Ceratopteridaceae is an improper family name for the clade that is now known to include the two genera Ceratopteris and Acrostichum . Although Ceratopteris was long isolated under its own family, due to adaptations for a dedicated aquatic existence, recent genetic study has determined that these two genera are allied.
The correct name for this taxon at the level of family is Parkeriaceae; in the Pteridophyte Phylogeny Group classification of 2016 (PPG I), it is treated as the subfamily Parkerioideae. [1]
Christenhusz et al., 2011, included these two genera alone in the subfamily Ceratopteridoideae (now the Parkerioideae) in their larger treatment of the family Pteridaceae in the order Polypodiales. [2]