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.
On rocks near the coast which have been nutrient-enriched by birds. A very rare, possibly endemic, species which is known from only two sites on the Isles of Scilly, one of which is a SSSI, the other unprotected, and the Channel Isles. There is also a doubtful record from Denbighshire. There are no known immediate threats to this species apart from its occurrence in small and restricted populations which should be surveyed to evaluate its current status.
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.