Family: Fabaceae

Origin, Description & Uses
Macroptilium bracteatum, commonly known as burgundy bean, is a fast-growing tropical legume native to South America, ranging from Peru and Brazil to northern Argentina. It is a trailing or climbing vine with attractive deep reddish-purple flowers and trifoliate leaves. Burgundy bean is valued primarily as a forage and cover crop because it improves soil fertility through nitrogen fixation, helps reduce erosion, and provides livestock feed in tropical and subtropical regions. It is also occasionally planted as an ornamental groundcover due to its vigorous growth and colorful blooms.

Risks & Threats
Burgundy bean is considered a low-risk species and is not currently known to cause significant environmental harm in Hawaii. While it can spread in favorable conditions, it has not demonstrated the aggressive invasive behavior seen in higher-risk tropical legumes. As with many fast-growing vines, occasional monitoring and maintenance may be needed to prevent unwanted spread into nearby vegetation or disturbed areas. When managed responsibly, burgundy bean can be a useful species for agriculture, erosion control, and landscaping with relatively low concern for impacts to Hawaii’s ecosystems.

High Risk Traits:

• Broad climate suitability (cool subtropics to >35°C)
  
• History of repeated introductions outside native range
  
• Congeneric weed (M. atropurpureum is invasive)
  
• Climbing/smothering growth habit
  
• Produces viable seed; rapid germination
  
• Self-compatible (primarily self-pollinating)
  
• Generates in <1 year (flowers 50–90 days)
  
• Intentionally spread by people (pasture legume)
  
• Prolific seed production (~170,000 seeds/kg)
  
• Tolerates defoliation/cutting (persistent)

Low Risk Traits:

• No evidence of naturalization
  
• Not a weed (garden, agricultural, or environmental)
  
• No spines, thorns, burrs, or toxicity
  
• Highly palatable to grazers (reduces weed spread)
  
• Short-lived perennial (2–3 years)
  
• No persistent seed bank (hard seed breaks down rapidly)
  
• No vegetative spread
  
• No wind, water, bird, or external animal dispersal