fleabane vs lamb's ears

fleabane

noun
  • Pluchea spp. (camphorweeds) 

  • Pulicaria spp. (false fleabane), especially common fleabane (Pulicaria dysenterica subsp. dysenterica, formerly Inula dysenterica) 

  • Erigeron spp., especially Erigeron acre (blue fleabane) 

  • Inula spp. (yellowheads) 

  • Also, in subfamily Cichorioideae, Vernonia spp. (ironweeds). 

  • Conyza spp. (butterweeds or horseweed) 

  • mostly in two tribes of subfamily Asteroideae 

lamb's ears

noun
  • Stachys byzantina, an ornamental low-growing perennial related to betony with soft, silky hairs on the leaves which give it an attractive silvery-gray color. 

  • Used other than figuratively or idiomatically: see lamb, ear. 

How often have the words fleabane and lamb's ears occurred in a corpus of books? (source: Google Ngram Viewer )