ILLUSTRATIONS 



Figures Page 



1. Section of fruit (grain ) of corn 7 



2. Seed of bean 8 



3. Iris. Fruit and seed 9 



4. Seedling of hollyhock and oats 12 



5. Seedling of bean and pea 13 



6. Resting cell and cell division 22 



7. Linkage map for the fruit fly 27 



8. Lima bean root 32 



9. Cross section of a root 34 



10. Longitudinal section of barley root 35 



11. Young root with root hairs ., 36 



12. Structure of a stem 54 



13. The seasonal history of an elm twig 61 



14. Methods of grafting 70 



15. A section of a leaf 73 



16. Stomatal penetration of fungus hyphae 99 



17. Cross section of an infected radish leaf 100 



18. A biennial plant, carrot 105 



19. Vegetative propagation of weeds by stems 106 



20. Zinnia flower 113 



21. Petunia flower 114 



22. Rose flower 115 



23. Domesticated varieties derived from wild cabbage 144 



24. Auxin and growth of Avena coleoptiles 153 



25. The nitrogen cycle 178 



