Fall Color: Oaks and Hickories
Missouri Hickories, yellow, Shumard Oak - yellow, Black Oak - yellow
Shingle Oak - yellow-brown/red-brown, Bur Oak - yellow, Pin Oak - red, bronze
Scarlet Oak - scarlet, White Oak - purple
Many people suppose that Jack Frost is responsible for the color change, but he is not. Some leaves begin to turn color before we have any frosts. The changes in colors are the result of chemical processes which take place in the tree as it prepares for winter.
All throughout spring and summer, the leaves have served as factories, manufacturing the food necessary for the tree's growth. The food–making process takes place inside leaf cells in tiny structures called chloroplasts. The chloroplasts contain chlorophyll which gives the leaf its green color. The chlorophyll absorbs energy from sunlight and uses it to transform carbon dioxide and water to carbohydrates such as sugars and starches.
Along with the green pigment, chloroplast also contain pigments called carotenoids. Carotenoids are yellow and orange in color and are common in many plants such as carrots, corn, daffodils and bananas.
Most of the year these yellowish colors are masked by the greater amount of green chlorophyll. But in fall, because of the shorter days and cooler temperatures, the leaves stop their food making process. The chlorophyll breaks down, the green color disappears and the yellow and the orange colors become visible.
Carotenoids tint the leaves of hardwood species such as hickory, ash, maple, birch , cottonwood and sassafras.
The reds, purples, and their blended combinations come from another group pigments in the cells, called anthocyanins.
These pigments are not present in the leaf through the growing season. They develop in late summer in the sap of the cells. The formation of anthocyanins depends on the amount of sugar in the leaf and weather conditions.
Warm, sunny days followed by cool night favor the formations of brilliant red colors. Sugar is made in the leaves during the daytime, but cool nights prevent movement of the sugar from the leaves. Anthocyanins are formed from the trapped sugars. The brighter the light during this period, the greater the production of anthocyanins.
Anthocyanins give the color to common fruits such as cranberries, red apples, blueberries, cherries and plums. In our autumn forests, they show up vividly in the maples, oaks, sweetgum, dogwood and blackgum. These same pigments often combine with the carotenoids to give deeper oranges, fiery reds and bronzes typical of many hardwood species.
Missouri has a great variety of trees, shrubs and vines. Their leaves turn at different times, and as a result, Missourians enjoy a fall color season that may last four to six weeks. Sassafras, sumac and Virginia creeper are some of the earliest to change. They begin to show their fall colors in mid-September. By late September, the blackgum, bittersweet and dogwood are changing. The peak of fall color is usually mid-October. This is when the maples, ashes oaks and hickories are at the height of their fall display. Usually by late October, the colors have faded and the leaves are beginning to drop form the trees.
