38 THE HUMAN SIDE OF TREES 



a remarkable change. The tree withdraws into its 

 interior the carbohydrates and the albuminous sub- 

 stances composing the leaf -pulp. The chlorophyll 

 or green colouring-matter changes chemically to 

 form, with deposited iron and other minerals, the 

 bright colours emblematic of the season. The 

 leaves grow shrivelled and unattractive until the 

 corky rings at their bases finally give way and they 

 fall. What little substance of value they contain 

 goes to enrich the soil below. Next year the tree 

 will have a whole new set of lung-stomachs. 



Leaves of a few tree families indolently remain 

 on the boughs all winter. They are there by suf- 

 ferance only and serve no needed purpose. 



The flowers are the trees' organs of reproduction. 

 All trees have them, though in some they are in 

 the form of inconspicuous catkins which are liable 

 to be overlooked. On the other hand, many tree- 

 flowers, notably those of the edible fruits, are as 

 luxurious and beautiful as any garden favourite. 



Most trees are bi-sexual. They bear flowers 

 which contain both stamens and pistils, or produce 

 blossoms which though individually of one sex occur 

 in both male and female form on the same tree. 

 The stamens manufacture the floury pollen which 

 is conveyed by wind or insect to other trees. The 

 pistils receive visiting grains of the male element, 



