fleabane vs selfheal

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 

selfheal

noun
  • A small, herbaceous European plant with blue-violet flowers from any species of genus Prunella. 

  • Especially, Prunella vulgaris. 

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