shrubbery vs underbrush

shrubbery

noun
  • Shrubs collectively. 

  • A planting of shrubs; a wide border to a garden where shrubs are thickly planted; or a similar larger area with a path winding through it. 

underbrush

noun
  • The small trees and other plants that clutter the floor of a forest. 

verb
  • To clear (an area) of underbrush. 

  • To work among the underbrush. 

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