Cashew is a species of fruit tree that produces the cashew "nut" commonly found in stores around the world. However, despite its appearance, cashews are not actually nuts, they are seeds from their fruit. The fruit is unusual because shortly before the seed matures the pedicel (stalk) enlarges and becomes a sweet cashew apple. Another unique quality of cashews is an oil found in their shells. This oil is highly caustic and, if it contacts the skin, causes severe burns. For this reason, cashews must be carefully processed to obtain the delicious, well-known kernel that is enjoyed worldwide for its rich flavor. The cashew nutshell oil contains the same substance found in poison ivy and poison oak, which are members of the same family as the cashew, along with mangoes and pistachios.