Wherefrom the Colors?
Autumn is a season when New York’s Hudson Valley, and much of the Northeast, unfolds in all its glory. Not this autumn, though. What’s going on in the leaves this year? Is there anything I can do about it?.
Chlorophyll is what makes leaves green, but hidden behind that green, all season long, are some of autumn’s colors. Chlorophyll must be continually synthesized for a leaf to stay green. The shorter days and lowering sun of waning summer are what trigger leaves to stop producing chlorophyll and let some of the other colors come to the fore.
Yellows and oranges, no longer masked by chlorophyll green, come from carotenoids, which help chlorophyll do its job of harvesting sunlight to convert into plant energy. Thank carotenoids for the warm, yellow glow they give to gingko, aspen, hickory, and birch leaves.
Tannins are another pigment, actually metabolic wastes, that all summer …