Ricky Shykes, age 13, of Duluth, Minnesota, for his question:

Why do leaves change color in the fall?

Nature never fails to perform this miracle every year on schedule. Every year, most of us find time to admire it    and to wonder how in the world the green trees of summer can possibly change to colors that rival the rainbow. As we know, the multitude of subtle greens were blends of green and yellowish chlorophyll. All summer, the predominent green chlorophyll used the energy of sunlight to manufacture basic plant food from carbon dioxide in the air and water with dissolved chemicals from the soil. There was so much of it that it masked other chemical pigments that also were in the leaves.

The papery leaves of deciduous trees are too fragile to survive the winter. Come fall, their work is done and the green chlorophyll is broken down. As it disappears, other colored chemicals get a chance to be seen. Various carotinoid pigments range from pale yellows to rich orange reds. The anthocyanins vary from red through blue and violet. Each species of deciduous tree displays its own blend of these and other pigment chemicals.