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.
Ponderosa lemon
The ponderosa lemon ("Citrus " x "pyriformis") is a citrus hybrid of a pomelo and a citron. It is not the same as the 'Yuma Ponderosa' lemon pomello hybrid, that is used as citrus rootstock.