Chinese broccoli

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A plant (Brassica oleracea var. alboglabra) in the mustard family grown for its dark green leaves and stalks, used as a vegetable in eastern Asian cuisine.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun kailan: a long, blue-green vegetable that is a varietal of the species Brassica oleracea, with thick, glossy stems and leaves typically eaten in Chinese and particularly Cantonese cooking.