CHAPTER VIII 



POLLINATION AND FERTILIZATION 



106. Pollination. By the term pollination the conveyance 

 of pollen to the pistil is meant. Some of the various means 

 by which this result is secured are discussed later on in the 

 ^ present chapter. In whatever way 



fl% i A the pollen is carried from the sta- 



mens to the pistil (usually by the 

 wind, by ani- 



B ^ss^ JT~ > L mals, or by 



contact of the 

 anthers with 

 the stigma), 



FIG. 105. Types of pollen grains 



A, dandelion ; B, hemp ; C, gentian ; 



D, squash. All greatly magnified. 



After Kerner 



FIG. 106. Types of pollen grains 



A, evening primrose, the grains united 



by sticky threads; B, marsh mallow. 



Greatly magnified. After Kerner 



its lodging place in the higher seed plants is on the stigma. 



This generally has a rough, often moist and sticky surface. 



107. The pollen grain and its germination. 1 Pollen grains are 



of many forms, a few of which are shown in Figs. 105 and 106. 



1 The logical order of treatment would be to say all that is to be said 

 about pollination before dealing with its result, fertilization. It is, however, 

 more convenient to discuss the minute structure of pollen and the pistil soon 

 after Chapter VII is completed, and then to give details of some of the 

 modes by which pollination is secured. 



116 



