ajid Old World Birches. 173 



by the Eed Indians of Canada.""^ There is, then, no evidence 

 from the descriptions and comparisons of Michaux and other 

 well-ioformed Enropeau anthors that the American Betulcv 

 papyrifera is separable from the true B, alba of northern 

 Europe. 



The American tree presents numerous but apparently incon- 

 stant variations in the size and toothing of its leaves, and the 

 size of its strobiles and achenes. These variations, however, 

 are verv closely matched by specimens in American herbaria 

 of the European Betida. a.Tha. {B. jyuhescens, Ehrh.). If, for 

 example, we compare branches collected by Kobert Chalmers 

 at Campbellton, Xew Brunswick, in 1887, or Rydberg's No. 

 1,005, from the Black Hills of South Dakota (distributed as 

 B. occideidalis) with a Bohemian specimen from Taiisch and 

 Russian material from Regel ; Macoun's Cypress Hills (Assin- 

 iboia) material (Xo. 5,919) with Christiania (Norway) mate- 

 rial from Blytt ; a sheet in the Gray Herbarium, collected on 

 Lake Winnipeg by Bourgeau, with Hampe's Xo. 1,321 from 

 the Hartz Mts., in central Germany ; or Clement's No. 2,919 

 from Nebraska and Bedford (^Massachusetts) material of Wm. 

 Boott's with the 1807 sheet of B. pidjescens sent by Regel to 

 the Gray Herbarium ; we cannot help being impressed by the 

 identity of the pubescence, leaf-outline, strobiles, etc. Other 

 comparisons of American and European specimens emphasize 

 this identity ; so that, in view of these facts and the essential 

 similarity of bark, branches and stature, as pointed out by 

 Michaux and others, there seems no question that Betula 

 papyrifera is the true B. alba of Linnseus. 



Betula alha^ forma occidentalis. 



In the discussion of Betula papyrifera in his Silva, Pro- 

 fessor Sargent ref ers+ to the tree of the northwest coast, a form 

 which '* differs from the eastern {^papnjrifera7\ in its greater 

 height and rather darker colored bark, in its more pubescent 

 branchlets, which sometimes do not become glabrous until their 

 second season, although vigorous shoots of young plants in the 

 east are often clothed with thick pubescence, and in its rather 

 larger leaves, which, on the lower surface, are also more pubes- 

 cent." Later, however, the same author has identified:!: this 

 large tree with B. occidentalism Hooker.^ not the small tree or 

 half-shrub taken for B. occidentalis by Nuttall and other 

 American authors, including Sargent, Silva, ix, 65, t. 153 ; 

 and he concludes that the bark '' is very different from that 

 of the eastern tree, and it is probably best to consider it a 

 species." 



* Syme, English Botany, yiii, 184. f Sargent. Silva, ix, 59. 



X Sargent, Bot. Gaz., xxxi, 288 (1901). § Fl. Bor.-Am., ii, 155 (1839). 



