Phylum [Tracheophyta] Sinnott ex Caval.-Sm. (1998) - vascular plants Subphylum Polypodiophytina Reveal (1996) [monotypic] Class Polypodiopsida Cronquist, Takht. & Zimmerm. (1966) - ferns Subclass Ophioglossidae Klinge (1882) Order Psilotales Prantl (1884) [monotypic] 5 Family Psilotaceae J.W.Griff. & Henfr. (1855) - whisk ferns