CHAPTER XX. 



FERTILIZATION OF FLOWERS. 



IF we compare the flowers of different plants, we shall find 

 almost infinite variety in structure, and this variation at first 

 appears to follow no fixed laws ; but as we study the matter 

 more thoroughly, we find that these variations have a deep 

 significance, and almost without exception have to do with the 

 fertilization of the flower. 



In the simpler flowers, such as those of a grass, sedge, or 

 rush among the monocotyledons, or an oak, hazel, or plantain, 

 among dicotyledons, the flowers are extremely inconspicuous 

 and often reduced to the simplest form. In such plants, 

 the pollen is conveyed from the male flowers to the female 

 by the wind, and to this end the former are usually placed 

 above the latter so that these are dusted with the pollen 

 whenever the plant is shaken by the wind. In these plants, 

 the male flowers often outnumber the female enormously, and 

 the pollen is produced in great quantities, and the stigmas 

 are long and often feathery, so as to catch the pollen readily. 

 This is very beautifully shown in many grasses. 



If, however, we examine the higher groups of flowering 

 plants, we see that the outer leaves of the flower become more 

 conspicuous, and that this is often correlated with the develop- 

 ment of a sweet fluid (nectar) in certain parts of the flower, 

 while the wind-fertilized flowers are destitute of this as well 

 as of odor. 



If we watch any bright-colored or sweet-scented flower for 

 any length of time, we shall hardly fail to observe the visits 

 of insects to it, in search of pollen or honey, and attracted to 

 the flower by its bright color or sweet perfume. In its visits 



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