Begoniaceae, the begonia family of flowering plants in the order Cucurbitales. The Begoniaceae consists of two genera: Begonia, with some 1,000 species, and Hillebrandia, with one species. The family is distributed throughout most tropical and warm temperate regions, with a large percentage of species being native to the Americas. Hillebrandia is endemic to Hawaii.
A majority of species are perennial herbs, some climbing, with succulent stems and thick rhizomes or tubers; some species are shrubs. The leaves are usually simple (i.e., single-bladed) but may be compound (composed of several leaflets); they are commonly asymmetrical, with one side much larger than the other. There are paired leafy stipules at the base.
Most species are monoecious, with flowers of both sexes developing on the same plant; the flowers are unisexual. Male flowers have two petal-like sepals, two petals, and numerous stamens. Female flowers have two to several perianth parts and one pistil, with an inferior ovary, often winged. The fruits are usually capsules and often have well-developed wings. The fruits have numerous minute seeds.
Many species and hybrids of Begonia are cultivated as ornamentals; otherwise the family has little economic importance.