Rumex acetosella aka Field Sorrel

Rumex acetosella, or sheep sorrel, is in the Polygonaceae family. This herb lives for years. It comes from temperate Eurasia, including Britain and Ireland. It grows on heaths, in acid grasslands, and on disturbed ground. It grows fast and spreads by creeping rhizomes, or underground stems. These can make settled patches hard to remove. Though small, it can become an aggressive weed.

The plant forms a low rosette, with flower stems standing upright. Garden plants reach about 0.3–1.6 feet (0.1–0.5 metres) tall. RHS gives a similar range for their spread. NC State lists a narrower spread of 0.3–0.5 feet (0.1–0.15 metres). The green leaves have smooth edges and no hairs. Leaves at the base have an arrow shape with two lower lobes. Leaves grow in turn on each side of the stems. Thin flower stems have red ridges and branch near their tips.

NC State records blooms from March through November. Tiny blooms form spike-like groups called racemes. These make up a branched flower head, or panicle. Female flowers are red, while male flowers are yellow-green. Red fruits called achenes follow the flowers. The reddish flowers and seedheads add colour to meadows. Sheep sorrel suits wildlife gardens and lawns with mixed species. RHS reports that it supports more than 50 insect species. NC State lists copper butterflies among those that feed on it.

Grow sheep sorrel in sun or partial shade. It does best in acid to neutral soil that drains well. Sandy ground suits it, but loam and clay loam also work. Sources give a range from dry to moist soil. RHS lists chalk, clay, loam, and sand as suitable soils. It rates the plant H4 for UK hardiness. NC State lists USDA zones 4a–8b. Plants may keep growing through winter where winters are mild. Grow more from seed or by dividing plants. It needs no routine pruning. Removing dead flowers helps limit its spread by seed. Slugs and aphids may attack it. Disease is seldom a problem.

The sour leaves give food a lemon-like taste. Use small amounts raw or cooked, in salads or soups. PFAF also lists cooked roots as edible. Seeds can be eaten raw or cooked. Roots can yield green, brown, or grey dyes. Edibility does not mean the plant is harmless. Its oxalic acid can harm kidneys when eaten in large amounts. People prone to kidney stones, gout, or arthritis need extra care. Large amounts can also harm pets, including cats and dogs. Cooking lowers oxalic acid, but does not make large servings safe.