bract vs leaf node

bract

noun
  • A leaf or leaf-like structure from the axil out of which a stalk of a flower or an inflorescence arises. 

leaf node

noun
  • One of the spots upon a stem where buds and intercalary meristems occur, usually marking the end of a season's growth. 

  • A node, in a tree, that has no children. 

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