grove vs understory

grove

noun
  • A small forest. 

  • A place of worship. 

  • An orchard of fruit trees. 

  • A lodge of the Ancient Order of Druids. 

verb
  • To cultivate in groves; to grow naturally so as to form groves. 

  • To plough or gouge with lines. 

  • To cultivate with periodic harvesting that also serves to create order (gaps and lines of trees) to facilitate further harvesting. 

understory

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

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