Cashews grow on a tree, specifically the tropical evergreen Anacardium occidentale. This plant belongs to the Anacardiaceae family, which also includes mangoes and poison ivy. The cashew tree produces a fleshy pseudofruit and the seed marketed as the cashew nut. The seed develops uniquely outside the fleshy part of the fruit.
The Cashew Tree and Its Growth
The cashew tree is a tropical species native to northeastern Brazil. Portuguese explorers spread the tree globally in the 16th century, and it is now commercially cultivated across many tropical regions. Today, the largest producers include Vietnam, India, and Côte d’Ivoire.
This evergreen requires a frost-free, tropical climate and has an extensive root system, allowing it to thrive in coastal areas. While wild trees can reach 46 feet, commercial agriculture prefers dwarf cultivars that grow to about 20 feet. These smaller trees are favored for earlier maturity and higher yields, making harvesting more efficient. A distinct dry season during flowering helps ensure good production.
The Unique Anatomy of the Cashew Fruit
The cashew develops two distinct structures: the cashew apple and the kidney-shaped nut hanging from its end. The cashew apple is a pseudofruit, or “false fruit,” which is the swollen pedicel connecting the flower to the tree.
The true fruit is the hard, kidney-shaped structure attached to the bottom of the apple, classified by botanists as a drupe. Inside the drupe’s shell is the single seed, known commercially as the cashew nut. The apple develops after the drupe matures, expanding during the final two weeks of ripening. Both structures ripen and fall from the tree together.
Why Raw Cashews Are Not Safe
Cashews are never sold in their shells due to the presence of a toxic chemical called urushiol. This oily compound is the same skin irritant found in poison ivy and poison oak. Urushiol is concentrated in the space between the two layers of the hard shell surrounding the nut.
Contact with this oil can cause allergic contact dermatitis, resulting in an itchy rash. To make the seed safe for consumption, it must undergo industrial processing involving heat treatment. In-shell cashews are steamed or roasted at high temperatures to neutralize the toxic oil before shelling. This necessary safety process contributes to the high cost of cashews. Even cashews labeled “raw” have been steamed to remove urushiol, meaning they have had no other flavoring or additives applied.