CHAPTER X 
POLLINATION AND FERTILIZATION 
124. Pollination. In the great majority of flowering plants 
seed production depends indirectly upon pollen. Of course the 
pollen grain, in order to act, must be transferred from the anther, 
where it was formed, to the pistil, in which are the ovules to 
be affected. This transference of 
pollen is called pollination. 
In the higher seed plants the 
pollen is received on the surface of 
the stigma, which is usually rough, 
moist, and sticky, and therefore 
readily retains the grains which 
reach its surface. The details of 
the pollinating process differ so 
much in different kinds of flowers 
that even a mere statement of the 
various types requires considerable 
space. The significance of pollina- 
tion will appear more clearly if 
Fic. 117. ‘Typesof pollen grains we first give a very brief account 
A, dandelion; B,hemp; C,gen- of the results of pollination, and 
tian; D, squash. All greatly , 
iiapridien. Adhar Warier then consider a few of the modes 
of transference of pollen. 
125. Pollen grains; formation of pollen tubes. The form of 
pollen grain for any given kind of flower, as a lily, a hollyhock, 
or a cucumber blossom, is quite constant, but those of differ- 
ent kinds are so often unlike that the whole number of forms 
observed is very great. Usually the grains are separate, like 
those shown in figure 117, but in many kinds they are united by 
134 
