arum lily vs calla

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. 

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. 

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