True Colors of Autumn Leaves

September 15, 2022

Life On Greenacres

There are so many wonderful advantages that come with the season of fall. Warm apple cider, pumpkin patches and corn mazes, and wrapping yourself in a warm blanket while sitting by a fire stargazing. The list can go on, really. But have you ever wondered what causes those leaves to take on their beautiful shades of red, orange, and gold? Well you’re about to find out.

Green is for Chlorophyll

A common misconception is that leaves change color when the weather begins to cool in autumn, when in reality it’s their true colors that are beginning to peek through. The main reason for this reversion back to their fiery foliage we all enjoy is the breakdown of chlorophyll.

Chlorophyll is a powerful molecule that is responsible for converting carbon dioxide (CO2) and water (H2O) into sugar. Specifically a monosaccharide sugar called glucose. As trees prepare for the next growing season, and temperatures begin to drop with less sunlight available, less chlorophyll is produced. The slow decrease in chlorophyll production gives way to all the reds, oranges and golds seen throughout the fall.

Creating Red Foliage

The color that creates the beautiful blazing effect trees like the Northern Red Oak, Forest Pansy Redbud, or Red Maple have, is due to a pigment called anthocyanins. This pigment is not part of the trees true colors, instead it’s produced during the process of temperatures cooling. In preparation to revert nutrients to the roots and twigs of a tree, the anthocyanin acts as a chemical sunscreen. Without anthocyanin to redirect excess light and UV radiation, this excess energy absorbed by the tree will eventually destroy cells and the plant itself.

Orange Foliage

Another flaming color seen in the autumn is bright orange. This pigment is due to a molecule called carotenoids, which is also found in carrots, oranges, and even bell peppers. As the production of chlorophyll slowly decreases the green pigment seen in leaves, the orange shade of carotenoid shows through.

Golden foliage

Gold is another majestic color leaves begin to show. The pigment responsible for this yellow shade is called xanthophyll. Corn, squash, and even pumpkins carry xanthophylls. Along with carotenoid, xanthophyll is another molecule that is present in the leaf, but overpowered by the green pigment from chlorophyll in the warmer spring and summer months. Once temperatures begin to drop and there is less sunlight, yellow hues begin to push through until the whole leaf is completely golden.

Where and When to See Fall Foliage

Timing will be a key factor on where fall foliage can be enjoyed. The farther north one travels, the sooner the foliage begins to turn due to cooler temperatures. For example, northeastern states like Maine and Vermont will be at peak for color as early as mid-September. In October, the great plains may be near or at their peak for fall color. Where as the southern states like Tennessee or Georgia might be patchy or partially beginning the process of changing color.

The Take Away

The next time you’re driving along a tree lined road while enjoying all its magnificent color, just remember it’s not that the leaves are changing color. They are simply showing you their true colors from the lack of chlorophyll being produced.

For a cozy fall recipe, click here!