Horseradish

Horseradish, Armoracia rusticana, is a perennial plant in the family Brassicaceae, the same family as mustard, wasabi, broccoli, cabbage and radish, likely native to Southeastern Europe and Western Asia and used as both a root vegetable and a culinary spice or condiment worldwide. It grows to about 1.5 meters with hairless, bright green, unlobed leaves up to a meter long and fragrant white four-petaled flowers in dense clusters, and it is cultivated chiefly for its large, white, tapered root. The intact root has little aroma, but cutting or grating it releases the enzyme-triggered compound allyl isothiocyanate, or mustard oil, which irritates the sinuses and eyes; once exposed to air or heat the root loses its pungency, darkens and turns bitter, and it is used widely as a spice and condiment, including in sauce preparation and traditional ceremonial dishes.