Jerusalem artichoke vs turnip

Jerusalem artichoke

noun
  • The tuber of this plant, eaten as a vegetable. 

  • A variety of sunflower, Helianthus tuberosus, native to North America, having yellow flower heads and edible tubers. 

turnip

noun
  • The yellow root of a related plant, the swede or Brassica napus. 

  • The white root of Raphanus sativus var. longipinnatus, also known as a daikon. 

  • A fool or simpleton. 

  • The white root of a yellow-flowered plant, Brassica rapa, grown as a vegetable and as fodder for cattle. 

verb
  • To feed or graze (livestock) on turnips. 

  • To plant with turnips. 

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