STRUCTURE OF THE STEM 



75 



90. Grafting. — When the cambium layer of any vigor- 

 ously growing stem is brought in contact with this layer 

 in another stem of the same kind or 

 a closely similar kind of plant, the two 

 may grow together to form a single 

 stem or branch. This process is called 

 grafting, and is much resorted to in 

 order to secure apples, pears, etc., 

 of any desired kind (Fig. 46). A 

 twig known as the scion from a tree 

 of the chosen variety is grafted on to 

 any kind of tree of the same species 

 known as the stock, and the result- 

 ing stems will bear the wished-for 

 kind of fruit. Often one species is 

 grafted on another, as the pear on the 

 quince or the apple. Rarely trees dif- 

 fering as much as the chestnut and the 

 oak may be grafted together. Some- 

 times grafting comes about naturally 

 by the branches of a tree chafing 

 against one another until the bark 

 is worn away and the cambium layer 

 of each is in contact with that of the 

 other, or two separate trees may be joined by natural 

 grafting. 



Fig. 46. Grafting. 



At tlie left scion and stock 

 are shown ready to be 

 united ; at the right they 

 are joined and ready to 

 coTer with grafting wax. 



