124 BOTANY. 



em continent were then common in many parts of this 

 continent, and tropical or sub-tropical species flourished 

 abundantly in Nebraska and Dakota. 



214. Moreover, we learn by such a study that many of 

 the plants of the present were not yet in existence in cer- 

 tain geological periods. As we go back in geological time 

 the vegetation is less and less like that of to-day. Thus 

 the higher flowering plants (Dicotyledons) were not in ex- 

 istence earlier than the Cretaceous period, while the Lilies 

 and their relatives date back to the Triassic. The great 

 Carboniferous vegetation, from which our coal was derived, 

 contained no plants with true flowers. There were no 

 grasses or sedges, no lilies or orchids, no roses or violets, 

 no oaks or maples. There were cone-bearing trees and 

 tree-ferns, as well as gigantic club-mosses and horsetails; 

 but even these were very different from any now living. 



215. The foregoing table (Fig. 59) will show the main 

 facts as to the distribution of the principal branches of the 

 Vegetable Kingdom in geological time. It must be re- 

 membered that the geological record is as yet only frag- 

 mentary, and in all probability many of the lines will be 

 carried down much further as our knowledge becomes more 

 complete. 



