What’s in a leaf? Colors, that’s what! Here the fall colors are already beginning. The summer has been wet and the fall seems to be creeping up upon us with great rapidity. Already the maple trees are changing colors into yellow, red and orange.
Leaf colors are caused by pigments in the leaf. The most famous of these pigments in chlorophyll. Chlorophyll is what gives the leaves their green hue for most of the year, and it’s also the color of a growing leaf. With the help of the sun, the chlorophyll helps the plant turn water and carbon dioxide into carbohydrate-based energy.
In the fall, the shorter day lengths and cooler days tell the trees that it will soon be time to go dormant for the winter. Their leaves begin to change color as the chlorophyll fades away. As the leaf nears the end of its life, the chlorophyll breaks down into its nitrogen components. The nitrogen is reabsorbed by the plant.
The interesting thing about leaves is that they consistently have several colors inside them. Leaves contain green, yellow, and red pigments all year round. However, the yellow and red are overwhelmed by the chlorophyll, so they are essentially invisible in many plants. In a few plants like Japanese maples, you can see the other pigments in the leaves. As the chlorophyll moves out of the leaves in the fall, the other colors begin to emerge. Carotenoids produce a yellow color. Anthocyanins produce a pink and red color.
This fall, take a look at different leaves. Determine what pigments the leaves have. Are there different pigments in different parts of the leaf? Sometimes leaves have a fungus that attacks them and prevents the leaf from reabsorbing the chlorophyll in certain parts of the leaf. Sometimes leaves will be red on one side and orange on another. Why could this be?