Spanish moss vs traveller's joy

Spanish moss

noun
  • A gray epiphyte that hangs down from trees, Tillandsia usneoides, native to the southeastern US and throughout humid tropical and subtropical parts of the Americas. 

traveller's joy

noun
  • A climbing shrub native to Europe, Clematis vitalba. 

How often have the words Spanish moss and traveller's joy occurred in a corpus of books? (source: Google Ngram Viewer )