Moroccan citron
The Moroccan citron was described by the Moroccan professor Henri Chapot, as being a sweet citron, meaning that its pulp is low in acid. 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. The Moroccan citron which is acidless is completely lacking the red color. This designation was cited by Herbert John Webber and Leon Dexter Batchelor the editors of the fundamental treatise on citrus, namely The Citrus Industry, which was published by the University of California, Riverside in 1967.
Diamante citron
While Calabria is at the southern point of Italy, and its climate most Mediterranean, it is the most suitable for the citron. Even though, during the winter it is still too cold for the citron; this is why the farmers need to protect them with blue or green plastic covers. Most of the citron trees in the area are grafted onto foreign citrus rootstock, in order to save them from frost and disease. This practice renders their fruits non-kosher for the Sukkot ritual, and therefore in order for a mashgiach to certify a citron as kosher, he must first carefully inspect the tree to confirm it was not grafted.