THE FLOWER AND ITS PARTS 



95 



Pollen of Another Variety of Plant Sometimes Re- 

 quired for Fertilization of the Ovule. In some of our 

 fruits, the pollen 

 from one flower 

 will not form fruit 

 or seed in the pis- 

 til of the same 

 flower, or of an- 

 other flower of the 

 same variety. The 

 pistil of the Bart- 

 lett pear will not 

 often form a fruit, 

 if it receives pollen 

 only from Bartlett 

 pear flowers. It 

 must receive pol- 

 len from some 

 other kind of 

 pear flower than 

 the Bartlett. So 

 an orchard plant- 

 e d entirely t o 

 Bartlett trees sel- 

 dom bears much 

 fruit. In planting 

 an orchard, it is 

 wise, as a rule, to 

 plant trees of sev- 

 eral Varieties tO- FIG. 52. Fertilization of the ovule. The pol- 

 len tubes pass through the stigma and style, 

 f- finally entering the cavity of the ovary. 



