The science behind fall foliage

fall foliage

Autumn is one of the most beautiful times of the year for witnessing fall foliage across the country. For colors to fully peak, the process can take weeks – but not anymore. A new time-lapse video of over 6,000 leaf photos reveals the biology behind this transformation. Despite the popularity of fall foliage, the science behind the changing leaves isn’t widely known.

David Lee, professor emeritus in the Department of Biological Sciences, told the Smithsonian one of the biggest misconceptions is that red and yellow leaves change in the same way, when they actually endure completely different processes.

Lee explains how the breakdown of chlorophyll unveils the yellow pigments hiding underneath. On the other hand, the red color comes from the release of a pigment called anthocyanin which forms as the leaf dies.

Scientists are still trying to find out the function of red pigments. There are several hypotheses suggesting that this color is used to protect plants from herbivory or that red pigments offer photo-protection when the leaf is vulnerable.

“With work like Reiser’s video, we can now examine the changing leaves with a fresh perspective, bringing new questions into focus and magnifying the puzzle of nature’s ever-evolving palette,” said Lee.

While there is still much science to learn, Lee is hopeful the mystery of color change will continue to fascinate researchers and observers in the field.

This article first appeared in the Smithsonian on August 14, 2019.