hickwall vs thousand-leaf

hickwall

noun
  • A European green woodpecker, Picus viridis. 

  • A lesser spotted woodpecker, Dryobates minor. 

thousand-leaf

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

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