LIFE HISTORY OF A FERN 



205 



it holds the male and female gametes or sex cells. These cells 

 after fertilization produce leafy structures (fronds) which bear the 

 asexual spores. These spores when ripe germinate and the life 

 cycle begins over again, a sexual generation alternating with an 

 asexual generation. 



Practical Exercise 7. Compare, by means of labeled diagrams, the life his- 

 tories of the moss and fern. 



l^TERIDOPHYTA ] 



Rlicirieaje-/ B^uisetineae^I^copodlneae 



horsetails 



olu fa-rn o&&<2,$ 



These pteridophytes include three classes : the true ferns, the horsetails, and the club mosses. 

 There are about 8000 known species. 



Self-Testing Exercise 



The (1) or ferns have (2) of generations in their life 



history. In the gametophyte generation, a small (3) structure. 



called a (4), holds the (5) and the (6) cells. 



The fertilized egg produces leafy structures which bear (7) 



spores. The pteridophytes include the (8), the (9), 



and the (10). 



PROBLEM X. WHAT ARE SOME EXAMPLES OF 

 SPERMATOPHYTES ? 



The spermatophytes (Gr. sperma, seed), or seed-bearing plants, 

 include two groups : 



The gymnosperms (Gr. gymnos, naked), or naked-seed plants, 

 are a small group related to the ferns on one side and the flowering 

 plants' on the other. Two classes are found : the cycads, of which 

 group the so-called tree ferns are examples, and the conifers or 

 evergreens, as pines, spruces, firs, hemlocks, cypress, and others. 

 There are only about 450 species of gymnosperms. The cycads 

 are practically confined to the tropical regions. They have leaves 

 much like the ferns and their stems are covered with scales. In 



