snake bean vs yard-long bean

snake bean

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

  • Bobgunnia madagascariensis, a poisonous legume found in Africa. 

yard-long bean

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