Annual or perennial herbs to shrubs or trees, with acid sap. The principal genus is Oxalis in which there are nearly 500 species. Leaves usually compound, either digitate or pinnate, alternate or the basal opposite. The flowers are bisexual, regular; sepals and petals 5, stamens 10, hypogynous, the outer 5 opposite the petals; styles 5, separate; stigmas capitate or somewhat bifid. Ovary superior, 5- celled, 2 to many-ovuled; fruit a capsule or berry-like. (Munz, Flora So. Calif.).