Polypodium appalachianum aka Appalachian Polypody

Polypodium appalachianum has two common names: Appalachian rockcap fern and Appalachian polypody. It stays green year-round and lives for many years. It belongs to the polypody family, Polypodiaceae. Its native range spans eastern Canada and the eastern United States. It grows in a temperate climate, but is not native to Britain or Ireland. Its species name refers to the Appalachians. Wild plants grow on moist, rocky sites at high and low heights above sea level. In the Smoky Mountains, it also grows on other plants as an epiphyte.

This small fern forms low mats from creeping rhizomes, or spreading stems. Plants reach about 0.5–1 foot (0.15–0.3 metres) in height and spread. The fronds rise in rosettes, or rings, from the rhizomes. Dense patches help hold organic matter on bare rock. The stems are golden-brown, with a pale, powdery coat. They have no scent. This low, spreading form fits small spaces in shaded gardens. Its green fronds give cover past the main growing season.

The fronds are pinnatifid, with deep lobes and no hairs. They range from oblong to lanceolate, or lance-shaped. Each blade is widest near its base. This trait helps tell the fern apart from others. Each frond can reach 1.25 feet (0.38 metres) long. Fronds can be about 0.29 feet (0.09 metres) wide. The pinnae, or frond lobes, have round tips. Their edges are smooth or have slight teeth. This fern makes no flowers or fruit. It breeds through spores instead. Round or kidney-shaped sori grow on all but the lowest pinnae. These groups hold spores and turn from yellow to brown with age.

Grow this fern in deep shade, with little or no direct sun. It needs moist, acidic soil that drains well. Shallow, rocky ground suits the way it grows in the wild. NC State lists it for USDA zones 3–8. It copes with cold, but is sensitive to heat. Keep its need for cool shade in mind when choosing a site. A shaded rock slope or the ground beneath woodland trees meets its stated needs.

Use it in native plantings, shade gardens, or rock gardens. NC State lists songbirds among the wildlife it draws. The fern resists deer and needs little care. The same source reports no serious plant problems. Watch for Florida fern caterpillar, a pest. The supplied evidence does not assess whether humans can eat this fern. It also does not assess whether the fern is toxic.