Reproduction in Relation to Agriculture 221 



Bureau of A griculture, P. /. 



FIG. 137. Four types of Indian corn. From left to right : Sweet corn, which has a 

 high sugar content and shrivels when dried ; dent corn, which has a depression in 

 the crown of each kernel due to the shrinking of the endosperm ; flint corn, which has 

 a hard endosperm and rounded kernels; and popcorn, which is a small, extremely 

 flinty variety. 



The methods used by the plant breeder depend upon the 

 reproductive structures and habits of the particular plants 

 with which he is working. For example, the means by which 

 a plant is naturally pollinated will determine how it must be 

 handled at the time of flowering to secure self-pollinated seed 

 or cross-pollinated seed. Methods of vegetative propagation 

 may be used to multiply the plant after a desirable variety 

 has been produced. In this way the plant grower avoids 

 cross-pollination and the variations that appear when many 

 cultivated crops are grown from seed. The best ways of 

 propagating particular crops vegetatively may be found 



