Lumia (citrus)
A recent genomic analysis of several species commonly called 'lemons' or 'limes' revealed that the various individual lumias have different genetic backgrounds. The 'Hybride Fourny' was found to be an F1 hybrid of a citron- pomelo cross, while the 'Jaffa lemon' was a more complex cross between the two species, perhaps an F2 hybrid. The Pomme d'Adam arose from a citron-micrantha cross, while two other lumias, the ‘Borneo’ and ‘Barum’ lemons, were found to be citron-pomelo-micrantha mixes.
Citrus taxonomy
The pomelo ("Citrus maxima"), a second of the core species from which most citrus hybrids have derived, is native to southeast Asia. Among the hybrids deriving from mandarin/pomelo crosses, there is a direct correlation between the proportion of pomelo DNA in the hybrid and fruit size, while the more palatable mandarins are those that have received specific genes from pomelos that alter their acidity. Some of the more common pomelos are genetically pure, while a number have a single small region of introgressed mandarin DNA on one chromosome, the result of a cross followed by extensive backcrossing with pomelo.