Cystodium is a fern in its own family, Cystodiaceae.[2] It contains a single species: Cystodium sorbifolium(Sm.) J.Sm. 1841.[3] Because it looks like a small tree fern, it had previously been placed in the tree fern family Dicksoniaceae. Subsequent analysis had moved it to the Lindsaeaceae,[3] but the most recent phylogenetic studies have placed it in its own separate family, Cystodiaceae, with a sister relationship to the current Lindsaeaceae.[4] A fossil species of the genus Cystodium sorbifolioides is known from the Cenomanian aged Burmese amber in Myanmar.[5]
^Cystodiopteris USDA-ARS Germplasm Resources Information Network (GRIN) 28 January 2010