254 Plant Life and Evolution 



abundant plant remains from Cretaceous and Ter- 

 tiary deposits throughout most of the Northern 

 Hemisphere, which give a very good idea of the 

 character of the vegetation of those periods. The 

 fossils are largely impressions of leaves, mainly of 

 trees and shrubs, the more delicate herbaceous vege- 

 tation having left no traces. The leaf impressions 

 are often exceedingly perfect, and in many cases 

 quite unmistakable, and it is evident from a study 

 of these fossils that many modern genera were well 

 represented. Oaks, poplars, willows, planes, com- 

 mon northern types of the present day, were com- 

 mon and widespread, and with these, very often 

 in localities now quite unfitted for their growth, 

 were genera belonging to warm climates, like the 

 magnolias, palms, and laurels. The conclusion 

 has been drawn that during the early Tertiary there 

 was a fairly uniform flora throughout what is now 

 the north temperate and sub-polar regions, but that 

 the climate was much warmer than that now pre- 

 vailing in the northern regions. While we have 

 little knowledge from the fossil record of the her- 

 baceous plants accompanying the trees and shrubs 

 whose remains occur in Tertiary deposits, a study 

 of the distribution of the living species gives us 

 some clue as to what many of these probably were. 

 Such widespread types as buttercups, anemones, 

 violets, lilies, and many other familiar flowers, 

 were in all probability represented by species not 

 very different from their living descendants, and 



