The mustard plant is a 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.

https://en.wikipedia.org/wiki/Mustard_plant