Sapindaceae

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

Characteristics
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.
Dodonaea viscosa flowers

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 are related to Rutaceae, and both are usually placed in an order Sapindales or Rutales, depending on whether they are kept separate and which name is used for the order.The most basal member appears to be Xanthoceras. Some authors maintain some or all of Hippocastanaceae and Aceraceae, although this may result in paraphyly.The former Ptaeroxylaceae, now placed in Rutaceae, were sometimes placed in Sapindaceae.The family is divided in 5 or 6 subfamily depending on treatment.

Notable species
Sapindaceae includes many species of economically valuable tropical fruit, including the lychee, longan, pitomba, korlan, rambutan, mamoncillo and 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. Saponins extracted from the drupe of Sapindus species are effective surfactants and are used commercially in cosmetics and detergents.