The basin for The Big Cypress receives on average 55 inches (140 cm) of water in the rainy season.[57] Most of The Big Cypress sits atop a bedrock covered by a thin layer of limestone that contains quartz, creating a sandy soil that hosts a variety of vegetation.[56] The majority of trees are bald cypress (Taxodium distichum) and pond cypresses (Taxodium ascendens). Cypresses are conifers that are uniquely adapted to thrive in flooded conditions, with buttressed trunks and root projections that protrude out of the water, called "knees".[58]