FUNCTION AND FORM 87 



plant, while the other will readily tolerate 

 shade. 



This toleration only applies to the plant 

 taken as a whole, and there are limits beyond 

 which endurance of shade does not go. Most 

 people who have wandered through a dense 

 and well-tended wood must have been struck 

 by the great difference between the forms of 

 the individual trees which compose it and 

 those of the same species grown in the open 

 or in the hedgerow. The clean tall trunks 

 and the compact small crown of the forest 

 tree contrast strongly with the spreading 

 growth of the park specimen. And yet the 

 difference is merely a consequence of the 

 different conditions of illumination. A tree 

 grown in the open exposes its leaves to light 

 on all sides. The spreading limbs space out 

 the foliage and the leaves are all more or less 

 actively functional. But closer inspection 

 reveals the fact that it is only the leaves on 

 the periphery of the tree and its branch 

 systems which are thus flourishing. The 

 inner portion is bare of leaves, or at any rate 

 comparatively so. This is because the inner 

 twigs which become shaded by the outer 

 ones are starved, and sooner or later they die 

 and fall off. The leaves they bore did not 

 act efficiently, and they were quietly crushed 

 out of existence. 



Precisely the same thing, on a different 

 scale, happens when young trees are grown 

 close together, as in a well -managed forest. 



