The brown color of trees like oaks is made from wastes left in the leaves. Sunlight and the cool nights of autumn cause the leaves turn this glucose into a red color. In some trees, like maples, glucose is trapped in the leaves after photosynthesis stops. The bright reds and purples we see in leaves are made mostly in the fall. We just can't see them in the summer, because they are covered up by the green chlorophyll. Small amounts of these colors have been in the leaves all along. The green chlorophyll disappears from the leaves.Īs the bright green fades away, we begin to see yellow and orange colors. They begin to shut down their food-making factories. The trees will rest, and live off the food they stored during the summer. As the days get shorter, trees use this signal to "know" it's time to begin getting ready for winter.ĭuring winter, there is not enough light or water for photosynthesis. But the dark, dry days of winter are coming. Plants are busy growing all summer long and into autumn. Chlorophyll is what gives plants their green color. That means "putting together with light." A chemical called chlorophyll helps make photosynthesis happen. The way plants turn water and carbon dioxide into oxygen and sugar is called photosynthesis. Plants use glucose as food for energy and as a building block for growing. Oxygen is a gas in the air that we need to breathe. Plants use sunlight to turn water and carbon dioxide into oxygen and glucose. They take a gas called carbon dioxide from the air. Plants take water from the ground through their roots.
To answer those questions, we first have to understand what leaves are and what they do.
Many areas in the United States are among the best in the world for leaf viewing, including New England, the Southeast, the Northwest and the Great Lakes regions.įind maps, dates, and best scenic drives for fall colorsĭid you ever wonder how and why a fall leaf changes color? Why a maple leaf turns bright red? Where do the yellows and oranges come from? The changing fall foliage never fails to surprise and delight us. We all enjoy the colors of autumn leaves.
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