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
Widespread in the Mediterranean region, extending north along Atlantic coasts to S. England and S. Wales; also Macaronesia. Modern records in Britain are all from Cornwall and S. Wales, but there are pre-1950 records also from S. Devon and E. Kent.
Widespread but scarce in Cornwall and often occurring in small quantity, mainly in sites on and near the south coast from near Gweek to near the Devon border.
Habitat & Ecology
On earthy or rocky roadside banks and on crumbling shaley soil in rock crevices on low cliffs. It occurs in rather bare habitats in the open or in shade, commonly under overhangs and often where the substrata are periodically flushed by a trickle of water. It is a monoicous species in which sporophytes are common, maturing in Cornwall mainly during January to May. Arts (1994) reported the occurrence of rhizoidal tubers in specimens from several European countries, including one from Cornwall; these could serve as a means of aestivation, as propagules that could be dispersed, or both.
Occurs in unstable habitats, so at risk from erosion, collapse of banks and sometimes from natural plant colonisation leading to increased shading. Some sites are potentially at risk from road works.
No active conservation measures, although a few populations are on protected land. This species is listed on the UK BAP Priority Species list (2007).
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.