onion vs pseudanthium

onion

noun
  • The bulb of such a plant. 

  • A monocotyledonous plant (Allium cepa), allied to garlic, used as vegetable and spice. 

  • The genus Allium as a whole. 

  • An ounce. 

pseudanthium

noun
  • An inflorescence that looks and functions as if it were a single flower. 

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