Sapindaceae, also known as the soapberry family, is a family of flowering plants in the order Sapindales. There are about 140-150 genera with 1400-2000 species, including maple, horse chestnut and lychee.
Sapindaceae members occur in temperate to tropical regions throughout the world. Many are lactiferous, i.e. they contain milky sap, and many contain mildly toxic saponins with soap-like qualities in either the foliage and/or the seeds, or roots. The largest genera are Serjania, Paullinia, Acer and Allophyllus.
The largely temperate genera formerly separated in the families Aceraceae (Acer, Dipteronia) and Hippocastanaceae (Aesculus, Billia, Handeliodendron) were included within a more broadly circumscribed Sapindaceae by the APG. Recent research has confirmed the inclusion of these genera in Sapindaceae.
Plants of this family have a variety of habits, from trees to herbaceous plants or lianas. Their leaves usually spirally alternate, sometimes (in Acer, Aesculus, and a few other genera) opposite. They are most often pinnately compound, sometimes palmately, or just palmate (Acer, Aesculus), with a petiole lacking stipules, but having a swollen base.
Flowers are small and unisexual, or functionally unisexual, though plants may be either dioecious or monoecious. They are usually grouped in cymes grouped in panicles. They most often have four or five petals and sepals (petals are absent in Dodonaea). The stamens range from four to ten, usually on a nectar disc between the petals and stamen,their filaments are often hairy. The most frequent number is eight, in two rings of four. The gynoecium contains two or three carpels, sometimes up to six. There is usually only one style with a lobed stigma. Most often pollinated by birds or insects,with a few species pollinated by wind.
The fruits are fleshy or dry. They may be nuts, berries, drupes, schizocarps, capsules (Bridgesia), or samaras (Acer). The embryos are bent or coiled, without endosperm in the seed, but frequently with an aril.
Sapindaceae includes many species of economically valuable tropical fruit, including the lychee, the longan, the pitomba, the korlan, the rambutan, the mamoncillo and the ackee. Other products include Guarana, soapberries and maple syrup.
Some species of Maple and Buckeye are valued for their wood, while several other genera, such as Koelreuteria, Cardiospermum and Ungnadia, are popular ornamentals. Schleichera trijuga is the source of Indian macassar oil.