Asplenium

Asplenium is a genus of ferns comprising roughly 700 species, commonly known as spleenworts, and is often treated as the sole genus of the family Aspleniaceae, although some authors separate the smaller genus Hymenasplenium based on differences in chromosome count, rhizome structure, and molecular phylogenetic evidence. Its type species is Asplenium marinum, the sea spleenwort. Several distinctive growth forms within the genus carry their own common names: Asplenium nidus and related species are known as bird's-nest ferns for their large rosette-forming fronds, while members of the Camptosorus group are called walking ferns for their ability to root and form new plants where their elongated frond tips touch the ground. The genus occurs on every inhabited continent.