Oxyria digyna aka Alpine Mountain Sorrel

Oxyria digyna is a small perennial in the Polygonaceae family. Its common names include mountain sorrel, alpine sorrel, and kidney sorrel. It grows in subarctic and subalpine parts of the Northern Hemisphere. Its range includes Asia and North America. It is also native to Britain and Ireland. Wild plants grow in damp, rocky mountain sites, often near streams. They also grow on rich ground below bird roosts.

This plant forms an upright clump with a basal rosette. It reaches about 1 foot (0.3 metres) tall. The fleshy green leaves have kidney or heart shapes. The foliage dies back each year. Thin stems with a red tint rise above the leaves. They hold loose groups of small flowers. These start greenish and turn deeper red as they age. The flowering season runs from June to August. Plants reach their full size within one to two years.

In gardens, mountain sorrel needs cool soil and shade. The RHS lists both full shade and partial shade. Keep the soil moist, but allow excess water to drain. It accepts chalk, clay, loam, and sand. The RHS lists acid or neutral soil for garden use. PFAF, however, reports that wild plants avoid acid ground. Both sources place it in cold growing conditions. The RHS gives it an H7 hardiness rating. PFAF lists USDA zones 2–8.

Mountain sorrel suits wildlife gardens and planted beds. Its small clumps combine low leaves with taller flower stems. It needs no pruning, according to the RHS. Sow seed outdoors to raise new plants. It also seeds itself freely, so new plants may appear nearby. PFAF does not flag it as a weed threat. The RHS reports few pest or disease problems. Moisture and a cool, shaded site remain its main growing needs.

The leaves can be eaten raw, cooked, or fermented. Their sour taste can add bite to salads. They also serve as a cooked green. Eat only small amounts because they contain oxalic acid. Large amounts can reduce the calcium available to the body. Cooking lowers the amount of this acid. PFAF warns people with kidney stones, gout, or arthritis to take care. It also urges caution with rheumatism or excess stomach acid. The leaves contain vitamin C and have a history of use against scurvy. PFAF also records traditional use of cooked plant parts for dysentery.