Family: Fabaceae

Castanospermum australe, commonly known as Australian chestnut, black bean, or Moreton Bay bean, is a large evergreen tree native to eastern Australia and parts of New Guinea. It is easily recognized by its glossy, dark green compound leaves, showy red and yellow pea-like flowers, and large, woody pods containing oversized chestnut-like seeds. The tree can grow quite tall and wide, making it a popular choice as a shade or ornamental tree in parks and large landscapes. Historically, Indigenous Australians processed the seeds through careful soaking and cooking to remove toxins before eating them, and today the tree is mainly valued for its striking appearance, dense shade, and strong, decorative wood.

While Australian chestnut is not considered highly invasive, it can pose some concerns if planted in the wrong place. The large seeds are toxic if eaten raw and can be dangerous to children, pets, and livestock. Fallen pods and seeds can also be messy and create slip or trip hazards. Because the tree grows very large with a spreading root system, it may damage sidewalks, walls, or underground infrastructure when planted too close to buildings. In Hawaiʻi and other tropical regions, it should be used thoughtfully and monitored to ensure it does not spread beyond cultivated areas or displace native plants.

High Risk Traits:

• Elevation range exceeds 1000 m, demonstrating environmental versatility
  
• Grows in tropical climates
  
• Possibly naturalizing on Hawaii (Hawaiian Islands), naturalized on Norfolk Island, and a cultivation escape in New Zealand
  
• Seeds and foliage toxic to animals; seeds toxic to humans
  
• Shade tolerant
  
• N-fixing (may alter soil chemistry)
  
• Reproduces by seeds
  
• Seeds dispersed by water and intentionally by people
  
• Able to coppice and resprout after cutting

Low Risk Traits:

• No reports of invasiveness or negative impacts outside native range
  
• Unarmed (no spines, thorns, or burrs)
  
• Dioecious
  
• Not reported to spread vegetatively
  
• Large fruit and seeds unlikely to be inadvertently dispersed
  
• Recalcitrant seeds will not form a persistent seed bank