hawthorn tree vs thornbush

hawthorn tree

noun
  • A tree of the genus Crataegus, having small, apple-like fruits and thorny branches. 

thornbush

noun
  • Any of many thorny or spiny shrubs and bushes. 

  • Hyponyms: bramble, briar 

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