English name(s):
rock polypody fern, rock cap fern
Family:  Polypodiaceae
Description:
The blade of this rock fern has a leathery texture and is deep green on both the upper and underside surfaces. Usually positioned in rows on either side of the mid-vein are the round, pale brown sori.
Habitat:
rocky woods, slopes, and cliffs
Notes:
polys = many + podos = a foot
Henry David Thoreau described mats of this fern gracing rocky surfaces in early spring as “fresh and cheerful communities".
Additional notes:
syn. Polypodium vulgare L. var. virginianum (L.) Eaton

Plant identification
The Ohio State University Herbarium:
Geauga County, 20 July 1901, collector:  L.S. Hopkins  voucher specimen
✿ view additional voucher specimens and related information

Fen Finder booklet: page sequence 8, 11, 12, 14, 16
Hardy Fern Library: cites differences between P. virginianum and P. vulgare

Historical description:
How to Know the Ferns: A Guide to the Names, Haunts, and Habits of Our Common Ferns, Frances Theodora Parsons, 1899.
Group VI: Fertile and Sterile Fronds Leaf-like and Usually Similar, Fruit-Dots Round
p. 184 (PDF version, page 218).
...  the plant has a charm peculiarly its own, a charm arising partly from its vigor, from the freshness of its youth and the endurance of its old age, partly from its odd outlines, and partly from its usual environment, which entitles it to a more ready and universal recognition.
" The cheerful community of the polypody," as Thoreau calls it, thrives best on the flat surfaces of rocks. I recall the base of certain great cliffs where the rocky fragments, looking as though hurled from above by playful giants, are thickly covered with these plants, their rich foliage softening into beauty otherwise rugged outlines. Usually the plant is found in somewhat shaded places. Occasionally it grows on the trunks of trees and on fallen logs, as well as on rocks and cliffs.