galangal vs tormentil

galangal

noun
  • Any of several east Asian plants of genera Alpinia and Kaempferia in the ginger family, used as a spice, but principally Alpinia galanga. 

tormentil

noun
  • A low-growing herb (Potentilla erecta, syn. Potentilla tormentilla). 

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