and Old World Birches. 175 



a Niagara specimen collected bv Asa Gray ; and Piper's lS<o. 

 1,128 from Whatcom Co., Washington, cannot be distinguished 

 from Lowrie's material from Bald Eagle Mt, Blair Co., Penn- 

 sylvania (sheet No. 149,835, U. S. Nat. Herb.), and the old 

 specimen of Wm. Oakes's from Topsifield, Massachusetts, re- 

 ferred by Kegel to B. occidentalism var. conimittata ; and in 

 their leaves these trees very closely approach a Canoe Birch 

 growing at Oak Island, Revere. Massachusetts, and well-known 

 to the local botanists from its lustrous brown bark. From 

 herbarium specimens, then, there is no character by which to 

 separate the northwestern Betula occidentalis from the eastern 

 B. alba {jpa'pyrifera^. 



The important character upon which Professor Sargent lays 

 stress in his recent note- is the color of the bark, which in the 

 northwestern tree is usually brown. This character alone seems 

 hardly sufficient to separate specifically the two trees, espec- 

 ially in view of such brown-barked trees in the East as that on 

 Oak Island ; a tree growing at the foot of Mountain Pock, 

 Ellsworth, Maine (represented in the Gray Herbarium), with 

 gray-brown bark strongly .tinged with plum-color ; and Robin- 

 son and Schrenk's No. 139, from Newfoundland, in which the 

 old bark, though becoming pale, retains much of the brown 

 which is often seen in young trees. Furthermore, it is worthy 

 of note that the Pacific Coast tree is not thoroughly constant 

 in its bark. The Henderson plant of 1888, from the Gulf of 

 Georgia (essentially the type locality), was sent to the late 

 Sereno Watson, who called it B. occidentalis. Subsequently, 

 however, Professor Henderson, writing under date of Decem- 

 ber 9, 1897, of the difficulties in studying this group, said : 

 " Just where B. pajpyrifera leaves off and B. occidentalis be- 

 gins, I am, and always have been, at a loss to say." He then 

 comments upon a tree which " is undoubtedly B. "papyrifera 

 in every respect," adding, " and I have no doubt that my num- 

 ber 1,712, from the shores of Lummi Island, Gulf of Georgia, 

 sent Mr. Watson in *88, and referred by him to^. occidentalism 

 is the same thing." Thus it would seem that Betula alba 

 {jpapyrifej'a) is not constant in its pale bark in the East, and 

 that B. occidentalis of the Northwest may not always be dis- 

 tinguished by its dark bark. 



The tendency of another dark-barked northwestern tree to 

 become quite as pale as the eastern Canoe Birch will be noted 

 in the discussion of a species soon to be considered ; but in this 

 connection it is worth while to note a tendency to darkening 

 of color which has been observed in certain other northwestern 

 plants. It is well known that many species of Carex growing 

 in shade or in southern areas have pale or hyaline scales, while 



* Bot. Gaz., 1. c. 



