Marsilea villosa is an aquatic to semiaquatic fern. Marsilea villosa resembles a four-leaf clover, with four leaflets borne at the end of 1 to 45 cm (0.5 to18 in) tall leaf stalks. The leaves are borne in pairs along a thin rhizome. The leaves and rhizomes vary in pubescence, depending on the aridity of the habitat at the time of development. A hard sporocarp (hard-walled case containing male and female spores) is borne at the base of a leaf pair. The young sporocarp, like the rhizome, is covered with rust-colored hairs which are lost as the sporocarp matures. The plant occurs either in scattered clumps or as a dense interwoven mat.