whimberry vs whortleberry

whimberry

noun
  • The bilberry or whortleberry (Vaccinium myrtillus). 

whortleberry

noun
  • Vaccinium myrtillus (bilberry or blue whortleberry); 

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

  • Vaccinium uliginosum (bog whortleberry or bilberry). 

  • A berry of one of these shrubs. 

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