Saturday, 9 January 2010

Autumn, thou art a chemical reaction

Autumn is a time of great beauty with trees turning from a bright green to shades of brown and red, but why do these leaves lose their green colour and become the yellow, orange, and red we associate with Autumn?

Well when the air temperature drops the chlorophyll inside the leaves starts to break down and this reveals the other pigments that also exist naturally within the plant. Some examples of pigments include carotenoids and xanthophylls which usually give a yellow and or orange colour to the leaves.

At the same time as the chlorophyll breaking down a layer between the leaf and the main stem called the abscission layer also starts to grow which cuts off the water supply to the leaf. This eventually causes the leaf to fall off but before that happens, the sugars within the leaf also break down into anthocyanin which can give leaves that dark red colour. So there you go, if you ever wondered where those colours came from. Well now you know.

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