pistachio vs sweet chestnut

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. 

sweet chestnut

noun
  • The edible nuts of this tree. 

  • A type of deciduous tree native to Europe, Castanea sativa. 

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