CHAPTER SEVENTEEN 



REPRODUCTION IN RELATION TO AGRICULTURE 



THE reproduction of plants is of particular interest in agri- 

 culture because the reproductive structures themselves have 

 an economic value. In a former chapter the importance of 

 seeds and fruits as sources of food has been discussed. In this 

 chapter we shall consider the relation of reproduction to three 

 important phases of agriculture: plant propagation, plant 

 breeding, and weed control. Propagation and breeding fur- 

 nish better crop plants ; weed control provides more pro- 

 ductive fields. 



Vegetative multiplication. In the discussion of stems 

 (page 159) attention was called to the fact that one of the 

 advantages in underground stems lies in the facility with 

 which the plant may be multiplied. From rootstocks arise 

 new terminal and lateral buds that later form new aerial 

 shoots, and through the death of the older parts of the under- 

 ground stems these branches become separate plants. Bulbs, 



FIG. 133. Multiplication of the raspberry. The stems arch over and take root 



where they touch the ground, thus starting new plants. 



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