bramble vs understory

bramble

noun
  • Any thorny shrub. 

  • A cocktail of gin, lemon juice, and blackberry liqueur. 

  • The soft fruit borne by the species Rubus fruticosus formed of a black (when ripe) cluster of drupelets. 

  • Any of many closely related thorny plants in the genus Rubus including the blackberry and likely not including the raspberry proper. 

understory

noun
  • The layer of plants that grow in the shade of the canopy of a forest. 

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