Cashews are the seed of the fruit of a tropical tree native to South America, more specifically, it is native to the north-east of Brazil and the south-east of Venezuela but is quite widespread throughout the tropics, where it was introduced by the Portuguese in the sixteenth century.
In India and sub-Saharan Africa it has even naturalized, forming extensive forests.
The tree has a tortuous, pinkish and not very tall trunk, normally between 5 and 10 meters in cultivation, 15 m in nature.
The fruit is shaped like a kidney, and is a nut. Each is encased in a hard shell, sometimes referred to as a “pod” or “drupe".
The edible part is the seed inside the drupe. The fruit grows at the base of a yellow or red false fruit, an accessory fruit, called "cashew apple" about 5–11 cm long. The walnut has a smooth epicarp and a resinous, caustic mesocarp. This layer surrounding the seed contains an allergenic phenolic resin, anacardic acid. The hard exterior shell of cashews contains an oil called urushiol.
The false fruit derives from the hypertrophic development of the flower peduncle and the receptacle (in a process similar to what happens with the apple widespread in Europe). It has the shape and size of a small pear and contains an edible, fleshy, succulent, sugary and astringent pulp, from which highly appreciated juices are obtained.
The cashew apple is used also in jams, and jellies, though most cultivation is directed toward production of the valuable seed crop.
Almost all cashews produced in Africa between 2000 and 2019 were exported as raw nuts which are much less profitable than shelled nuts.
