blackseed vs love-in-a-mist

blackseed

noun
  • A spice plant with aromatic black seeds, Nigella sativa 

love-in-a-mist

noun
  • Nigella damascena, an annual flowering plant of the genus Nigella, the blooms of which are generally blue in colour, though also found in shades of pink, white or pale purple. 

How often have the words blackseed and love-in-a-mist occurred in a corpus of books? (source: Google Ngram Viewer )