n8 



PLANT LIFE. 



which are at first not distinguishable from them, except by 

 position (fig. 96). These become the branches. Both leaf 

 and branch have their origin usually in the outer layers of the 

 shoot, and can only be distinguished by the later course of 

 development. The growth of the branch is commonly 

 indefinite, while that of the leaf is generally limited ; the 



Fig. 134- 



Fig. 135. 



Fig. 134. — A seedling of wheat, with grain still attached cut through lengthwise, showing 

 the single primary leaf with its back applied to the store of reserve food in the grain 

 (the shaded part). The first two secondary leaves are also developing, and the primary 



root has extended. Magnified 4 diam. — After Kerner. 



leaves. A, a fir {Abies orientalis); B, the dog- 

 size. — After Kerner. 



Fig. 135. — Seedlings, showing primary 

 rose ; C, a morning-glory. Natural 



branch usually develops leaves and often buds as lateral out- 

 growths, while the leaf rarely forms buds normally ; the axis 

 of the branch is generally radial, like the parent axis, while 

 the leaf is generally flattened and dorsiventral. In most cases, 

 also, the leaf subtends the branch. Both leaf and branch 

 mark those points of the stem known as the nodes. 



