beet vs mangelwurzel

beet

noun
  • Beta vulgaris, a plant with a swollen root which is eaten or used to make sugar. 

  • A beetroot, a swollen root of such a plant. 

mangelwurzel

noun
  • A root vegetable, variety of Beta vulgaris, cultivated chiefly as cattle feed. 

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