Wasabi (わさび（山葵） , originally 和佐比; Eutrema japonicum/Wasabia japonica) is a plant of the Brassicaceae family, which includes cabbages, horseradish, and mustard.It is also called Japanese horseradish, although horseradish is a different plant (which is often used as a substitute for wasabi).t is also called Japanese horseradish, although horseradish is a different plant (which is often used as a substitute for wasabi).