Sickle Spleenwort
Asplenium polyodon
The Sickle Spleenwort (scientific name: Asplenium polyodon ), also commonly known as the Mare's Tail Fern, is an elegant and sophisticated evergreen fern native to New Zealand and widely distributed across the Pacific. A prominent member of the Aspleniaceae family, it is recognized for its gracefully arching, glossy dark green fronds featuring distinctive sickle-shaped pinnae. It thrives in a variety of moist forest environments across both islands, where it has evolved to grow as a terrestrial, lithophytic, or epiphytic plant. This comprehensive guide provides detailed information on its care, propagation, and its significant ecological importance within New Zealand's unique native forest ecosystems. Understanding this plant contributes to the appreciation of our rich biodiversity and heritage, and supports conservation efforts for all native species .
Plant Description
Identification and Physical Characteristics
Asplenium polyodon is a clump-forming perennial fern characterized by its exceptionally glossy, arching fronds that can reach lengths of up to 80 cm and spread up to a meter wide. The dark green foliage is simply pinnate, featuring uniquely curved, sickle-shaped leaflets (pinnae) that give the fern its common and scientific names. The plant grows from a stout, ascending rhizome covered in brown scales, arising from which are dark, shiny stipes. During the fertile phase, numerous linear sori develop on the undersides of the pinnae, facilitating the wind-dispersal of spores across its varied natural habitats, from coastal forests to high-rainfall montane environments.
Quick Facts
| Scientific Name | Asplenium polyodon |
|---|---|
| Height | 30-80 cm |
| Spread | 60 cm - 1 m |
| Water Needs | Moderate; requires consistent moisture |
| Light | Partial to full forest shade |
| Frost Tolerance | Moderate; hardy once established |
| Salt Tolerance | Moderate; found in coastal forests |
| Growth Rate | Moderate |
| Lifespan | Perennial Fern |
Climate Best Suited to
Sickle Spleenwort is well adapted to the various temperate climates of New Zealand, flourishing in regions with high humidity and consistent rainfall that mimic its natural forest origins across both islands.
Regional Suitability
| City | Climate Suitability |
|---|---|
| Auckland | High |
| Wellington | High |
| Christchurch | Medium |
| Nelson | High |
Plant Habitat
Natural Occurrence and Ecology
In its natural environment, Asplenium polyodon is a common and characteristic member of New Zealand's forest ecosystems. It has evolved to occupy specialized niches within lowland to montane forests, where it typically grows in the sheltered understory. It is frequently established as an epiphyte on the trunks of native trees or as a lithophyte on damp rocky outcrops and cliff faces. It also thrives terrestrially on the organic-rich forest floor. Its presence in these habitats highlights its adaptation to cool, shaded microclimates where moisture is consistent and protection from intense direct solar radiation is available throughout the year across the country.
Growing Requirements
Soil Requirements
Prefers well-draining, humus-rich soil high in organic matter.
- Well-drained
- High organic content
Light Requirements
Grows best in partial to full shade; avoid direct afternoon sun.
- Full Shade
- Partial Shade
Water Requirements
Requires regular watering and high humidity; avoid waterlogging.
- Regular
- High humidity preferred
Planting and Establishing
Establishment Guidance
To successfully establish Asplenium polyodon , choose a position that is shaded, sheltered, and ideally provides a cool, moist root run. Dig a hole twice the width of the root ball and enrich the ground with plenty of organic leaf mold or compost before planting. Ensure the crown is set at soil level to prevent rot. Planting during the cooler, moist months of autumn or early spring is ideal, allowing the fern to anchor its stout rhizome before summer dry spells. Providing a consistently humid micro-environment and applying a layer of organic mulch will help maintain the stable soil conditions this spectacular forest spleenwort prefers for healthy establishment.
