Common sorrel (Rumex acetosa, L. 1753)

Identity

Common sorrel (Rumex acetosa L., 1753), also called Meadow sorrel or Garden sorrel, is an herbaceous perennial in the genus Rumex, family Polygonaceae. Its accepted name in Plants of the World Online covers a species native to temperate Eurasia and northwestern Africa. ^{1 6}

Latin writers used Rumex for the elongated, lance-shaped leaves of sorrels and docks. The epithet acetosa comes from acetum, meaning “vinegar.” Oxalic acid gives the foliage its sour flavor, a feature already noticed by the Romans. ⁷

Recognition

Arrow-shaped, or sagittate, basal leaves form a rosette in Rumex acetosa. Their two basal lobes point backward along the leaf stalk. This backward direction, rather than the more forward-pointing lobes of Rumex acetosella (sheep’s sorrel), distinguishes the two more reliably than overall size. Basal leaves commonly measure 7–15 cm (3–6 in) before the flowering stem develops. ^{2 3}

An upright, sparsely branched flowering stem reaches 50 cm–1 m (20–39 in), occasionally 1.2 m (4 ft) in rich, moist soil, and carries a narrow panicle. Small flowers turn from greenish to reddish as they age and grow in spaced whorls along the stem. ^{2 3}

A nonfruiting clump may simply be male: Rumex acetosa is dioecious, with male and female flowers on separate plants. Failure to set fruit therefore does not necessarily indicate disease. ²

Useful taxonomy

Kew accepts Rumex acetosa L., published in 1753, within Polygonaceae and its subfamily Polygonoideae. ¹

Older floras and herbarium collections may use these synonyms:

• Acetosa pratensis Mill., an older synonym;
• Lapathum acetosa (L.) Scop., another historical name;
• Rumex acidus Salisb., a name now considered illegitimate.

Recognized subspecies include subsp. acetosa, subsp. biformis and subsp. nebroides. Leaf shape and geographic range provide their main distinguishing features. ⁷

French records from the national natural heritage inventory list several vernacular names for this same species. The names refer to Common sorrel rather than to separate botanical taxa. ⁸

Habitat and range

Temperate Eurasia and northwestern Africa make up the native range recorded for Rumex acetosa by POWO. Introductions have since established naturalized populations elsewhere, particularly in North America and Greenland. ^{1 5}

Damp meadows, pastures, streambanks and open woodland edges provide habitat for Common sorrel. It favors moist to wet soils, preferably acidic to neutral. ^{4 2}

Across its native French range, regional floras record it from mountain meadows to lowland pathsides. Its regular presence in pasture can suggest moist, moderately acidic soil rather than strongly calcareous ground. ⁸

Soil pH for Rumex acetosa lies between 5 and 7. Its taproot tolerates frost down to about −20 °C (−4 °F); the recorded hardiness range is USDA zones 3–7.

Life cycle and reproduction

Wind carries pollen from male Common sorrel plants to female flowers without the involvement of pollinating insects. Flowering falls in May–August in the temperate Northern Hemisphere calendar described here, with timing dependent on climate. ^{2 3}

After fertilization, each female flower forms a small brown achene enclosed by persistent valves that help wind dispersal. Abundant self-seeding and a deep taproot make established plants difficult to remove. ²

Spring-sown plants can yield their first leaves after eight weeks. Dividing established clumps in spring is a faster way to propagate a favored selection. ⁴

Caterpillars of the Small Copper (Lycaena phlaeas), a widespread butterfly of European grasslands, also feed on Rumex acetosa leaves. ⁹

Uses and risks

Young Common sorrel leaves have a lemon-like tartness and are eaten raw in salads or cooked in soups and sauces, particularly alongside oily fish. Culinary use is the species’ main role. ^{4 3}

Less acidic foliage distinguishes 'De Belleville', a selection chosen for more regular culinary use than the wild plant. ²

Traditional herbal accounts describe the species as astringent, diuretic and mildly laxative. Its vitamin C content also underlies historical use against fever and scurvy. ⁴

Older leaves contain more oxalic acid, the main concern with consumption. Excessive intake may aggravate kidney stones, gout or rheumatic conditions; cooking reduces some of the oxalic acid. The cited account does not identify documented acute toxicity for humans, cats or dogs, distinguishing Common sorrel from poisonous vegetable-garden plants. ⁴

Varieties, look-alikes and related plants

Only a few stable horticultural selections of Rumex acetosa are recognized. The best known is 'De Belleville', valued for milder acidity in cooking rather than ornamental qualities. ²

Several plants can be mistaken for Common sorrel:

• Rumex acetosella, sheep’s sorrel, is smaller, with basal lobes pointing more forward than backward and a more sharply acidic taste;
• Rumex scutatus, French sorrel, has shield-shaped, less acidic leaves and is sometimes cultivated instead of Common sorrel;
• Oxalis species are also called sorrels, although they belong to a different family, Oxalidaceae.

Backward-pointing basal lobes remain the most reliable identifying feature of Rumex acetosa. They are more consistent than plant size or the intensity of its sour taste. ²

Main sources

• Plants of the World Online / Kew, Rumex acetosa L.
• Royal Horticultural Society, Rumex acetosa - common sorrel
• Missouri Botanical Garden Plant Finder, Rumex acetosa
• Plants For A Future, Rumex acetosa
• USDA PLANTS Database, Rumex acetosa plant profile
• Integrated Taxonomic Information System, Rumex acetosa L.
• Tela Botanica, eFlore BDTFX: Rumex acetosa L. (official nomenclatural record 58578)
• INPN / MNHN–OFB, Rumex acetosa L., 1753, CD_NOM 119418 — original notice, Internet Archive 2023-03-22
• Butterfly Conservation, Small Copper (Lycaena phlaeas) foodplants