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.
Boronia citriodora
Boronia citriodora is also known as lemon-scented boronia, lemon plant, lemon thyme.
The shrub is endemic to Tasmania, with a widespread distribution.