Aaron's rod vs arum

Aaron's rod

noun
  • Goldenrod, the Solidago genus of North American plants with yellow flowers. 

  • Hylotelephium telephium (syn. Sedum telephium; orpine, livelong, or live-forever). 

  • A rod-shaped molding decorated with an entwined snake, and sometimes leaves, vines, and/or scrolls. 

  • Verbascum thapsus, the great mullein, common mullein, or hag-taper. 

arum

noun
  • A flower or plant in the genus Arum 

How often have the words Aaron's rod and arum occurred in a corpus of books? (source: Google Ngram Viewer )