black moss vs old man's beard

black moss

noun
  • Tillandsia usneoides (Spanish moss), a flowering plant, particularly after it has been dried for use as stuffing and decoration. 

  • Any of numerous species of dark-coloured mosses (Bryophyta), possibly species of the genera Grimmia, Andreaea, Syntrichia, Cinclidotus. 

  • Nostoc flagelliforme (fat choy), a terrestrial cyanobacterium eaten in Chinese cuisine. 

  • Bryoria fremontii (wila), a lichen eaten by First Peoples in North America. 

old man's beard

noun
  • Tillandsia usneoides, a bromeliad; Spanish moss. 

  • Used other than figuratively or idiomatically: see old, man, -'s, beard. 

  • Clematis aristata, an Australian climbing plant. 

  • Clematis vitalba, a climbing plant. 

  • Chionanthus virginicus, a tree. 

  • Usnea, a type of lichen. 

How often have the words black moss and old man's beard occurred in a corpus of books? (source: Google Ngram Viewer )