creeping Charlie vs gill-over-the-ground

creeping Charlie

noun

  • ground ivy, Glechoma hederacea 

  • Swedish ivy (Plectranthus verticillatus), in the mint family, a popular houseplant 

  • creeping Charlie (Pilea nummulariifolia), a houseplant in the nettle family 

  • moneywort 

gill-over-the-ground

noun

  • ground ivy 

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