Numerous types of oak trees have ranges that extend into southern parts of Alabama, with several growing in the coastal regions. These oaks, often used as landscaping tools for their shade, foliage and ability to grow in the hot and humid conditions, are identifiable by their different features. Assess such aspects of these oaks as their height, foliage and the fruit they produce to differentiate one species from another.
Estimate the size of the oaks you encounter in southern Alabama. The largest often approach 100 feet, such as the willow oak (Quercus phellos), Shumard oak (Quercus shumardii), white oak (Quercus alba) and overcup oak (Quercus lyrata). Look for the medium-sized oaks to grow to ranges of 40 to 50 feet, including the post oak (Quercus stellata) and Chapman oak (Quercus chapmanii). Small oaks in the 20- to 40-foot range in southern Alabama are the bluejack oak (Quercus incana), turkey oak (Quercus laevis) and blackjack oak (Quercus marilandcia).
Observe the shape of the leaves on southern Alabama's oak trees. Some possess multiple lobes with rounded ends, such as post oak and white oak. The post oak typically has five lobes, while white oak will have either seven or nine. Examine the lobes on the southern red oak (Quercus falcate) and species such as turkey and Shumard oak. The lobes will end in distinct points. Study the leaves on the oaks lacking any lobes, such as the swamp chestnut oak (Quercus michauxii) -- a type with kite-shaped foliage that has multiple teeth along the edges. Blackjack oak leaves have a pear shape, the leaves of willow oak are long and narrow, and the leaves on a laurel oak and live oak (Quercus virginiana) will be elliptical.
Study the unique acorns on some of these oaks, looking at their size and their caps -- the part that joins the acorn to the twigs. The cap of the overcup oak nearly encloses the acorn fully. The acorn of the swamp chestnut oak is as long as 1 1/2 inches. Those of Shumard oak are 1 3/10 inches long, with a saucerlike cap.
Inspect the foliage late in the fall and into winter to determine whether the southern Alabama oak species is evergreen or semievergreen. Live oak's leaves stay on the tree into spring before replacement foliage rapidly replaces it. Laurel oak is semievergreen, with the leaves lasting through the winter before falling off and new growth emerging on the branches. The foliage of the water oak (Quercus nigra) persists on the tree well into the winter months, as do those of the Chapman oak. The rest of the southern Alabama oaks lose their leaves during the autumn or early portion of winter.
Identify southern Alabama oaks by their fall foliage colors or, in some cases, by the color of their summer leaves. White oak leaves change to reds and browns, Chapman oaks turn yellow or red and southern red oak changes to brown. Species such as bluejack oak feature a bluish-green leaf during the warm months that changes to shades of red in fall. Water oak foliage also has a blue-green tint.