Cashew Nuts : A Brief History

Cashew, an evergreen tree native to South America and widely cultivated throughout the tropics for its fruits (cashew nuts). The cashew (Anacardium occidentale) belongs to the cashew family, Anacardiaceae, in the order Sapindales, class Magnoliopsida. It grows to 40 feet (12 meters) in height and has spreading branches and large oblong leaves 4 to 8 inches (10 to 20 cm) in length. The tree also possesses a system of latex tubes that ooze a milky juice when injured. The plant's yellowish flowers, less than 0.5 inch (1.3 cm) across, are borne in loose clusters (panicles) about 10 inches (25 cm) long. The flower consists of five sepals, five petals, ten or (usually) fewer stamens, and one pistil, this last enclosing a single ovule.

Northeastern Brazil is probably the original home of the cashew. During the late 16th century Portuguese missionaries took the nut tree to East Africa and India, where it became well-established. Today, the largest commercial plantations of cashews are mainly in the lowlands of Brazil and India. Some African countries also grow the nut.

Cashew nuts are actually the fruits of a cashew tree. The fresh nutmeat is green. The shape of the nut is like a large kidney bean, and it grows about 1 inch (2.5 centimeters) in length. Cashew nuts have two layers of shell. Between these layers is a strong oil that can blister the skin.

Cashew nuts grow on bushy, evergreen trees. These trees reach about 40 feet (12 meters) in height. They have low and spreading branches. Their leaves are oval, leathery, and up to about 8 inches (20 centimeters) long. The tree develops clusters of tiny five-petaled flowers. The nut develops from the flowers. When the nut is grown but not ripe, its stalk swells and becomes what is known as the cashew apple. The fruity cashew apple is shaped like a pear and grows to 2 to 4 inches (5 to 10 centimeters) in length. It has yellow flesh that is spongy and juicy, and the skin is reddish or yellow when ripe. Within 90 days, the nut ripens and both the nut and the apple fall to the ground.

Once the nuts fall to the ground they are gathered by hand. Farm workers take the nuts off the cashew apple and let the nuts dry in the sun. The nuts must then be roasted to burn off the oil in the shell, otherwise the oil can blister the skin. The inner shells are then broken open by hand, and the kernels are heated in order to remove the skins.

Roasted cashew nuts are a popular food. The nut has a double shell, between which lies a blackish, irritating oil called cardol, which is removed during the roasting process. Like the oils of certain other plants of the cashew family, such as poison ivy, poison oak, poison sumac, and poisonwood, cardol can cause a rash and blistering of the skin. It is sometimes used as an insecticide.

In addition to the nut, other parts of the cashew tree are used in various ways. The cashew apple is eaten fresh or dried and is used in beverages, jams, and candies. People use the wood from cashew trees as firewood and in such products as crates, boats, and furniture. The oil from the shells is extracted and used in paints, varnishes, and a wide variety of other products.