A plum is the smooth-skinned, single-stoned fruit of the European plum tree (Prunus domestica), a member of the rose family kin to cherry, peach and apricot. Its taut skin — yellow, red, purple or near-black, often dusted with a pale waxy bloom — gives way to juicy amber-to-crimson flesh that runs from mouth-puckeringly tart when underripe to honeyed and almost winey when soft. Eaten fresh, baked into tarts, simmered into jam, distilled into slivovitz, and dried whole into prunes.