Cashews Grow On Fruit

The familiar crescent-shaped cashew is just one part of a much larger and stranger botanical puzzle. It grows externally, dangling from the bottom of a fleshy, pear-shaped stalk called a cashew apple. This colorful "apple" is technically a pseudocarp, or false fruit, while the true fruit is the hard, kidney-shaped shell that encases the single cashew seed we eat. This unusual arrangement, where the seed develops outside the main fleshy part, makes the cashew tree a botanical oddity and explains why each "fruit" yields only one nut.

The reason you never find raw cashews in their shells at the grocery store lies within that shell's lining. It contains a caustic phenolic resin with urushiol, the same powerful chemical irritant found in poison ivy and poison sumac. Contact with this oil can cause severe skin rashes and allergic reactions. To render the nuts safe, they must undergo a careful heating process, typically roasting or steaming, which neutralizes the toxic oil. This delicate, labor-intensive procedure is essential for separating the prized kernel from its dangerous casing, a process perfected since the tree was first cultivated in its native Brazil.