Ecological Role
Biodiversity and Ecosystem Impact
Sickle Spleenwort plays a vital role in forest ecosystems by contributing to the structural complexity of the understory and creating micro-habitats for various native invertebrates. Its large, arching fronds offer shelter and cover for ground-dwelling fauna, while its glossy leaves help trap humidity at the forest floor level. By colonizing rocky banks and tree trunks, it contributes to the stabilization of fragile substrates and increases the overall biodiversity of the forest environment. Its minute spores are dispersed by the wind, allowing it to colonize new damp niches and support the natural successional processes of New Zealand's unique and intricate native botanical communities across both the North and South Islands.
Uses & Significance
Garden Uses
In a garden setting, Asplenium polyodon is a highly prized choice for shady native ferneries, rock gardens, or as an architectural specimen in a cool courtyard. Its exceptionally glossy, sickle-shaped foliage provides a high ornamental value year-round and adds a lush texture that contrasts beautifully with silver or light-coloured plants. Due to its clumping habit, it is perfect for adding greenery to vertical landscaping features or for growing in large pots where its arching fronds can be featured. It is highly valued by native plant enthusiasts wishing to create authentic forest displays that showcase the sophisticated beauty of New Zealand's diverse native spleenwort species.
- Shady ferneries
- Rock gardens
- Architectural specimen
Ecological Value
Beyond its ornamental appeal, this species is important for supporting local forest biodiversity. It provides a micro-habitat for ground-dwelling fauna and supports native forest health with its presence in riparian and montane margins. Historically, spleenworts were believed to possess medicinal properties to cure spleen ailments, reflecting their long-standing connection to human botanical interest. While specific Māori names for this particular fern are less widely detailed than for more prominent species, its presence indicates a healthy and moist forest environment, symbolizing the ancient forest heritage and ecosystem complexity of Aotearoa's native botanical lineage.
- Invertebrate refuge
- Forest understory diversity
Landscaping Uses
Modern landscaping can utilize Asplenium polyodon to create naturalistic understory layers in specialized native or contemporary designs. Its architectural foliage and arching habit make it a perfect softening element for the edges of forest paths or as a striking textural accent among large decorative rocks in a shaded garden. Designers often use it to add a sense of detail and 'wildness' to a project, where its glossy green colour can be highlighted. Its ability to maintain a neat habit while providing year-round structural interest makes it a reliable and decorative performer for high-impact native landscaping projects in cooler, sheltered regions across New Zealand.
Seasonal Care Calendar
Spring
As new fronds begin to emerge, ensure the soil remains consistently moist. This is the optimal time for maintenance pruning to remove any winter damage. Apply a light dressing of organic compost around the base to support the spring growth phase.
- Spring pruning
- Monitor growth
Summer
Provide regular watering during prolonged dry spells to maintain the lushness of the foliage. Ensure the plant remains well-shaded and protected from intense midday sun, which can quickly scorch the glossy fronds. Monitor for common pests.
- Consistent watering
- Provide shade
Autumn
The spores will mature and disperse. Tidy up the area by removing any large fallen leaves that might smother the central crown. Ensure the site remains well-drained as the weather becomes wetter and cooler.
- Tidy debris
- Check drainage
Winter
Naturally quite hardy in its native range but sensitive to severe frosts. Minimal intervention is needed during the dormant months; simply ensure the area stays free of heavy organic debris that could trap stagnant moisture around the base.
- Frost protection
- Clear debris
When to Prune and How Much
Asplenium polyodon requires very little pruning to maintain its graceful form. Maintenance is primarily limited to removing any dead, yellowing, or winter-damaged fronds at any time of the year before new growth cycle begins. This improves air circulation around the crown and reduces the risk of fungal diseases. Always cut fronds back to the base of the plant using clean, sharp tools. Avoid cutting into the healthy green fronds to ensure the plant remains vigorous and attractive. Proper maintenance ensures the plant remains a neat and distinctive architectural feature throughout the year.
- Remove dead fronds
- Maintenance thinning
Always use clean, sharp tools.
How to Grow Sickle Spleenwort
Cultivating Sickle Spleenwort ( Asplenium polyodon ) is a rewarding endeavor for any gardener interested in New Zealand's lush forest flora. This resilient species is best grown from spores or through the careful division of established clumps. Replicating its natural well-drained, organic-rich and humid forest understory habitat is the most critical factor for ensuring long-term success and maintaining its healthy, glossy foliage in a garden setting.
