Walnuts come from trees in the genus Juglans, of which there are around 15 species native to southwestern Asia, eastern Asia, and the Americas. The most widely cultivated is the Persian or English walnut, Juglans regia, whose seeds have been enjoyed since ancient times in western Asia and Europe, and among tree nuts are second only to almonds in worldwide consumption. In many European languages, the generic term for nut is also the word for walnut. The United States, France, and Italy are the major producers today. Walnuts have long been pressed for their aromatic oil, were once made into milk in Europe and China, and came to provide the rich, flavorful backbone of sauces in Persia (fesenjan), Georgia (satsivi), and Mexico (nogado). In some countries, immature “green” walnuts are harvested in early summer and pickled (England), used to flavor sweetened alcohol (Sicilian nocino, French vin de noix), or preserved in syrup (the Middle East).