A lime (from Arabic and French lim) is a citrus fruit, which is typically round, lime green, in diameter, and containing sour (acidic) juice vesicles. There are several species of citrus trees whose fruits are called limes, including the Key lime (Citrus aurantifolia), Persian lime, kaffir lime, and desert lime. Limes are an excellent source of vitamin C, and are often used to accent the flavours of foods and beverages. They are grown year-round in tropical climates and are usually smaller and less sour than lemons, although varieties may differ in sugar and acidic content. Plants with fruit called "limes" have diverse genetic origins; limes do not form a monophyletic group.