242 Plant Life and Evolution 



Hemisphere was still warm, and more uniform than 

 at the present time. Many familiar modern genera 

 flourished, and while these Cretaceous fossils are 

 almost entirely trees or shrubs, it is only reasonable 

 to suppose that many widespread herbaceous genera, 

 like Ranunculus and Geranium, also existed at the 

 same time. Among the early Cretaceous types may 

 be mentioned poplars, willows, and planes. Cer- 

 tain genera, which now are represented by isolated 

 species in remote regions, were at that time wide- 

 spread; such for example are the tulip-tree (Lirio- 

 dendron), Magnolia, and Sequoia, which once oc- 

 curred throughout much of the Northern Hemi- 

 sphere. These survivors of the late Mesozoic and 

 early Tertiary floras are at present mostly confined 

 to warm-temperate regions, such as Japan, the 

 warmer Atlantic States, and the mountains of Cali- 

 fornia, and suggest that the climates of these regions 

 represent approximately the climate of that period. 

 The number of angiosperms rapidly increases 

 during the Tertiary, and very many of our common 

 genera of trees and shrubs are clearly recogniza- 

 ble. Oaks, maples, walnuts, sassafras, and other 

 familiar forms, all very much like existing species, 

 are met with, and we may suppose that many of 

 the common herbaceous types, which now accom- 

 pany these, were also in existence, although owing 

 to their perishable nature they have left no recog- 

 nizable fossil remains. 



