The swamp of George L. Smith State Park is dominated by two trees:  a cypress, probably Taxodium distichum, and a tupelo, probably Nyssa aquatica. 

I think these are the two most common species in this type of habitat. There are several other species in genera Taxodium and Nyssa that occur in the region, but, not having keyed them out, I’ll stick with the most common of the species. Nyssa ogechee could certainly be present, but Taxodium ascendens doesn’t appear to have two distinct leaf forms, as I observed (but not photographed) in the cypress. An example of the two leaf forms can be seen here.