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 Polypodiales Link (1833) - cathetogyrates
           Suborder Lindsaeineae
             Family Cystodiaceae J.R.Croft [monotypic]
               Genus Cystodium J.Sm. (1841), nom. cons.