34 GENERAL BOTANY 



tree, for instance a Rain-tree, seems like a hollow green 

 dome of leaves supported by its branches. For if 

 there were leaves in the middle of the tree, they would 

 be shaded by the outer ones, and not get enough 

 light, those that were there have in fact died. 



Nor are they ever so crowded together that air 

 cannot pass easily between them ; it is only in very hot 

 and dry places that we find leaves closely overlapping 

 each other, and then it is because if spread out 

 widely, they would lose more water than the roots 

 could supply. For look at a branch of Banyan or 

 RAUWOLFIA or any other plant whose leaves stand 

 out horizontally, and notice that those which are near 

 together do not overlap each other, but each is as 

 fully exposed to the light as circumstances will allow. 



The functions of the stem and branches of the 

 shoot are now easily made out. Their first and chief 

 use is J.o bear the leaves, so that they may obtain 

 as much light and air as possible. For this reason 

 they must be strong to stand not only the weight 

 of the leaves and of each other, but the pressure 

 of the wind against them. It is on this account 

 that there is in the branches far more cellulose, 

 and that of a harder and stronger kind in the wood 

 than in the leaves. 



Most branches are round in cross section, like the 

 main trunk, but when a horizontal branch is rather 

 long and has to be specially strong to support the 

 weight of its leaves, it is often elliptical, thicker in 

 the vertical direction, than in the horizontal. This 

 can be seen in the long branches of Banyan trees, 

 that stretch over a road, and in the Firs and Pines 



