Mary Blackburn, age 12, of Jackson, Miss,, or her question.,

Why do the leaves change color, in the fall?

All summer long, countless delicate green leaves are busy making plant sugar. They do this by photosynthesis, the mysterious sunshine recipe, The green substance in the leaves is chlorophyll. This magic substance uses carbon dioxide from the air, water from the soil and sunlight to make basic plant food. This food is a simple sugar. _Later the plant processes this basic food into other substances to make roots, stems, woody tissues, petals and even sweet perfumes,

Come fall, certain trees get ready for the long winter rest. Their delicate leaves cannot survive the icy frost. The sap in their veins would freeze, bruise and rip their fragile tissues. So trees like the elm, the oak and the ash shed their leaves before winter comes. The job of closing down the little sugar making factories takes time. It is done step by step and in the process the forests deck themselves in the rainbow colors of fall.

First the chlorophyll is broken down into simple chemicals and the leaves lose their green coloring. Now we see that under the green chlorophyll there were other colors. The maple leaves show up in cherry red. The plum leaves take on tones of purple. The oak leaves become gold and brown. Where did all these radiant colors come from? They were there all the time, hidden or masked by the busy green chlorophyll.

The red tones are caused by chemicals called anthocyanins. In the maple, a cherry red tint often shows itself in the young spring leaves. Later, it is hidden by the busy chlorophyll. When the chlorophyll disappears in the fall, the anthocyanin chemicals show up their true colors.

If you have a very sharp eye, you can spot traces of purple in the plum tree, in the hazel and the barberry throughout the summer. Sometimes the purple chemical is not quite covered by the green chlorophyll. These blue and purple tones come from the same chemical which paints the maple tree with vivid red. These chemicals are the pigments which also paint the apples and tomatoes, the plums and the cherries.

The yellow tones of fall come from a chemical called carotene. Yes, this is the same pigment which colors the carrot. It also paints the yellow and orange zinnias, the golden rods, oranges and lemons, the yellow corn and the golden sunflowers.

The radiant colors of fall never last very long. They are only one step in a complicated project. The chlorophyll goes first, then the leaves dry up and fall to the ground. The busy little sugar factories are then closed down for the long, cold winter months.