bloodroot vs tetterwort

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. 

tetterwort

noun
  • Sanguinaria canadensis, the bloodroot. 

  • A plant used as a remedy for tetter, Chelidonium majus 

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