Friday, October 16, 2009

Overhead and Underfoot

The leaves underfoot on the hill have me wondering about the colors. Leaf colors must be more than just another form of weather to chat about… how ‘bout them leaves, eh?
But more to the point: why red? Why yellow? And what if there was a tree in which the leaves turned blue in the fall? Or lavender?

Turns out that yellow in leaf terms is really the absence of green. In the fall, when the chlorophyll production shuts down, the green drains away and we’re left with the yellow and orange substance of the leaf. It was there all along, just obscured by the green. The things that make the leaves yellow and orange are carotenoids, the same stuff that brings the color to that crunchy vegetable that ol' Bugs liked so much.

Reds and purples on the other hand are from anthocyanins, created in the autumn in the leaf. (Also responsible for the color in plums, strawberries and red apples.) The anthocyanins are actually sunscreen and coldscreen for leaves and allow them to survive reality a little bit longer than they would have as innocent green little leaves.

Maybe we’ll all turn a little redder as we get older and our green youth is drained away...

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