greater celandine vs petty spurge

greater celandine

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

petty spurge

noun
  • The plant Euphorbia peplus. 

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