The transformation begins: Why do leaves change colour in autumn?

We are entering the time of year when the leaves around us will soon begin to slowly changing colours. But why does this happen?

In spring and summer, most leaves are green. This is thanks to a substance called chlorophyll that is produced as the leaves produce energy for the tree.

As the days get shorter and temperatures cool, a cork-like substance forms at the base of each leaf so the tree can begin to conserve its water supply ahead of winter.

That substance cuts off the water supply to the leaf.

Without the water supply, the chlorophyll disintegrates and the green colour disappears, making way for the glorious hues of orange, red, and yellow we see during autumn.

The traditional russet colouring is always present in the leaf but is overshadowed by the green pigment during the warmer months.