legume vs string bean

legume

noun
  • The fruit or seed of leguminous plants (as peas or beans) used for food. 

  • A pod dehiscent into two pieces or valves, and having the seed attached at one suture, as that of the pea. 

  • Any of a large family (Fabaceae, syn. Leguminosae) of dicotyledonous herbs, shrubs, and trees having fruits that are legumes or loments, bearing nodules on the roots that contain nitrogen-fixing bacteria, and including important food and forage plants (as peas, beans, or clovers). 

string bean

noun
  • A yardlong bean (Vigna unguiculata subsp. sesquipedalis) 

  • A hyacinth bean (Lablab purpureus) 

  • Any long, slender green bean. 

  • A tall and thin person. 

  • An immature runner bean (Phaseolus coccineus) 

  • A common bean (Phaseolus vulgaris) 

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