Citron
A source of confusion is that "citron" or similar words in French (and other languages), and English are false friends, as they refer to the lemon. Indeed, into the 16th century, the English name "citron" included the lemon and perhaps the lime as well.
Moroccan citron
Chapot was probably first to describe this variety of citron in detail, along with illustrations of many forms of the fruit, and all the properties of the shrub, leaves and blossoms. 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.