helianthus vs heliotrope

helianthus

noun
  • Any plant, of the genus Helianthus, having large flower heads with dark disk florets and showy yellow rays; the sunflowers 

heliotrope

noun
  • The fragrance of heliotrope flowers. 

  • 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. 

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

adj
  • Light purple or violet. 

  • Keeping one’s face turned toward the sun. 

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