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Salviniaceae A family of ferns of specialized, floating, aquatic habit, that have no roots, and leaves in whorls of 3, 2 of which are oval and float while the third is submerged and divided into root-like, descending lobes. The floating leaves are covered with hairs and waxy papillae, and are concave above. The slender stems contain a vascular strand surrounding a tiny pith. The sporangia are of 2 kinds, megasporangia and microsporangia, borne in separate sporocarps on the tips of the root-like branches of the submerged leaves. The megaspores germinate to form green, female gametophytes floating at the water surface. There is 1 genus, with 12 species, mostly in tropical Africa, but also present in tropical and temperate America.