blue raspberry vs whitebark raspberry

blue raspberry

noun
  • An artificial flavor used in candy and soft drinks, which, despite the name, is not derived from any species of raspberry. 

whitebark raspberry

noun
  • The dark purple composite fruit of this plant, similar to a raspberry. 

  • A deciduous, viny shrub (Rubus leucodermis) with a pale, whitish bark. 

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