Oxalis violacea, the violet wood-sorrel, is a perennial plant and herb in the family Oxalidaceae. Oxalis species are also known as sour grass, sour trefoil, and shamrock. Oxalis violacea is cultivated as an ornamental plant.
Oxalis violacea emerges in early spring from an underground bulb and produces leaf stems 7–13 cm (2 3⁄4–5 in) tall and flower clusters on stems 9–23 cm (3 1⁄2–9 in) tall. The three-part leaves have heart-shaped leaflets. It is similar in appearance to small clovers such as the shamrock. The plant bears lavender to white flowers with white to pale green centers above the foliage, during April or May, rarely to July, and, with rain, sometimes produces additional flowers without leaves from August to October. Genus name comes from the Greek word oxys meaning acid, sour or sharp in reference to the taste of the leaves. Specific epithet means violet.