calla vs lily of the Nile

calla

noun
  • The calla lily, Zantedeschia aethiopica. 

  • A marsh plant native to cooler areas throughout the northern hemisphere, Calla palustris, having pale green flowers in a white spathe. 

lily of the Nile

noun
  • Zantedeschia aethiopica, a plant species in the family Araceae. 

  • Agapanthus praecox, a plant species in the family Alliaceae. 

How often have the words calla and lily of the Nile occurred in a corpus of books? (source: Google Ngram Viewer )