darnel vs ryegrass

darnel

noun
  • Various species of Lolium, especially as a weed in wheat fields. 

  • A species of ryegrass, Lolium temulentum, often found in wheat fields and often host to a fungus intoxicating to humans and animals. 

ryegrass

noun
  • Any of several species of tufted grasses of the genus Lolium. 

  • A collection of plants of any of the species, as in a lawn or field. 

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