AGRICULTURAL BOTANY 147 



containing the embryo of a new plant and the food 

 about it to nourish it during germination. 



Pollination is brought about by insects, which carry 

 the pollen on their bodies, by the wind, or by the force 

 of gravity, as the anthers are usually higher than the 

 stigma. Animals, birds, water, and man also play 

 an important part in pollination. 



It follows from what has been said above that a flower 

 that has no pistil can produce no seed, nor does every 

 flower that has a pistil necessarily produce seed. Pol- 

 lination is not always followed by fertilization, for 

 flowers that appear perfectly normal often fail to pro- 

 duce seed. 



Perfect and Imperfect Flowers. A perfect flower 

 is one that contains both stamens and pistils, as in the 

 apple. An imperfect flower may be staminate, having 

 stamens only, or pistillate, having pistils only. Some 

 plants, called monoecious, bear staminate a.nd pistillate 

 flowers on the same plant, as hickory, cucumber, and 

 corn, while others, called dioecious, have the two kinds 

 of imperfect flowers on different plants, as the hop. 



Cross-pollination. It is evident that pistillate 

 flowers can produce no pollen, therefore if the ovule of 

 these flowers is to be fertilized, it must be from pollen 

 from another flower which bears stamens. This pro- 

 cess is known as cross-pollination. The pollen may 

 come from a staminate flower on the same plant or 

 from one on a different plant of the same species or a 

 plant of a different species. In the last two cases the 

 fertilization results in a cross, or hybrid. 



Artificial cross-pollination may be accomplished by 

 first carefully clipping off the anthers of a perfect 

 flower before the pollen is mature, then inclosing the 



