pear lemon vs sweet lemon

pear lemon

sweet lemon

noun
  • Any of several plants that produce fruit resembling lemon or lime, but less acidic than lemon. 

  • A plant of the species Citrus medica (syn. Citrus limetta) or its fruit. 

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