#fissidentaceae

A cosmopolitan genus of mosses with almost 500 species, although the division of the genus into subgenera and sections appears to be a matter of ongoing argument.

The lower part of each leaf is doubled, creating a V-shaped, pocket-like flap clasping the stem and the base of the leaf above it - hence the common name. 'Fissidens means 'splitting tooth', and refers to the moss's peristome teeth—the structures surrounding the opening of the spore capsule—which are split into two.

Some Fissidens species are aquatic, and are popular plants in landscaped aquaria.