Bok choy (brassica chinensis) is classified as a cabbage. It does not look like the round European cabbages found in western supermarkets, or to Napa cabbage. Its white stalks look like celery without the stringiness. The dark green, crinkly leaves of the most common type are like Romaine lettuce. The Chinese commonly refer to bok choy as pak choi or "white vegetable." Another common name is white cabbage.