Autumn leaves and the compounds that cause their colours

What a lovely time of year—when the leaves of deciduous trees in many forests change from the deep greens of summer to the yellows, oranges and reds of autumn. But what makes the leaves change colour, and what compounds are responsible for nature's spectacular display?

Many of us will know the green of chlorophyll, but leaves also contain carotenoids. As the chlorophyll fades, the golden oranges of these carotenoids start to shine through. You may recognize one carotenoid, beta-carotene, from carrots.

Another carotenoid, xanthophyll, is responsible for the beautiful bright yellows.

The leaves of some trees also produce anthocyanin as autumn begins, which produces those beautiful deep reds.

This sketch features in my book Big Ideas Little Pictures

Also see:

• What causes seasons?