From The Food Encyclopedia by Jacques Rolland and Carol Sherman
The edible, furrowed, two-lobed nut encased in a hard, spherical shell produced by various Juglans species. The name is derived from the Old English wealh, meaning "foreigner", originally given to the Persian walnut, J. regia, to differentiate it from the island's abundant, wild hazelnuts. Now known, confusingly, as English walnut, this Persian or royal walnut is native from southeast Europe through to China. Other species include the North American J. californica (California walnut), J. cinerea (butternut or white walnut) and J. nigra (black walnut). Eaten by the Iroquois, white walnuts quickly became a common food of the early settlers. Today, walnuts are eaten fresh or roasted, on their own or used in baked goods, confections, pasta dishes, salad dressings, soups and stews. Ripe and unripe, they are pickled and preserved in sweet and savory syrups and condiments, especially in Asia. Walnuts are also ground into meal and cold-pressed into oil (usually used in uncooked dishes, since heating lessens its flavor). See also souari.
