A medium-sized (20–30 ft or 6–9 m high), spreading evergreen tree (Anacardium occidentale) native to Brazil, but now grown widely in the tropics for its edible nuts and the resinous oil contained in the shells. Cashews belong to the family Anacardiaceae in the order Sapindales. The fruit consists of a fleshy, red or yellow, pear-shaped receptacle, termed the apple, 2–3½ in. (5–8.7 cm) long at the distal end of which is borne a hard-shelled, kidney-shaped ovary or nut about 1½ in. (3.7 cm) long. The shell of this nut is about frac18-in. (3-mm) thick and consists of a smooth, relatively thin outer layer (exocarp) and an inner hard layer (endocarp). Between these layers is a porous layer (mesocarp), which is filled with a caustic black liquid that blisters the skin and makes the processing of the nut difficult.