116 SOILS AND PLANT LIFE 



every other row, we are able to secure cro^-fertilized ears 

 in the detasseled rows since their own pollen is destroyed 

 and they must be fertilized by that from other plants. 



If, now, the com from the detasseled rows is used as 

 seed, it will ordinarily produce more vigorous plants and 

 likewise a larger yield per acre than will seed which has 

 been fertilized in part by its own pollen. This is true, 

 however, only of the first year's crop as after this much of 

 the seed is again self -fertilized. 



Next summer, suppose you make an experiment of this 

 sort by detasseling every other row in a part of your field 

 at home. The following spring plant some of the seed 

 from these detasseled rows and compare the yield secured 

 with that from other seed. 



QUESTIONS 



1. What is the business of flowers ? 



2. From memory, draw a diagram of the flower of a petunia 

 and name its parts. 



3. Name two cultivated plants which have their flower 

 parts on different parts of the plant. 



4. Name several cultivated plants which have both stamens 

 and pistils in the same flower. 



5. Define the term pollination. 



6. What are the two agents by which plants secure cross- 

 pollination? 



7. Name four ways by which plants adapt themselves to 

 wind pollination. 



8. Name four ways by which plants adapt themselves to 

 pollination by insects. 



9. Define the term fertilization, and trace the steps after 

 the pollen grain reaches the stigma. 



10. Tell briefly how you could cross by hand one blossom 

 with another. 



