cowberry vs deerberry

cowberry

noun
  • The berry of this shrub. 

  • A shrub native to the cool temperate areas of the Northern Hemisphere (Vaccinium vitis-idaea). 

deerberry

noun
  • Maianthemum dilatatum (snakeberry), or its fruit. 

  • Mitchella repens (partridgeberry), or its fruit. 

  • Gaultheria procumbens (Eastern teaberry or checkerberry), or its fruit. 

  • Vaccinium stamineum (squaw huckleberry), or its fruit. 

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