organisms see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Domain Eukaryota Chatton, 1925 - eukaryotes
     Kingdom Plantae Haeckel (1866) - plants
       Subkingdom Viridaeplantae Cavalier-Sm. (1981) - green plants see [unranked] Viridiplantae Cavalier-Smith, 1981
         Land plants
           Phylum Cycadophyta Bessey (1907) see Subclass Cycadidae Pax (1894)
             Order †Bennettitales Bessey (1910) see Order Cycadeoideales E.W.Berry (1916)
               1 Family †Cycadeoidaceae orth. inval. see Family Cycadeoideaceae Buckland (1833)
               2 Family †Williamsoniaceae Nath. (1913)