So I looked 'em up, and what I found is that Montgomery County pretty much represents the absolute southern extent of their natural range.
One wonders what controls this: what makes the tree grow on THIS spot along Peach Creek but not THAT one nearby? I am used to seeing microclimatic variations here near the coast, but there are no perceptible differences to me in this particular case. Is it one degree cooler on average ten miles further north? One inch less annual rainfall? The trees may be the only living things that can parse the answer to why they grow where they do, and they ain't talkin'.