CHAPTER V 



REPRODUCTION AND DISPERSAL 



§ I. General considerations. § 2. Sexual and Asexual Reproduction. 

 § 3. Seed Formation. § 4. Parthenogenesis and Apogamy. § 5. 

 Sex Distribution in Flowering Plants. § 6. Determination of Sex. 

 § 7. Changes in Sex Distribution in the Course of Evolution. § 8. 

 Secondary Sex Characters. § 9. Pollination — the Stamens and the 

 Pollen. § 10. Pollination and Fertilisation. § 11. Pollination — 

 Agencies. I. Entomophilous Flowers; II. Ornithophilous Flowers; 

 III. Malacophilous and Chiropterophilous Flowers ; IV. Anemophilous 

 Flowers; V. Hydrophilous Flowers. § 12. Pollination — Floral 

 Mechanisms. § 13. Cross- and Self-Pollination. § 14. Self- 

 Sterility. § 15. Self-Pollination. § 16. Pollination — General Con- 

 siderations. § 17. The Seed and the Fruit. § 18. Dispersal. 



§ I. General Considerations 



By reproduction we understand the process of giving rise 

 to a new individual by a parent organism. As we shall see 

 later the meaning of the term individual is not at all easy 

 to define, especially in the plant kingdom. Here we may 

 take it that when an organism produces, in a specialised 

 fashion, a cell, which, under suitable conditions, develops 

 into a new organism similar to the parent, a new individual 

 has arisen. To such a process we would confine the term 

 reproduction. In the reproductive cell the inheritance of 

 the race is gathered and a fresh start is made. To the 

 increase in the number of independent plants which takes 

 place, both naturally, and especially in gardening practice, 

 by the rooting of parts detached from the parent we would 

 apply some different term such as vegetative multiplication^ 

 or, conveniently, the gardener's word propagation. In 

 such cases the new plant does not start afresh from the 

 beginning. 



Reproduction in plants takes place in two ways, asexiially 



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