heliotrope vs turnsole

heliotrope

noun
  • A light purple or violet colour. 

  • Particularly, a purple-flowered plant of the species Heliotropium arborescens. 

  • A bloodstone (a variety of quartz). 

  • An instrument, employed in triangulation, that uses a mirror to reflect sunlight toward another, very distant, surveyor. 

  • The fragrance of heliotrope flowers. 

  • A plant that turns so that it faces the sun. 

adj
  • Light purple or violet. 

  • Keeping one’s face turned toward the sun. 

turnsole

noun
  • A purple dye obtained from Chrozophora tinctoria. 

  • A heliotrope; so named because its flowers are supposed to turn toward the sun. 

  • The euphorbiaceous plant Chrozophora tinctoria. 

  • A sunflower. 

  • A sun spurge (Euphorbia helioscopia). 

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