THE LEAVES. 



97 



the apex (fig. 58, '-^'S. 4). These swellings are the rudiments 

 of the leaves, into which they become transformed by further 

 development. Similar swellings appear later just above the 

 leaf rudiments, which are at first not distinguishable from 

 them, except by position (fig. 58, a, b, c). These become 

 the branches. Both leaf .and branch have their origin usually 

 in the outer layers of the shoot, and can only be distinguished 



\\l 



Fig. 86. 



Fig. 85.— 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 Kemer. 

 Fig. 86.— Seedlings, showing primary leaves. A, a fir; B, the 

 Fig. 85. dog-rose ; C, a morning-glory. Natuial size.— After Kemer. 



by the later course of development. The growth of the 

 branch is commonly indefinite, while that of the leaf is gen- 

 erally limited; the branch usually develops leaves and often 

 buds as lateral outgrowths, 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 dorsiven- 

 tral. In most cases, also, the leaf subtends the branch. 

 Both leaf and branch mark those points of the stem known 

 as the nodes. 



