CONTENTS 



PAGE 



List of Illustrations xiii 



Introduction i 



PART I. COLLECTING THE MATERIAL 



CHAPTER 



I. The Western Cycads 7 



Zamia 7 



Microcycas 9 



Dioon edule 11 



Ceratozamia 21 



II. The Australian Cycads ........ 25 



Macrozamia 27 



Bowenia 32 



Cycas 36 



III. The African Cycads 41 



Stangeria 42 



Encephalartos 45 



PART 11. THE LIFE-HISTORY 



IV. The Vegetative Structures 67 



The Stem 67 



The Leaf 79 



The Root 8s 



V. The Reproductive Structures 87 



The Female Cone 87 



The Female Gametophyte 92 



VI. The Reproductive Structures {Continued) . . 100 



The Male Cone icx) 



The Male Gametophyte 103 



VII. Fertilization 112 



VIII. The Embryo and Seedling 121 



The Embryo 121 



The Seedling 131 



xi 



