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.
Corsican citron
The tree produces large fruit, ellipsoid to very slightly obovate; basal area slightly depressed and radially furrowed; apical nipple suppressed or indistinct. Color lemon-yellow when ripe. Rind very thick and fleshy, sweet with some bitter after-taste; surface rather rough, bumpy, and commonly somewhat ribbed. Flesh crisp and solid; lacking in juice; flavor sweet without acid. Seeds white yellowish. This giant citron can measure up to 25 cm in length and weigh up to 4 kg.