Napa cabbage

Napa cabbage (Brassica rapa subsp. pekinensis), also called Chinese cabbage or pe-tsai, is a biennial herb of the mustard family (Brassicaceae). In the first year it forms a barrel- or cylinder-shaped head 30–50 cm tall and 1–3 kg, made of tightly packed leaves; the leaf blades are broad with white stalks and veins, and the inner leaves are pale yellow and crisp-sweet. In the second year it bolts into a flowering stem with small yellow flowers in a raceme (typical of Brassicaceae), insect-pollinated but largely self-pollinating. Napa cabbage originated in northern China, has been grown for over 1,500 years, and is one of the most important brassica vegetables in Asia.

Napa cabbage is a familiar East Asian vegetable: cooked in hotpot, stir-fried with meat, blanched, used as dumpling filling and in salads; it is especially pickled into kimchi in Korea and into pickled or dried mustard greens in China and Vietnam. It is low in calories and rich in vitamins C and K, provitamin A, folate, calcium and fibre, suiting weight-loss diets. Its mild sweetness and crunch also make it good in sweet-and-sour vinegar salads. In Vietnam napa cabbage is grown mainly in the northern winter season (Red River Delta, Moc Chau, Sa Pa) and in the cool season in Da Lat; being a cold-loving crop it bolts readily in heat. The leaves are also used in folk medicine as cooling and diuretic.