Ceratopteris richardii is a fern species belonging to the genus Ceratopteris, one of only two genera of the Ceratopteridoideae subfamily of the Pteridaceae. It is one of several genera of ferns adapted to an aquatic existence. C. richardii was previously regarded as being part of the species Ceratopteris thalictroides. This particular species is of special scientific interest because a patented strain has been developed as a scientific aid and teaching tool in biology, called "C-fern."