pigeonweed vs winterberry

pigeonweed

noun
  • Synonym of pokeweed (“the plant Phytolacca americana”) 

winterberry

noun
  • The fruit of this plant. 

  • A species of holly native to the United States and Canada and producing red berries, Ilex verticillata. 

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