The citron (Citrus medica) is a large, fragrant, thick-skinned citrus fruit grown almost entirely for its rind rather than its flesh. Inside the bumpy yellow peel lies a deep layer of white pith and only a little dry, acidic or faintly sweet pulp — so the fruit is prized for its intensely perfumed zest and for the candied peel ("succade") that flavours fruitcakes, panettone and confectionery the world over.