cowberry vs lingonberry

cowberry

noun

  • The berry of this shrub. 

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

lingonberry

noun

  • The berry of this shrub. 

  • A berry-bearing shrub, Vaccinium vitis-idaea, native to the cool temperate areas of the Northern Hemisphere. 

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