thousand-leaf vs yarrow

thousand-leaf

noun
  • Achillea millefolium or common yarrow, a flowering plant widespread in the temperate Northern Hemisphere, featuring finely divided leaves. 

yarrow

noun
  • Common yarrow, Achillea millefolium, the type species of the genus. 

  • The green woodpecker, Picus viridis. 

  • Any of several pungent Eurasian and North American herbs, of the genus Achillea, used in traditional herbal medicine. 

How often have the words thousand-leaf and yarrow occurred in a corpus of books? (source: Google Ngram Viewer )