The docks and sorrels, genus Rumex, are a genus of about 200 species of annual, biennial, and perennial herbs 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.
Some are nuisance weeds (and are sometimes called dockweed or dock weed), but some others are grown for their edible leaves.
Rumex species are used as food plants by the larvae of a number of Lepidoptera species, and are the only host plants of Lycaena dispar and Lycaena rubidus.
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.
Uses
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.
Culinary
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.
Medicinal
In traditional Austrian medicine, R. alpinus leaves and roots have been used internally for treatment of viral infections.
Rumex nepalensis is also has a variety of medicinal uses in the Greater Himalayas, including Sikkim in Northeastern India.