Family: Myrtaceae

Melaleuca quadrifida, commonly known as one-sided bottlebrush or common net bush, is an evergreen shrub to small tree native to southwestern Western Australia. It is characterized by narrow, needle-like leaves and showy red flower clusters that form along one side of the stems, creating a distinctive bottlebrush appearance. Blooming mainly in spring to early summer, the flowers attract birds and other pollinators. Due to its drought tolerance and adaptability to well-drained soils, this plant is widely used in ornamental landscaping, hedges, and restoration-style plantings in dry and coastal environments.

In Hawaiʻi, Melaleuca quadrifida is primarily grown as an ornamental and is not known to be invasive at this time. There are no widespread reports of it spreading into natural areas or causing ecological harm. Nevertheless, because some members of the myrtle family (Myrtaceae) have become invasive elsewhere, it is important to monitor plantings and prevent escape into unmanaged landscapes. Using plants responsibly and favoring low-risk species helps protect Hawaiʻi’s native ecosystems.

High Risk Traits:

• Adaptable to a range of environmental conditions (possesses environmental versatility)
  
• Native to Mediterranean climate, but able to grow in tropical climates
  
• Naturalized outside native range in Australia
  
• Regarded as a weed in Australia, with potential negative environmental impacts
  
• Other species have become invasive
  
• Unpalatable to browsing animals (due to essential oils)
  
• Potential host of myrtle rust
  
• Tolerates many soil types
  
• Forms dense stands in native range
  
• Reproduces by seeds
  
• Hybridizes with other Calothamnus species
  
• Self-compatible
  
• Seeds dispersed by people (and possibly wind)
  
• Serotinous - seeds persist on plants for years prior to release
  
• Able to resprout after cutting, hard pruning and fire

Low Risk Traits:

• Unarmed (no spines, thorns, or burrs)
  
• Ornamental
  
• Not reported to spread vegetatively
  
• Seeds remain on plant until fire triggers release (may limit ability to spread in absence of fire)