caryopsis vs oats

caryopsis

noun
  • A type of fruit in which the fruit skin is stuck to the seed coat; especially the grain of a cereal. 

oats

noun
  • Seeds of an oat plant, especially prepared as food. 

  • A mass of oat plants (genus Avena, especially Avena sativa). 

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