<P> Mustard plants are any of several plant species in the genera Brassica and Sinapis in the family Brassicaceae . Mustard seed is used as a spice . Grinding and mixing the seeds with water, vinegar, or other liquids creates the yellow condiment known as prepared mustard . The seeds can also be pressed to make mustard oil, and the edible leaves can be eaten as mustard greens . </P> <P> Although some varieties of mustard plants were well - established crops in Hellenistic and Roman times, Zohary and Hopf note, "There are almost no archeological records available for any of these crops ." Wild forms of mustard and its relatives, the radish and turnip, can be found over west Asia and Europe, suggesting their domestication took place somewhere in that area . However, Zohary and Hopf conclude: "Suggestions as to the origins of these plants are necessarily based on linguistic considerations ." Encyclopædia Britannica states that mustard was grown by the Indus Civilization of 2500 - 1700 BCE . According to the Saskatchewan Mustard Development Commission, "Some of the earliest known documentation of mustard's use dates back to Sumerian and Sanskrit texts from 3000 BC". </P>

Which parts of mustard plant can be eaten