Lygodium microphyllum produces a creeping stem from which the leaves that are very long grow, the longest exceeding 30 meters. The leaves have rachis, which are similar to the vine and can climb other vegetation. What appear to be individual leaves that sprout from the rachis are actually leaflets, which are smaller segments of the main leaf.
I. Appearance and Characteristics
Lygodium microphyllum (commonly known as, variously, climbing maidenhair fern, Old World climbing fern, small-leaf climbing fern, or snake fern) is a climbing fern originating in tropical Africa, Southeast Asia, Melanesia and Australia. It is an invasive weed in Florida where it invades open forest and wetland areas. The type specimen was collected in the vicinity of Nabúa, on the island of Luzon in the Philippines by Luis Née.
Fern with dark brown, wiry rhizomes and climbing, twining fronds of indeterminate growth, to 30 m long, main rachis (leaf stalk above petiole) wiry, stemlike. Leafy branches off main rachis (constituting the pinnae) once compound, oblong in overall outline, 5-12 cm long. Leaflets (pinnules) usually unlobed, stalked, articulate (leaving wiry stalks when detached), glabrous below. Fertile leaflets of similar size, fringed with tiny lobes of enrolled leaf tissue covering the sporangia along the leaf margin.
Lygodium microphyllum causes problems in the environments where it is invasive. The plant damages wetland ecosystems, harming endangered species. The ferns ability to grow up and over trees and shrubs and to form dense horizontal canopies allows it to cover whole communities of plants, reducing native plant diversity. Old World climbing fern can grow in many diverse ecosystems. Lygodium microphyllum poses problems for fires, both natural and man-made, because it can lead fire into the tree canopy, killing trees. The fern rapidly spread in South Florida’s public conservation lands.
Recently, the USDA approved the use of insects to keep the fern contained. Insects (Austromusotima camptozonale, Neomusotima conspurcatalis) and mites (Floracarus perrepae) have been released in several state parks to control the fern. Although some populations were devastated by a bout of cold weather, recently, reports of new activity have been made.
II. How to Grow and Care
Old world climbing fern typically thrives in a humid, warm climate, making it quite challenging to care for in non-tropical environments. Special care points include ensuring consistently high humidity and managing its invasive growth tendencies by regular pruning. Given its rapid spread and need for specific conditions, old world climbing fern is labeled as a difficult plant to care for in domestic settings.
Sunlight
Old world climbing fern flourishes in conditions of full sun exposure, which significantly contributes to its vigorous growth and enhances its health. This plant displays a remarkable tolerance to partial sun, though deviation from full sunlight may affect its vitality, potentially resulting in less robust growth.
As an outdoor plant, old world climbing fern demonstrates adaptability and can perform well in various light environments; however, optimal health is achieved under maximal light. Ideally, old world climbing fern should be positioned in outdoor landscapes where sunlight is abundant to ensure it reaches its full growth potential.
Watering
Thriving in its native tropical rainforest habitat, old world climbing fern has adapted to environments with high humidity and consistent moisture. This species exhibits a preference for regular hydration but can tolerate short periods of dryness. It requires watering every week to maintain its lush growth. As an evergreen plant, old world climbing fern retains its foliage year-round, necessitating a steady water supply even during cooler months when indoor conditions may vary.
Fertilizing
For old world climbing fern, apply high-nitrogen fertilizer monthly during the growing season to support its vigorous climbing habit. A balanced formula promotes overall health, while increasing the ratio of nitrogen enhances foliage density. Administer half the recommended quantity to avoid overfertilization, integrating it into moist soil to prevent root burn. In winter, reduce application as growth slows. Ensure even distribution to encourage uniform growth, avoiding direct contact with the fronds to minimize damage. Experienced gardeners should monitor growth, adjusting feeding as needed for optimal vitality.
Propagation
Originating from tropical and subtropical regions, old world climbing fern is known for its climbing habit and delicate foliage. Old world climbing fern propagates effectively through division, a practical approach tailored for its growth habits. Gardeners should select healthy sections of rhizomes and separate these gently to maintain root integrity. Ensuring each division has adequate roots and shoots will optimize the success of new plants. Post-division, plant fragments in a moist, well-draining medium to encourage establishment, keeping them in stable environmental conditions.
Transplanting
The transitional period from the thaw of early spring to the cusp of summer warmth is prime for old world climbing fern’s move. Select a spot with ample shade and well-drained soil. Be convincing in ensuring the new location mirrors the sheltered, humid embrace of its natural setting.
III. Uses and Benefits
- Medicinal uses
Lygodium microphyllum has been used locally in folk medicine to treat skin ailments and problems, swelling and dysentery.
- Other uses
Lygodium microphyllum fibers (as well as other species of Lygodium), known as nito, are used to weave traditional salakot hats in the Philippines.
IV. How to Control
Remove Old World climbing fern from your property and plant native species in its place. Multiple herbicide treatments are often required to kill Old World climbing fern. The aboveground portion of the plant will die quickly, but herbicides move poorly within the root system so the plants can regrow from the intact roots.
Report Old World climbing fern in natural areas on IveGot1.org or using the IveGot1 reporting app.
- Biological Control
The United States Department of Agriculture Animal and Plant Health Inspection Service (USDA/APHIS) recently approved the release of three species of arthopods that feed specifically on Old World climbing fern. Two of these species, the brown lygodium moth larvae (Neomusotima conspurcatalis) and a microscopic mite (Floracarus perrepae) are being reared and released as part of the Comprehensive Everglades Restoration Plan (CERP).
