Mustard is a plant in the cabbage family that is native to Europe and the Mediterranean region. Like other species in the Brassica family, mustard is harvested for its zesty-tasting leaves that are cooked and eaten as a vegetable in summer. Mustard is also grown and harvested for its seeds, which range in color and flavor sharpness depending on variety. Like peppercorns, mustard seed has a long history of use globally and remains one of the most widely traded spices in the world today. In addition to culinary use, mustard seed is used to make heat-producing poultices. Powdered mustard seed is also used as a laundry aid – it helps to break up protein-based stains, such as dried egg yolk.