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
Known from outside Britain only in S. Ireland, but also reported from N. Spain and W. Germany. Cornwall has a large majority of all populations. There are modern records also from single sites in Cheshire and Cardiganshire and older records from Devon (three sites) and Merionethshire (one site, 1923). It is a member of a rather critical genus of very small leafy liverworts and not generally distinguished from C. massalongi until after the study by Paton (1984). It appears to be a polyploid derivative of C. massalongi (Paton, 1999).
Widely scattered on old copper-mining areas, with ca 45 sites known by modern records.
Habitat & Ecology
Like C. massalongi it is restricted to acidic copper-contaminated substrata, but often occurs in drier situations than that species. At most of its localities it grows on minespoil in rather bare places where colonisation by vascular plants is inhibited. Typical sites include banks, crevices in Cornish hedges built of mine-spoil, edges of old tracks and edges of small flushes or streams. It is distinctly commoner than C. massalongi in W. Cornwall. The species is paroicous and occasionally produces perianths, but sporophytes are unknown. Foliar gemmae are common.
At greatest risk from landscaping and ' tidying' of areas of old mine-spoil, especially where topsoil is spread over the copper contaminated substrata. Other threats include shading from taller plants colonising its habitat (or planted tree saplings), development on old mine areas, work to cap old mine-shafts and dumping of rubbish.
Treated as Vulnerable in UK Red-list (Church et al ., 2001), but not listed under the IUCN Red List. Stewart (1995) proposed that the species should be added to Appendix 1 of the Bern Convention and Annexe IIb of the EU Species and Habitats Directive. Treated as a priority species in the UK BAP. Although with ca 45 known sites this species is not rare in parts of Cornwall, its conservation should be regarded as a high priority because our populations form ca 80% of all those currently known and several sites are currently at risk. Several Cornish sites are protected within SSSI and these need monitoring to ensure they do not become shaded.
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.