Family: Myrtaceae

Origin, Description & Uses
Eucalyptus globulus (blue gum) is a fast-growing evergreen tree native to southeastern Australia and Tasmania. It is widely planted around the world for timber, pulpwood, windbreaks, and ornamental use due to its tall stature, smooth peeling bark, and distinctive blue-green, aromatic leaves. The species is also an important source of eucalyptus oil, commonly used in medicinal products, cleaning solutions, and fragrances. Its adaptability to a variety of climates and soils has made it a popular choice for forestry and landscaping.

Risks & Threats
Eucalyptus globulus is considered a high-risk species in many regions because of its potential to spread beyond cultivation and disrupt natural ecosystems. It produces large quantities of seed, can form dense stands, and may outcompete native plants for light, water, and nutrients. Its leaf litter can alter soil conditions and suppress the growth of other species, while the high oil content in its foliage increases fire risk. Although this species is currently not known to be naturalized in the Hawaiian Islands, it possesses traits that are cause for concern and could detrimentally impact tropical island ecosystems if introduced more widely.

High Risk Traits:

• Broad climate suitability (tolerates temperate to high-elevation tropical climates)
  
• Naturalized beyond native range (California, southern Europe, New Zealand)
  
• Environmental weed (displaces native species; listed as a pest plant in California)
  
• Congeneric weed (other Eucalyptus species are significant weeds)
  
• Allelopathic (litter and oils inhibit understory growth)
  
• Unpalatable to grazing animals (gains competitive advantage in grazed areas)
  
• Creates fire hazard (accumulates flammable debris; volatile oils intensify fires)
  
• Forms dense thickets (monospecific stands reduce biodiversity)
  
• Tolerates wide range of soils (acidic, alkaline, clay, poor soils)
  
• Prolific seed production (hundreds of tiny seeds per capsule)
  
• Wind-dispersed seeds
  
• Resprouts after cutting or fire
  
• Intentionally planted (timber, pulp, ornament, oils)

Low Risk Traits:

• No spines, thorns, or burrs
  
• Non-toxic (to animals or humans)
  
• Shade intolerant (requires full sun)
  
• No vegetative reproduction (no root suckers or fragmentation)
  
• No specialist pollinators (pollinated by common insects and birds)
  
• Not dispersed by water or animals
  
• Controlled by herbicides (glyphosate, triclopyr)