The dekopon is the knobbed, seedless premium eating mandarin — a tangor bred in Japan from Kiyomi and ponkan and sold worldwide as Sumo Citrus. Instantly recognisable by the raised bump at its stem end, it is unusually large for a mandarin, peels away in a single sheet from a loose, bumpy rind, and eats intensely sweet and low in acid, with a firm, honeyed, seedless flesh that has made it one of the most sought-after fresh citrus of the winter season.