There are no U.S. grade standards for Bok Choy. These instructions have been developed by the Specialty Crops Inspection Division to assist officially licensed inspectors in making inspections, writing certificates and to assist in the proper identification of specialty type fruits and vegetables.
Bok Choy (Chinese Chard, Boy-Toyo, Pak-Choy, Paak-Tsoi, Bok Toy) is probably the best known of all the Orient-grown vegetables. The plant is a general favorite because of the pleasing sweet, crisp taste of it petioles (supporting stems). It is a native of Asia and belongs to the same family as Napa and Michihle.
There are four forms of Bok Choy. The most common is the one with thick white stalks, each with a leaf which is large, dark green and rather oval in shape. The other lesser known types include the seedling stage of the above and is the result of thinning the plants; a stout form with luxuriant leaves and fleshy petioles without flower buds or blossoms; and a flowering type which is slender and has long, round, narrow petioles and narrow leaves and tops which bear yellow blossoms.