EEK! A Tree's True Color - Homework Help

EEK! A Tree's True Color
Wisconsin Department of Natural Resources

While you were playing in the hot sun during summer vacation, the trees on the streets, in the parks and in the forests were working hard to keep you cool. To feed the shiny green leaves that make shade, trees use sunlight to convert water and carbon dioxide into sugar. This is called photosynthesis.

Now it's autumn, and you're ready -- okay, almost ready -- to go back to school. Those hardworking trees, on the other hand, need to take a break from all that photosynthesizing. When leaves change color, from green to yellow, bright orange or red, you'll know trees are beginning their long winter's rest.

Where do leaf colors come from?
Leaf color comes from pigments. Pigments are natural substances produced by leaf cells. The three pigments that color leaves are:
* chlorophyll (green)
* carotenoid (yellow, orange, and brown)
* anthocyanins (red)

Chlorophyll is the most important of the three. Without the chlorophyll in leaves, trees wouldn't be able to use sunlight to produce food.

Carotenoid create bright yellows and oranges in familiar fruits and vegetables. Corn, carrots, and bananas are just a few of the many plants colored by carotenoid.

Anthocyanins add the color red to plants, including cranberries, red apples, cherries, strawberries and others.

Chlorophyll and carotenoid are in leaf cells all the time during the growing season. But the chlorophyll covers the carotenoid -- that's why summer leaves are green, not yellow or orange. Most anthocyanins are produced only in autumn, and only under certain conditions. Not all trees can make anthocyanins.

Please visit the web site to learn more.