gemmule vs topknot

gemmule

noun
  • Synonym of plumule (“the first bud, or growing point, of a plant embryo, situated above the cotyledons”) 

  • In the obsolete theory of pangenesis propounded by the English scientist Charles Darwin (1809–1882): a hypothetical particle once thought to be the basis of heredity. 

  • Synonym of dendritic spine (“a small membranous protrusion from the dendrite of a neuron that typically receives input from a single axon at the synapse”) 

topknot

noun
  • The brown topknot, Notoclinus compressus 

  • The New Zealand topknot, Notoclinus fenestratus 

  • A small European flounder (Phrynorhombus regius, syn. Rhombus punctatus). 

  • A decorative headdress. 

  • A decorative knot of hair on the crown of the head, sometimes having ribbons or feathers. 

  • Several species in the genus Zeugopterus 

  • A crest or knot of feathers upon the head or top, as of a bird. 

  • The Norwegian topknot, Phrynorhombus norvegicus 

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