The turnip is the round, white storage root of Brassica rapa, a cool-season brassica whose smooth skin is washed purple where the crown rises into the light. Crisp and peppery when raw, it turns sweet, mellow and faintly mustardy once cooked — boiled, roasted, mashed and simmered into stews across Europe and Asia. Small young turnips are tender enough to eat raw, while the leafy tops are cooked in their own right as turnip greens.