IOO IMPERFECT AND PERFECT FLOWERS 



Cross Fertilization. When the pollen of one flower 

 fertilizes the ovules of another flower, the action is called 

 cross fertilization. This is one of the ways of producing 

 many varieties of plants. Cross fertilization is often 

 brought about by the wind or by insects, and sometimes 

 by intention of the gardener. 



Plant Breeding By crossing certain plants with 

 others of a similar kind, and carefully collecting the seeds 

 that result, new and improved varieties are obtained. 

 When an improved variety of any plant is obtained, the 

 seeds from the plant are planted and selected so as to 

 make a distinct breed. 



Great progress has been made at the Experiment Sta- 

 tions in making valuable breeds of wheat, oats, and corn. 

 The yield in each' case has been increased from three to 

 ten bushels per acre. 



QUESTIONS AND EXERCISES. 



1. What are imperfect flowers? 



2. Name some kinds of plants that have imperfect 

 flowers. 



3. What is the difference between pistillate and staminate 

 flowers? 



4. How are imperfect flowers fertilized? 



5. How may flowers be cross fertilized? 



6. When the maples are in bloom look for some trees 

 that bear only pistillate flowers and others that bear only 

 staminate flowers. Make the same observations for the 

 cottonwood trees. 



