Family: Commelinaceae

Origin, Description & Uses:
Tradescantia spathacea, commonly known as oyster plant, Moses-in-the-cradle, or boat lily, is a low-growing, evergreen perennial native to southern Mexico and Guatemala. It forms dense clumps of sword-shaped leaves that are green on top and rich purple underneath, with small white flowers nestled within distinctive purple, boat-shaped bracts. Its colorful foliage, tolerance of heat and shade, and ability to thrive in a variety of landscape conditions have made it a popular ornamental groundcover for gardens, borders, containers, and tropical landscapes.

Risks & Threats:
Tradescantia spathacea is naturalized on Kauaʻi and Oʻahu and is potentially naturalizing on Hawaiʻi Island. It possesses traits that are cause for concern, including rapid vegetative spread through creeping stems and stem fragments, dense mat formation, and tolerance of both shaded forests and disturbed habitats. These characteristics allow it to outcompete native vegetation, suppress seedling establishment, and alter the structure of tropical plant communities. Because it is already naturalized in parts of Hawaiʻi and could detrimentally impact tropical island ecosystems, planting this species is discouraged. Where possible, choose a low-risk or native alternative for landscaping. In areas where oyster plant is already widespread, gardeners and land managers should prevent it from spreading into natural areas by properly disposing of garden waste, controlling existing infestations, and avoiding planting it near forests, streams, or other sensitive habitats.

High Risk Traits:

• Thrives in tropical climates
  
• Widely naturalized
  
• Garden weed
  
• Environmental weed
  
• Other Tradescantia species have become invasive
  
• Toxic to animals and people if consumed; sap causes dermatitis
  
• Shade-tolerant
  
• Tolerates many soil types
  
• Forms dense ground cover that excludes other vegetation
  
• Reproduces by seeds and vegetatively
  
• Self-compatible
  
• Seeds dispersed by wing and intentionally by people
  
• Damaged plants easily resprout from the root

Low Risk Traits:

• Unarmed (no spines, thorns or burrs)
  
• Ornamental
  
• Seeds do not store well and may not form a persistent seed bank
  
• Herbicides might provide effective control