plumule vs pompon

plumule

noun
  • The first bud, or growing point, of a plant embryo, situated above the cotyledons. 

  • One of the featherlike scales of certain male butterflies. 

  • The aftershaft of a feather. 

  • A down feather. 

pompon

noun
  • A hardy garden chrysanthemum with button-like flower heads. 

  • A bundle of yarn, string, ribbon, etc. tied in the middle and left loose at the ends, so as to form a puff or ball, as for decoration or a showy prop for cheerleading. 

  • Any of several dwarf varieties of the Provence rose. 

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