pokeberry vs pokeweed

pokeberry

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

pokeweed

noun
  • A poisonous North American plant, Phytolacca americana, with reddish stems, broad leaves, clusters of white flowers, and dark purple berries. 

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