Every autumn our forests change into a brilliant mosaic of yellow, orange and red as the leaves change colour. In other seasons, we see only green due to high concentrations of chlorophyll relative to other pigments. The yellow (carotenoids) was present in the leaf all year round and can now revel itself, because in fall as chlorophyll dies it exposes those pigments that were already present but masked by the abundance of chlorophyll. In comparison, the red (anthocyanins) is actually a new addition to the leave in the autumn! Why produce red pigments? Well, the trees could be doing this to protect against harmful effects of light at low temperatures or because red signals poison to migrating insects causing them to avoid munching the tree’s few remaining leaves. Which colour will be more dominate on a tree, and how bright it will be is also a mystery we can continue to enjoy!
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