This widespread southeastern species of wet sites has often been confused with related species. C. caroliniana (2n = 48) differs from complanata (2n unknown) and hirsutella (2n = 52) in its perigynia (FNA 23, W), which are minutely beaked (0.1-0.2 mm versus beakless), terete to subtriangular in cross-section (versus flattened-triangular), and usually more spreading (at >45 degrees versus appressed-ascending). Leaf blades are mostly glabrescent, as in complanata.