Fern sports are plants that show marked change from the normal type or parent stock as a result of mutation.
The term Morphotype is also used for any of a group of different types of individuals of the same species in a population.
[3] Scaly Male Fern Dryopteris affinis and Male Fern Dryopteris filix-mas have a number of commercially available and naturally occurring sports or subspecies.
Examples are D. affinis polydactyla Dadds, A. filix-femina plumosum, A. filix-femina corymbiferum, and D. filix-mas Barnesii [4] The frond of a sport may be branched at the tip and at the tips of the pinna, the colour may vary, and variegation may occur; fronds generally remain bilaterally symmetrical.
In Athyrium and Dryopteris species white maggots of Chirosia betuleti create mop-head galls on fern frond tips that look somewhat like fern sports, however this is physical damage and not a growth form.