calla vs calla lily

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. 

calla lily

noun
  • A common name for certain flowering plants in the genus Zantedeschia; not related to either the genus Calla or the true lilies (Liliaceae) 

  • A flower of one of these plants. 

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