American pokeweed vs red nightshade

American pokeweed

noun

  • Phytolacca americana, pokeweed. 

red nightshade

noun

  • Phytolacca americana syn. Phytolacca decandra 

  • Solanum villosum 

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