X MORPHOLOGY OP SPBRMATOPHYTES 



CHAPTER PAGE 



IV. — Gnetales 113 



The vegetative organs 113 



The stem 116 



The leaf 118 



The root 118 



The spore-producing members 119 



The microspdrangium . 119 



The megasporangium 130 



The gametophytes 134 



The female gametophyte 134 



The male gametophyte 127 



Fertilization 129 



The embryo 130 



V. — Fossil Gymnosperms 134 



Cordaitales 135 



Bennettitales 142 



Cycadales 150 



Ginkgoales 150 



Coriiferales 151 



VI. — Comparative Morphology of Gymnosperms 158 



The vegetative organs 153 



The stem . 158 



The leaf 155 



The root 155 



The spore-producing members 156 



The microsporangium 156 



The megasporangium 157 



The gametophytes 160 



The female gametophyte 160 



The male gametophyte 162 



Fertilization 164 



The embryo 165 



VIL — The Phyloqeny of Gymnosperms 168 



VIII. — Geographic Distribution of Gymnosperms 175 



Cycadales 175 



Ginkgoales 176 



Coniferales 176 



Gnetales 178 



Summary of Literature cited 180 



Appendix 185 



