Domain Eucaryota
   Subdomain Chlorota Doweld (2001)
     Kingdom Chlorobiota C.Jeffrey ex Doweld (2001) - plants see Subkingdom Viridiplantae Caval.-Sm. (1981)
       Subkingdom Pteridobiotina Britton & A. Br. (1896)
         Superphylum Cycadophytanae Doweld (2001)
           Phylum †Cycadeoideophyta T.N.Taylor (1981) [monotypic] see Class Cycadeoideopsida D.H.Scott (1923)
             Class †Cycadeoideopsida D.H.Scott (1923) [monotypic]
               Order †Cycadeoideales E.W.Berry (1916)
                 1 Family †Westersheimiaceae Němejc (1968)
                 2 Family †Sturianthaceae Doweld (2001) [monotypic]
                 3 Family †Williamsoniaceae Nath. (1913)
                 4 Family †Cycadeoideaceae Buckland (1833)
                 5 Family †Williamsoniellaceae Nakai (1943)