Picris echioides vs oxtongue

Picris echioides

oxtongue

noun
  • A flowering plant of the genus Anchusa, especially Anchusa officinalis (true alkanet). 

  • Beef tongue (a foodstuff). 

  • A flowering plant of the genus Picris, especially Picris echioides (bristly oxtongue). 

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