PLANT

Sapindus is a genus of the Lychee family, Sapindaceae, native to the warm temperate and tropical regions of the Old and New Worlds. The genus includes both deciduous and evergreen species. Members of the genus are generally known as soapberries or soapberries because the fruit is used to make soap. The Latin words sapo, meaning 'soap', and indicus, meaning 'of India'.

Leaves are alternate, 15-40 cm (5.9-15.7 in) long, pinnate (except in S. oahuensis, which has simple leaves), with 14-30 leaflets, the terminal leaflet often absent. Flowers in large panicles, each flower small, creamy white. Fruit is a small, leathery-skinned drupe 1-2 cm in diameter, yellow to blackish ripening, containing one to three seeds.

USE

Drupes (soap nuts) contain saponins, which have surface-active properties, having been used for washing by ancient Asian and Native American peoples.

Folk medicine
Soaps' have historically been used in folk remedies, but since the efficacy of such treatments has not been subjected to scientific scrutiny, there are no confirmed health benefits from the use of 'soaps' for the treatment of any human disease. Soapnut contains saponins.

Insecticide
Sapindus species are used as food plants by the larvae of some lepidopteran species (moths and butterflies) including Endoclita malabaricus. Soapnut kernel extracts interrupt the enzyme activity of larvae and pupae and inhibit the growth of the Aedes aegypti mosquito, an important vector of viral diseases.

CULTIVATION

Location and climate: it is a tree that likes places exposed to full sun for many hours a day and is suitable for cultivation in warm-temperate areas such as those in southern Italy including the islands. It tolerates high temperatures but fears cold, especially frost, and is therefore difficult to cultivate where the climate is particularly harsh.
Soil: although Sapindus mukorossi is a tree that adapts to any type of soil, even poorly fertile and stony soil, it prefers cool, limey, well-drained soil.
Watering: the soap tree is a plant that requires continuous watering in its first years of life. Later it is content with rainwater although it does not disdain regular watering during periods of prolonged drought and in summer. Watering should be thinned out or suspended during the vegetative rest period from November to March.