The descriptive text, below the map, is from the Cornish Red Data Book (2009). The map on this web page depicts the organisms distribution and shows the records made pre-2000 and those made since.
Range & Status
In Europe this Oceanic Temperate fern is confined to the western seaboard. Sporophyte (spore-bearing generation) plants, with characteristic fern fronds are very rare, whereas the gametophyte (gamete-bearing generation), which looks like green fuzz and could be mistaken for a bryophyte or alga, is much more widespread. However, recently some gametophyte populations in Britain and Ireland have been producing sporophytes.
Two of the Cornish sporophyte localities are considered native and the other two the result of deliberate introduction. The gametophyte (presumably native) has been recorded in at least ten sites.
Habitat & Ecology
It requires shade and high humidity, and cool sites where it grows on rocks and in crevices adjacent to constant running or dripping clean freshwater (or lateral movement of ground water).
Over-collecting of sporophyte plants in the past has led to the loss of many old sites in the British Isles and remains a threat.
It also has the following conservation statuses: WCA: Sch8, Berne: A1, HabDir: Annex
I.J. Bennallick, S. Board, C.N. French, P.A. Gainey, C. Neil, R. Parslow, A. Spalding and P.E. Tompsett. eds. 2009. Red Data Book for Cornwall and the Isles of Scilly. 2nd Edition.Croceago Press.
The Cornish Red Data Book Project was led by the Cornwall and Isles of Scilly Federation for Biological Recorders (CISFBR). The full text and species accounts (minus the maps) are available on the CISFBR website.