90 GENERAL BOTANY 



roadside. A young tree has branches and leaves 

 close to the ground. The branches of an old tree 

 are entirely destitute of leaves except at their ends,, 

 and there is thus formed a hollow crown of foliage 

 supported by the branches, like an umbrella by its 

 frame. The same is true of the Banyan, Mango and 

 indeed all trees, though in some the outer leaves make 

 so little shade that a few others can grow on the 

 inner branches as well (see fig. 20, p. 102). 



But, besides all this, many kinds of trees have their 

 own peculiar shape by which they can be recognized 

 even at a distance. This is due to, among other 

 things, the angle at which the branches leave the main 

 axis. In PITHECOLOBIUM, the Rain tree, they slope 

 steeply upwards, at an angle of about 50 to the 

 vertical. The secondary branches leave them again on 

 the lower side at a similar angle, and there is thus 

 formed a regular hemispherical crown. 



The large branches of CASUARINA again are much 

 more upright, while the small ones bring their bend 

 down again, giving to the tree its peculiar drooping 

 graceful appearance. Those of the Banyan grow 

 almost horizontally, and when supported by their pillar- 

 roots, spread very widely. 



But the shape depends also very much on the tree's 

 immediate surroundings. If it is in the open, and not 

 shaded by other trees or by buildings, it grows freely 

 and to its natural shape. But when it is with other trees, 

 the shape may be quite different. Branches that are 

 shaded and cannot get sufficient light, are on that ac- 

 count robbed of their due supply of sap by the more 

 favoured shoots and therefore wither and fall off, while 



