Do Oak Trees Turn Color Early Like Maple Trees?

Oak Characteristics

• Oak trees can either be evergreen or deciduous, depending on the species. Deciduous species are usually broadleafed, hardwood trees whose leaves drop in the autumn. These leaves often produce brilliant color displays as they lose their green chlorophyll. Evergreen species do not shed their leaves in the fall, but stay consistently green all year. They are often coniferous -- or have needle-like leaves -- though evergreen oaks, like the Japanese evergreen oak and the ring-cupped oak, are among the few evergreen species that have flat leaves.

Oak vs. Maple

• Deciduous oaks lose their leaves in the autumn, often producing brilliant, fire-colored displays of red, orange, yellow and purples -- though they are not noted for turning particularly early on in the fall, as some maple species do. Some oak species are also more flashy than others. For instance, red oaks produce deep magenta, red, purple and sometimes yellow leaves, while willow oaks turn a yellow-brown in the fall. Brown leaves often remain on pin and white oak branches well into the winter. Unlike most oaks, a variety of maple species are often specifically grown for their dazzling leaf displays. The leaves of the red maple cultivar, Autumn Flame, for example, turn red and orange relatively early in the fall and remain on the tree for several weeks.

When Leaves Change Color

• Scientists are still not entirely sure why deciduous tree leaves change color when they do, according to experts at Rowan University, but they have identified several influential factors. While specific cultivars, like the red maple Autumn Flame, often change early, precisely when most deciduous leaves change is heavily influenced by environmental factors. Shorter days and cooler nights trigger the change; therefore, if two individuals of the same species are living in different areas of the country that shift to cooler fall temperatures at different points in the season, their leaves will change at different times. For instance, an oak planted in Iowa will change colors earlier than an oak planted in South Carolina. Some oaks also need very specific temperature ranges to produce their distinctive colors. Red oaks, for example, only turn deep red and magenta with plenty of sun and temperatures between 0 and 45 degrees Fahrenheit.

Why Leaves Change Color

• As the weather cools in the fall, photosynthetic food production -- made possible by the green leaf pigment chlorophyll -- slows and the pigment xanthophyll becomes visible, producing yellow, gold and orange leaf colors. Many scientists believe this pigment is always present but hidden under the more dominant green of the chlorophyll. Reds and purples, however, are not hidden -- they emerge as a result of the leftover glucose trapped in the leaves from the food produced earlier in the season. Because this glucose contains the red pigment anthocyanin, it becomes visible as the chlorophyll disappears.