Mustard tuber , angiosperm, a family of the Dicotyledon class. Mostly herbaceous plants. Mustard is the mustard in a class, generally refers to the leaf mustard a category, such as nine mustard, Brassica juncea , porcine blood mustard, yuba mustard and the like. Pickled mustard is a semi-dry non-fermented pickle. It is made by pickling the stem with mustard green as a raw material. It is one of the famous Chinese specialty products, as well as European sauerkraut and Japanese pickles.