- Name also: Garden Sorrel, Narrow-leaved Dock, Spinach Dock
- Family: Dock Family – Polygonaceae
- Growing form: Perennial herb.
- Height: 30–80 cm (12–32 in.). Stem glabrous, branched from inflorescences on.
- Flower: Regular, small, unisexual. Male flower: Perianth-segments 6, with membranous margins, often red, under 2 mm long. Stamens 6. Female flower: Perianth consists of 2 whorls of 3. Segments of outer whorl small, green, and erect. Inner whorl forms the fruit-enclosing valves whose segments are elliptic and thin, greenish or red, with entire margins, and a small pimple at the base. Valves longer than fruit. Pistil formed from 3 fused carpels, styles 3. Inflorescence a raceme.
- Leaves: Hairless. Stalk of basal leaves is fairly long. Blade sagittate, 2–5 times longer than broad, basal lobes usu. entire. Stem leaves alternate, almost stalkless. Ochrea membranous, brownish.
- Fruit: Brown, roundish, three-edged, glossy achene.
- Habitats: Meadows, waysides, yards, broadleaf woods, spring verges.
- Flowering time: May–July.
Common sorrel is a typical plant of grasslands, fields and pastures. It is dioecious and wind pollinated. The leaves taste slightly acid. The acidity is caused by oxalic acid, which is also present in the leaves of the related sheep’s sorrel (R. acetosella). The latter differs from common sorrel in being smaller and having hastate leaves.
Common sorrel has been used as a pot-herb, although oxalic acid is poisonous in larger quantities. It is a polymorphous species and several variations and subspecies are recognised, worth mentioning is northern ssp. lapponicus.
Compact Dock (Thyrse Sorrel)
NOT TRANSLATED YET. Aho- ja niittysuolaheiniä harvinaisempi suolaheinälajimme on silmälläpidettäväksi luokiteltu tulisuolaheinä. Se on suolaheinistä kookkain (jopa 1,2 m) ja selvästi tuuhein. Sen kukinto on kahteen kertaan haarova. Neljäs suolaheinälajimme, pohjoinen tenonsuolaheinä (R. graminifolius) on suolaheinistämme pienin ja harvinaisin.