Turnip greens are the dark, coarse leaves growing above the swollen root of the turnip, Brassica rapa — the same plant that gives the familiar white-and-purple root, but eaten here for its top growth rather than the bulb below. Assertively bitter, faintly peppery and hearty, they are a cornerstone of the cooking of the American South, where they are stewed low and slow with smoked pork until meltingly tender, and of Portugal and Galicia, where the same young shoots are prized as grelos and nabiça. Cooked quite differently from the root and usually filed apart from it, they are a winter and early-spring green built for long, savoury braises.