black cumin vs blackseed

black cumin

noun

  • A spice plant with aromatic seeds (Nigella sativa). 

  • A cultivated variety of cumin (Cuminum cyminum). 

  • A spice plant related to cumin with dark seeds and an edible root (Bunium bulbocastanum). 

blackseed

noun

  • A spice plant with aromatic black seeds, Nigella sativa 

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