beggar-ticks vs bur marigold

beggar-ticks

noun
  • Any of several plants, of the genus Bidens, having yellow flowers and prickly fruit. 

  • The barbed fruit of these plants, which sticks to clothing and to animal fur. 

bur marigold

noun
  • A plant, the beggar's ticks (Bidens spp.). 

How often have the words beggar-ticks and bur marigold occurred in a corpus of books? (source: Google Ngram Viewer )