Tags: Fern.
Regnellidium is a monotypic genus of ferns of family Marsileaceae. The single living species Regnellidium diphyllum Two-leaf Water Fern is native to South Eastern Brazil and adjacent regions of Argentina. It resembles its relatives from the genus Marsilea but has 2-lobed leaves (rather than 4). This fern is sometimes grown in aquaria. It is the only non-flowering plant that produces latex.