arum vs calla lily

arum

noun
  • A flower or plant in the genus Arum 

calla lily

noun
  • A flower of one of these plants. 

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

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