Which plant is the source of the pungent condiment traditionally made from its grated rhizome in Japan?

Japanese horseradish, commonly called wasabi, is the plant source of the pungent Japanese condiment made from a grated rhizome.

Its scientific name is Eutrema japonicum, and it belongs to the cabbage family, Brassicaceae. The plant grows naturally along cool mountain streams in Japan, where clean, moving water and shaded conditions support its development.

The characteristic heat comes from isothiocyanates, compounds released when the plant tissue is damaged by grating. This differs from the capsaicin heat of chili peppers. Freshly grated wasabi is highly aromatic and loses intensity relatively quickly.

Much restaurant “wasabi” outside Japan is a mixture based largely on horseradish, mustard, starch, and green coloring because true wasabi is difficult and expensive to cultivate. Common horseradish is related, but it is a different species and has a sharper, longer-lasting flavor.