chess flower vs fritillary

chess flower

fritillary

noun
  • Any of several bulbous perennial plants, of the genus Fritillaria, having flowers with a spotted or chequered pattern. 

  • Any of several butterflies, of the family Nymphalidae, having wings with black or silvery spots. 

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