Forestry, Wildlife & Fisheries News |
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Weather shift causes fall leaf color displayBy Bonnie Coblentz MISSISSIPPI STATE -- The beauty of Mississippi's fall leaf color display helps ease the bad feelings many have about raking the acres of dead leaves that follow. Andy Londo, forester with the Mississippi State University Extension Service, said decreased daylight and falling temperatures make deciduous tree leaves change color and shed. "In our region, tree shed is preceded by color change," Londo said. "Leaves change color because of a change in the pigment, which is affected by the change in weather." The main pigment in plants is chlorophyll, the substance responsible for photosynthesis. Chlorophyll absorbs red and blue wavelengths of light, causing the plant to appear green. "As the length of day shortens and temperatures cool, the amount of chlorophyll in the leaves decreases, photosynthesis decreases and other pigments begin to take over," Londo said. Carotene, the pigment responsible for the orange color of carrots, is one of the pigments that becomes prominent. The effects of carotene can be seen in the yellow leaves of fal sweet gum and cottonwood trees. A third group of pigments are the anthocyans, or those that absorb blue, blue-green and green light and give off a red appearance. In Mississippi, red maples and several oaks turn this color in the fall. "These pigments are common in leaves, regardless of the species," Londo said. "The tree species and weather conditions determine whether or not leaves change color and how vivid they get. The brightest colors are caused by dry, sunny days in the fall followed by cool, dry nights." Other specific fall leaf colors include purplish-red dogwoods; red, brown or russet oaks; and golden-bronze hickories. Elm leaves shrivel up and fall off with hardly any color change. Leaves shed from trees when their veins seal themselves off and the leaf dies. Norman Winter, Extension horticulturist at the Central Research and Extension Center in Raymond, urged homeowners to consider fall color when choosing trees and shrubs for the landscape. The Chinese Pistache and the gingko put on a real show in the fall. The new hybrid crepe myrtles named after Indian tribes color up well, too. "There are a few bushes that change and give incredible fall color. The Virginia willow or sweetspire has fragrant white blossoms that arch over in the spring, then the leaves change to burgundy in the fall and last an incredibly long time. Henry's Garnet is one of the most popular of this species," Winter said. "Burning Bush, known scientifically as Euonymus alata, and nandina change in the fall and stay red all winter." Winter said it is important to have evergreen shrubbery so landscapes are not bare once leaves have fallen. "The primary source of color in the winter is green. If you don't have green, your landscape will look like Siberia," Winter said. "You also need pockets of seasonal color from such plants as pansies, violas, kale and cabbage." -30- Released:
Oct. 28, 2004 |
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