lingonberry vs whortleberry

lingonberry

noun
  • The berry of this shrub. 

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

whortleberry

noun
  • A berry of one of these shrubs. 

  • Vaccinium vitis-idaea (lingonberry or red whortleberry); 

  • Vaccinium myrtillus (bilberry or blue whortleberry); 

  • Vaccinium uliginosum (bog whortleberry or bilberry). 

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