Christmas berry vs desert-thorn

Christmas berry

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

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

desert-thorn

noun
  • Any desert-growing member of the genus Lycium 

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