x PREFACE. 



seventh edition of the Manual, so on that account it 

 has been quite unnecessary to change the index in 

 any respect. The supplement, being alphabetically 

 arranged, furnishes an index in itself, and, of course, 

 it contains all the nomenclatorial revisions. 



The introduction in the supplement of a score of 

 new species that is, species new to the book re- 

 sults from the fact that some new Birches, Ashes, 

 and Maples have been discovered in the past decade, 

 and also that a number of rather rare trees have 

 become somewhat common. In all cases I have drawn 

 or described these species from types in the Gray 

 Herbarium of Harvard University. One is disposed 

 to believe that the work of investigation connected 

 with the tribe Betula is not yet altogether complete, 

 for there are some very puzzling phases of the northern 

 Birches ; but the reader will undoubtedly be glad to 

 know that both Professor Fernald's and Mr. Blanch- 

 ard's trees are not difficult to find in the localities 

 given in this book. That there is always the trouble- 

 some " intergradient " with which one must reckon 

 goes without saying; in that case it is better to sub- 

 mit the specimen to the botanist. But the guidance 

 which one may obtain from a careful drawing, it 

 must be acknowledged, is almost limitless. It was 

 John Buskin who once said (it is one of his char- 



