Why is there an acorn and leaf used for the insignia on Navy Flight Surgeon's wings. What is the meaning?

Although there have been many designs for the Medical Corp staff insignia, the current Oak Leaf and Acorn design are a reflection of those within the field desiring to enforce the idea that they are US Naval Officers, first, and Medical Professionals second.

As noted in the fine report, entered by the previous contributor in the first URL, below, the Oak Leaf symbolizes strength and the Acorn symbolizes development. Both have been used extensively, intoning those meanings throughout naval history.

The Oak Leaf and Acorn design was introduced in a General Order, 01 November 1883, and went into effect 01 July 1884. It beat out a competitor, the maroon Geneva cross, set in a silver Maltese cross.

The Naval Flight Surgeon corps, adds a wing to the Medical Corps device, which obviously indicates the staff corps' aerial ties. The first insignia was designed by Dr. H.J. "Tex" Rickard, who had been designated a Naval Flight Surgeon in July 1940. There have been a few changes since, including the change of the wing to be identical to that of Naval Aviators, as initially recommended by Captain Rickard.

The report, in the first URL, below, "The History of theNavy Medical Corps Insignia: A Case for Diagnosis", contains the full history, including some alternative theories that have been used to explain the device, such as the thought that they were used throughout the years to indicate a connection with Druidic healers, even though no information exists, militarily or otherwise, that such symbolism has ever been used to express such a link.

The report linked in the second URL, below, "Insignias", contains a cornucopia of information about current and past US Naval Uniforms and Insignia, including that of the Naval Flight Surgeons, as of 2005.