The following is an excerpt from Whole Foods Companion: A Guide for Adventurous Cooks, Curious Shoppers, and Lovers of Natural Foods by Dianne Onstad. It has been adapted for the Web.
Chinese Cabbage (Brassica chinensis, B. rapa)The Latin name Brassica derives from the Celtic bresic; chinensis designates the plant’s Chinese origins.
Long appreciated for its delicate flavor and crisp texture, Chinese cabbage has been cultivated since before the Christian era. It has been described as a cabbage that even cabbage haters love—it is crisper, juicier, sweeter, and more tender than common cabbage. There are several varieties of Chinese cabbage, the two most popular being bok choy and Pe-tsai. All form a head, but the head varies from round like cabbage to elongated like romaine lettuce; also, the crinkly leaves may curl inward or outward.
In most markets, at least one form or another of Chinese cabbage is available year-round. Select fresh, light-colored greens with plump ribs. Squeeze the heads to find a firm, heavy one. Avoid those that have wilted leaves with any rot spots. Small dark specks, however, are naturally occurring. Chinese cabbage stores exceptionally well (but not so long as cabbage), and the flavor even improves when it is slightly wilted.