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.
In Britain this indistinct species is restricted to west Cornwall and the Isles of Scilly, and also occurs in the Channel Islands. Here it grows on exposed granite rocks and stones on the coast. There appears to be no immediate threats to this species, however, its British sites need to be re-surveyed to ascertain potential problems and to determine the size of the populations. Two of its seven known sites in the Isles of Scilly are within SSSI.
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.