'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.
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 (
alkaloids with
soap-like qualities) in either the foliage and/or the seeds. 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.
[1][2]
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.
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.
Classification
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.
[3] The family is divided in 5 or 6 subfamily depending on treatment.
Notable species

Longan fruits.
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 others, such as ''
Koelreuteria'', ''
Cardiospermum'' and ''
Ungnadia'', are popular ornamentals. ''
Schleichera trijuga'' is the source of Indian
macassar oil.
References
1. Plant Systematics: An Integrated Approach, , Gurjaran, Singh, Science Publishers, 2004,
2. Phylogenetic inference in Sapindaceae ''sensu lato'' using plastid ''mat''K and ''rbc''L DNA sequences., , Mark G., Harrington, Systematic Botany, 2005
3. Sapindaceae Juss. Watson, L., and Dallwitz, M.J.