422 



MEMOIRS OF THE XEW YORK BOTANICAL GARDEN 



cies is known, in the mountains of Mexico, otherwise the genus is 

 confined to the eastern part of the continent. T. americana 

 ranges from Georgia and Texas in the south to New Brunswick 

 and Manitoba in the north, and T. heterophylla northward from 

 the Gulf States to New York and westward to Illinois and Ten- 

 nessee. 



The genus Yaccinium, even in its modern limited definition, 

 has a wide geographic distribution in the subtropical to boreal 

 zones of the Xorthern Hemisphere, both in the Old "World and 

 the New, and extending southward in the mountainous regions 

 of India and South America. V. cormyhosum, in its various 

 varieties or forms, ranges from Newfoundland to Minnesota 

 southward to the Gulf States. 



Vitis is a cosmopolitan genus, native in the tropical and tem- 

 perate zones of both the Eastern and the Western Hemispheres. 

 V. aestivalis ranges throughout eastern North America from 

 Ontario, "Wisconsin, and Louisiana to the Atlantic coast. F. ri- 

 paria (= F. vulpina Linnaeus) ranges from Nova Scotia to 

 Manitoba southward to Maryland and Arkansas, and F. cordi- 

 folia from New England to Nebraska southward to the Gulf 

 States. 



A flora composed of or including the above generic and spe- 

 cific elements would be broadly recognized as prevailingly New 

 "World in its general facies, and as overwhelmingly representa- 

 tive of the Northern Hemisphere ; but a critical analysis of these 

 elements, in detail, reveals certain other features of geographic 

 and zonal distribution tliat are interesting. 



The first feature that will naturally attract attention is the 

 Ijresence of tropical elements, rej^resented by the genera Cis- 

 sampelos, Ficus, and Passi flora, and the subtropical genus Ce- 

 hatJia. The presence of these genera, if it has any climatic sig- 

 nificance attaching to it, indicates at least a subtropical tem- 

 perature. The other genera (Abtiis, Betula, Hicoria, Platanus, 

 Quercus, Tilia, Vaccinium, and Vitis) possess but little climatic 

 significance as they are all represented in temperate as well as 

 in subtropical regions. In general, it may be said that it would 

 be justifiable to infer that such a flora would be indicative of 

 climatic conditions that now prevail in North America approxi- 

 mately 900 miles further south than British Columbia. 



