Shore dock, Rumex rupestris, is one of Europe’s most threatened endemic vascular plants. The UK is the world stronghold for this species. It is currently known from three locations in Wales, one being Pembrokeshire. Colonies supporting 50-100 individuals are considered to be large, most (especially those on rocky shores) generally hold fewer than ten individuals. The total UK population is estimated to comprise <650 plants. Shore dock is currently known to occur in only one site within the SAC.
Shore dock grows on rocky, sandy and raised beaches, shore platforms and the lower slopes of cliffs, and rarely in dune slacks. Plants may be found growing in isolation on the strand-line and at the base of flushed cliffs. However, it occurs only where a constant source of freshwater, running or static, is available. It favours growing by the side of streams entering beaches, on oozing soft-rock cliffs, and in rock clefts where flushing occurs.