Kingdom [Plantae] Haeckel (1866) - plants Division Gymnospermophyta Cleal (1994) - seed plants see Infraphylum Gymnospermae auct. Class Cycadopsida Brongn. (1843) Order †Trigonocarpales - medullosans 1 Family †Trigonocarpaceae 2 Family †Potonieaceae see Family Hexapterospermaceae Doweld (2001), nom. cons. prop.