skokeberry vs winterberry

skokeberry

noun
  • A pokeberry; a pokeweed (the plant Phytolacca americana or its dark red or purple fruit). 

winterberry

noun
  • The fruit of this plant. 

  • A species of holly native to the United States and Canada and producing red berries, Ilex verticillata. 

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