Monday, October 26, 2009

Seeing Red!

By Gardennia nutti

I’m seeing red. In my yard, on my street, along the highway….Red! At first I thought it was the result of my new rose colored glasses, but alas, even when looking through clear lenses I still see red. Leaves contain pigments: chlorophyll (green) and carotenoids (yellow and orange). Both chlorophyll and carotenoids are present in the chloroplasts of leaf cells throughout the growing season, but during the growing season the amount of chlorophyll is so high that the green color masks the other pigments. When the days grow shorter in the fall, chlorophyll production stops and that pigment breaks down allowing the carotenoid pigments to show through. This explains the wonderful gold and orange leaves, but why am I seeing red? The answer lies with anthocyanin pigments which are produced in response to bright light and excess plant sugars within leaf cells. Warm days in early fall encourage sugar production in the leaf, and cool nights cause leaf veins to close, thus trapping the sugars in the leaf. Light plus abundant sugar creation encourages production of anthocyanin – the red and crimson I’m seeing this fall.


  1. Thanks for the explaination. I've always wondered how this works. Some fall seasons the colors are even more intense. I presume that is due to the larger spread between daytime and nighttime temperatures.some years?

  2. The more intense colors come from two things 1) more sun exposure and 2) more extreme day and night temperatures. We had a great year for fall colors indeed!
    -Gardennia nutti