Family: Poaceae

Origin, Description & Uses
Rytidosperma semiannulare (Tasmanian wallaby grass) is a perennial bunchgrass native to southeastern Australia, where it grows in grasslands, woodlands, and open forests. It forms small to medium clumps of fine, upright green blades and produces delicate flowering structures that turn golden as they mature. In its native range, it plays an important ecological role in supporting soil stability and providing habitat for insects and small wildlife. It is sometimes used in ecological restoration and native landscaping for its drought tolerance, low maintenance needs, and natural appearance in meadow or prairie-style plantings.

Risks & Threats
This species is considered low risk and is not known to be naturalized or invasive in Hawaiʻi. It does not currently show traits associated with aggressive spread or ecological disruption in tropical island environments. However, as with any non-native plant, ongoing evaluation is still important to ensure it does not establish beyond intended plantings or compete with native vegetation under local conditions. Using well-studied native or Polynesian-introduced grasses remains the best option for restoration and landscaping projects focused on protecting Hawaiʻi’s ecosystems.

High Risk Traits:

• Elevation range exceeds 1000 m, demonstrating environmental versatility
  
• Thrives in tropical climates
  
• Possibly naturalizing on Oahu, Hawaiian Islands (confirmation needed)
  
• Latex highly caustic to the skin, possibly poisonous if ingested
  
• Tolerates many soil types
  
• Seeds dispersed by birds and intentionally by people
  
• Seeds able to be stored for extended periods; May form a persistent seed bank
  
• Able to coppice and resprout after cutting

Low Risk Traits:

• No reports of invasiveness or naturalization (with the possible exception of Oahu(), but no evidence of widespread introduction outside native range
  
• Unarmed (no spines, thorns or burrs)
  
• Provides fodder for livestock (palatable despite reports of toxicity)
  
• Ornamental
  
• Not reported to spread vegetatively
  
• Limited ecological information makes accurate risk prediction difficult