Mizuma is a Japenese green that grows easily. Its leafy and something between a lettuce and a brassica. When young, the delicate leaves can be used in salads. Its really great in Miso soup, too. When it gets bigger, you chop it 1" pieces and steam it or it can be cooked like collards.

If you let it go to seed, you may get some volunteer. Its very hardy and I always keep a patch in my garden.