marsh marigold vs mayweed

marsh marigold

noun
  • Caltha palustris, a perennial plant with bright yellow flowers. 

mayweed

noun
  • A mayflower. 

  • corn chamomile, field chamomile, Anthemis arvensis. 

  • Plants of the genera Matricaria and Tripleurospermum. 

  • stinking chamomile, Anthemis cotula. 

How often have the words marsh marigold and mayweed occurred in a corpus of books? (source: Google Ngram Viewer )