White sapote (Casimiroa edulis), also known as custard apple and cochitzapotl in Nahuatl (meaning '"sleep-sapote") is a species of tropical fruiting tree in the family Rutaceae, native to eastern Mexico and Central America south to Costa Rica.
Mature trees range from 5-16 m tall and are evergreen. The leaves are alternate, palmately compound with 3-5 leaflets, the leaflets 6-13 cm long and 2.5-5 cm broad with an entire margin, and the leaf petiole 10-15 cm long.
The fruit is an ovoid drupe, 5-10 cm in diameter, with a thin, inedible skin turning from green to yellow when ripe, and an edible pulp, which can range in flavor from bland to banana-like to peach to pear to vanilla flan.
The pulp can be creamy-white in green skin varieties or a beige-yellow in yellow skin varieties. It contains from one to five seeds that are said to have narcotic properties. Along with their seeds, the leaves of the trees are known to have a sedative effect and are very good agents for lowering arterial blood pressure.
In the past 40 years, extensive experiments have been carried out on the white sapote's seeds which have yielded the identity of many pharmacologically active compounds, including: n-methylhistamine, n-dimethylhistamine, zapotin and histamine.
Unlike the mamey sapote, white sapote is a member of the family Rutaceae, to which citrus belongs. The black sapote is also unrelated and is actually a species of persimmon. This confusion may be due to the fact that "sapote" comes from the Nahuatl (Aztec) word tzapotl, used to describe all soft, sweet fruit.