Korean morning glory vs green dragon

Korean morning glory

green dragon

noun
  • A tincture of cannabis, typically made by soaking the flowers, leaves, or stems in ethyl alcohol. 

  • Used other than figuratively or idiomatically: see green, dragon. 

  • Any of several plants in the family Araceae, including the North American species Arisaema dracontium and the Asian genus Pinellia. 

How often have the words Korean morning glory and green dragon occurred in a corpus of books? (source: Google Ngram Viewer )