black alder winterberry vs skokeberry

black alder winterberry

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

skokeberry

noun
  • A pokeberry; a pokeweed (the plant Phytolacca americana or its dark red or purple fruit). 

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