Oxalis ( /ˈɒksəlɨs/) is by far the largest genus in the wood-sorrel family Oxalidaceae: of the approximately 900 known species in the Oxalidaceae, 800 belong here. The genus occurs throughout most of the world, except for the polar areas; species diversity is particularly rich in tropical Brazil, Mexico and South Africa.

Many of the species are known as wood-sorrels (in American English typically written "woodsorrels" or "wood sorrels") as they have an acidic taste reminiscent of the unrelated sorrel (Rumex acetosa) proper. Some species are called yellow-sorrels or pink-sorrels after the color of their flowers instead. Other species are colloquially known as false shamrocks, and some are rather misleadingly called "sourgrasses". For the genus as a whole, the term oxalises is also used.

Read more about OxalisDescription and Ecology, Use By Humans, Selected Species