Lime is a term referring to a number of different species and hybrids of shrublike trees of the genus Citrus, as well as the name for the popular edible fruit of these plants. Lime plants are characterized by a spiny or thorny stem, green and leatherly leaves, and clusters of small and aromatic white flowers. The fruit, which is similar to the lemon, is juicy, oval (egg-shaped), small (3-6 centimeters in diameter), acidic, and typically green or yellowish green even when mature (but will turn yellow like the lemon if exposed to a cool winter environmental conditions). The lime fruit tends to be smaller and rounder (globular) than the lemon, and with a sweeter and more acidic pulp and a thinner rind.
The Citrus genus is a group of flowering plants in the family Rutaceae (orange family) that originated in tropical and subtropical southeast Asia and that have a distinctive berry with the internal parts divided into segments. Besides limes and lemons, other members of the Citrus genus include oranges, citrons, grapefruit, pomelos (pummelo, pommelo), and mandarins (tangerines). Most members of the Citrus genus arose as hybrids, and the hybridized types of citrus may or may not be recognized as species according to different taxonomies (Katz and Weaver 2003).
The fruit of the lime serves the plant's individual purpose of reproduction while also providing a number of values for human beings. Like the lemon, the lime is used for such culinary purposes as being diluted and sweetened and made into a drink, being used as a garnish for drinks, and used for flavoring for desserts, condiments, salad dressings, meats, and vegetables. The extracts and essential oils are used in cleaning products and perfumes, among other uses.