Bok choy (Brassica rapa subsp. chinensis), also called pak choi or Chinese white cabbage, is a non-heading, cool-season brassica grown for its loose rosette of smooth, glossy, spoon-shaped dark-green leaf blades carried on broad, crisp, juicy white or pale-green leaf stalks. Mild, sweet and faintly mustardy, it is a staple of stir-fries, soups and braises across East Asia, where the quick-wilting leaves and the snappy, water-rich stems are often added at different stages so each keeps its texture.