Japanese Horseradish/Wasabi Root for Pungent Condiment

Wasabi (Eutrema japonicum or Wasabia japonica) or Japanese horseradish is a plant of the Brassicaceae family, which also includes horseradish and mustard in other genera. A paste made from its ground rhizomes is used as a pungent condiment for sushi and other foods. It is similar in taste to hot mustard or horseradish rather than chili peppers in that it stimulates the nose more than the tongue.
The plant grows naturally along stream beds in mountain river valleys in Japan. The two main cultivars in the marketplace are E. japonicum 'Daruma' and 'Mazuma', but there are many others. The oldest record of wasabi as a food dates to the 8th century CE. The popularity of wasabi in English-speaking countries has tracked that of sushi, growing steadily starting in about 1980.
Due to issues that limit the Japanese Wasabi plant's mass cultivation and thus increase its price and decrease availability, outside of Japan the Western Horseradish plant is generally used in place of the Japanese Horseradish. This version is commonly referred to as "Western Wasabi" in Japan.