cultivar vs morphology

cultivar

noun
  • A cultivated (not necessarily botanical) variety of a plant species or hybrid of two species. 

morphology

noun
  • The study of the form and structure of animals and plants. 

  • The study of the internal structure of morphemes (words and their semantic building blocks). 

  • The form and structure of something. 

  • Mathematical morphology. 

  • The study of the structure of rocks and landforms. 

  • A description of the form and structure of something. 

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