Cystopteridaceae
Introduction '''Cystopteridaceae''' is a family of ferns in the order Polypodiales. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), the family is placed  in the suborder Aspleniineae of the order Polypodiales, and includes three genera. Alternatively, it may be treated as the subfamily '''Cystopteridoideae''' of a very broadly defined family Aspleniaceae.Cystopteridaceae are small or medium-sized ferns in forests and crevices. They generally have thin laminae, and small, round, naked sori.
Genera Three genera are accepted in the PPG I classification, and by the ''Checklist of Ferns and Lycophytes of the World'' . One hybrid genus also exists:*''Acystopteris'' Nakai*''Cystopteris'' Bernh. *''Gymnocarpium'' Newman*''×Cystocarpium'' Fraser-Jenk. ''Cystopteris chinensis'' has been placed in a separate genus, ''Cystoathyrium'', but the genus is not accepted by recent sources.
Phylogenetic relationships ''Gymnocarpium'' and ''Cystopteris'' have been found to be sister to the remaining Aspleniineae.External phylogenyInternal phylogeny
References