Cashew

Cashews are commonly called nuts, but botanically each edible kernel is the seed of the cashew tree's true fruit. The cashew, Anacardium occidentale, belongs to the same plant family as the mango, pistachio, poison ivy and poison oak.

The English word "cashew" ultimately derives from the Portuguese caju, itself borrowed from a Tupi name for the tree.

The cashew is native to tropical South America, including Brazil. Portuguese traders carried it to parts of Africa and India during the 16th century, and it subsequently spread through tropical Asia.

The kidney-shaped true fruit grows at the end of a fleshy, pear-shaped stalk called the cashew apple. The apple is an accessory fruit rather than a true fruit and may be red or yellow when ripe.

Cashew apples are juicy but highly perishable. Where the trees are grown, the apples are used to make juice, alcoholic drinks, jams and jellies; they contain considerably more vitamin C by weight than oranges.

Cashew trees generally begin bearing three to five years after planting. Depending on the variety and growing conditions, they may not reach full production until about eight to ten years after planting.

Côte d'Ivoire is the world's leading producer and exporter of raw, in-shell cashews, while Vietnam is the leading processor and exporter of shelled cashew kernels.

The world's largest cashew tree grows at Pirangi do Norte in the Brazilian state of Rio Grande do Norte. Guinness World Records gives its spread as about 8,500 square metres (2.1 acres), roughly the area occupied by 70 ordinary cashew trees.

The Pirangi tree's extraordinary spread is attributed to a genetic mutation. Four of its five main branches grow outwards and form new roots when they touch the ground, creating secondary trunks that remain connected to the original tree.

Cashews are sold without their shells because a caustic oily resin lies between the shell layers. It can blister human skin and must be removed by controlled heat treatment and careful processing.

Cashew nutshell liquid has industrial uses. Its derivatives are used in products including brake linings, resins, varnishes, lubricants and paints.

A 28-gram (one-ounce) serving of raw cashews contains about 157 calories and 5.2 grams of protein. It is especially rich in copper and also supplies magnesium, phosphorus, zinc and iron.

Informal food calendars in the United States mark November 23 as National Cashew Day, although it is not an official federal observance.

Sources: Encyclopaedia Britannica; Kew Science: Plants of the World Online; Guinness World Records; Food and Agriculture Organization; World Bank; Observatory of Economic Complexity; USDA FoodData Central; Online Etymology Dictionary