cockspur vs common barnyard grass

cockspur

noun
  • A blade for tying to the foot of a gamecock. 

  • A kind of hawthorn (Crataegus crus-galli). 

  • A kind of grass (Echinochloa crus-galli). 

common barnyard grass

How often have the words cockspur and common barnyard grass occurred in a corpus of books? (source: Google Ngram Viewer )