Kingdom Chlorobiota C.Jeffrey ex Doweld (2001) - plants see Subkingdom Viridiplantae Caval.-Sm. (1981)
Count: [*†*] 10p;24c;72o;262f;1685g; †5p;17c;56o;141f;593g
   Subkingdom Pteridobiotina Britton & A. Br. (1896)
  Count: [*†*] 6p;9c;20o;58f;370g; †2p;12c;42o;103f;488g
     Superdivision Cycadophytanae Doweld (2001) see Superphylum Cycadophytanae Doweld (2001)
    Count: [*†*] 5p;5c;9o;12f;83g; †2p;12c;37o;72f;361g
       Division Cycadophyta Bessey (1907)
      Count: [*†*] 1c;2o;2f;10g; †1c;2o;7f;28g [2 May 2023]
         Class †Cycadeoideopsida D.H.Scott (1923) [monotypic]
        Count: [†*] †1o;5f;17g [2 May 2023]
           Order †Cycadeoideales E.W.Berry (1916)
          Count: [†*] †5f;17g [2 May 2023]
             Family †Williamsoniaceae Nath. (1913)
            Count: [†*] †5g [1 May 2023]
               1 Genus †Cycadocephalus Nath. (1902)
              Count: -
               2 Genus †Fredlindia J.M.Anderson & H.M.Anderson (2003)
              Count: -
               3 Genus †Ischnophyton Delev. & R.C. Hope (1976)
              Count: -
               4 Genus †Weltrichia Braun (1847)
              Count: -
               5 Genus †Williamsonia Carruth. (1870), nom. cons. prop.
              Count: -