bearberry vs cascara buckthorn

bearberry

noun
  • Any of three dwarf shrubs of the genus Arctostaphylos, which principally grow in arctic and subarctic regions and bear edible berries. 

  • Arctostaphylos uva-ursi, the common bearberry. 

  • Arbutus menziesii. 

cascara buckthorn

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