184: Fernald — Relationships of some American 



than is occasionally seen in B. alha {B. pa/pyrifera) in the 

 I^ortheast and already mentioned in the discussion of B. occi- 

 dentalis. The color of the bark, then, furnishes no satisfac- 

 tory reason to separate Betula Tienaica from the Asian B. 

 pendula, var. japonica. 



Betula pendula (typical). 



The broad-leaved var. japonica is not the only form of 

 Betula pendula which crosses from Europe and Asia into 

 North America. As already noted, the typical European B. 

 pendula with leaves cuneate at base extends across northern 

 Asia. Some of the specimens which have been referred to 

 B. alaslcana are quite inseparable in their leaves, branches, 

 and strobiles from European specimens; and, furthermore, 

 this characteristic European form extends southward and east- 

 ward in America to western Illinois, the Great Lakes, and the 

 St. Lawrence Yalley. Sheet JS'o. 351,017 of the United States 

 JS[ational Herbarium, collected as B. populifolia in woods at 

 Warren, Illinois, by L. M. Umbach, is not distinguishable from 

 sheet ]S'o. 25,340 from Sungaria in central Asia, nor from 

 material in the G-ray Herbarium collected in Sweden {Bloni- 

 herg, ^o. 1,691). Sheet No. 261,119 of the U. S. National 

 Herbarium, collected by Professor James Fowler in Ontario as 

 B. populifolia^ has the strobiles and leaves of B. pendula and 

 it cannot be separated from material in the Gray Herbarium 

 from Christiania, Norway {Blytt\ and from St. Petersburg, 

 Pussia {Begel). A sheet in the Herbarium of the Geological 

 Survey of Canada (No. 12,950), collected in the Province of 

 Quebec as B. popxilifolia by W. Scott, is quite identical with 

 sheet No. 149,801 of the U. S. Nat. Herb, from Savoy. Vari- 

 ous other leaf-specimens from Quebec, Manitoba, and other 

 regions of temperate North America are probably B. pendula, 

 but without fruit it is at present unwise so to refer them. The 

 American specimens cited were gathered as the endemic Betula 

 populifolia, at least one of them in " woods " ; and since 

 undoubted B. pejidula is found from the Saskatchewan Plains 

 northward, there seems little question that the European tree, 

 crossing Asia, is truly indigenous likewise in the northeastern 

 sections of America, just as are Coptis trifolia, Drosera 

 Totundifolia, Yihurnutn Opidus, Lysimachia thyrsiflora, and 

 many other well known sjDecies" which occur in northern 

 Europe, central and northern Asia, Japan, northwestern Amer- 

 ica, and northeastern America. 



* Among them Caltha palustris, Viola Selkirkii, Parnassia palustris, 

 Potentilia palustris, Cit^caea alpina, Pyrola minor, Moneses grandiflora, 

 Menyanthes trifoliata, Rumex persicarioides, Allium Schoenoprasum, Juncus 

 effusus, Eriophorum gracile, Carex filiformis, Hierochloe horealis, etc., etc. 

 See Gray, Mem. Am. Acad., n. s., vi, 377-499; and Extract ''Flora of 

 Japan" in Sci. Pap. of A. Gray, selected by C. S. Sargent, ii, 124-141. 



