Anacardium is a genus of approximately 13 species of flowering trees and shrubs in the family Anacardiaceae, order Sapindales, native to the tropical and subtropical regions of the Americas. The genus is best known for Anacardium occidentale, the cashew tree, which is widely cultivated across the tropics for its edible cashew nuts and cashew apples. The characteristic feature that gives the genus its name is the arrangement of the nut: the true fruit (the cashew nut, encased in a hard shell) hangs below a swollen, fleshy, pear-shaped stem known as the cashew apple — placing the seed visibly outside and above the accessory fruit.
Species range from the large-canopied Anacardium giganteum found in Amazonian forests to the low-growing savanna shrub Anacardium humile of the Brazilian cerrado. The genus has a deep fossil record: Anacardium germanicum from the Eocene Messel Pit of Germany represents the oldest known species, far outside the genus's present-day range, while Anacardium gassonii from Panama documents the group's presence in the Americas by the Oligocene-Miocene boundary.
Etymology
The name Anacardium derives from Greek: ana ("upwards") and -cardium ("heart"), a reference to the fact that the true nut — the botanical heart of the fruit — is positioned externally, above the fleshy accessory fruit rather than inside it.
Distribution
The genus is native to tropical regions of the Americas, ranging from Mexico and the Caribbean south through Central and South America, with the highest diversity in Amazonia and the Brazilian cerrado. The fossil record shows the lineage once extended to central Europe during the Eocene (Messel Pit, Germany), with documented presence in Panama by the Oligocene-Miocene.
History
The earliest known member of Anacardium, A. germanicum, comes from the Eocene Messel Pit fossil site in Germany, indicating the genus once had a much broader distribution. By the Oligocene-Miocene the lineage had reached the Americas, as evidenced by A. gassonii from Panama. Anacardium occidentale was introduced to Asia and Africa by Portuguese traders in the 16th century, and today the cashew is one of the world's major tree crops.
Cultural Uses
Anacardium occidentale is the principal economic species. Its kidney-shaped nut, always found hanging below the fleshy cashew apple, is roasted and sold globally. The cashew apple itself is eaten fresh or fermented into juice, wine, and vinegar across Brazil, India, and West Africa. The shell liquid (CNSL, cashew nutshell liquid) is an industrial raw material used in friction linings, paints, and resins.
