Family: Iridaceae

Origin, Description & Uses:
Neomarica gracilis (apostle plant, walking iris) is a tropical perennial native to parts of South America, where it grows in warm, shaded forest edges and moist environments. It is best known for its attractive, iris-like flowers—typically pale blue to white with striking markings—and long, sword-shaped green leaves that form dense clumps. A unique feature of this plant is its “walking” growth habit: after flowering, new plantlets form on the flower stalks and gradually bend to the ground, where they take root and spread. Because of its unusual reproduction and ornamental blooms, apostle plant is commonly used in tropical landscaping as a border plant, groundcover, or accent in shaded gardens.

Risks & Threats:
In Hawaiʻi, Neomarica gracilis is considered to have low invasive risk overall, but it is potentially naturalizing on Oʻahu and Maui, meaning it may occasionally spread beyond cultivated gardens in suitable moist, shaded habitats. Its ability to reproduce vegetatively through plantlets allows it to slowly expand in favorable conditions, particularly in disturbed areas or garden edges. However, it is not currently known to form dense, damaging infestations or significantly displace native ecosystems. Even so, it should be monitored in natural or semi-natural areas, and gardeners are encouraged to manage spread responsibly and consider native or non-spreading alternatives in sensitive landscapes.

High Risk Traits:

• Thrives in tropical climates
  
• Anecdotal reports of weediness in landscaping
  
• Unconfirmed reports of toxicity
  
• A host of the nettle caterpillar
  
• Shade-tolerant
  
• Tolerates many soil types
  
• Reproduces by seeds and vegetatively by plantlets
  
• Arillate seeds may be dispersed by birds, ants and intentionally planted by people
  
• Missing information on reproductive biology and seed ecology reduces accuracy of risk prediction

Low Risk Traits:

• Widely cultivated, with no reports of invasiveness in natural areas or agricultural setting
  
• Unarmed (no spines, thorns, or burrs)
  
• May require specialized pollinators