Wasabi, is a member of the Brassicaceae family, which includes cabbages, horseradish, and mustard. It is also called Japanese horseradish, although it is not actually from the horseradish species of plants. Its root is used as a condiment and has an extremely strong flavor. Its hotness is more akin to that of a hot mustard than that of the capsaicin in a chili pepper, producing vapours that stimulate the nasal passages more than the tongue. The plant grows naturally along stream beds in mountain river valleys in Japan. There are also other species used, such as W. koreana, and W. tetsuigi. The two main cultivars in the marketplace are W. japonica 'Daruma' and 'Mazuma', but there are many others.
Contributions by Eyrian, Bunchofgrapes, and JALockhart.