322 



REPRODUCTION 



also allow some of the buds of the stock to grow, forming a 

 crown with many kinds of varieties in it. Grafting is generally 

 most successful between closely related plants and may be ac- 

 complished only when the scion and stock show a structure gen- 

 erally similar. 



A cutting grafted on a stock instead of being cultivated on a 

 substratum is relieved from the necessity of replacing the root 

 system, and is furnished with water and mineral salts by a root- 

 system of comparatively great capacity. It is this difference in 



B 



a 



155 156 



FIG. 155. A, winter bud of Philotria. , apex of growing shoot. 



FIG. 156. Illustrating crown grafting, a, stock with three scions inserted, 

 pared scion. After Percival. 



pre- 



amount of nutrition which is chiefly responsible for the differ- 

 ences between the growth of a grafted cutting and a branch on 

 the plant from which the cutting was taken. 



The union of a scion and stock showing the greatest differences 

 may be made in herbaceous plants where such unlike forms as 

 Lycopersicum and Tradescantia have been grafted. The rapidity 

 with which the union of scion and stock takes place makes these 

 forms most useful for an experimental study of the subject. 1 



1 Wright, J. S. Cell union in herbaceous grafting. Bot. Gazette. 18 : 184. 

 I893- 



