Family: Myrtaceae

The Division of Forestry and Wildlife of the Hawaiʻi Department of Land and Natural Resources has designated L. scoparium as one of “Hawaiʻi’s Most Invasive Horticultural Plants.” All species in the genus are discouraged from planting. Cultivated since at least 1927, members of this genera are naturalizing around the state. The popular essential oil, tea tree oil, comes from a different genus and species altogether.

Description and Dispersal:

• Shrub up to 16 ft tall with shredding bark
  
• L. scoparium has thin leaves (1/2 in long by 1/10 in wide), small white or pink flowers (1/2 in) and round wooden seed capsules (1/4 in)
  
• L. polygalifolium has longer leaves (up to 1 in long by 1/10 in wide) and white or greenish flowers (1/2 in)
  
• Seeds spread by wind

High Risk Traits:

• Broad climate suitability (temperate to subtropical)
  
• Naturalized in Hawaii and beyond native range
  
• Acts as an agricultural, environmental, and congeneric weed
  
• Forms dense thickets that suppress other plants
  
• Tolerates a wide range of infertile soils
  
• Produces viable seed & hybridizes naturally
  
• Self-compatible, no specialist pollinators needed
  
• Propagules dispersed intentionally (horticulture), unintentionally, and by wind
  
• Prolific seed production
  
• Benefits from fire (post-fire seed release)

Low Risk Traits:

• Unpalatable to grazing animals but not toxic
  
• No evidence of toxicity to humans or animals
  
• No vegetative fragmentation
  
• No persistent soil seed bank (seed bank short-lived)
  
• Does not resprout after decapitation (cutting effective)