Propagation by Grafting. 211 



g To save girdled trees; 



h To avoid insect injury to the trunk or root, as in 

 grafting the peach on the plum, or the European grape 

 on the American. 



385. The Plants that Unite by Grafting. Plants of dif- 

 ferent varieties of the same species (21) almost always 

 unite by grafting. Examples, the Ben Davis and Bald- 

 win apples, the Bartlett and Seckel pears. 



Plants of different species of the same genus (21) often 

 unite by grafting. Examples, the peach unites with the 

 plum, many pears unite with the quince; the tomato 

 unites with the potato. 



Plants of different genera in the same family or order 

 (21) sometimes unite by grafting. Examples, the chest- 

 nut unites with the oak; the pear unites with the thorn. 



The apparent resemblance of two plants of different 

 species is not always evidence that they will unite by 

 grafting, e. g., the peach and apricot, though resembling 

 each other in many respects, do not readily unite by 

 grafting, but both unite freely when worked upon the 

 plum, though the latter apparently differs from both the 

 peach and apricot more than these differ from each other. 



Many plants unite freely when grafted in one direction, 

 that fail to unite when worked in the opposite direction j 

 e. g. , many cultivated cherries unite freely when worked 

 upon the mahaleb cherry, while the latter fails to unite 

 when worked upon any of the cultivated cherries; many 

 pears unite freely when grafted upon the quince, but the 

 quince does not freely unite when worked upon the pear. 

 The only sure way of determining what species may be 

 united by grafting is by trial. 



