Family: Fabaceae

Acacia pycnantha, commonly known as broadleaf wattle or golden wattle, is a fast-growing tree native to southeastern Australia and the floral emblem of that country. It is widely planted as an ornamental for its bright yellow, fragrant flowers and as a source of tannins and timber. The species is highly adaptable, tolerating drought, poor soils, and disturbed areas, which has led to its use in revegetation and erosion control projects. Its ability to fix nitrogen makes it a hardy colonizer that can quickly establish in degraded landscapes.

Outside of its native range, however, Acacia pycnantha can present risks as an invasive species. It has naturalized in parts of South Africa and the Mediterranean region, where it spreads aggressively and alters native plant communities. The tree’s prolific seed production, rapid growth, and resprouting after disturbance allow it to form dense stands that displace local vegetation and reduce biodiversity. In places like Hawaiʻi and other Pacific islands, introduction of this species could threaten fragile ecosystems by outcompeting native plants and altering fire regimes.

High Risk Traits:

• Naturalized beyond native range (California, South Africa)
  
• Forms dense thickets that smother native vegetation
  
• Tolerates a wide range of soil conditions
  
• Produces viable seed
  
• Hybridizes naturally (with A. williamsonii)
  
• Produces prolific seed (>1000/m²)
  
• Forms persistent seed bank (>1 year)
  
• Dispersed by multiple vectors (water, birds, ants, wind, human activities)
  
• Fire-adapted (resprouts and fire-stimulated germination)
  
• Nitrogen-fixing woody plant

Low Risk Traits:

• Not shade-intolerant
  
• Not toxic to humans or animals
  
• Self-incompatible (requires cross-pollination)
  
• Does not reproduce by vegetative fragmentation