Wood sorrel (Oxalis acetosella) is a creeping woodland perennial in the Oxalidaceae family. It's native to parts of Asia and most areas of Europe, including the UK. It's used as an indicator of ancient woodland in southern and eastern England.
Traditionally called ‘Alleluia’ – a reference to the emergence of the flowers between Easter and Whitsun – wood sorrel has over 20 other common names across the UK, including ‘cuckoo sorrel’ and ‘sleeping Molly’. The genus Oxalis comes from the Greek word for 'acid' and refers to the sharp taste of the leaves, as does the species name acetosella, which derives from the Latin for 'vinegary' or 'sour'.
When wood sorrel flowers in spring it provides a source of nectar and pollen for early pollinators such as hoverflies and bees, and it's included in the list of RHS Plants for Pollinators. It's worth noting that plants in the Oxalis genus are poisonous to pets.
How to grow wood sorrel
As its name suggests, wood sorrel usually grows under trees at the edge of woodlands and in hedgerows. It thrives in moist but well-drained, fertile soil in partial shade. Its delicate white spring flowers are ideal for shady banks and brightening up areas of dappled shade under deciduous trees and shrubs.
How to identify wood sorrel
Wood sorrel grows to around 10cm in height and has trefoil leaves, meaning it's divided into three leaflets. Each heart-shaped leaflet is fresh green but purplish on the underside. In April and May, it produces delicate five-petalled white flowers with lilac veining. These open in the daylight and fold closed at night, or when it rains.
There are several other oxalis plants which are sometimes referred to as wood sorrel, such as creeping wood sorrel or yellow oxalis (Oxalis corniculata), pink wood sorrel or pink sorrel (Oxalis articulata) and strawberry oxalis or pink wood sorrel (Oxalis crassipes ‘Rosea’). These plants have a similar trefoil leaf to wood sorrel, but the flowers are yellow or pink, rather than white, and creeping wood sorrel can have bronze-brown leaves rather than green.
Wood sorrel could also be confused with other plants like clover and medick which have a similar leaf shape. Wood anemone (Anemone nemorosa) is another potential lookalike, although its flowers lack the lilac veining of wood sorrel petals, and its leaves are different, having visible lobes.
Wood sorrel leaves are edible, so are perfectly fine to eat. They have a sour, lemony taste, sometimes described as like sharp apples. They should be consumed only in small amounts as they contain oxalic acid which can be toxic if eaten in large quantities. People with rheumatism, arthritis, gout, kidney stones, kidney disease, hyperacidity or any other condition (including pregnancy) affected by the consumption of oxalic acid should check with a doctor before eating wood sorrel.
If you are foraging, make sure you use a good field guide to identify plants or go on a guided walk with an expert. Don’t pick unless you're absolutely certain your identification is correct. Only collect leaves where plants are abundant (generally the advice is only to harvest from one in 20 plants) and leave plenty behind for wildlife. Seek permission before foraging and bear in mind that uprooting any plant is illegal without the landowner’s permission.
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Where to grow wood sorrel
Wood sorrel grows well in dappled shade on banks and slopes where some other plants might struggle. It's ideal for woodland and wildlife gardens, and to use as underplanting with shrubs and trees.
How to plant wood sorrel
Plant wood sorrel plugs, small plants or rhizomes in spring in any humus-rich, moist but well-drained soil.
How to care for wood sorrel
Wood sorrel requires little care once established. Plants should gradually naturalise and spread without being too vigorous. However, some other oxalis species can become invasive and may need to be controlled, so keep an eye out for these and remove plants before they can set seed.
How to propagate wood sorrel
Wood sorrel spreads by rhizomes and is best propagated by dividing plants in spring or taking root cuttings. It's illegal to dig up wood sorrel from the wild without permission, so propagation can only be done from plants growing in gardens.
Pests and diseases
- Wood sorrel can be bought as rhizomes, plug plants or small potted plants
- When buying rhizomes, always check that they are firm, with no signs of damp or mould
- Plant out in spring and water well in dry periods for the first year