MAPLE FAMILY 



jNIuch of the splendor of our radiant forest? in earlj 

 autumn is due to the brilliant coloring of the Sugar INIaple, 

 It glows in red wliich 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 

 beai"s 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 

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

 vidual trees vai'v in time and manner of change, and to some 

 degi'ee these peculiarities are fixetl ; for example, certain 

 ti'ees always turn yeliow, others always turn red, while there 

 ai'e others lliat vary with changing conditions. 



'I'here seems to be a very general popular impression that 

 the colors of the leaves in autunui 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 snumier than to the frosts of autumn. If the 

 sunnner iuis been rainy, keeping the leaves full of sap and 

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

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



Two great problems are connected with the fall of the 

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

 goi-geous coloi's ; and the other, how is it they fall leaving 

 no open wounds l)ehind ? What are the morphological and 

 |)h\-si(;logicai changes wdiich produce these results? The 

 fnlU;wing is perhaps as clear a statement of the present 

 o|)inion of biologists as can be given in popular form : 



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

 chanije in environmental conditions, but is brought about with a complex inti r- 

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

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

 no furtlicr 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. 

 T... tliis 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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