HYBRIDIZATION 



635 



V 



seeds. If pollen from one plant is placed on the pistil of another 

 of an allied species or variety, fertilization may take place and new- 

 plants will be eventually produced from the seeds. This process 

 is known as hybridizing, and the plants produced by this process 

 known as hybrids. This process is a most painstaking one, if 

 worth-while results 

 are to be obtained. 

 The two plants to 

 be crossed must be 

 selected with great 

 care, they must be 

 carefully protected 

 from possible self- 

 pollination, and the 

 transfer of pollen 

 must be so re- 



... . , . . How is artificial pollination accomplished ? 



stricted that no 



pollen except the desired kind shall reach the pistil. After the 

 transfer of pollen, the flower must be covered, to prevent any other 

 alien pollen from reaching the pistil. 



Hybrids are extremely variable and often are apparently unlike 

 either parent plant. Most hybrids have to be perpetuated by 

 means of some of the methods of vegetative propagation, as they 

 rarely breed true and often do not produce seeds. 



Practical Exercise 18. What kind of plants would you select for a hybridiz- 

 ing experiment ? Why are all parts of the flower except the pistil cut away in 

 the diagram on page 634 ? What will happen to the pollen placed on the 

 stigma ? Why is the flower covered after artificial pollination ? 



Self-Testing Exercise 



All plants and animals in nature tend to (1). (2) 



tends to make living things like their ancestors (3) varia- 

 tions do not influence heredity (4) variations or 



(5) produce new kinds of plants that breed true. In selective planting 



the farmer picks out the (6) from the (7) (8) 



rather than most perfect (9) (10) (11) 



produces no new (12) in plants. 



