pigeonweed vs possumhaw

pigeonweed

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

possumhaw

noun
  • American winterberry, Ilex verticillata. 

  • Deciduous Holly, Ilex decidua. 

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