308 



GENERAL BOTANY 



The spores, in a suitably moist and warm location, produce a 

 little plant, the gametophyte, which bears the sex organs, as in 

 the gametophyte plants of the algse and the mosses. 



GAMETOPHYTE AND EMBRYO 



Habit. The gametophyte produced by the germination of the 

 spores is a green, heart-shaped body resembling a moss leaf in 



its general struc- 

 ture (Fig. 177, <?). 

 The entire plant 

 is not more than 

 one fourth of an 



Gamctophyle i i 



inch in length 

 and is furnished 

 with rhizoids on 

 its under surface, 

 which anchor it 

 to the moist soil 

 on which it grows. 

 The margins of 

 the little plant 

 are composed of 

 a single layer of 

 cells, but the 

 central portion is 

 several cells in 

 thickness. This 

 thick portion is 

 called the cushion and bears the reproductive organs and the 

 rhizoids. It is thus equipped like the moss for carrying on its 

 own nutrition and for producing the sex organs necessary for 

 sexual reproduction. 



Sexual reproduction. The reproductive organs (Fig. 177) re- 

 semble those of the liverwort and moss so closely that it will not 

 be necessary to describe them in detail. The archegonia are borne 

 at the anterior end of the cushion, while the antlieridia are more 



cell 



Neck canal cells 



FIG. 177. Spore germination, gametophyte, and sex 

 organs in ferns 



a, b, two stages in spore germination; c, mature gameto- 

 phyte with antheridia and archegonia; d, mature an- 

 theridium with sperms; e, sperms with cilia; /, young 

 archegonium ; g, mature archegonium 



