This is a perennial with creeping roots. It grows as a clump of arrow-shaped leaves with outward-facing lobes at the base. These distinguish it from Common Sorrel (Rumex acetosa) which has downward-facing lobes (see inset picture). In May and June a flowering stem up to 60 cm high produces tiny green flowers which turn to red-orange (female flowers) or orange-yellow (male flowers) borne on separate plants; these are wind-pollinated.
Sorrel has long had medicinal and culinary uses, the oxalic acid content gives the leaves a mildly sour flavour and they can be added to salads or cooked like spinach. It is grown as a cut-and-come-again crop, providing greens from spring to autumn; the flowering stems are removed to put the energy into leaf production. If the leaves of Common Sorrel are boiled to a pulp it can be used as a stewed rhubarb substitute to serve with crème fraîche, yoghurt or ice cream. French Sorrel (Rumex scutatus) has smaller triangular leaves with a more concentrated flavour. Medicinally it is used as a spring tonic, and has astringent properties that cleanse the blood.

Common Sorrel is not usually a problem weed and is easily removed - the roots are fairly shallow and it remains as a single clump. However, Sheep's Sorrel forms a loose mat of roots which spread over a large area if allowed. Hand weeding is easy for a small infestation, but all of the fine, yellowish, rubbery roots need to be traced and removed. Any roots remaining will soon regrow.
The regrowth is best treated with a systemic or translocated weedkiller such as Glyphosate to ensure more rapid eradication. In the lawn it is killed by selective weedkillers - MCPA or 2,4-D - applied in late spring.

Nicholas Culpepper
(17th century astrologer-physician)
"Of great use against the scurvy if eaten in spring as salad."