Citrus taxonomy refers to the botanical classification of the species, varieties, cultivars, and graft hybrids within the genus Citrus, subgenus Papeda, and related genera, found in cultivation and in the wild. Citrus taxonomy is complex. Cultivated citrus are derived from various forms of old citrus species found in the wild. Some are only selections of the original wild types, while others are hybrids between two or more ancestors. Citrus plants hybridize easily between species with completely different morphologies, and similar-looking citrus fruits may have quite different ancestries.