Mizuna (Brassica juncea var. japonica) also known as Xiu Cai, Kyona, Japanese Mustard, Potherb Mustard, Japanese Greens and California Peppergrass.
Mizuna is a Japanese mustard green with dandelion-like jagged edge green leaves with a mild, sweet earthy flavor.
It has been culitaved in Japan since ancient times, but most likely originated in China.
Mizuna makes an excellent salad green, and is frequently found in Mesclun. It is also used in stir-frys and soups.