Citron
There are also a number of citron hybrids; for example, ponderosa lemon, the lumia and rhobs el Arsa are known citron hybrids, some are claiming that even the Florentine citron is not pure citron, but a citron hybrid.
Greek citron
Historically speaking, the citron is considered by numerous writers, to be introduced to Europe by the troops of Alexander. It was also described by Theophrastus, who succeeded Aristotle as the curator of the Botanical garden in Athens.