Oxalis violacea, the violet wood-sorrel, is a perennial plant and herb in the Oxalidaceae family.<ref name="grin">Template:GRIN</ref> Oxalis species are also known as sour grass, sour trefoil, and shamrock.
It is native plant in much of the United States, from the Rocky Mountains east to the Atlantic Ocean and Gulf of Mexico coasts, and through Eastern Canada. It has a tendency to cluster in open places in damp woods and on stream banks, and in moist prairies.<ref name="grin"/>
Oxalis violacea emerges in early spring from an underground bulb and produces leaf stems Template:Cvt tall and flower clusters on stems Template:Cvt tall.<ref name="FNA">Template:EFloras</ref> 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.<ref name="FNA" />
All parts of the plant are edible; flowers, leaves, stems, and bulb. Oxalis is from the Greek word meaning sour, and this plant has a sour juice. It is used in salads. Moderate use of plant is advisable, as it should not be eaten in large quantities due to a high concentration of oxalic acid, ("salt of lemons") which can be poisonous.<ref>Template:Cite book</ref>
Oxalis violacea is cultivated as an ornamental plant, for use as a flowering groundcover or perennial plant in traditional and native plant gardens, and for natural landscaping projects.<ref>Template:Cite web</ref> It spreads rapidly by runners and bulbs.<ref name="npin">Template:NPIN</ref> In gardens the plant prefers partial shade and moisture.<ref name="npin"/>