snake bean vs yardlong bean

snake bean

noun
  • Vigna unguiculata subsp. sesquipedalis, a widely cultivated edible legume. 

  • Bobgunnia madagascariensis, a poisonous legume found in Africa. 

yardlong bean

noun
  • A vigorous climbing annual vine (Vigna unguiculata subsp. sesquipedalis) grown primarily for its strikingly long (35-75 cm) immature pods with uses very similar to that of a green bean. 

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