lycopod vs spike moss

lycopod

noun

  • Any member of the Lycopodiophyta. 

  • A club moss. 

spike moss

noun

  • Any of various simple vascular plants, of the family Selaginellaceae, that resemble mosses and produce spores. 

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