This image clearly illustrates why this tree has its given common name, because it will grow in swamps, unlike most other trees.
This image clearly shows the multitude of knee-like woody protrusions above the ground. These growths come from the root system of the tree and are called Pneumataphores. And the job of a pneumataphore is to gather Oxygen from the air and deliver it to the roots. Thus the tree can grow in swamps.
And just to prove the point, here are some newly planted and staked Swamp Cypress Trees.
The foliage is very feathery, and the tree itself is deciduous, with the added benefit of a very reliable autumn leaf colour. The final image below shows the Cupressus-like cones forming.