Richea pandanifolia vs tree heath

Richea pandanifolia

tree heath

noun
  • The flowering plant Erica arborea, native to east Africa and the Mediterranean. 

  • Erica scoparia (green heath, besom heath, broom heath) 

  • Dracophyllum arboreum (Chatham tree heath) 

  • especially Trochocarpa laurina of Australia and New Zealand. 

  • Other plants of genus Erica of similar habit 

  • Ecological domains characterized by large numbers of such species of ericaceous plants. 

How often have the words Richea pandanifolia and tree heath occurred in a corpus of books? (source: Google Ngram Viewer )