bloodroot vs greater celandine

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. 

greater celandine

noun
  • A European perennial herb, Chelidonium majus, a flower of the poppy family with yellow flowers, native to Europe and western Asia. 

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