arum lily vs lily of the Nile

arum lily

noun
  • Any of several flowering plants, of the family Araceae, but especially Zantedeschia aethiopica, the calla lily that has a showy 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 arum lily and lily of the Nile occurred in a corpus of books? (source: Google Ngram Viewer )