Fall Colors

The brilliant reds and yellow of fall are just starting to appear on area trees like this one, in the 900 block of North Washington. The cool nights and sunny days forecast for the rest of the week should bring the colors to their peak towards the end of October.

Why do leaves change colors?

According to the Missouri Department of Conservation, leaves that turn yellow and orange contain cells with autumn colors in them all the time -- crystalline pigments called carotenoids -- the substances that give things like daffodils and carrots their color. It's just that during the summer, the green chlorophyll is more active, processing sunshine, water and carbon dioxide into food for the plants. As days shorten and temperatures cool, less energy is available for making the plant's food and the chlorophyll breaks down, letting the other colors appear. Some red and purple leaves create sugars that cause the color change. If the trees don't receive enough water, leaves may drop without changing dramatically.