American winterberry vs black alder winterberry

American winterberry

noun
  • Ilex verticillata, a species of holly native to eastern North America in the United States and southeast Canada, from Newfoundland west to Ontario and Minnesota, and south to Alabama. 

black alder winterberry

noun
  • A deciduous holly shrub, Ilex verticillata, native to eastern North America, growing best in moist circumstances. 

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