The word `deciduous` comes from Latin, meaning "to fall off." What is it that makes a trees leaves change color, and eventually to fall off? Although the leaves do it, the trees themselves start it, but they are doing this in order to survive. However it comes about, the performance dazzles the eye and stirs the heart of those who see it. And even as the extravaganza reaches its climax, next year's performance is waiting in the wings. When cells divide, they're growing. As the ratios of these specialized plant hormones change, trees stop making the famous energy-producing chemical chlorophyll. They pull in all the nutrients they can from the leaves, and cut the leaves off from their main stems.In September/October in the Northern Hemisphere, the curtain opens on the show, quietly and without fanfare. A tiny band of cells where the leaf's stem is attached to the twig begins to loosen and dry out. Between these cells and the twig, a layer of corklike cells begins growing. It is scar tissue forming even before the amputation of the leaf takes place.It is the season for brightly lighted days and cool, crisp nights-requirements for the colorful extravaganza that is to
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AUTUMN LEAVES PROVIDE A SPECTACULAR SIGHT