RELATIONSHIPS OF THE WHITE OAKS OF EASTERN 

 NORTH AMERICA, 



With an Introductory Sketch of their Phylogenetic History.^ 



By MARGARET V. COBB. 



(Plates IV- VI.) 



(Read April 23, 19 15.) 



I. History of the Fagace^ : A Reconstruction. 



Prantl's Classification of the Fagacece. 



'Quercus. 

 Castanese-^ Pasania. 

 Castanea. 



JToocpap J 



^ [Nothofagus. 



The five or six genera of the family Fagacese to which the oaks 

 belong were well differentiated at least as far back as the Cretaceous 

 age. The beeches are sharply separated from the remainder of the 

 family (the pasanias, chestnuts and oaks), and are undoubtedly the 

 more primitive of the two groups. Nothofagus, the genus of primi- 

 tive beeches, is a characteristically sub-Antarctic genus, still surviv- 

 ing in Tasmania, New Zealand, and the southern part of South 

 America (a South Pacific distribution). Fagus itself, once more 

 widely spread, is now found only in Japan, North America and 

 Europe. 



The pasanias, chestnuts and oaks are at present in possession of 

 the temperate and tropical regions of Asia, North America, Europe 

 and Mediterranean Africa. Species are most numerous in south- 

 east Asia and in Mexico (regions separated by the Pacific). Pasa- 

 nia is limited to southeast Asia, except for one species in California 



1 This paper owes a great deal to the extensive knowledge and the never- 

 failing interest and aid of Dr. William Trelease, under whom the work was 

 done at the University of Illinois in the year 1913-14. 



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