lemon, one of the citrus fruits, from a tree ( Citrus limon ) of the family Rutaceae (orange family), probably native to India. A small tree (to about 15 ft/5 m tall) with thorny branches and purple-edged white blossoms, it requires a mild, equable climate. The European crop is centered on the islands and coasts of the Mediterranean. In the United States, lemons are grown chiefly in S California, Arizona, and Florida. The trees are prolific, and under ideal conditions can produce ripe fruit practically all the year. In the United States the fruit is cut from the tree while green, at a standard size, and the good lemons are placed in cool, dark rooms to ripen slowly; the skin grows yellow, thin, and pliable, and the quality of the fruit is similar to when ripened on the tree. The imperfect fruit is manufactured into lemon oil, lemon juice, citric acid, pectin, and other useful products. There are seedless varieties. The sweeter Meyer lemon is lemon crossed with either a mandarin or an orange, and the Ponderosa lemon is a lemon-citron hybrid that has grapefruit-sized fruits. Lemons have better preservative qualities than other citrus fruits and are thus more easily transported. The fruit is high in vitamin content (especially in ascorbic acid, or vitamin C) and has long been known as a preventive of scurvy. Lemons have a refreshing, acid flavor; they are used in summer drinks, such as lemonade and punch, and are often preferred to vinegar as an ingredient in sauces and salad dressings. Lemon juice is the main source of citric acid. Lemon oil, or the essential oil extracted from the skin, usually while green, is manufactured mostly in Italy and France. It is used in the making of lemon extract, perfumes and cosmetics, and furniture polish. Lemon is classified in the division Magnoliophyta, class Magnoliopsida, order Sapindales, family Rutaceae.