Oxalis acetosella

Oxalis acetosella, the wood-sorrel or common wood-sorrel, is a herbaceous rhizomatous flowering plant in the family Oxalidaceae. The specific epithet acetosella refers to its sour taste. The common name wood-sorrel is often used for other plants in the genus Oxalis.

In much of its range, most of Europe and parts of Asia, it is the only member of its genus and hence simply known as wood-sorrel. While 'common wood-sorrel' may be used to differentiate it from most other species, this name is also used for the North American Oxalis montana.