From Spores
Propagation from spores is a delicate but effective method for producing new plants. Collect mature spores from the undersides of the fronds when they appear dark and ready to release. Sow them onto the surface of a sterilized, moist, peat-based seed-raising mix. Cover the tray with glass or plastic to maintain high humidity and keep it in a warm, bright spot out of direct sunlight. Germination involves the growth of a prothallus, which requires a thin film of water for fertilization to occur. Once young fernlings appear, they should be pricked out into individual containers and kept consistently moist until they are large enough for planting.
Sow spores in a sterilized mix.
- Collect mature spores
- Maintain high humidity
Keep moist until fernlings appear.
From Cuttings
Vegetative propagation via division of established clumps is the fastest method for producing new plants and is best performed in early spring as new growth commences. Carefully lift a healthy clump and divide the central stock into smaller sections, ensuring that each new section has at least one active growing point and a substantial portion of the original root system. These divisions should be replanted immediately into a moist, well-draining potting medium and kept in a cool, bright spot until signs of new growth are observed, indicating that they have successfully re-established themselves and are ready for the garden or a specialized container.
Division is best attempted in early spring.
- Select healthy rhizomes
- Replant in moist soil
Additional Methods
Ensuring the right growing environment is often more critical than complex propagation techniques for this species. It thrives when its roots are kept cool and moist within an organic substrate, making it perfect for specialized shady rockeries or native borders. Avoid areas subject to intense midday heat or prolonged drought, which can cause the glossy fronds to scorch and wither. Once established, the fern is relatively low-maintenance, requiring only regular watering and occasional misting during dry periods to maintain its healthy architectural form and vibrant dark green presence throughout its lifespan in your garden.
Once planted, it requires very little intervention.
- Monitor soil moisture
- Maintain high humidity
Pests & Diseases
This species is remarkably resistant to most common garden pests, though it may occasionally attract scale insects or aphids if grown in overly stagnant or dry spots. Regular monitoring and the use of non-toxic, organic controls are recommended to keep the foliage healthy. The primary risk in cultivation is root or crown rot, which occurs if the soil remains waterlogged or if drainage is poor. Maintaining good air circulation and ensuring appropriate humidity levels are the best ways to ensure the long-term health and resilience of this hardy native spleenwort throughout its life in your native plant collection.
Cultural Significance
As a specialized forest endemic, Asplenium polyodon is a valued component of New Zealand's botanical heritage. While specific traditional Māori uses for this particular fern are less widely documented than for more prominent ferns like pikopiko, its presence in the landscape was considered a sign of a healthy, moist forest environment. Today, it stands as a symbol of the unique evolutionary history of our native spleenworts and the ongoing commitment to protecting the specialized forest habitats where this beautiful Sickle Spleenwort currently thrives across the country, representing the ancient forest heritage of Aotearoa.
- Forest heritage
- Botanical curiosity
Bonus Tip
To truly showcase the spectacular sickle-shaped beauty of the Mare's Tail Fern, plant it in a position where its glossy fronds can catch the dappled forest light. The way the light reflects off the leathery dark green leaflets creates a sophisticated and lush visual effect that brings a touch of wild New Zealand forest elegance directly into your own shaded garden or courtyard landscape design.
Related Plants
Explore other native plants that share similar characteristics or habitats with Sickle Spleenwort ( Asplenium polyodon ), offering further insights into New Zealand's diverse flora. These related species provide context and opportunities for complementary planting in your garden.
Plant Conservation
Conservation Status and Threats
Currently classified as 'Not Threatened' nationally, Asplenium polyodon remains a stable and common part of New Zealand's forest biodiversity. However, its continued success is linked to the preservation of its specialized lowland and montane habitats, which can be vulnerable to land development and the spread of aggressive invasive weeds. Ensuring that these natural forest environments remain protected from excessive human disturbance is key to maintaining the healthy populations of Sickle Spleenwort that currently thrive across its wide natural range on both the North and South Islands.