CH. IV] LOBED LEAVES 39 



The arrangement of the lobes, and their sizes and 

 numbers, differ in different cases. 



The rule is that the type of venation is correlated 

 with the type of lobing, and of these types there are, as 



Fig. 11. Simple lobed leaf of the Mulberry, Moms alba. 



we have seen, two principal forms. Leaves of the more 

 elongated forms I refer to the trees and shrubs with 

 which we are here concerned are apt to follow the 

 pinnate type, the lobes being developed right and left 

 along the leaf; one of the secondary ribs, also developed 

 right and left along the midrib, passing into each, and 



