Generally 3 small heads per bunch.
Bok choy is a dark leafy green in the cabbage family. It is generally associated with Chinese cuisine, and often appears in stir fries, soups, and steamed dishes. The plant has a mildly spicy flavor that hints at the relationship to mustard, and grows readily in many parts of the world outside of China, although it is not widely used in other regional cuisines. It is also available in many grocery stores, and sometimes identified as Chinese cabbage or Chinese white cabbage. Bok choy should not be confused with Napa cabbage, which is also sometimes labeled as Chinese cabbage in grocery stores.
The formal name for bok choy is Brassica rapa ssp. chinensis. The plant has dark green, crisp leaves and crunchy white stems, both of which are high in calcium along with vitamins A and C. Superficially, bok choy vaguely resembles a head of celery with bunches of dark green leaves, and it is called celery cabbage in some parts of the world for this reason.
Because bok choy has a high water content, it will rapidly turn limp and mushy when cooked. For this reason, it is usually added to a recipe at the end, or very briefly cooked. The stems take more time to cook than the leaves, and many cooks separate the stems and leaves so that the stems can be thrown in approximately one minute before the leaves, allowing them more time to cook. The zesty flavor and crunch are excellent additions to Chinese food, but the delicious vegetable can also be tossed with pasta or added to a sauteed vegetable medley.