Christmas berry vs boxthorn

Christmas berry

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

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

boxthorn

noun
  • Any plant of the genus Lycium. 

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