Christmas berry vs Michigan holly

Christmas berry

noun
  • Synonym of toyon (“plant or its berry”) (Photinia arbutifolia, syn. Heteromeles arbutifolia) 

  • Synonym of spiceberry (“plant or its berry”) 

Michigan holly

noun
  • American winterberry, Ilex verticillata. 

How often have the words Christmas berry and Michigan holly occurred in a corpus of books? (source: Google Ngram Viewer )