164 



ELEMENTARY STUDIES IN BOTANY 



and that produced by the short stamens, for the pollen from 

 the long stamens is more effective on the long styles than 

 it is on the short ones, and vice versa. This means that 

 the pollen of either kind of flower is not effective on the style 

 of the same flower. The body of the visiting insect fills the 

 tube of the small corolla and projects above it. In visiting 

 both kinds of flowers, one region of the body receives a 



FIG. 131. Flowers of innocence (Houstonia) : A, form with short stamens and long 

 style ; B, form with long stamens and short style. After GRAY. 



band of pollen from the short stamens, and another region of 

 the body receives a band of pollen from the long stamens. 

 In this way the insect is soon carrying about two bands of 

 pollen, which come in contact with the stigmas of the short 

 styles and of the long styles. 



100. Pollination and plant-breeding. The purpose of 

 practical plant-breeding is to improve the old races of useful 

 plants and to produce new ones. In this work advantage is 

 taken of pollination to produce certain results. Probably the 



