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.
Rangpur (fruit)
"Citrus" × "limonia" was introduced into Florida in the late nineteenth century by Reasoner Brothers of Oneco, who obtained seed from northwestern India. Though often described as a lemon hybrid, genomic analysis has shown it to be an F1 hybrid of a female citron ("Citrus medica") and a male mandarin orange ("Citrus reticulata").