Terrestrialor aquatic perennials, evergreen or decidiuous, heterosporous plants, occurring in aquatic or seasonally wet habitats. Stem erect, short, 2- or 3-lobed; roots dichotomously branched, arising from a basipetal growing point beneath the rhizome. Leaves in a rosette, flat or cylindrical; leaf base spathulate with a membranous margin and a delicate triangular ligule on adaxial surface where leaf narrows. Sporangia sessile, ovoid or globose, initially embedded in the adaxial surface of the leaf base below the ligule, partially or entirely covered by a thin velum.