The cashew nut grows outside its fruit, wrapped in a poison ivy relative's oil
A cashew hangs beneath a fleshy, pear-shaped 'apple' that is not truly the fruit at all. The real fruit is the kidney-shaped shell, and it carries an irritant chemically related to poison ivy's urushiol. That is why you never see cashews sold in the shell, and why raw ones must be roasted or steamed first.
The cashew tree, Anacardium occidentale, is a tropical evergreen native to South America that can reach 14 metres. Portuguese explorers met it in the 16th century; colonists in Brazil were exporting the nuts by the 1550s and planted the tree in Goa between 1560 and 1565, from where it spread across Southeast Asia and into Africa. The English name comes from Portuguese caju, from a Tupi word said to mean nut that produces itself. The largest known cashew tree, in Parnamirim, Brazil, sprawls over about 7,500 square metres.
Botanically it is a puzzle. After the kidney-shaped drupe forms, the flower stalk swells into the cashew apple, a yellow or red accessory fruit 5 to 11 cm long, called marañón in Central America. Its juice makes a sweet, astringent drink or can be fermented and distilled into liquor. The drupe holds a single seed inside a double shell laced with anacardic acid and related compounds that cause dermatitis. Shell derivatives go into varnishes, lubricants and paints, and cardanol from waste shells is being studied for nanomaterials.
Growing cashews has been transformed by dwarf cultivars. Traditional trees take three years to bear and eight to pay off, yielding about a quarter tonne per hectare; dwarf trees up to 6 m tall produce after one year and top a tonne per hectare. The tree likes hot lowlands with a strong dry season, roughly between 25 degrees north and south. World production in 2024 was 4.2 million tonnes in shell, led by Ivory Coast and India. Nearly all African cashews from 2000 to 2019 left the continent as less profitable raw nuts, which the African Cashew Alliance hopes to change.
Raw cashews are 44 percent fat and 18 percent protein. Indian cooks grind them into korma sauces and sweets like kaju barfi, and Pampanga in the Philippines makes a cashew marzipan. Allergy affects up to 6 percent of children and 3 percent of adults, less often than with peanuts or other tree nuts.
Source: Cashew
