It was, historically, only a personal nickname of Geoffrey, as was " Beauclerc " of his father-in-law (Henry I.) and " Curtmantel " of his son (Henry II.), and was derived from his wearing in his cap a sprig of the broom (genet) plant, "which in early summer makes the open country of Anjou and Maine a blaze of living gold."
These may be divided into three classes: first, the sprig of rue in silver, with sundry emblems attached to it, all of which refer to the worship of Diana, whose shrine at Capua was of considerable importance; secondly, the serpent charms, which formed part of the worship of Aesculapius, and were no doubt derived largely from the ancient eastern ophiolatry; and lastly charms derived from the legends of the Sirens.
Shortly before St Patrick's Day the queen issued an order which intensified this interest, that Irish soldiers might in future wear a sprig of shamrock in their headgear on this national festival.