Walnut is the nut of any tree belonging to the family of Juglandaceae. A walnut, technically, is the seed of a drupe and thus not a true botanical nut. The walnuts are nutrient-dense with essential fatty acids and protein. The two most common major species of walnuts are grown for their seeds – the Persian walnut and the black walnut. The Persian walnut originated in Persia while the black walnut is native to eastern North America.