Sumac, sourwood, blueberry, mountain ash, Virginia creeper, and others will begin turning in late September. Although fall foliage is broadly classified as red, orange or yellow, the southern Appalachian forests are bathed in a varied collage of shades and hues. Yellows run the gamut from the lemon-colored tulip poplar to the golden hickories. Crimson maples and maroon sourwoods are lumped as red. Oranges range from the grapefruit colored basswood to the burnt umber of beech and white ash.
Many factors contribute to the myriad of fall colors.
The physiology of the species, the health and vigor of the particular specimen, soil types and climatic conditions are just some of the parameters that come into play. The genesis of the color change is the approaching winter. Hardwoods shut down photosynthesis and go into a dormant state during the winter. The xanthophyll and carotene pigments responsible for the yellow and orange fall colors have always been present in the leaves. During the spring and summer growing season they are masked by the production of chlorophyll, which is responsible for the green color.