Family: Asphodelaceae

Origin, Description & Uses
Xanthorrhoea preissii, commonly known as the grass tree, is an iconic plant native to the southwestern region of Western Australia. Despite its tree-like appearance, it is a long-lived perennial distinguished by a stout trunk topped with a dense crown of narrow, grass-like leaves. Mature plants produce impressive flowering spikes that can rise several feet above the foliage, attracting a variety of native pollinators. Grass trees are highly valued as ornamental landscape plants for their striking architectural form, exceptional drought tolerance, and ability to thrive in well-drained soils. They are well suited to water-wise gardens and are also culturally significant to Indigenous Australians, who have traditionally used various parts of the plant for food, tools, resin, and medicine.

Risks & Threats
Xanthorrhoea preissii is considered a low-risk species for Hawaii. It has a very slow growth rate, limited natural spread, and relies on specific environmental conditions for successful seed germination and establishment. There is no evidence that it has become invasive or naturalized in Hawaii or other regions where it is cultivated. While any non-native plant should be monitored when introduced to new environments, this species poses little risk of spreading into natural ecosystems and is considered an appropriate choice for responsible ornamental planting.

High Risk Traits:

• History of repeated introductions (ornamental trade)
  
• Highly combustible; creates fire hazard
  
• Tolerates wide range of soil types
  
• Produces viable, germinable seed
  
• Seeds intentionally dispersed by people
  
• High seed output (2,100–6,000 per plant)
  
• Resprouts and flowers prolifically after fire

Low Risk Traits:

• Not naturalized or weedy
  
• No spines, thorns, or burrs
  
• Palatable to grazers; no evidence of toxicity
  
• Not toxic to humans
  
• Not shade-tolerant (prefers full sun)
  
• Slow to mature (first flowers at 4+ years, often much later)
  
• Seeds lack dispersal adaptations; fall near parent plant