filament vs midrib

filament

noun
  • The stalk of a flower stamen, supporting the anther. 

  • A continuous object, limited in length only by its spool, and not cut to length. 

  • A fine thread or wire. 

  • Such a wire, as can be heated until it glows, in an incandescent light bulb or a thermionic valve. 

  • A massive, thread-like structure, such as those gaseous ones which extend outward from the surface of the sun, or such as those (much larger) ones which form the boundaries between large voids in the universe. 

midrib

noun
  • The strengthened vein down the middle of a flower petal or simple leaf or leaflet. 

  • The continuation of the petiole of a pinnately compound leaf around which the leaflets attach. 

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