blackberry vs tree heath

blackberry

noun
  • A fruit-bearing shrub of the aggregate species Rubus fruticosus and some hybrids. 

  • The soft fruit borne by this shrub, formed of a black (when ripe) cluster of drupelets. 

  • The blackcurrant. 

verb
  • To gather or forage for blackberries. 

tree heath

noun
  • Other plants of genus Erica of similar habit 

  • 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. 

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

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