Rhobs el Arsa
The Rhobs al Arsa has long been viewed as a citron hybrid, though a different cultivars have been suggested for the parent, for example, Moroccan citron as a male parent and sour orange as the female parent, citron or lemon and a mandarin., or citron and the lime. Detailed genomic analysis has shown Rhobs al Arsa to be highly similar to several cultivars of "Citrus limetta", the limetta or Persian sweet lime, and likely shared a common origin with them, arising from a cross between citron ("Citrus medica") and sour orange ("Citrus" × "aurantium"). The common lemon arose from a distinct hybridization event involving the same two species.
Citrus
The generic name originated from Latin, where it referred to either the plant now known as citron ("C. medica") or a conifer tree ("Thuja"). It is somehow related to the ancient Greek word for cedar, κέδρος ("kédros"). This may be due to perceived similarities in the smell of citrus leaves and fruit with that of cedar. Collectively, "Citrus" fruits and plants are also known by the Romance loanword "agrumes" (literally "sour fruits").