floccule vs tussock

floccule

noun
  • A small, loosely aggregated mass of material suspended in, or precipitated from a solution; a floc. 

tussock

noun
  • A tuft or clump of green grass or similar verdure, forming a small hillock. 

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