either of two widely cultivated members of the mustard family (Brassicaceae). Brassica pekinensis, also called celery cabbage, forms a tight head of crinkled light green leaves. One type, Michihli, or Tientsin, forms slender cylindrical heads about 45 cm (18 inches) tall. It has long been grown in the United States as a salad vegetable. Napa is similar, but its heads are shorter and thicker, 30 cm (12 inches) tall. Brassica chinensis, also called Chinese mustard, or bok choy, has glossy dark green leaves and thick, crisp white stalks in a loose head. Its yellow-flowering centre is especially prized. All Chinese cabbages are delicate and crisp, qualities that enable them to combine with a wide variety of foods. Kimchi, the universal Korean pickle, is often made with Chinese cabbage.