May blossom vs hawthorn tree

May blossom

noun
  • A species of flower-bearing hawthorn with edible berries, Crataegus monogyna. 

hawthorn tree

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

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