The Congaree National Park is mostly swamp. They have a boardwalk that takes you across. W/o that, it would be nearly impassible. There are big bald cypress & water tupelo. Cypress have “knees” that stick up through the mud. The brochure says that scientist have not yet figured out the purpose. Maybe there is no purpose. Shit just happens.
I know all the photos look alike but consider. The bald cypress you can recognize by the knees. The next picture is the tupelo. Notice the way the base of both species flair out to provide stability. Notice also the water lines part way up the trunks. The water sometimes rises five feet or more above the ground level. It is a water dominated ecosystem.