A caduceus is a winged rod, with two serpents entwined about it; it was the token of the Greek god Hermes (or Mercury, to the Romans). In period it was considered a merchant’s symbol; in modern America, it has become the symbol of the physician. The caduceus is a period charge, found in the allusive arms of Mercurio or Mercurius, c.1555 [BSB Cod.Icon 267:781].
A similar charge is the “rod of Aesculapius”, also called “Aaron’s rod”: this is a stick or staff, entwined with a single serpent. It, not the caduceus, is more correctly a symbol of the medical profession. When blazoned “proper” in Society armory, the staff is brown and the serpent green.
At one time, Society armory reserved both the caduceus and the rod of Aesculapius to medical professionals. Currently, there are no restrictions on either charge. For related charges, see staff, thyrsus.
Carlina Vincenzi bears: Azure, three caducei Or.
Merfyn Gareth ap Mouric bears: Sable, an Aaron’s rod argent.
Mary Teresa Hathaway bears: Azure, a rod of Aesculapius and in chief three roses slipped and leaved fesswise argent.