Rumex sanguineus L., Wood Dock

Account Summary

Growth form and identification

In the past, there has been some confusion between this short-lived, rosette-forming perennial and the closely related R. conglomeratus (Clustered Dock), but the identification differences are now much clearer and better known (Lousley & Kent 1981; Stace 2010; Sell & Murrell 2018). R. sanguineus normally grows 30-60 cm tall and produces a few upright flowering stems that arise directly from the rootstock. Basal rosette leaves are 15-30 cm, oblong lanceolate, and in one variety of the plant (var. sanguineus), they develop a strongly marked blood-red or purplish coloration in the midrib and veins (Sell & Murrell 2018). The stems and inflorescence branches of this variety are also often suffused with purplish-red, and together with the leaves this makes the plant sufficiently attractive to induce a small minority gardeners to actively choose to cultivate it (Griffiths 1994). The common, wild form of the plant is var. viridis Sibth., which does not have this strong degree of red or purple coloration.

At the flowering stage, R. sanguineus can be separated from R. conglomeratus (Clustered Dock) by the panicle being less diffuse on account of its branches being more acutely and more vertically arranged. The inflorescences of both species have sparse, widely separated flowering cymes scattered along their length. The inflorescences of R. sanguineus are leafy only at their extreme base. In addition, the three inner, tongue-shaped sepals (or tepals) of each newly opened flower are conspicuously unequal in size, and at the fruiting stage, usually only one of them bears a well-developed, swollen, almost spherical tubercule, c. 1 mm in diameter, which is as wide as, or wider than the tepal that bears it (Lousley & Kent, 1981; Webb et al. 1996).

Variation

The characteristic feature that probably is most regularly relied upon to distinguish R. sanguineus from R. conglomeratus is the solitary swollen tubercule on the inner tepal of the fruiting flower. However, sometimes this character can be unreliable: in addition to the large tubercule on one tepal, occasionally the other two tepals in the fruiting flower surrounding the nut may each display minor, vestigial tubercule swellings, or very rarely all three tepals surrounding the single, trigonous, nut-like fruit bear large, globose tubercles like those of R. conglomeratus. Variants with a well-developed tubercule on all inner tepals have been collected in several places in S Sweden (Jonsell et al. 2000).

As is always the case, a minimum of two characters should be tested to distinguish between similar species; in this case, the very unequal size of the three inner tepals of the R. sanguineus flower prior to fruiting would provide the necessary confirmation.

Three varieties are recognised by Sell & Murrell (2018), namely: var. sanguineus mentioned above, with parts suffused blood-red; var. sanguinalis (Moss) P.D. Sell, which has leaves, stems and inflorescences ± suffused with rusty red; and var. viridis Sibth., the common native form with leaves, stems and inflorescences ± green.

Comparison of the preferred habitats of these two Dock species

The difference between these two rather similar Dock species, R. sanguineus and R. conglomeratus, can readily be related to their habitat requirements and tolerances: R. sanguineus occurs in lowland areas in both half-shade and full sun conditions on a range of soil types (although probably more frequently on calcareous substrates). In terms of habitat, R. sanguineus ranges from the margins of damp deciduous woods and hedgerows to ± dry roadside verges. More rarely it can appear as a ruderal on waste ground. On the other hand, R. conglomeratus is more ecologically confined, being usually found in much wetter or damper conditions than R. sanguineus – essentially it is frequent only in low-lying marshy ground on lakeshores, stream-sides and ditches, including winter-wet meadows and pastures, although it too can rather more rarely than R. sanguineus behave as a ruderal on disturbed ground in quarries, waste tips and in gardens (Lousley & Kent 1981).

Hybrids

R. sanguineus forms hybrids with R. crispus, R. conglomeratus (see that species account on this website), R. obtusifolius (Broad-leaved Dock) and R. pulcher (Fiddle Dock) (Lousley & Kent 1981). Of these, the hybrid with R. obtusifolius (Rumex × dufftii Hausskn.) is the most frequently recorded in Ireland, having been found in a total of 18 hectads widely scattered across the island (Stace et al. 2015).

Fermanagh occurrence

Wood Dock has been recorded slightly less often than Clustered Dock in Fermanagh but it is considerably the more widespread of the two species, occurring in 204 of the tetrads, 38.6% of those in the VC. Like R. conglomeratus, Wood Dock is most commonly found in the Fermanagh lowlands, but in this case it is also scattered across the Western Plateau at moderate altitudes.

British and Irish occurrence

R. sanguineus is a widespread and quite frequent plant in S England, Wales and throughout most of Ireland (although here in many areas it is rare or absent down the W and SW coasts). Further north in Britain, however, it becomes scarce, and in Scotland beyond the River Clyde it becomes progressively rarer and more coastal in its occurrence (Preston et al. 2002).

European and world occurrence

Wood Dock is widespread in W & C Europe, but it does not penetrate beyond 60N in Scandinavia, confining it to the southern shores of that large peninsula landmass. To the south of Europe, it extends only thinly into the Iberian peninsula, Italy, the Balkans, Sicily, Corsica and Sardinia. Beyond this, as a native species it reaches Turkey, the Caucasus and N Iran. It is an introduction in E North America and in scattered stations in temperate regions of the S Hemisphere, including S Africa and Australia (Jalas & Suominen 1979, Map 461; Hulten & Fries 1986, Map 669; Jonsell et al. 2000).

The record of occurrences of R. sanguineus in New Zealand in the 1930s and later has been rejected by Webb et al. (1988, p. 983), due to the absence of vouchers, and the possibility of confusion with R. conglomeratus, which is also present as an alien throughout both islands.

Names

The genus name 'Rumex' is an old Latin name for Sorrel from Pliny derived from the Latin 'rumo' to suck, from the Roman habit of sucking Sorrel leaves to allay thirst (Johnson & Smith 1946). The Latin specific epithet 'sanguineus' translates as 'blood-red' from 'sanguis', 'inis', 'blood' (Gilbert-Carter 1964), a reference to the colour that generally develops in the leaf mid-rib and side veins. The English common name 'Wood Dock' is a typical book name that merely indicates one of the main habitats of the plant.

Threats

None.

• Find out more about the format of the species accounts
• View abbreviations
• View references for all species accounts
• View a gazetteer of all the sites