Aaron's rod /(âr"ŭnz rŏd`)/

Aar·on's rod

Aaron's rod
  1. A rod with one serpent twined around it, thus differing from the caduceus of Mercury, which has two. (Arch.)
  2. A plant with a tall flowering stem; esp. the great mullein, or hag-taper, and the golden-rod. (Bot.)