cockspur vs cockspur thorn

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). 

cockspur thorn

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