THE 



AMERICAN JOURNAL OF SCIENCE 



[FOURTH SERIES.] 



Art. XX. — The Relationships of some American and Old 

 World Birches ; by M. L. Fernald. (With Plates Y-YI.) 



[Contributions from the Gray Herbarium of Harvard University, New 

 Series, No. xxiii.] 



A RECENT attempt satisfactorily to identify some birches 

 from the alpine summits of I^ew England has made it neces- 

 sary to study in detail certain species of the Old World. In 

 this detailed study so many well-known European and Asian 

 forms have been found identical with trees and shrubs of 

 America which have ordinarily passed as endemic, that the fol- 

 lowing notes are offered as a partial solution of the difficulties 

 which have long surrounded the species of Betiila. The 

 writer has been specially fortunate in having constant access 

 to a large suite of specimens in the Gray Herbarium which 

 were examined and labelled by Regel in the preparation of his 

 monograph on the Betulacese in DeCandolle's Prodromus.* 

 The material in the United States National Herbarium and in 

 the Herbarium of the Geological Survey Department of Can- 

 ada has been generously loaned by Messrs. F. Y. Coville and 

 J. M. Macoun, the collections of the Arnold Arboretum have 

 been placed at his disposal, and valuable specimens and notes 

 on north w^estern forms have been freely furnished by Profes- 

 sors L. F. Henderson and C. Y. Piper. Thus it has been 

 possible to examine a very complete representation of the 

 genus. 



The birches are trees of boreal range. Unknown in the 

 southern hemisphere and the tropics, they abound throughout 

 the northern and mountainous sections of I^ortli America, 

 Europe and Asia, reaching a more extreme northern range on 

 both continents than any other trees.f By Regel and other 



* Regel in DC. Prodr., xvi, part 2 (1864), 161-189. 



t See F. A. Michaux, Hist, des Arb., ii, 129, and Sylva, ii, 47; Sargent, 

 Silva, ix, 46 ; Eehder in Bailey, Cyc. Am. Hort., i, 158. 



Am. Jour. Sci. — Fourth Series, Vol. XIV, No. 81. — September, 1902. 

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