SHAPES OF TREES 91 



the main stem grows taller and thinner. For this reason 

 when trees are planted for the sake of their timber, they 

 are put fairly close together. The stem then grows very 

 straight upwards, and there being no large branches 

 the ' grain ' of the wood is straight and free of 

 knots. But if the tree is grown for the sake of its 

 fruit, it must have plenty of room to branch side- 

 ways, and not be made to suffer from overcrowding. 

 A tree that is on the edge of a wood, with one side 

 shaded by other trees and the other in the open air, 

 grows outward all the more widely, because on the side 

 towards the other tree its branches die off, and there 

 is then more sap for the others. It becomes therefore 

 very much one-sided. 



It is for this reason that trees grown for shade by 

 a roadside should be fairly close together. They then 

 do not grow much towards each other, and more 

 water and sap is available for the branches that grow 

 across the road, and these therefore grow the more 

 quickly. 



2. When we come to look at the branching more 

 closely and in detail, we find there considerable dif- 

 ferences in the way in which the smaller branches arise. 

 When the leaves are alternate, the branches are 

 naturally alternate too, and when they are opposite, one 

 would expect to find the branches also opposite. 

 Modifications of these two fundamental arrangements 

 are however caused by the development of some and 

 suppression of other buds. 



The simplest arrangement is when the main axis 

 continues to grow more strongly than any of the side 

 branches, these latter arising occasionally, and being 



