Family: Myrtaceae

Origin, Description & Uses:
Eucalyptus crebra, commonly known as ironbark, is native to eastern Australia, where it grows in open woodlands and dry forests. This medium to tall tree is recognized for its dark, deeply furrowed “ironbark” bark, narrow lance-shaped leaves, and clusters of small white flowers that attract pollinators. It is well adapted to warm, seasonally dry climates and poor soils. Ironbark has been widely planted for its exceptionally hard, durable wood, which is valued for construction, fencing, fuelwood, and charcoal. It is also used in landscaping and windbreaks due to its toughness and drought tolerance.

Risks & Threats:
In Hawai‘i, ironbark is naturalized on Kaua‘i, O‘ahu, and Lāna‘i, and may be spreading on Moloka‘i. Despite its ability to establish outside cultivation, it is currently considered low risk. It does not appear to spread aggressively or dominate native ecosystems. However, as with other Eucalyptus species, it has the potential to alter local conditions by contributing leaf litter, increasing fire risk due to its oil-rich foliage, and competing with native plants in dry habitats. Continued observation is recommended to ensure that it remains a manageable component of the landscape and does not expand into sensitive natural areas.

High Risk Traits:

• Naturalized on Kaua'i, O'ahu and Lana'i
  
• Broad climate suitability (wide altitude, latitude, and rainfall range)
  
• History of repeated introductions outside native range
  
• Congeneric weeds exist (Eucalyptus species are principal weeds)
  
• Tolerates a wide range of soil conditions
  
• Produces viable seed that germinates easily
  
• Hybridizes naturally with other species
  
• Propagules dispersed intentionally by people (forestry species)
  
• Propagules adapted for wind dispersal
  
• Prolific seed production
  
• Tolerates coppicing, mutilation, and fire

Low Risk Traits:

• No evidence of weed status
  
• No spines, thorns, or burrs
  
• Not toxic to animals or humans
  
• Not parasitic, allelopathic, or a climbing habit
  
• Does not form dense thickets
  
• No vegetative reproduction
  
• No persistent seed bank (seeds germinate readily)