starthistle vs thorn

starthistle

noun
  • Any of the genus Centaurea of herbaceous thistle-like flowering plants. 

thorn

noun
  • A sharp protective spine of a plant. 

  • That which pricks or annoys; anything troublesome. 

  • A letter of Latin script (capital: Þ, small: þ), borrowed from the futhark; today used only in Icelandic to represent the voiceless dental fricative, but originally used in several early Germanic scripts, including Old English where it represented the dental fricatives that are today written th (Old English did not have phonemic voicing distinctions for fricatives). 

  • Any shrub or small tree that bears thorns, especially a hawthorn. 

verb
  • To pierce with, or as if with, a thorn (sharp pointed object). 

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