Cashew nuts grow on the outside of a fruit called a cashew apple.

The cashew tree is native to Brazil but grows in many tropical countries today. The cashew apple is not a typical fruit. It is an accessory fruit formed from the flower stalk. The true fruit is the small, kidney-shaped shell hanging below it. This shell contains the seed we eat as a nut.The shell of the cashew nut contains a chemical called urushiol. This is the same substance found in poison ivy. It causes skin rashes and chemical burns on contact. Workers must roast or steam the nuts at high temperatures to destroy the toxin. This process makes the nuts safe to touch and eat.The cashew apple is also edible and contains five times more Vitamin C than an orange. It has very thin skin and spoils quickly after being picked. Because it is so fragile, it is rarely shipped to other countries. Most people only eat the apple in the regions where the trees grow.