Ceratopteris richardii is a fern

Fern

A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...

 species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 belonging to the genus Ceratopteris

Ceratopteris

Ceratopteris is the only genus among homosporous ferns that is exclusively aquatic. It is pan-tropical.-Description:Erect aquatic or subaquatic ferns of moderate size...

, one of only two genera

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of the Ceratopteridaceae

Ceratopteridaceae

Ceratopteridaceae is the 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...

 family. 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

Ceratopteris thalictroides

The species Ceratopteris thalictroides is a fern species belonging to the genus Ceratopteris, one of only two genera of the Ceratopteridaceae family. The species represents a special living form of ferns, and is thus of great botanical interest...

. 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."