Greater copperwort belongs to a group of plants called liverworts. They are closely related to mosses and, in many cases, resemble them closely. Greater copperwort is a very difficult species to identify as it resembles other liverworts in the Cephaloziella family. It has leaves that are minute, barely 0.5 mm across. (Botanists tend to use the micrometre as a unit of measurement when dealing with liverworts. One micrometre equals 1/1000 mm.) Its leaves are arranged in two rows on the stem, accompanied by a third row of tiny underleaves. Each leaf is divided into two lobes.
Liverworts and mosses do not produce flowers but they can manufacture their own food by photosynthesis, unlike fungi which obtain their food source from another organism, alive or dead. Most liverworts reproduce by spores, in a similar way to fungi. They can also reproduce vegetatively and greater copperwort seems to use this method exclusively as no spore capsules have ever been observed. A liverwort can regenerate when the plant is damaged or parts of it decay. They can also produce new growth on healthy parts of the plant structure. A plant cell divides and forms a bud-like growth which then turns into a leafy shoot or stem, while still attached to the main body of the plant.
This species appears to be endemic to the UK as it has not been recorded anywhere else. So far, it is known from over 30 sites in Cornwall, three sites in Devon, and one recently discovered in Cheshire. It was also recorded from a site in North Wales, but has not been seen there for over 60 years.
As its name suggests, greater copperwort is associated with copper-enriched soil, rocks, walls and spoil from old copper mines. Further surveys of abandoned mine sites in Cornwall and Devon might reveal more populations of this plant.
Greater copperwort's association with old mine workings has put its survival at risk from redevelopment and the need to make the mine shaft openings safe. There is also a problem when spoil heaps are re-landscaped, or when scrub and taller vegetation shades out the liverwort.
Greater copperwort is included in the UK Biodiversity Action Plans and is also listed in English Nature's Species Recovery Programme. In the winters of 1995 and 1996, English Nature commissioned surveys of old mine sites to establish numbers of populations of the liverwort. Further surveys carried out in East Cornwall in 1998 re-discovered greater copperwort at several of its historic sites. A register of rare bryophytes has been compiled by the Cornwall Wildlife Trust.
The important target for conserving this species is, initially, maintenance of the known populations, and to increase their extent where possible. It is also planned to establish ex-situ stocks of the greater copperwort as a safeguard against extinction of the wild populations.
Management of a few of the existing sites is underway, concentrating on removal of scrub which threatens the species in some of its locations. It may be possible to re-introduce it back to the site in Wales where it was formerly recorded. Work on this species will provide valuable data for the preservation of other liverworts. The Action Plan for the greater copperwort is linked with that of another rare species, the Cornish path moss, which is found in association with it at two sites.
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