The docks and sorrels, genusRumex, are a genus of about 200 species of annual, biennial, and perennialherbs in the buckwheat family, Polygonaceae.
Members of this genus are very common perennial herbs with a native almost worldwide distribution, and introduced species growing in the few places where the genus is not native.[1]
Some are nuisance weeds (and are sometimes called dockweed or dock weed), but some are grown for their edible leaves.[2]Rumex species are used as food plants by the larvae of a number of Lepidoptera species, and are the only host plants of Lycaena rubidus.[3]
Description
They are erect plants, usually with long taproots. The fleshy to leathery leaves form a basal rosette at the root. The basal leaves may be different from those near the inflorescence. They may or may not have stipules. Minor leaf veins occur. The leaf blade margins are entire or crenate.
The usually inconspicuous flowers are carried above the leaves in clusters. The fertile flowers are mostly hermaphrodites, or they may be functionally male or female. The flowers and seeds grow on long clusters at the top of a stalk emerging from the basal rosette; in many species, the flowers are green, but in some (such as sheep's sorrel, Rumex acetosella) the flowers and their stems may be brick-red. Each seed is a three-sided achene, often with a round tubercle on one or all three sides.
Taxonomy
The genus was first described by Carl Linnaeus in 1753. Within the family Polygonaceae, it is placed in the subfamily Polygonoideae. The genus Emex was separated from Rumex by Francisco Campderá in 1819 on the basis that it was polygamous (i.e. had both bisexual and unisexual flowers on the same plant). However, some species of Rumex subg. Acetosa also have this characteristic, and most other features that are supposed to distinguish Emex are found in species of Rumex. Accordingly, in 2015, Schuster et al. demoted Emex to a subgenus of Rumex.[4]
Within the subfamily Polygonoideae, Rumex is placed in the tribe Rumiceae, along with the two genera Oxyria and Rheum. It is most closely related to Rheum, which includes Rhubarb.[4]
These plants have many uses. Broad-leaved dock (Rumex obtusifolius) used to be called butter dock because its large leaves were used to wrap and conserve butter.
Rumex hymenosepalus has been cultivated in the Southwestern US as a source of tannin (roots contain up to 25%), for use in leather tanning, while leaves and stems are used for a mordant-free mustard-colored dye.
These plants are edible. The leaves of most species contain oxalic acid and tannin, and many have astringent and slightly purgative qualities. Some species with particularly high levels of oxalic acid are called sorrels (including sheep's sorrel Rumex acetosella, common sorrel Rumex acetosa, and French sorrel Rumex scutatus), and some of these are grown as leaf vegetables or garden herbs for their acidic taste.[5][6]
In the United Kingdom, Rumex obtusifolius is often found growing near stinging nettles, owing to both species favouring a similar environment, and there is a widely held belief that the underside of the dock leaf, squeezed to extract a little juice, can be rubbed on the skin to counteract the itching caused by brushing against a nettle plant.[7] This home remedy is not supported by any science, although it is possible that the act of rubbing may act as a distracting counterstimulation, or that belief in the dock's effect may provide a placebo effect.[8]
In traditional Austrian medicine, R. alpinus leaves and roots have been used internally for treatment of viral infections.[9]
Rumex nepalensis is also has a variety of medicinal uses in the Greater Himalayas, including Sikkim in Northeastern India.[10]
^ abSchuster, Tanja M.; Reveal, James L.; Bayly, Michael J. & Kron, Kathleen A. (2015). "An updated molecular phylogeny of Polygonoideae (Polygonaceae): Relationships of Oxygonum, Pteroxygonum, and Rumex, and a new circumscription of Koenigia". Taxon. 64 (6): 1188–1208. doi:10.12705/646.5.
^Friis, Else Marie (1985). "Angiosperm Fruits and Seeds from the Middle Miocene of Jutland (Denmark)". The Royal Danish Academy of Sciences and Letters. 24 (3).
^Macroscopic plant remains from the freshwater Miocene of the Nowy Sącz Basin (West Carpathians, Poland) by Maria Łańcucka-Środoniowa, Acta Palaeobotanica 1979 20 (1): 3-117.
^National Academies of Sciences, Engineering, and Medicine; Health and Medicine Division; Food and Nutrition Board; Committee to Review the Dietary Reference Intakes for Sodium and Potassium (2019). Oria, Maria; Harrison, Meghan; Stallings, Virginia A. (eds.). Dietary Reference Intakes for Sodium and Potassium. The National Academies Collection: Reports funded by National Institutes of Health. Washington (DC): National Academies Press (US). ISBN978-0-309-48834-1. PMID30844154.((cite book)): CS1 maint: multiple names: authors list (link)
