bloodroot vs tormentil

bloodroot

noun
  • A North American plant, Sanguinaria canadensis, of the poppy family, which has a red root and sap and a single white flower in early spring. 

tormentil

noun
  • A low-growing herb (Potentilla erecta, syn. Potentilla tormentilla). 

How often have the words bloodroot and tormentil occurred in a corpus of books? (source: Google Ngram Viewer )