cornflower blue vs harebell

cornflower blue

noun
  • A bright blue color, with a tint of purple. 

adj
  • Of a bright blue color, with a tint of purple 

harebell

noun
  • A perennial flowering plant, Campanula rotundifolia, native to the Northern Hemisphere, with blue, bell-like flowers. 

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