Phylum [Tracheophyta] Sinnott ex Caval.-Sm. (1998) - vascular plants Subphylum Polypodiophytina Reveal (1996) [monotypic] Class Polypodiopsida Cronquist, Takht. & Zimmerm. (1966) - ferns Subclass Polypodiidae Cronquist, Takht. & Zimmerm. (1966) Order Salviniales Link (1833) - water ferns Family Salviniaceae Martinov (1820) - floating ferns 1 Genus Azolla Lam. (1783) 2 Genus Salvinia Séguier (1754)