Citrus

Among the most important tree fruits globally, originating in southern China, northern India, and Southeast Asia. All common domesticated citrus descend from just three parent species — citron (C. medica), mandarin (C. reticulata), and pummelo (C. grandis) — with the rest being natural and intentional hybrids of extraordinary variety. All citrus are non-climacteric: they ripen gradually on the tree, lack starch reserves, and cannot improve in sweetness after harvest. Their meaty peel, gel-making pectins, and robust post-harvest shelf life make them the most shippable of fresh fruits.