Asplenium rhizophyllum aka Walking Fern

Asplenium rhizophyllum is a small evergreen fern called walking fern. It belongs to the spleenwort family, Aspleniaceae. Its native range covers eastern Canada and the eastern United States. It grows on shaded cliffs, mossy rocks, and fallen trunks. It also grows near streams and in ravines. Limestone is a frequent home, though it also grows on acidic rocks. Some states list it as threatened or endangered near its range limits.

Plants form arching clumps about 0.17–1 foot [0.05–0.3 metres] tall and wide. A short rhizomatous crown bears shallow, fibrous roots. Smooth green stems support fronds that spread from the base. Young plants hold their fronds close to the ground. Each frond is simple, rather than split into leaflets. Its narrow, triangular blade ends in a long, thin tip. Frond size varies a great deal within one plant. The upper face is dark green and slightly leathery. The lower face is paler, with a few hairs. Frond bases may be heart-shaped or have ear-like lobes. Edges may be smooth or have shallow waves.

This fern makes neither flowers nor fruit. Instead, it produces spores, visible from May through October. Sori lie beneath the fronds in rows angled toward their edges. The plant also spreads without spores. A frond tip can take root when it touches damp soil. New plants then grow around the parent. This slow spread gives the walking fern its common name. Its species name refers to the same rooting habit.

Grow it in light to deep shade, away from strong winds. It needs plenty of moisture and humid air. Thin, rocky soil suits its shallow roots. NC State lists alkaline soil as its growing preference. In the wild, however, it also occurs on sandstone and other acidic rocks. The soil may be moist or wet at times. Long dry spells are harmful. Its listed hardiness range covers USDA zones 4 through 8.

Walking fern suits woodland plantings, native gardens, and shaded rock walls. It can also grow on shaded banks and slopes. Sites near water features can provide the humid air it needs. Its green fronds offer year-round foliage in these small spaces. Deer resistance adds to its value in woodland gardens. Slugs, snails, and some aphids may damage the plant. Keeping its need for moisture in mind matters when choosing a site.