A Stiidy of Leaves 



45 



running around the margin which prevents tearing. The thin 

 broad leaves of a banana have no such border. The wind 

 would bring such a strain on the trees that they would be 

 blown down were it not that the leaves tear down between the 

 veins. The younger leaves are rolled, so that the wind does 

 not injure them. The date palm defends itself in the same 

 way, only it is done earlier and the leaf has a more tidy 



Fig. 53. — Firmly bound \t?S oi Senccio. 



appearance. It looks like a compound leaf when it is quite 

 unfolded. Examine young date leaves. 



When leaves are branched, the branching depends upon 

 the branching of the veins. In some leaves there is a strong 

 central vein, from which other veins branch on either side as 

 the pinnae branch from the quill of a feather. Such venation 

 is termed pinnate. Or several strong veins may start from 

 the base or lower portion of the leaf, and the venation is said 

 to be palmate (hand-like). 



In dicotyledons the prominent veins join each other so 

 as to form an irregular network. In monocotyledons they 

 usually run more or less parallel. Simple leaves are sometimes 



