pokeberry vs white alder

pokeberry

noun
  • Synonym of pokeweed (the plant Phytolacca americana or its dark red or purple fruit). 

white alder

noun
  • American winterberry (Ilex verticillata). 

  • Grey alder (Alnus incana) 

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