The current status of Rumex rupestris Le Gall (Polygonaceae) in England and Wales, and threats to its survival and genetic diversity

All U.K. sites from which Rumex rupestris Le Gall, a dock endemic to N.W. Europe, had previously been recorded, and which could be identified from herbarium specimens and Flora records, were surveyed. The objectives were to obtain up-to-date information on the distribution of this apparently declining species, the size of its extant populations and the suitability of previously occupied sites for re-introduction under the Species Recovery Programme. The amount of genetic variation, and its distribution within and between populations was measured using isozyme electrophoresis. Although a relatively large amount of the total variation found is held within individual populations, there is evidence of some isolation of populations by distance. Results also support the expectation that larger populations hold more genetic diversity. Possible threats to the survival of populations and to variation within the species are discussed.