plumule vs vibrissa

plumule

noun
  • The aftershaft of a feather. 

  • One of the featherlike scales of certain male butterflies. 

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

  • A down feather. 

vibrissa

noun
  • Any similar feather near the mouth of some birds. 

  • The thick hairs found inside the nostrils of humans and other mammals. 

  • Any of the tactile whiskers on the nose of an animal such as a cat. 

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