The mandarin (Citrus reticulata) is the loose-skinned, easy-peel sweet citrus — the group that includes tangerines, clementines and satsumas. Smaller, sweeter and far less acidic than an orange, it slips out of its thin, puffy rind in seconds and falls apart into segments that pull cleanly away. More than a snack fruit, it is one of the three ancestral citrus species from which oranges, grapefruits and most cultivated citrus descend.