The vibrant colours of Fall are one of the best parts of the season. The trees’ luminous oranges and breathtaking reds draw us out into nature, to enjoy the crisp air and the leaves crunching under our feet. But what is it that makes the leaves change their colour?
The science behind the seasonal costume change is very simple.
A deciduous tree (unlike an evergreen, which stays green year round) drops its leaves at the end of each year’s growing season. But before they fall off, the tree first recycles the leaves’ chlorophyll – the green chemical that uses sunlight to make sugar. As the tree draws the green chlorophyll back into its twigs, the leaves change colour, creating spectacular seasonal shows of red, yellow and gold.
As it turns out, different elements are responsible for different colours appearing on the tree. As a leaf dies, the carotenoids turn from yellow to orange to red, while scarlet anthocyanins are produced from the leaf’s sugars. The more sugars a leaf contains, the brighter its autumnal colours are likely to be.
Colourful puzzle solved – happy Fall!