goat's-beard vs whitethorn

goat's-beard

noun
  • A woodland plant of the family Rosaceae, Aruncus dioicus. 

  • A yellow-flowered Eurasian plant, of the genus Tragopogon. 

whitethorn

noun
  • Vachellia constricta, formerly Acacia constricta, whitethorn acacia, a shrub in the family Fabaceae. 

  • Ceanothus leucodermis, chaparral whitethorn, a shrub in the family Rhamnaceae. 

  • Bursaria spinosa, a small Australian shrub. 

  • Crataegus monogyna, a hawthorn species native to Europe, northwest Africa and western Asia. 

How often have the words goat's-beard and whitethorn occurred in a corpus of books? (source: Google Ngram Viewer )