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Polypodium Eastern North America Group |
P. appalachianum is a parent of P. virginianum and the two are very similar, the differences confined to rhizome scale coloring, blade shape, pinna tips, and a downward facing notch between the lowest pinna and stipe. These differences are inadequate to explain separate species status, which rests in microscopic characters: spore size and chromosome counts. |
| Species | Rhizome Indument | Blade Form | Pinnae | Distribution |
|---|---|---|---|---|
| appalachianum | scales lanceolate, mostly uniformly golden brown | oblong to narrowly lanceolate, usually widest near the near base | linear, entire to slightly dentate, broadest near the base, apex more pointed than virginicum, at least near the base of the the blade | eastern North America |
| virginianum | scales lanceolate, base and margins light brown, sometimes with dark central stripe | oblong to narrowly lanceolate, usually widest near middle, occasionally at or near base | linear, entire to slightly dentate, apex rounded | north-central Canada south to Arkansas, east to North Carolina, north to Newfoundland; also perhaps Japan, Korea, Mongolia, eastern Siberia |
Characters listed were chosen for their value in distinguishing between species.
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