Family: Polypodiaceae

Origin, Description & Uses:
Pyrrosia piloselloides, commonly known as dragon’s scale fern, is a small creeping fern native to tropical and subtropical regions ranging from southwestern India and Assam through Southeast Asia to Japan and Papuasia. This unusual epiphytic fern grows along tree trunks, rocks, and walls, producing slender creeping rhizomes covered with tiny overlapping fronds that resemble reptile scales. Its compact growth habit and distinctive appearance have made it popular as an ornamental fern for hanging baskets, mounted displays, terrariums, and tropical gardens. It is especially valued in humid landscapes because it tolerates heat and moisture well and can establish on a variety of surfaces.

Risks & Threats:
Dragon’s scale fern is naturalized on Oʻahu and possesses traits that are cause for concern in Hawaii. Its ability to spread vegetatively along bark, rocks, and other surfaces allows it to establish dense mats that may compete with native epiphytic plants and alter sensitive tropical island ecosystems. Because it thrives in humid environments and reproduces efficiently from fragments and spores, it may continue spreading into disturbed forests, urban areas, and landscaped settings. While it is not currently among Hawaii’s most widespread invasive ferns, continued cultivation and movement could increase its distribution. Choosing a low risk or native alternative is recommended when suitable options are available. In areas where this species is already established, careful management and avoiding new plantings near natural areas can help minimize further ecological impacts.

High Risk Traits:

• Thrives in tropical climates
  
• Naturalized on Oahu (Hawaiian Islands)
  
• A potential pest in tree plantations in Malaysia, with a smothering, shading and strangulation effect on young leaves, shoots, buds and flowers
  
• Shade-tolerant
  
• Epiphytic, able to smother trees in plantations
  
• Reproduces by spores and vegetatively by rhizomes and fragments
  
• Gametophytes are self-fertile
  
• Reaches maturity in <1 year
  
• Spores dispersed by wind; intentionally cultivated by people
  
• Birds use fern for nesting material; viability of fern fragments unknown
  
• Prolific spore production

Low Risk Traits:

• Unarmed (no spines, thorns, or burrs)
  
• Non-toxic