CHAPTER V 



SEED-PLANTS 



THE MODERN PLANT TYPE 



A3 the primitive land plants adapted themselves 

 more and more perfectly to the increasingly 

 diverse conditions associated with their new en- 

 vironment, the evidences of their aquatic ancestry 

 became less and less apparent, and finally in the 

 highest of all plant types, the flowering plants or 

 seed-plants, all indications of their derivation from 

 aquatic ancestors have quite disappeared. 



Mosses and Ferns, Transitional Forms. The 

 mosses and ferns illustrate the transitional stages 

 through which the seed-plants, or as these are often 

 called, the " Phanerogams," have passed in the 

 course of their evolution from their primitive 

 aquatic ancestors, the green algae. It is evident that 

 the course of this evolution has proceeded along 

 several quite different lines. In the mosses, or 

 bryophytes, the history of the gametophyte, or sex- 

 ual phase of the plant's development, illustrates the 

 limitations of this aquatic organism in adjusting 

 itself to the radically different water conditions to 



