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.
Citropten
Citropten is a natural organic compound with the molecular formula CHO. It is found in the essential oils of citrus such as lime, lemon, and bergamot.