Family: Lamiaceae

Origin, Description & Uses
Premna odorata (alagau) is a small tree or shrub native to Taiwan, tropical Asia, and northern Australia. It is valued for its fragrant leaves and clusters of small flowers, and is often grown as an ornamental or traditional medicinal plant. In some regions, the leaves and roots are used in herbal remedies, while the wood may be used for small tools, fuelwood, or carving. Its attractive foliage and adaptability also make it useful for hedges and landscaping in tropical climates.

Risks & Threats
Premna odorata is considered a low-risk species for Hawaiʻi. While it can grow well in tropical environments, there is little evidence that it spreads aggressively or causes significant environmental harm. Occasional naturalization may occur in disturbed areas, but it has not shown the invasive tendencies seen in higher-risk species. As with any introduced plant, responsible cultivation and monitoring are recommended to help prevent unintended spread into native ecosystems.

High Risk Traits:

• Suited to tropical/subtropical climates (native to Taiwan & Philippines)
  
• Tolerates a wide range of soil conditions (e.g., limestone forests)
  
• Produces viable seed
  
• Fleshy fruit dispersed by birds & survives gut passage

Low Risk Traits:

• No spines, thorns, burrs, or climbing habit
  
• Not parasitic, toxic, or allelopathic
  
• Unlikely to disperse unintentionally (no attachment)
  
• Not dispersed by wind, water, or external animal transport