Bok choy, pak choi or pok choi is a type of Napa cabbage, used as food. Chinensis varieties do not form heads and have green leaf blades with lighter bulbous bottoms instead, forming a cluster reminiscent of mustard greens. It has a flavor between spinach and water chestnuts but is slightly sweeter, with a mildly peppery undertone. The green leaves have a stronger flavor than the white bulb.
Chinensis varieties are popular in southern China, East Asia, and Southeast Asia. Being winter-hardy, they are increasingly grown in Northern Europe. Now considered a subspecies of Brassica rapa, this group was originally classified as its own species under the name Brassica chinensis by Carl Linnaeus. They are a member of the family of Brassicaceae or Cruciferae, also commonly known as the mustards, the crucifers, or the cabbage family.