54 



Principles of Plant Culture. 



69. Portions of Cambium from different plants may 

 Unite by Growth. If a section of cambium from one 

 part of a plant is closely applied to the cambium of an- 

 other part of the same plant, or of another closely re- 

 lated plant, the two portions of cambium may unite by 



st ^ f 



^fV- -W 



FIG. 22. Showing transverse section of corner of a bean stem 

 (Vicia faba). C cambium layer; e epidermis; Cu cuticle; St 

 stoma. The dark, oval-shaped spots, extending both sides of the 

 cambium layer are the vascular bundles; W wood cells of the 

 vascular bundles. Moderately magnified. (After Potter.) 



growth, a fact of great importance in horticulture since 

 it renders grafting possible (383). Plants having no 

 cambium layer (70) cannot, as a rule, be grafted, be- 

 cause their stems have no layer of dividing cells the 

 only cells that unite by growth. 



70. How Stems Increase in Diameter. There is no 

 cambium layer in plants having but one cotyledon 

 (45), of which Indian corn, the grasses and palms 

 are examples. In such plants there is no clear separa- 



