euonymus vs spindle tree

euonymus

noun
  • Any of many (often decorative) trees, shrubs and woody vines, of the genus Euonymus. 

spindle tree

noun
  • Any of certain trees or any species belonging to the Euonymus genus, a group of flowering plants in the staff vine family. 

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