A common, medium to large tree with a short trunk and a compact, rounded crown, commonly reaching a height of 50 feet and a diameter of 2 feet, but sometimes considerably larger.
One of the most widespread oaks in Texas, common to both East and Central Texas, west to the Panhandle, growing on upland soils either deeply sandy or on gravelly clays with poor surface drainage.
Simple, alternate, usuallv 4" to 6" long and nearly as broad, highly variable but typically 5-lobed, no bristle-tips, the lobes broadest at the ends and often forming a "cross" shape, thick and somewhat leathery, dark green and shiny on the upper surface, lighter green and finely-pubescent beneath.
Male and female flowers borne in spring on the same tree, the male flowers on drooping, clustered catkins, 2" to 4" long, the female flowers inconspicuous.
An acorn, requiring one season to mature, oval, 0.5" to 0.75" long, set one-third to one-half its length in a gray, bowl-shaped cup which has thin scales, sometimes with a short stalk.
Thick, gray-brown, developing narrow, irregular fissures and scaly ridges on older trunks.
Heavy, hard, close-grained, light to dark brown and durable in contact with the soil; used for crossties and fence posts and occasionally for lumber.
Sand post oak (Quercus margarettiae) occurs on deep sands and has smaller leaves with downy pubescence; bottomland post oak (Q. similis) occurs on the wet lowlands of southeast Texas.
The species is so common it gives rise to the name for an entire ecoregion: the Post Oak Savannah.