The Fall of the Leaves 



The leaves of certain trees in regions of mild winters persist 

 until they are pushed oflF by the swelling buds in spring. Others 

 cling a year longer, in sorry contrast with the new foliage. We 

 may believe that this is an indolent habit induced by climatic 

 conditions. 



Leaves of evergreens cling from three to five years. Families 

 and individuals differ; altitude and latitude produce variations. 

 An evergreen in winter is a dull-looking object, if we could compare 

 it with its summer foliage. Its chlorophyll granules withdraw 

 from the surface of the leaf. They seek the lower ends of the 

 palisade cells, as far as they can get from the leaf surface, assume 

 a dull reddish-brown or brownish-yellow colour, huddle in clumps, 

 their water content greatly reduced, and thus hibernate, much 

 as the cells of the cambium are doing under the bark. In this 

 condition, alternate freezing and thawing seem to do no harm, 

 and the leaves are ready in spring to resume the starch-making 

 function if they are still young. Naturally, the oldest leaves 

 are least capable of this work, and least is expected of them. 

 Gradually they die and drop as new ones come on. As among 

 broad-leaved trees, the zone of foliage in evergreens is an outer 

 dome of newest shoots; the framework of large limbs is practically 

 destitute of leaves. 



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