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.
Moroccan citron
As to the Diamante citron (Yanova) and the Greek citron (Corfu), he argued based on the booklet from the Salant partners, that since some of them are proven to be grafted, no certification may be granted to the rest, since it is impossible to determine if the non-grafted citrons are not descendants of the grafted ones.
As to the Moroccan and Yemenite citrons he argued, that although there were no grafted trees ever discovered among those kinds, they should be unfit, in light of the differentiation from the Ashkenazi types. The Moroccan citron is allegedly noted for its seedlessness, and the Yemenite for its pulplessness, both are too much different in morphology from the traditional Yanova and Israeli esrogs.