Free-floating, "mosslike" plants often completely covering the surface of ponds and ditches and coloring it a velvety green or, in late summer and fall, red. Stems 1-3 cm. long, pinnately branched, rooting from below, the roots hanging in the water. Leaves 2-lobed, imbricately disposed over upper surface of plant, usually concealing stems, the surface minutely papillose. Sporocarps usually in pairs on lower side of stem; massulae within microsporangia beset with septate or nonseptate, terminally barbed hairs or glochidia; microspores 6-100; megasporocarp rounded below, conical above, often described as "acorn shaped," containing a single megaspore. (Mason 31).