Lemon --- Orange

Orange or lemon are all members of the genus Citrus flowering plants of the tribe Rutaceae (orange-jerukan tribe). Its members form a tree with fleshy fruit with a sour taste fresh, although many of its members who have a sweet taste. Sour taste comes from citric acid content which is to be contained in all of its members.
The name "orange" is sometimes also attributed to some other clan members who are allied in the same tribe, as kingkit. In everyday language, the mention of "orange" or "lime" (in Sumatra and Malaysia) often means "tangerine" or "sweet orange". In Java, "lime" (or "limo") means "lemon".
Oranges are very diverse and some species can intersect and produce interspecies hybrids ('interspecific hybrid) which has a distinctive character, which differs from its parental species. This variety is often difficult for classification, naming and recognition of its members, because new people can see the difference after the flowers or fruit appear. The result is not clear how many of its kind. Recent studies indicate is a strong relationship with the genus Fortunella Citrus (kumkuat), Poncirus, and Microcitrus and Eremocitrus, so there is the possibility of the merger. Citrus itself has two (subgenus), the Citrus and papeda.
Originally oranges are from East Asia and Southeast Asia, forming an arc that stretches from Japan continue south until then veering westward toward the eastern Indian. Sweet orange and citron (lemon) originated from East Asia, while grapefruit, lemon and lime from Southeast Asia.
Many members of the oranges which are utilized by humans as food, fragrances, and industrial. Citrus fruit is a source of vitamin C and the fragrance / perfume essential. The leaves are also used as spice. (Wikipedia)