Ipomoea alba vs moonflower

Ipomoea alba

moonflower

noun
  • Species in genus Cereus and in Hylocereus. 

  • Any of several vines of the genus Ipomoea, especially Ipomoea alba. 

  • Species of Datura, including Datura inoxia. 

  • Species of Mentzelia, including Mentzelia pumila. 

  • The corn marigold, Glebionis segetum. 

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