This is a Bald Cypress, Taxodium distichum. It’s called “bald” because it loses its leaves in winter.
I’m looking at the widened base of the tree – called the “buttress”. Buttresses in architecture stabilize wall structures by providing extra width and mass at needed points. Botanists tend to think that the buttress of a cypress tree provides extra stability to keep the tree up in the mucky ground of a swamp – and also in high winds. Generally, the buttresses of these trees are higher and wider in wetlands that have higher flood levels.
My drawing of the buttress is a little abstracted. I really like the flare of the buttress as well as its fluted quality – the way the base of the tree waves in and out as it gets wider.
And here's a link to the Southeastern Natural Sciences Academy:
You can find information on their programs, and on how to get to the swamp.