Family: Asphodelaceae

Origin, Description & Uses
Dianella caerulea, commonly known as cerulean flaxlily, flax lily, or bamboo flax lily, is a clumping, grass-like perennial native to Australia. It features arching, strap-shaped leaves and produces delicate blue to violet star-shaped flowers followed by bright blue berries. This hardy plant is widely used in landscaping as a groundcover or border plant due to its drought tolerance, adaptability to sun and shade, and low maintenance requirements. Its attractive foliage and colorful berries make it popular in residential and commercial plantings.

Risks & Threats
Although valued as an ornamental, Dianella caerulea is naturalized on Oʻahu and possesses traits that raise concern in Hawaiʻi. It spreads by both underground rhizomes and seed, allowing it to form dense clumps that may outcompete nearby vegetation. Its tolerance of a range of environmental conditions increases its potential to expand beyond cultivated areas into natural ecosystems. Because it is already naturalized and has characteristics associated with invasive plants, caution is recommended when planting or distributing this species to help ensure it does not negatively impact Hawaiʻi’s native habitats.

High Risk Traits:

• Naturalized in Florida: Escaped cultivation and invaded natural areas.
  
• Naturalized on O'ahu
  
• Invasive weed: Requires active herbicide management in Florida parks.
  
• Bird-dispersed: Fleshy fruits are attractive to birds, aiding spread.
  
• Vegetative spread: Forms spreading clumps via underground shoots (ramets).
  
• Resprouts after disturbance: Can regenerate after mutilation or fire.
  
• Shade tolerant: Can establish in forests and closed woodlands.
  
• Broad soil tolerance: Grows in sandy, loamy, and poor soils.
  
• Potential toxicity: May be toxic to livestock or humans (neurological effects reported).

Low Risk Traits:

• No physical defenses: Lacks spines, thorns, or burrs.
  
• Palatable fruit: Eaten raw by Indigenous Australians (sweet, nutty flavor).
  
• Not allelopathic or parasitic: No evidence of chemical suppression or host dependence.
  
• Low self-pollination: Requires specific native bees (buzz-pollination).
  
• No persistent seed bank: No strong evidence of seeds surviving >1 year.
  
• Not a fire hazard: Evergreen perennial does not increase fire risk.
  
• No congeneric weed risk: Other Dianella species not widely invasive.