Polypodium appalachianum is a fern species native to eastern North America.

For years, P. virginianum—long considered a variety of the British Polypodium vulgare—was recognized as having cryptic races, with diploid, triploid, and tetraploid representatives.

Since the triploid specimens bore abortive spores, it was apparently the hybrid between the diploid and tetraploid groups.

[2] P. appalachianum is an epipetric plant, preferring sandstone or other hard, noncalcareous rocks.

Throughout much of its range, it will be found to grow in places more sheltered from the sun and heat than is P. virginianum.