Peanuts are legumes, not true nuts.

Despite the name, peanuts don’t grow on trees the way almonds, walnuts, or hazelnuts do. The peanut plant flowers above ground, but after pollination the stem bends down and pushes the developing pod underground to mature, a highly unusual growth habit called geocarpy. Botanically, that makes the peanut a legume, part of the same family as beans, peas, and lentils, rather than a true nut.

The distinction matters beyond trivia. Peanut allergies and tree nut allergies are caused by different proteins, and a person allergic to one is not automatically allergic to the other, even though warning labels often lump “peanuts and tree nuts” together for caution. The word “nut” in “peanut” survives mainly because of its nut-like taste, shape, and culinary uses, not its botany.