E. V. Wulff 



—86- 



Historical Plant Geography 



ranean Basin and the other on islands in the Atlantic Ocean (Azores, 

 Madeira, Canary Is.); (e) one portion in southern Italy and the other 

 in the Balkans; (/) one portion in the Balkans and the other in Asia 

 Minor; (g) one portion in the Crimea, a second in Transcaucasia, and 

 a third in Asia Minor. Among the many other variations of this type 

 we may mention discontinuous areas having one portion in the Medi- 

 terranean Basin and the other in the mountains of tropical Africa, or in 

 Cape Province, or in CaHfornia, etc. 



8. Tropical Types.— In the tropics of both the Old and New Worlds 

 we find, just as in the preceding vegetation zones, a number of types of 

 discontinuous areas characteristic of the plants in this flora. The 

 existence of such discontinuities is particularly evident in areas of 



Fig. 13. — North-South American discontin- 

 uous area of Sarraceniaceae; i, Darlingtonia; 

 2, Sarracenia; 3, Heliamphora. (After Hutch- 

 inson). 



so-called pan-tropical species, i.e., those now distributed in tropical 

 and subtropical regions of Asia, Africa, and America. But, in addition, 

 we have within the tropics a number of more localized discontinuities, 

 which we may designate as paleotropical discontinuities, occurring in the 

 areas of species and genera distributed in tropical Africa and Asia, and 

 also in some cases in Madagascar, Polynesia, and the Malay Archi- 

 pelago and neotropical discontinuities, occurring within the limits of the 

 tropics of the New World. Among the more important tropical types 

 of discontinuous areas we hst the following: 



a. Asia- Africa Type.— To this type we refer the areas of plants 

 common only to the floras of Africa and continental Asia. It is a 



