pokeberry vs yellow nightshade

pokeberry

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

yellow nightshade

noun
  • Physalis crassifolia 

  • Solanum villosum 

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