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.
Citronellal
Citronellal or rhodinal or 3,7-dimethyloct-6-en-1-al (CHO) is a monoterpenoid, the main component in the mixture of terpenoid chemical compounds that give citronella oil its distinctive lemon scent.