African lily vs arum lily

African lily

noun
  • Any of certain flowering plants of the genus Agapanthus, especially Agapanthus umbellatus. 

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. 

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