Why Leaves Turn Color in the Fall

Next to 'why is the sky blue' and 'where do babies come from,' 'why do leaves turn color in the fall' might be the most frequently asked question about nature. Every autumn, millions of Americans make a pilgrimage of sorts--not to religious shrines in the usual sense, but to express a deeply seated, perhaps evolutionary based sense of wonder at nature. From car windows, scenic overlooks, well trod trails and hotel balconies, they gaze at the display of leaf color in America's mountains and valle

Barry Palevitz
Dec 9, 2001
Next to 'why is the sky blue' and 'where do babies come from,' 'why do leaves turn color in the fall' might be the most frequently asked question about nature. Every autumn, millions of Americans make a pilgrimage of sorts--not to religious shrines in the usual sense, but to express a deeply seated, perhaps evolutionary based sense of wonder at nature. From car windows, scenic overlooks, well trod trails and hotel balconies, they gaze at the display of leaf color in America's mountains and valleys.

According to Nancy Gray, a park ranger at Great Smoky Mountains National Park, more than 1.2 million people visited the 800-square-mile sylvan paradise in the southern Appalachians in October 2000, "mostly on weekends and in the last two weeks of the month" when leaf color peaks. "We have more than 100 species of native trees, most of which change color," Gray says. "It's pretty...