The Collaborative International Dictionary of English v.0.48:

crinkle root \crinkle root\, crinkleroot \crinkleroot\n.
   a North American herb (Dentaria diphylla) with pungent
   scaly or toothed roots; -- called also toothwort.

   Syn: pepper root, toothwort, Cardamine diphylla, Dentaria
        diphylla.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Cardamine diphylla
    n 1: North American herb with pungent scaly or toothed roots
         [syn: crinkleroot, crinkle-root, crinkle root,
         pepper root, toothwort, Cardamine diphylla, Dentaria
         diphylla]