horseradish vs mustard greens

horseradish

noun
  • A plant of the mustard family, Armoracia rusticana. 

  • A pungent condiment made from the root of the plant. 

mustard greens

noun
  • Brassica juncea, a mustard plant with edible leaves, seeds, and stem. 

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