Family: Thelypteridaceae
Origin, Description & Uses
Macrothelypteris torresiana (Mariana maiden fern, Torres’s fern, or wood fern) is a large tropical fern native to the western Indian Ocean region, tropical and subtropical Asia, and parts of the Pacific. It is valued for its lush, arching fronds and ability to grow quickly in moist, shaded environments. This fern is sometimes cultivated as an ornamental for tropical gardens, landscaping, erosion control, and naturalized woodland plantings because of its hardy nature and attractive foliage. In Hawaiʻi, it has become naturalized on Kauaʻi, Oʻahu, Molokaʻi, Maui, and Hawaiʻi Island, where it commonly grows along roadsides, forest edges, stream corridors, and disturbed wet habitats.
Risks & Threats
Macrothelypteris torresiana is naturalized in Hawaiʻi and possesses traits that are cause for concern in tropical island ecosystems. This species spreads readily by spores, grows aggressively in disturbed and shaded habitats, and can form dense stands that compete with native vegetation for light, moisture, and space. Its ability to colonize forests, gulches, and other moist environments may contribute to the displacement of native ferns and understory plants, potentially altering ecosystem structure and regeneration processes. Because of these invasive tendencies, this fern could detrimentally impact tropical island ecosystems if its spread continues unchecked. When possible, Plant Pono recommends choosing a low risk or native alternative for landscaping and restoration projects.
High Risk Traits:
- Elevation range exceeds 1000 m, demonstrating environmental versatility
- Thrives in tropical climates
- Naturalized in Hawaiian Islands and widely naturalized elsewhere
- A disturbance-adapted weedy fern (potentially negative environmental impacts)
- Shade-tolerant
- Reproduces by spores and spreads vegetatively by rhizomes
- Reaches maturity in several months
- Spores dispersed by wind, water and possibly other vectors
- Prolific spore production
Low Risk Traits:
- Naturalized for over 100 years. May have already achieved maximum distribution in Hawaiian Islands and any negative impacts may have already been manifested
- Unarmed (no spines, thorns, or burrs)
