amaranth vs richweed

amaranth

noun
  • The characteristic purplish-red colour of the flowers or leaves of these plants. 

  • A red to purple azo dye used as a biological stain, and in some countries in cosmetics and as a food colouring. 

  • Any of various herbs of the genus Amaranthus. 

  • The seed of these plants, used as a cereal. 

richweed

noun
  • Pilea pumila, a herb of the nettle family with a smooth, juicy, pellucid stem. 

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