Mustard greens are the leaves of the mustard plant. They are extremely nutritious Containing huge amount of vitamins and minerals. Mustard greens are green in color, some are dark red or deep purple in colour. Mustard greens are crumpled or flat in texture and having toothed, scalloped, frilled or lacey edges. This plant also produces the Acrid-tasting brown seeds that are used to make Dijon mustard.