A prized variety of lemon from the south of Naples. It is left to ripen on the tree so that its flavour is less acid. It is larger than ordinary lemons and has a knobbly skin. The Amalfi lemon is officially recognized as unique by the PGI, or Protected Geographic Indication, which was awarded in 2001. It is pale yellow in colour, has few seeds and is quite large, with a prominent nipple. It has a number of oil glands and is used in the making of limoncello. It is said that the rich volcanic soil provided by Mount Vesuvius contributes to the sweetness and complex, deep flavour of the Amalfi lemon.