[Chap. XLIX FERNS, CLUB MOSSES AND EQUISETUMS 



663 



Fig. 310. The walking fern (Cainpfosorus rhizophyUus) . New plants develop 

 \ egetati\'ely from buds at the apex of the leaf blades. Photo by R. T. Wareham. 



Sporangia may develop on the under side of a green fern leaf (Fig. 

 311). They may occur in irregular lines or areas, or co\er nearly the 



Fig. 311. The life history of a fern. The gametophyte (A) bears egg cells and 

 sperms in archegonia and antheridia. When one of the sperms from an antheridium 

 (B) unites with an egg cell in an archegonium (C), a zygote is formed. From 

 this zygote the leafy fern plant (D) develops and bears spores in sporangia (F 

 and G) on the lower side of the leaves. By the bursting of the sporangium (H) 

 the spores are set free. When these spores germinate on moist substrates a new 

 gametophyte, like the one represented by A, develops from each of them. 



