Unknown to most, bracken is a home for a wide variety of faeries, of untold variety and very often of a nature that exists nowhere else on earth except within a particular large bracken. Many of these faeries are less that a tenth the size of a sprite and many are invisible. However, with knowledge of bracken gained from the study of ferns, the character will be able to quietly call upon these creatures in time of need.
There are two ways in which a character can gain protection from a bracken; the first, if the character wishes to hide, the character need only lay down and the leaves of the bracken will be closed over top, hiding the character from discovery. So long as the character remains in place, does not move and does not make a sound, the character cannot be found in bracken except by magical means.
Alternately, if the character is forced to defend against an enemy, he or she will gain aid from the faerie-folk while standing in a bracken, granting them a +1 protection against all attacks, physical or magical. Enemies will feel themselves grasped by the bracken, the character will be shifted out of the way of missile weapons as best the faeries can manage and the overall magical strength of the bracken will give a +1 to all saving throws. It isn't much help, but the faeries do what they can.
Characters with this knowledge will be able to seek out brackens if pursued with a chance equal to the number of points of knowledge they possess (presuming, of course, that they are seeking within a woodland). Note that this benefit only applies to places in the wild, not patches of ferns grown in a domestic garden.
See Mosses & Ferns