''Asplenium haughtonii'', also known as the Barn fern, is a species of

fern A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes except t ...

in the family

Aspleniaceae The Aspleniaceae (spleenworts) are a family of ferns, included in the order Polypodiales. The composition and classification of the family have been subject to considerable changes. In particular, there is a narrow circumscription, Aspleniaceae ...

. It is native to

Saint Helena Saint Helena () is a British overseas territory located in the South Atlantic Ocean. It is a remote volcanic tropical island west of the coast of south-western Africa, and east of Rio de Janeiro in South America. It is one of three constitu ...

Taxonomy

A global phylogeny of ''Asplenium'' published in 2020 divided the genus into eleven clades, which were given informal names pending further taxonomic study. ''A. haughtonii'' belongs to the "''A. cordatum'' subclade" of the "''Schaffneria'' clade". The ''Schaffneria'' clade has a worldwide distribution, and members vary widely in form and habitat. There is no clear morphological feature that unites the ''A. cordatum'' subclade. The sister species of ''A. haughtonii'' is '' A. phillipsianum'' from

Socotra Socotra or Soqotra (; ar, سُقُطْرَىٰ ; so, Suqadara) is an island of the Republic of Yemen in the Indian Ocean, under the ''de facto'' control of the UAE-backed Southern Transitional Council, a secessionist participant in Yemen’s ...

, and the two together are sister to the African '' A. cordatum''. These three are scaly ferns of dry habitats; the other two species in the subclade are sister to them, and are walking ferns, with long undivided leaves and proliferating leaf tips.

Etymology

The English name Barn fern is derived from a basalt hill located on the north-east of Saint Helena called The Barn. This hill is believed to carry 60% of the entire ''A. haughtonii'' population.

Distribution

They are found at elevations of 250–600 m. It is found on the

drylands Drylands are defined by a scarcity of water. Drylands are zones where precipitation is balanced by evaporation from surfaces and by transpiration by plants (evapotranspiration). The United Nations Environment Program defines drylands as tropical ...

of the island. It is widely distributed, although they are usually found in remote areas.

Status

It is listed as critically endangered by the IUCN.

Threats

In 2012, an emergency extension area to a runway of St Helena airport caused massive destruction of the species' habitat. Before this event, individuals were abundant in Dry Gut which comprised a large majority of the world population.

Conservation

Before the development of this extension occurred, some conservationists rescued as many individuals as possible for relocation. About 1,000 individuals were moved into the St Helena Government's Endemic Plant Nursery.

References

* {{Taxonbar, from=Q17057048 Flora of Saint Helena Critically endangered plants haughtonii Plants described in 1868