oxalis

Oxalis is a genus of flowering plants in the family Oxalidaceae, comprising about 550 species of herbaceous plants. They are widely distributed in warm and temperate regions and are commonly known as wood sorrel or sorrel. Several species are grown as ornamentals, while others have become naturalized or invasive outside their native ranges.

Most Oxalis species have trifoliate leaves, each leaflet typically heart-shaped and arranged in a set of three. The leaflets often resemble a clover and can display a range of colors, including green and purple. Leaves frequently exhibit nyctinasty, folding at night or in response to touch. Flowers have five petals and may be yellow, white, pink, or purple, depending on the species.

Habitats vary from woodlands and grasslands to lawns and disturbed ground. Many Oxalis species spread by runners, bulbs, or tubers and can form dense mats. Several species, such as Oxalis pes-caprae (Cape oxalis) and Oxalis corniculata (creeping wood sorrel), are considered invasive in some regions.

Uses and cautions: Some species are grown as ground covers or indoor ornamental plants, such as Oxalis triangularis (purple shamrock). Leaves and flowers of many species are edible and used in salads or as garnish, but they contain oxalic acid and should be eaten in moderation. Excessive consumption can irritate the digestive tract and, in susceptible people, contribute to kidney stone formation. Animals may also be affected by high oxalate levels.

Taxonomy and overview: Oxalis is the largest genus in Oxalidaceae. The classification of the many species is complex and frequently revised as new data become available. Common names vary by region and species.