certain species. Some of these need a much closer study in the 

 field before we can become acquainted with their forms and hybrids. There 

 is also a great difficulty in referring some of these species to distinct sec- 

 tions. It is evident that many of my observations cannot be regarded as 

 final and I desire to induce as many students as possible to take an earnest 

 interest in the study of these difficult forms and to point out the defects 

 in our present knowledge. I am sorry that I had to break off my stud- 

 ies too soon, as with more time I might have reached different conclusions 

 with regard to certain of these species and forms. Nevertheless I hope 

 that my notes contain some valuable hints for other salicologists. As for 

 the preceding notes this study is mainly based on the collections mentioned 

 in notes vii and viii. I wish again to address my best thanks to all the 

 gentlemen who have helped me. 



a. THE SPECIES OF THE SECTION DISCOLORES. 



By recent authors the species of this section are mostly referred to the 

 section Capreae which comprises some well-known European species. It 

 may be that these American forms can be united with those of the Old 

 World, but the more I become acquainted with American Willows the less 

 I find, at least in most cases, a close relationship even with forms that are 

 widely spread through Europe and Asia. Of course, I do not pretend to 

 know enough of these species to draw final conclusions from the material I 

 have studied. Our knowledge of the Asiatic Willows is, to-day, much too 

 limited. But, in my opinion, we can gain less by uniting groups or species 

 of different geographical distribution and of different morphological aspect 

 than by keeping them apart- It is often difficult to describe the differences, 

 and it is only by good sketches of the characters of the flowers and fruits 

 and of other features that the reasons can be made clear why I prefer to 

 regard many of the American Willows to be not so closely related to Euro- 



