Family: Fabaceae

Origin, Description & Uses:
Vigna hosei is a creeping, perennial legume native to tropical Southeast Asia, including Taiwan, Borneo, Java, and the Malay Peninsula. It produces long trailing stems, trifoliate leaves, and small yellow to pale yellow flowers followed by slender seed pods. Because it grows rapidly and forms a dense mat, it has been widely planted as a cover crop in orchards and plantations, as a forage plant for livestock, and for erosion control and soil improvement through its ability to fix nitrogen.

Risks & Threats:
In Hawaiʻi, Vigna hosei is naturalized on Oʻahu and Hawaiʻi Island and is potentially naturalizing on Maui. This species possesses traits that are cause for concern, including vigorous vegetative growth, dense ground cover formation, and the ability to spread beyond cultivation. It can smother low-growing vegetation, compete with native plants, and alter natural plant communities, potentially impacting tropical island ecosystems. Because it is already naturalized in parts of the state, further planting should be avoided, particularly near natural areas or on islands where it is not yet widespread. Managing existing populations and preventing additional spread can help minimize negative impacts. Whenever possible, choose a low-risk or native groundcover or cover crop as an alternative.

High Risk Traits:

• Elevation range exceeds 1000 m, demonstrating environmental versatility
  
• Thrives in tropical climates
  
• Naturalized on Oahu and Hawaii (Hawaiian Islands); widely introduced and naturalized elsewhere
  
• A weedy vine that may negatively affect agriculture (but valued as a cover crop under trees)
  
• Other Vigna species are invasive
  
• Shade-tolerant (could possibly invade intact forest)
  
• Tolerates many soil types
  
• Smothering growth habit
  
• Reproduces by seeds and vegetatively by rooting at nodes
  
• Self-compatible
  
• Able to reach maturity in 6 months
  
• Seeds dispersed by gravity, possibly by water and intentionally by people

Low Risk Traits:

• Despite reports of weediness, valued as a palatable livestock forage, or as a cover plant under plantation trees
  
• Unarmed (no spines, thorns, or burrs)
  
• Provides fodder for livestock
  
• Seed production reported to be poor (could limit potential to spread)
  
• Certain herbicides may provide effective control