Citrus taxonomy
All of these hybrids have in turn been bred back with their parent stocks or with other pure or hybrid citrus to form a broad array of fruits. Naming of these is inconsistent, with some bearing a variant of the name of one of the parents or simply another citrus with superficially-similar fruit, a distinct name, or a portmanteau of ancestral species. The Ponderosa lemon ("Citrus limon" × "medica") and Florentine citron ("Citrus x limonimedica") are both true lemon/citron hybrids, the Bergamot orange is a sweet orange/lemon hybrid and the Oroblanco is a grapefruit/pomelo mix, while tangelos are tangerine (mandarin)/pomelo or mandarin/grapefruit hybrids, orangelos result from grapefruit backcrossed with sweet orange, and a sweet orange backcrossed with a tangerine gives the tangor. One lumia, a member of the sweet lemons, is the product of crossing a lemon with a pomelo/citron hybrid, though another lumia variety, the Pomme d'Adam, is a micrantha/citron cross, like the Key lime. The most common and commercially popular 'limes', the Persian limes, are Key lime/lemon hybrids that combine the genetic lineages of four ancestral citrus species: mandarin, pomelo, citron and micrantha.
Citrus
A variety of flavours can be derived from different parts and treatments of citrus fruits. The rind and oil of the fruit is generally very bitter, especially when cooked, so is often combined with sugar. The fruit pulp can vary from sweet to extremely sour. Marmalade, a condiment derived from cooked orange and lemon, can be especially bitter, but is usually sweetened to cut the bitterness and produce a jam-like result. Lemon or lime is commonly used as a garnish for water, soft drinks, or cocktails. Citrus juices, rinds, or slices are used in a variety of mixed drinks. The colourful outer skin of some citrus fruits, known as zest, is used as a flavouring in cooking; the white inner portion of the peel, the pith, is usually avoided due to its bitterness. The zest of a citrus fruit, typically lemon or an orange, can also be soaked in water in a coffee filter, and drunk.