70 THE BOOK OF NATURE STUDY 



Yellow Iris . . vol. 3 page 221 



Amaryllideae .... Daffodil . . ,, 3 156 



Liliaceae Tulip . . 3 148 



Junceae . . . . . Woodrush . 3 152 



Gramineae Rye-Grass . 3 180 



GYMNOSPERMS 



Coniferae Scots Pine 4 62 



POLLINATION OF FLOWERS 



It was pointed out in the introductory chapter (Vol. III. p. 101) 

 that the construction of flowers had to be studied in the light of 

 the need for transfer of pollen from the stamens to the stigma. 

 This process of pollination is an essential preliminary to the 

 development of seeds capable of reproducing the plant. Under 

 each plant described above the method of pollination and the rela- 

 tion of this to the structure of the flower has been more or less fully 

 considered. Such a study of individual cases forms the best way 

 of approaching the subject. It may, however, be of use to place 

 some general considerations before the student, although for any 

 full treatment of the subject reference must be made to one or other 

 of the works cited in the bibliography below. The flowers already 

 described will provide us with examples of the general statements 

 that can be made regarding pollination, and will save us entering 

 into details of floral structure. 



Many flowers contain both stamens and pistil, and the simplest 

 method of pollination would be for the pollen to fall directly on 

 the stigma of the same flower. This is known as self-pollination, 

 and is found to occur in many instances. An extreme case has 

 been seen in the small flowers of the Sweet Violet (Vol. III. p. 128), 

 which never open, and in other flowers which are inconspicuous 

 and have no efficient means for the transfer of pollen from flower 

 to flower self-pollination is also the rule. The account of the 

 flower of the Shepherd's Purse (Vol. III. p. 214) may be consulted 

 as an example of this. In very many flowers self-pollination 

 occurs as a last resort, and leads to good seed being formed. In 

 most flowers, however, the arrangements are such as to lead either 

 regularly or occasionally to the conveyance of pollen from one 



