Family: Fabaceae

Origin, Description & Uses:
Senna spectabilis, commonly known as spectacular cassia, crown of gold tree, whitebark senna, or casia amarilla, is a medium-sized flowering tree native to southwestern Mexico and tropical regions of Central and South America. It is widely cultivated in tropical and subtropical areas for its showy displays of bright yellow flowers, which often cover the canopy when the tree is in bloom. Its attractive appearance, rapid growth, shade value, and adaptability to a range of environmental conditions have made it a popular ornamental tree in parks, gardens, roadsides, and landscape plantings.

Risks & Threats:
Senna spectabilis is naturalized on Oʻahu and possesses several traits associated with invasive behavior, including prolific seed production, rapid growth, and the ability to establish in disturbed and natural habitats. In regions where it has escaped cultivation, it can form dense stands that compete with native vegetation, alter habitat structure, and reduce biodiversity. Because tropical island ecosystems are particularly vulnerable to invasive species, further spread of this tree could negatively impact native plant communities and ecosystem function. Given its high-risk status, Plant Pono recommends choosing a low-risk or native alternative when suitable options are available. Where Senna spectabilis is already established, landowners and managers should prevent its spread into new areas and avoid planting it near natural or unmanaged habitats to help minimize additional ecological impacts.

High Risk Traits:

• Thrives in tropical climates
  
• Naturalized on Oahu, (Hawaiian Islands) as well as the Philippines and East and southern Africa
  
• An environmental weed in Tanzania, and perhaps elsewhere in Africa, forming dense stands and excluding native vegetation
  
• Other Senna (and Cassia specie) are invasive
  
• Unpalatable to browsing and grazing animals
  
• Tolerates many soil types
  
• Forms dense thickets
  
• Reproduces by seeds
  
• Rapid growth
  
• Seeds dispersed by mud stuck to vehicles, by water, gravity and intentionally by people
  
• Able to coppice and resprout after cutting

Low Risk Traits:

• Unarmed (no spines, thorns, or burrs)
  
• Requires full sun (may prevent spread into intact forests)
  
• Not nitrogen fixing
  
• Not reported to spread vegetatively
  
• Herbicides may provide effective control