Asplenium rhizophyllum
walking fern
Overview
Asplenium rhizophyllum is a small evergreen fern that grows in tufts on shaded, moss-covered limestone and dolomite rock. Unlike most ferns, its fronds are simple and undivided: narrowly triangular blades 1.5-12 in (4-30 cm) long, leathery, and bright green, tapering from a heart-shaped or eared base to a long, thread-like tip. The arching frond tips bend down to the rock, and where they touch a moist surface they root and produce a new plantlet, so colonies spread outward step by step and give the plant its common name walking fern. Spore-bearing sori form as short brown lines along the veins on the underside of fertile fronds. Rosettes are 2-6 in (5-15 cm) across, and a colony can carpet a boulder over several years. It requires constant shade, high humidity, and a calcareous, moss-covered surface, and it fails on acidic substrate or in direct sun. The fronds persist through winter, though they may shrink in hard freezes. Its narrow habitat on limestone outcrops limits where it can be grown.
Native Range
Native to eastern North America, from Quebec and Ontario west to Minnesota and south through the Appalachians and Ozarks to Georgia, Alabama, and Oklahoma. It grows almost exclusively on shaded, moss-covered limestone and dolomite outcrops in moist woodland.Suggested Uses
Grown on shaded limestone rock gardens, tufa, and moss-covered walls in cool, humid sites. Used in native woodland and fern plantings where alkaline rock and constant shade are present.How to Identify
Appearance
Size & Dimensions
Height2" - 1'
Width/Spread6" - 1'6"
Reaches mature size in approximately 3 years
Bloom Information
As a fern, A. rhizophyllum reproduces by spores and bears no flowers. Spores ripen in brown linear sori on the frond undersides from summer into fall. New plantlets also form where frond tips root on contact with moist rock.
Detailed Descriptions
Foliage Description
bright greenGrowing Conditions
Sun Requirements
Tolerates up to 4 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Grows in full to part shade on moist, moss-covered limestone or in gritty, alkaline, sharply drained soil. It needs a soil or rock pH from about 7.0 to 8.0 and steady humidity around the roots. Constant moisture without standing water suits it, as the thin rosettes dry quickly in sun or wind. Hardy to USDA zone 4, roughly -30 F (-34 C), with evergreen fronds through winter. It establishes slowly and resents transplanting once rooted to a surface. Acidic soil, drought, and direct sun cause the fronds to brown and die.Pruning
No routine pruning is needed. Dead or winter-damaged fronds are removed in spring as new growth appears. Rooted plantlets can be separated to start new colonies.Container Growing
✓ Suitable for container growing
Minimum container size: 1 gallons