European alder vs black alder

European alder

noun

  • Black alder (Alnus glutinosa). 

black alder

noun

  • Wood or other product of the tree. 

  • A tree (Alnus glutinosa), of many practical uses, growing in moist conditions in Europe. 

  • American winterberry, Ilex verticillata. 

How often have the words European alder and black alder occurred in a corpus of books? (source: Google Ngram Viewer )