The post oak was named for its use in making fence posts. It's a unique species of oak, sometimes having a crooked appearance with stout branches and short twigs. Acorns are small, but valuable to wildlife.
Widespread across central and southeastern US, from Texas to Illinois, Ohio, New Jersey and south to Florida. Not found in the northernmost or western part of the country.
Upland and rocky soils, sandy soils, well-drained or dry soils, and poor soils. Not typically found in rich bottomlands.
Burr Oak - Bark and general appearance of the tree is often similar; however, habitat is usually different. Both trees have irregularly-lobed leaves, but leaves of post oak are thicker and with more blocky lobes than those of burr oak. Burr oak leaves have shallow or no lobes near the apex, while post oak leaves generally resemble a "+" shape. Acorns of burr oak are much larger and with shaggy caps. Post oak acorns are small with fairly smooth, scaly caps.
White Oak - Leaves and bark may occasionally have a similar appearance. However, white oak leaves are not as thick and leathery, and have more lobes than those of post oak. White oak bark is also shaggy on the upper portion of the tree. Post oak bark remains fairly consistent from the base to the top of the tree. White oak acorns are also larger than those of post oak.
Overcup Oak - Leaves and bark may be fairly similar in some trees. However, habitat is different, with post oak favoring dry and poor soils, while overcup oak prefers swampy areas. Overcup oak leaves generally have narrower lobes, and usually more lobes than those of post oak. Bark of overcup oak is usually a darker shade of gray than that of post oak. Acorns of overcup oak are large, round, sometimes flat; with caps covering most of the nut. Acorns of post oak are much smaller, with caps only covering 1/3 to 1/2 of the nut.