Now that fall is here we’ve watched the rich green tree leaves turn to bold, beautiful orange, red, bronze, brown and even purple colors. Why do the colors change? Well, allow us to tell you!
The color change is caused by chemical changes that happen in the tree as the summer season fades into fall. According to the College of Environmental Science and Forestry (ESF) at the State University of New York, during the spring and summer leaves are little factories where all a tree’s food is made. That food-making process happens in cells containing chlorophyll, which is what gives leaves their green color. There are other pigments such as yellow, orange and red at play during this time, too, but they are masked by the green pigments.
But, when fall arrives the changes in the length of daylight and changes in temperature signal the leaves to stop their food-making process. And then the change begins, according to ESF:
“The chlorophyll breaks down, the green color disappears, and the yellow to orange colors become visible and give the leaves part of their fall splendor. At the same time other chemical changes may occur, which form additional colors through the development of red anthocyanin pigments. Some mixtures give rise to the reddish and purplish fall colors of trees such as dogwoods and sumacs, while others give the sugar maple its brilliant orange.”
The color intensity is related to the weather and temperatures. For example, low temps that are above freezing will favor anthocyanin formation producing bright reds in maples, but an early frost would weaken the brilliance. Good Housekeeping has an article that has more on the how certain colors are born.
Of course, the color changing process isn’t the only thing happening. The leaves area also preparing to make their descent to Earth.
“At the point where the stem of the leaf is attached to the tree, a special layer of cells develops and gradually severs the tissues that support the leaf,” ESF describes. “At the same time, the tree seals the cut, so that when the leaf is finally blown off by the wind or falls from its own weight, it leaves behind a leaf scar.”
So, there you have it. Thanks for reading!