XVI 



CONTENTS 



D. Green sporogonia . 



E. Liverworts as pioneers . 

 Section 74. Mosses 



A. Reproduction 



B. Increase of the sporophyte 



CHAPTER TEN: THE VASCULAR PLANTS 



Section 75. Introductory 413 



PTERIDOPHYTES : 



Section 76. Ferns 415 



Section 77. Horsetails 422 



Section 78. Club mosses 424 



Selaginella ......... 425 



SPERMATOPHYTES : 



Section 79. Gymnosperms 431 



A. Two kinds of cones 432 



B. Pollination 432 



C. The pollen tube 434 



D. The embryo 434 



E. The seed 435 



F. Why two sets of names ? 436 



G. Pollen grains not exactly microspores . . . 437 

 H. The female gametophyte ..... 437 



/. Generations in the seed ..... 437 



J. Summary of the life history of a gymnosperm . 438 



K. General summary 439 



Section 80. Angiosperms 440 



A. The greatest group of plants 441 



B. The flower 441 



C. The male gametophyte 443 



D. The female gametophyte 443 



E. Double fertilization ' 444 



f. Plant breeding 446 



KEY TO INDEX AND GUIDE IN REVIEW 450 



INDEX . . 454 



