CHAPTER XII 



THE MANY REMARKABLE ARRANGEMENTS BY 

 WHICH PLANTS SECURE UNION OF THE SEXES 



Cross pollination; Flowers 



]HE preceding chapter should have made it quite clear 

 that plants possess sex; that this is the same, both 

 female and male, as it is among animals; that a union 

 of the two is generally needful for the production of 

 offspring; and that the offspring is usually better in quality if the 

 uniting sex cells are derived from separate parent plants. But 

 the union of sex cells from separate parents presents a difficult 

 problem to those plants which, including all of the higher and 

 more familiar kinds, are sedentary, and therefore unable to come 

 together by their own powers of locomotion, as animals, and indeed 

 some of the water plants, so readily do. Specifically, their prob- 

 blem is this, to secure the transfer of the small and light pollen 

 grains, which contain the male cells, from the anthers of one 

 plant across some space to the stigmas, which give access to 

 the female cells contained in the ovules, of another, after which, 

 of course, fertilization proceeds by the methods already described 

 very fully in the chapter on Reproduction. The problem of cross 

 fertilization, therefore, resolves itself in such plants into one of 

 cross pollination, which is effected by methods that we must now 

 consider in detail. 



Let us first dispose of the simpler methods displayed by the 

 Water plants, which in some cases possess an animal-like power 

 of independent locomotion by swimming, particularly in their 



