i9 14-] SOUTHEASTERN NORTH AMERICA. 243 



Apocynaceae in the development of a latex-system and in other spe- 

 cializations, and the elaborate contrivances for entomophily in the 

 former family reach a degree of complexity almost comparable with 

 that of the Orchidacere. The Loganiaceae, also not represented in 

 the Wilcox flora, are lianas characteristic of South America and i\sia 

 and regarded by Engler as relatively primitive and possibly the an- 

 cestral stock of the Gentianales and Rubiales. The order as a whole 

 is numerically massed in the tropics by reason of the many tropical 

 genera of the two largest families — the Asclepiadaceae and Apocy- 

 nacese, which together contain three fourths of the existing species 

 of the order. 



The family Oleacese, sometimes considered as an order, the 

 Oleales, contains 21 genera and about 400 existing species. There 

 are three small genera peculiar to Asia and four peculiar to America, 

 the remaining fourteen genera being found in more than one conti- 

 tinental area. The three largest genera Fraxinns ( 40), Mayepea ( 50) 

 and Jasminum (160) are all cosmopolitan. Eight of the twenty-one 

 genera have been found fossil and it is evident that the family has an 

 extended history, although there are no known Cretaceous records 

 worthy of credence. Nor is the record well enough known to war- 

 rant generalizations. It is obvious from the early Eocene occur- 

 rence of leaves of Fraxinns associated with characteristic fruits, that 

 the family must have been evolved before the close of the Upper 

 Cretaceous but none of the genera have any well-marked or abun- 

 dant known representation until Tertiary times. 



The genus Fraxinns Linne has two species in the Wilcox flora, 

 a characteristic samara, and foliage identical with that described 

 by Heer from western Greenland as Fraxinns Johnstrupi. The lat- 

 ter furnishes an interesting instance of the extended distribution of 

 members of the Eocene flora, at the same time illustrating the north- 

 ward radiation of floras during the Eocene. Upward of ten addi- 

 tional Eocene species are known all of which are American and rang- 

 ing from Tennessee to Alaska and Greenland. The Oligocene marks 

 the appearance of the genus in Europe from which time to the pres- 

 ent the genus has been represented throughout the warmer parts of 

 the north temperate zone, at least four of the existing species mak- 

 ing their appearance in the Pleistocene. 



