Cornish Biodiversity Network  -  Supporting Wildlife Recording

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Cornish Red Data (2009)

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.

Southbya tophacea - Green Blackwort

Range & Status

Widespread around the Mediterranean, on European, African and W. Asian coasts, extending north along Atlantic coasts of Europe to Ireland and Wales; also Caucasus and Macaronesia. In Britain it is restricted to a few widely scattered areas in N. Wales (two), S. Wales (one) and Cornwall (two).

Regional Distribution

Known in two areas along the north coast of W. Cornwall, around Porthtowan and around Gear Sands.

Habitat & Ecology

Grows in moist calcareous habitats with sparse vegetation. The Cornish sites are on sandy and clayey mine-spoil near the coast and in bare places in neighbouring grasslands that probably receive drainage from mine-spoil. Leiocolea turbinata (Raddi) H.Buch is an almost constant associate. It is a dioicous species in which perianths are frequent but sporophytes only occasional (maturing in Cornwall from January to May).


Locally frequent on parts of Gear Sands, where the main risk to its survival is probably from shading due to growth of taller plants, such as could happen if the present intensive rabbit grazing were to be reduced so that coarse grasses and scrub were to spread further.


Some Cornish populations are on SSSI and other protected land.

Click here to see Dr. David Holyoak's Bryophyte Flora for this species


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.

Cornish Biodiversity Network. 2017.