chlamys vs perigonium

chlamys

noun
  • A short poncho-like cloak caught up on the shoulder, worn by hunters, soldiers, and horsemen in Ancient Greece. 

perigonium

noun
  • The sterile parts of a flower; collectively, the sepals and petals (or tepals); the perianth. 

  • The modified leaves around the antheridia in a bryophytic plant. 

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