MAPLE FAMILY 



Much of the splendor of our radiant forest? in early 

 autumn is due to the brilliant coloring of the Sugar Maple. 

 It glows in red which deepens into crimson, it flames in yel- 

 low that darkens into orange. These wonderful leaves will 

 show colors as pure as any on the finest porcelain ; a dark 

 green leaf will show a single spot of crimson, a dark red 

 bears a single lobe of rose pink. The next will have a patch- 

 work of yellow and purple and scarlet, like a palette set for a 

 sunset picture. Sometimes a single branch will turn bright 

 scarlet while all the rest of the tree remains green. Indi- 

 vidual trees vary in time and manner of change, and to some 

 degree these peculiarities are fixed ; for example, certain 

 trees always turn yellow, others always turn red, while there 

 are others that vary with changing conditions. 



There seems to be a very general popular impression that 

 the colors of the leaves in autumn are dependent upon the 

 frosts. Careful observation does not sustain this view. It 

 is true that the brilliancy of the autumnal coloring varies ; 

 but the changes are now referred rather to the character of 

 the preceding summer than to the frosts of autumn. If the 

 summer has been rainy, keeping the leaves full of sap and 

 the cuticle thin and distended, the autumn tints are brilliant ; 

 but if the summer has been dry the tints are dull. 



Two great problems are connected with the fall of the 

 leaves of deciduous trees. One, why do they take on such 

 gorgeous colors ; and the other, how is it they fall leaving 

 no open wounds behind ? What are the morphological and 

 physiological changes which produce these results ? The 

 following is perhaps as clear a statement of the present 

 opinion of biologists as can be given in popular form : 



The casting of the leaf is not a sudden and quick response to any single 

 change in environmental conditions, but is brought about with a complex inter- 

 play of processes begun days or perhaps weeks before any external changes 

 are to be seen. The leaf is rich in two classes of substances, one of which is of 

 no further benefit to it, and another which it has constructed at great expense 

 of energy, and which is in a form of the highest possible usefulness to the plant. 

 To this class belong the compounds in the protoplasm, the green color bodies, 

 and whatever surplus food may not have been previously conveyed away. The 



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