Family: Fabaceae

Origin, Description & Uses
Mucuna pruriens (cowitch, velvet bean) is a fast-growing tropical vine native to the Old World tropics and subtropics, including parts of Africa, Asia, and the Pacific. It produces long trailing stems, large trifoliate leaves, and striking purple flowers that develop into fuzzy seed pods covered in irritating hairs. The plant is widely known for its use as a cover crop and green manure because it can improve soil fertility by fixing nitrogen. In some regions, it has also been used in traditional medicine, and its seeds are a natural source of L-DOPA, a compound used in treatments related to Parkinson’s disease. However, the plant’s seed hairs can cause intense skin irritation, giving rise to its common name “cowitch.”

Risks & Threats
Although Mucuna pruriens is currently not known to be naturalized in the Hawaiian Islands, it does possess traits that are cause for concern, and which could detrimentally impact tropical island ecosystems. It is a vigorous climbing vine capable of rapidly smothering vegetation, forming dense mats that block light and outcompete native plants. Its ability to fix nitrogen can also alter soil nutrient balances, potentially changing habitat conditions over time. In addition, its irritating seed hairs can pose risks to people, pets, and livestock. Because of these characteristics, it should be approached with caution, and planting is not recommended in natural areas. When available, choosing a low-risk or native alternative is strongly encouraged to help protect Hawaii’s ecosystems.

High Risk Traits:

• Naturalized & an agricultural weed (Mexico, Mozambique, Jamaica, Madagascar)
  
• Congeneric weed (M. coriacea)
  
• Climbs & smothers (vine to 10 m)
  
• Broad climate & soil tolerance
  
• Causes human skin irritation
  
• Self-pollinating (cleistogamous)
  
• Viable, persistent seed bank
  
• Generates in <1 year
  
• Intentionally spread by people

Low Risk Traits:

• No spines, burrs, or thorns
  
• No toxicity to animals
  
• No vegetative spread
  
• Moderate seed production
  
• No wind, water, bird, or external animal dispersal (large seeds)
  
• Herbicide-susceptible
  
• No resprouting after fire/mutilation