He discovered that the acidity in the more common citrons or lemons, is represented by red on the inner coat of seeds specifically on the chalazal spot, violet pigmentation on the outer side of the flower blossom, and also by the new buds that are reddish-purplish.

He also mentions that the true citron of Morocco, which is traditionally only grown in the region of Assads, for the sake of the mitzva of four species, and is oblong, acidless and rather dry, is much different than the rounded citron hybrid, Rhobs el Arsa, that is more commonly grown for food in the entire country of Morocco, and its taste is acidic and fruity.

[4] The precise location of cultivation is at the village Assads in the Taroudant Province, and a 100 km east of Agadir, as was numerously reported by rabbinical and secular sources.

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.