Not a large family, mostly tropical. Ours are low herbs, with sour juice, often with rootstocks or scaly bulbs; leaves with three or several leaflets; flowers perfect; sepals five, often unequal; petals five, stamens ten to fifteen; ovary superior, five-celled, the five styles usually separate; fruit a capsule, containing several or many seeds. By some botanists this is merged in the Geranium Family.

There are many kinds of Oxalis. The Greek name means "sour," in allusion to the sour taste of these plants, which contain oxalic acid. The leaves are alternate, at nightfall the leaflets droop and fold together; the stamens are ten, five long and five short, all with anthers, with filaments broadened and united at base.