pocan vs red nightshade

pocan

noun

  • The poke, Phytolacca americana (formerly Phytolacca decandra). 

red nightshade

noun

  • Phytolacca americana syn. Phytolacca decandra 

  • Solanum villosum 

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