pepper root
noun
1The root of a pepper of the genus Piper; especially that of the Polynesian P. methysticum, used to make kava.
2 US any of several plants of the genus Cardamine (formerly called Dentaria), especially C. diphylla, whose roots have a pungent taste like watercress.
Origin
Mid 17th century; earliest use found in Mercurius Politicus.