THE DEVELOPMENT OF THE PLANT 61 



The great Lepidodendra and Sigillaria disappear, and 

 the cycads and conifers gain the upper hand. The 

 swamp area is being reduced, and the solid continental 

 surfaces are growing. By the end of the Primary epoch 

 the old forms have almost entirely disappeared, and we 

 have an age of Gymnosperms (cycads and conifers) with 

 the survivors of the great fern family. In the next, the 

 Cretaceous period, the Angiosperms, or highest type of 

 plants, make their appearance and supersede the older 

 types. A large number of trees and flowering plants 

 that are familiar to us to-day have left their leaves and 

 branches in the Cretaceous strata. The brighter earth 

 was beginning to bear the aspect which it would later 

 present to the eyes of man. Not only palms, but the 

 oak, maple, willow, beech, poplar, walnut, sycamore, 

 laurel, myrtle, fig, plane, ivy, magnolia, and many others, 

 spread quickly over the land from Greenland (then part 

 of the northern continent) to the south of Europe. 



In spite of local traces of glaciation, the climate of the 

 earth was still generally warm. The abundant vegeta- 

 tion that has been found in the Cretaceous strata of 

 North Greenland includes scores of different kinds of 

 ferns, and the laurel, fig, and magnolia, and thus betrays 

 a temperature 30C above that it has to-day. But trees 

 now appear (in the Cretaceous) that shed their leaves 

 periodically, and we know that a winter season has set 

 in, and the climate of the earth is growing colder. 

 Palms still flourish in high latitudes, the flowering 

 plants continue to advance toward present types, and 

 grasses (of an early type) begin to clothe the plains. As 

 the Tertiary epoch wears on, and the cold increases, 

 Europe takes on a clothing of evergreens, and finally 

 only patches of moss and arctic vegetation peep out of 

 the snows for the reindeer to browse on ; while the 

 flowering plants develop their myriads of forms and hues 



