knotgrass vs verdolaga

knotgrass

noun
  • An annual plant, Polygonum aviculare, found in fields and wasteland 

  • Paspalum distichum, a weedy perennial grass of wet areas 

verdolaga

noun
  • Portulaca oleracea, common purslane. 

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