gill-over-the-ground vs ground-ivy

gill-over-the-ground

noun

  • ground ivy 

ground-ivy

noun

  • Glechoma hederacea, an aromatic, perennial, evergreen creeper of the mint family Lamiaceae 

How often have the words gill-over-the-ground and ground-ivy occurred in a corpus of books? (source: Google Ngram Viewer )