Family: Fabaceae

Origin, Description & Uses
Senna bicapsularis is a flowering shrub or small tree native to tropical America. It is valued for its bright yellow blossoms, attractive foliage, and extended blooming period, making it a popular ornamental plant in tropical and subtropical landscapes. The species is commonly used as a hedge, screen, specimen planting, or for erosion control, and its flowers can attract pollinators such as bees and butterflies. Its rapid growth and adaptability to a variety of environmental conditions have contributed to its widespread cultivation.

Risks & Threats
Although Senna bicapsularis is not currently known to be naturalized in the Hawaiian Islands, it possesses several traits that are cause for concern and could detrimentally impact tropical island ecosystems. The species produces abundant seeds, grows quickly, and can form dense stands that compete with native vegetation for sunlight, water, and nutrients. In regions outside its native range, it has demonstrated the ability to escape cultivation and establish in disturbed habitats. These characteristics suggest the potential for spread and ecological impacts if introduced more widely in Hawaiʻi. To help protect native ecosystems, it is recommended that gardeners and landscapers choose a low-risk or native alternative whenever suitable options are available.

High Risk Traits:

• Highly suited to tropical/subtropical climates (USDA zones 8a–11)
  
• Naturalized in Africa and other regions outside native range
  
• Forms dense thickets that smother native vegetation and restrict wildlife
  
• Listed as an environmental weed in South Africa (Category 3) and Australia
  
• Congeneric species (S. obtusifolia) are significant invasive weeds
  
• Toxic to cattle (purgative effects)
  
• Produces numerous viable seeds
  
• Persistent seed bank (>1 year) with hard-coated, dormant seeds
  
• Actively planted as ornamental, hedge, and medicinal plant
  
• Nitrogen-fixing (can alter soil conditions)

Low Risk Traits:

• Not a garden, agricultural, or forestry weed
  
• Lacks spines, thorns, or burrs
  
• Not shade-tolerant (prefers full sun)
  
• No vegetative reproduction
  
• No external seed attachment for accidental dispersal
  
• Not a produce contaminant
  
• No major pests or diseases reported
  
• Controlled by herbicides (cut-and-paint, foliar sprays)