''Asplenium fontanum'', commonly known as fountain spleenwort or smooth rock spleenwort, 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 ...

, native to rocky areas in Western Europe.

Description

''Asplenium fontanum'' is a rhizomatous fern with fronds up to long grouped in bundles. The rhizomes are clad in dark brown scales. The fronds are born on stems that may be as long as the blades. These are

pinnate Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, and in ...

, with eight to twenty toothed pinnules up to long on each side, the longest being in the middle of the blade. The basal part of the stem is brown and the remainder of the stem and the blade are bright green. The sori are distributed in groups of two or three on the underside of the pinnules.

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. fontanum'' belongs to the "''A. incisum'' 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 has evolved within the ''A. incisum'' subclade to define it, but members of the subclade do share a chestnut-brown stipe base. It forms a clade with '' A. foresiense'', and the two together are sister to the North American '' A. platyneuron''.

Distribution and habitat

This species grows in Western Europe, occurring mainly in the mountains of Spain, France, Italy, Switzerland and Austria. It is a rupicolous (rock-dwelling) species growing in cracks and fissures in

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

crags in cool and shady positions. It prefers relatively high mountain areas, but also occurs at lower elevations on north-facing rocks or under overhangs. Its altitudinal range is . In the nineteenth century it was reported as growing in the British Isles, with records from

Amersham Amersham ( ) is a market town and civil parish within the unitary authority of Buckinghamshire, England, in the Chiltern Hills, northwest of central London, from Aylesbury and from High Wycombe. Amersham is part of the London commuter belt. ...

churchyard, from beside a waterfall in

Westmorland Westmorland (, formerly also spelt ''Westmoreland'';R. Wilkinson The British Isles, Sheet The British IslesVision of Britain/ref> is a historic county in North West England spanning the southern Lake District and the northern Dales. It had an ...

Northumberland Northumberland () is a county in Northern England, one of two counties in England which border with Scotland. Notable landmarks in the county include Alnwick Castle, Bamburgh Castle, Hadrian's Wall and Hexham Abbey. It is bordered by land on ...

and on the castle walls at

Alnwick Alnwick ( ) is a market town in Northumberland, England, of which it is the traditional county town. The population at the 2011 Census was 8,116. The town is on the south bank of the River Aln, south of Berwick-upon-Tweed and the Scottish bor ...

; the fern does not grow in Britain any longer.

Status

Although its total area of occupancy is low, having disappeared from Britain and other European countries, the population of this fern is stable, and the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

has assessed its conservation status as being of "

least concern A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...

". Some populations may be threatened by quarrying, mining or other human activities, but the IUCN notes that the main threat it faces is likely to be from

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...

; a rise in average temperatures or prolonged droughts may affect it adversely.

References

* {{Taxonbar, from=Q913901 fontanum Flora of Spain Flora of France