vascular plants see Phylum Tracheophyta Sinnott ex Caval.-Sm. (1998)
   euphyllophytes see Clade Euphyllophyta Lecointre & Le Guyader 2006 [Cantino & Donoghue 2020]
     monilophytes - ferns see Clade Monilophyta Cantino & Donoghue 2007 [Doyle, Cantino & Donoghue 2020]
       Class Psilotopsida D.H.Scott (1909) see Subclass Ophioglossidae Klinge (1882)
         Order Psilotales Prantl (1884)
           1 Family Psilotaceae J.W.Griff. & Henfr. (1855) - whisk ferns