pistachio vs pistachio tree

pistachio

noun
  • The nutlike fruit of this tree. 

  • A pale green colour, like that of a pistachio seed. 

  • A deciduous tree (Pistacia vera) grown in parts of Asia for its drupaceous fruit. 

pistachio tree

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