friendship tree vs money tree

friendship tree

money tree

noun
  • A cheap tree sculpture, decorated with currency, used as a raffle prize because it would be illegal to offer a cash prize. 

  • The jade plant, Crassula ovata. 

  • An imaginary tree from which money can be plucked. See money doesn't grow on trees. 

  • The cocoa tree, Theobroma cacao. 

  • A kind of holy tree believed to bring money and good fortune. 

  • The Malabar chestnut, Pachira aquatica. 

  • A miniature tree sculpture decorated with currency, often used as a raffle prize or a gift. 

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