Wasabi

wasabi, (Eutrema japonicum), also called Japanese horseradish, plant of the mustard family (Brassicaceae) and a pungent paste made of its ground rhizomes. The plant is native to Japan, South Korea, and Sakhalin, Russia, and its cultivation is limited because of its specific growing requirements. Given the high price and limited availability of true wasabi rhizomes, the wasabi paste of Western restaurants is commonly made from horseradish (Armoracia rusticana), another plant of the mustard family.