Many articles that describe post oaks mention their cross-shaped leaves. Often, it's said that the leaf resembles a Maltese cross. Perhaps you can see the resemblance in the shapes of the leaf at left and the Maltese cross at right.
The post oak leaves in the photo above are a bit ragged, but some of them do demonstrate the cross-like shape that is typical of post oaks in this area.
Post oaks are quite drought resistant. This post oak retained its leaves during the past summer of extreme drought, while some drought-sensitive trees in our area dropped a good portion of their leaves or even died.
Post oaks often grow in areas that tend to be dry, such as "rocky or sandy ridges and dry woodlands with a variety of soils" (according to the USDA Forest Service.) True to form, this post oak is growing on a knoll on top of a long, broad ridge. In the fence row between two farms, with a field on one side and a pasture on the other, it gets the full access to sunshine that it needs.
Mature post oaks may reach 50 or more feet in height and about the same distance in spread. They are slow-growing trees, but long-lived, often surviving 300 to 400 years. Their acorns are eaten by a wide variety of birds and animals. (If you look carefully, you can see a few acorns on the branch in the photo.)
Three things that post oaks don't like and may not survive are:
1. Standing in water
2. Trying to grow in shade
3. Having their roots disturbed or their soil compacted.
If you want a post oak in your yard, you'll probably have to plant it yourself. The acorns germinate in the fall, so look for them right now and plant them soon.
If you're building in an area where there are already post oak trees, don't drive on the ground under them. The best way to protect them during construction is to install a fence that encompasses the entire area beneath their canopy.
Images of post oaks