A cool-weather vegetable in the cabbage family (Brassicaceae) grown for the fat, rounded, turnip-like swelling of its stem just above the soil surface. Missouri Botanical Garden PlantFinder describes a low, compact annual crop about 0.75-1 foot tall and wide that rarely flowers and is best picked young, when the bulb reaches 2-3 inches across and is tender and sweet — left larger it turns tough and woody. It needs cool temperatures and grows poorly once daytime highs consistently exceed 80°F, so it is typically grown as a spring or fall crop. Both the swollen stem and the leafy tops are edible, raw or cooked.