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October 27, 2009

The Chemistry of Autumn Colors

Chemical of the Week has an informative article about where the fall color in trees and shrubs comes from, from a chemical standpoint. Written by University of Wisconsin-Madison Chemistry Professor Bassam Z. Shakhashiri, The Chemistry of Autumn Colors reveals why in the fall leaves go from green to yellow and red.

Summarizing he says:

The range and intensity of autumn colors is greatly influenced by the weather. Low temperatures destroy chlorophyll, and if they stay above freezing, promote the formation of anthocyanins. Bright sunshine also destroys chlorophyll and enhances anthocyanin production. Dry weather, by increasing sugar concentration in sap, also increases the amount of anthocyanin. So the brightest autumn colors are produced when dry, sunny days are followed by cool, dry nights.

For the complete discussion, see:
http://scifun.chem.wisc.edu/chemweek/fallcolr/fallcolr.html or the pdf version:
http://scifun.chem.wisc.edu/chemweek/PDF/fall_colors.pdf

Posted by Katie Newman at October 27, 2009 4:43 PM