Marsileaceae Mirb.
Sporocarps one or more at or near base of stipes, hairy, firm, about globose, containing the sori, rupturing by 1 or 4 slits. Sori 4 or more, bearing sporangia on a receptacle; megasporangia below, the large megaspore imbedded in a thick layer of mucilage; microsporangia above, with numerous minute microspores. Spores tetrahedral. Rhizome far-creeping, branching, solenostelic; fronds linear, or 2-4-foliate, in 2 rows. Subaquatic to aquatic ferns of 3 genera.
