THE EVOLUTION OF PLANT REPRODUCTION 



63 



journey on the part of the sperm. The fertilized c^g, while still in 

 the megaspore, grows into an embryo sporophyte with rudi- 

 mentary roots and leaves. When the megaspore drops to the 

 ground, the embryo is well on its way to becoming a new spore- 



SEXUAL PLANTS 



Fig. 37. — The life history of the little club moss. 



producing generation. During alternation of generations in the 

 little club moss (fig. 37), the gametophyte has become reduced 

 to an insignificant heterotrophic parasite within the reproductive 

 tissues of the sporophyte. 



