burnt sienna vs red sorrel

burnt sienna

noun
  • dark reddish brown colour, like that of roasted sienna. 

adj
  • Of a dark reddish brown colour, like that of roasted sienna. 

red sorrel

noun
  • The plant roselle (Hibiscus sabdariffa). 

  • Rumex acetosella 

How often have the words burnt sienna and red sorrel occurred in a corpus of books? (source: Google Ngram Viewer )