Shore Dock

Rumex rupestris is a coarse stout woody perennial 30–50 cm (12–20 in) (sometimes up to 70 cm (28 in)) tall, with one or two shoots arising from the stock. The thick, dull bluish green leathery basal leaves are 10–30 cm (3.9–11.8 in) long with entire, wavy leaf margins. They are elliptic or broadly ovate-lanceolate shaped, tapering rather abruptly to a truncate or subcordate base. The petiole is less than a third the length of the leaf blade. Stem leaves are oblong-lanceolate, tapering gradually towards the base, with an acute tip at the leaf end. The leaf margins are wavy, crenate and subsessile. The inflorescence comprises a dense panicle with ascending branches, usually making an angle of about 45 degrees with the main stem. The branches have numerous short crowded branchlets and 5–20 whorls of densely packed flowers. The valves or tepals are blunt and entire, each measuring 3–4 mm (0.12–0.16 in) x 2–2.5 mm (0.079–0.098 in). Each valve bears a very swollen smooth elongated tubercle that occupies over 2/3 of the valve length, and almost the entire width. These swollen tubercles are the critical feature that distinguishes the species from similar species such as Rumex conglomeratus with considerably smaller tubercles. Vegetative identification of R. …

Rumex rupestris is a European endemic restricted to small, scattered populations along the Atlantic coasts of western Europe. Its known distribution covers coastal areas of Anglesey, south Wales, south-western England, the Channel Islands, through France to Galicia and northern Spain. It was reported to be locally common on the Isles of Scilly, but more recently it is thought it may be extinct there. Shore dock grows at or just above the mean high water mark in low-lying (up to 60 metres (200 ft)) coastal habitats, always with a constant supply a freshwater and in the presence of bare ground created by coastal erosion. Habitats typically include damp cliff edges or bases, seepage zones and wave-cut platforms. Less commonly, the plant grows in dune slacks and on sand or shingle beaches, as well as bedrock crevices with a submerged supply of freshwater from springs. It does not appear to have any specific soil requirements and can grow in soil-free crevices in sedimentary or metamorphic rocks, as well as fine blown sand and shingle.

R.rupestris occurs in very small localized populations often comprising fewer than 10 individuals per site, growing either separately or in small clumps. Populations occupy small areas of suitable habitat usually covering less than 1m2 and rarely extending beyond a few square meters. Although this plant occurs only in very small, scattered colonies, these could be functioning as components of larger metapopulations in the wider landscape. The floating fruits are dispersed by sea wave action, which potentially enables the plant to colonize new areas along the coast (PlantLife). However, due to the dynamic nature of the coastal environment where it grows, R. rupestris individuals that do become newly established in a small area of suitable habitat may survive for only one or a few years before being eradicated. Nevertheless, individuals occasionally reappear in sites from which they previously disappeared. Rumex rupestris is a poorly competitive pioneer species favouring bare ground. It is susceptible to outcompetition by vigorous perennials such as Phragmites australis and Rubus fruticosus and therefore relies on regular coastal erosion and physical habitat disturbance to suppress stronger competitors, thereby allowing sufficient recruitment to seedlings. …