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 Osmundales Bercht. & J.Presl (1820) [monotypic] Family Osmundaceae Martinov (1820) Genus Plenasium C.Presl (1836)