Parent taxon: Cycadophyta according to A. B. Doweld 2001
See also Lapasha and Miller 1985, Mabberley 2000 and Meyen 1984
Sister taxa: Acozamites, Aldania, Almargemia, Amphibennetites, Androlepis, Antherangiopsis, Bennettitacearum, Bernettia, Bjuvia, Blastolepis, Bolbopodium, Bucklandiopsis, Campylophyllum, Clathropodium, Cloughtonia, Colymbetes, Crossozamia, Ctenidium, Ctenopteris, Cycadangium, Cycadea, Cycadeacites, Cycadeocarpus, Cycadeomyelon, Cycadeorachis, Cycadeostrobus, Cycadinocarpus, Cycadites, Cycadocaulum, Cycadocephalus, Cycadofilix, Cycadophycos, Cycadophyllum, Cycadopites, Cycadopsis, Cycadopteris, Cycadorachis, Cycadoxylon, Cyclozamia, Cylindropodium, Dioonitocarpidium, Doratophyllum, Encephalartites, Endogenites, Eurycycadolepis, Fittonia, Guilliera, Harringtonia, Hisingera, Jacutiella, Jensensispermum, Jirusia, Laconiella, Lepidanthium, Leptopterophyllum, Lunzia, Macropterygium, Macrotaeniopteris, Macrotorellia, Megalozamia, Morrisia, Navajoia, Novoguineoxylon, Ontheodendron, Pachytestopsida, Palaeocycas, Phasmatocycadopsida, Plagiozamiopsis, Plagiozamites, Platylepis, Polypodiolites, Pramelreuthia, Pseudopterophyllum, Pseudoptilophyllum, Pteronilssonia, Pterozamites, Ptychoxylon, Quervainia, Russellites, Schizopodium, Sedgwickia, Sewardia, Sinoctenis, Taeniophyllum, Taeniopteridium, Tessellaria, Westersheimia, Yatesia, Zamiophyllum
Subtaxa: Boweniaceae Crassofilicites Cycadales Deltolepis Dioales Drepanozamites Gnetales Lagenostomales Manebachia Marantoidea Orthogoniopteris Pteridospermales Stangeriaceae Strangerites Trigonocarpales Welwitschiales