Domain Eucaryota
   Subdomain Chlorota Doweld (2001)
     Kingdom Chlorobiota C.Jeffrey ex Doweld (2001) - plants see Subkingdom Viridiplantae Caval.-Sm. (1981)
       Subkingdom Lycopodiobiotina Doweld (2001)
         Phylum Isoëtophyta Doweld (2001)
           Subphylum Isoëtophytina Doweld (2001)
             Class Isoëtopsida Rolle (1884)
               Order †Takhtajanodoxales Snigirevskaya (1980) see Order Isoëtales Prantl (1874)
                 1 Family †Chaloneriaceae Pigg & G.W.Rothwell (1983)
                 2 Family †Takhtajanodoxaceae Snigirevsk. (1980) see Family Chaloneriaceae Pigg & G.W.Rothwell (1983)
                 3 Family †Suavitaceae J. Rice, Rothwell, G. Mapes & R. Mapes (1996)