The leaves of the deciduous trees of the hardwood forest drop each autumn. Just before falling, they suddenly glow with color. This annual pageant has tremendous visual appeal and is the main attraction of West Virginia’s fall tourism season. The eastern United States is the best place in the world to see colorful foliage.

Changing day length determines the onset of fall color. As summer ages, the days become shorter. When the appropriate day length is reached, a hormone begins to form in the leaves of hardwood trees. This chemical diffuses downward in the outer ring of the leaf stem cells, causing an abscission layer where the leaf stem is attached to the twig. The abscission layer begins near the outer edge of the leaf stem and grows inwardly, slowly decreasing the flow of water into the leaf. Chlorophyll, which provides the leaf 's green color, can exist only in the presence of water. As the leaf is strangled, the chlorophyll breaks down and other pigments, which have been masked by the green, begin to show through. Carotenoids and xanthophylls provide the yellow and brownish colors of the fall foliage display. The reds are from anthocyanin, a pigment created by the conversion of sugar that can no longer move out of the leaf.

Trees have their own distinct colors. By early September sumac is a bright red. Birch turns golden; aspen greenish-gold; sugar maple reddish-orange to gold; soft maple ruby red; black gum deep red; hickories bright yellow; white ash and sourwood bluish to purplish; sassafras reddish becoming yellow; American beech yellowish to brown; flowering dogwood deep red; sycamore brown; yellow poplar bright yellow; and oaks leathery brown, although white oak is occasionally a deep burgundy and scarlet oak is named for its bright red color.

The leaves first color and then fall, a process essentially complete by Halloween. Leaf color usually peaks in the higher mountains and northern counties of West Virginia by late September and in the southern counties by mid-October. By November, nearly all of the colorful leaves have dropped, except on white oaks and American beech, which often hold some leaves until spring.