lizard tail vs lizard's tail

lizard tail

lizard's tail

noun
  • Houttuynia cordata, chameleon plant, a herbaceous perennial plant native to Japan, Korea, southern China and Southeast Asia. 

  • Crassula muscosa, rattail crassula, a succulent plant native to South Africa 

  • Used other than figuratively or idiomatically: see lizard, tail. 

  • Saururus cernuus, a medicinal and ornamental plant native to eastern North America. 

How often have the words lizard tail and lizard's tail occurred in a corpus of books? (source: Google Ngram Viewer )