Family: Fabaceae

Origin, Description & Uses:
Vigna luteola, commonly known as hairy cowpea or yellow vigna, is a trailing or climbing perennial legume native to tropical and subtropical regions of the Americas, although it is now found throughout much of the world’s tropics. It produces slender vines with three-part leaves and bright yellow, pea-like flowers followed by narrow seed pods. This species is well adapted to wet habitats such as marshes, streambanks, coastal areas, and other disturbed sites. As a nitrogen-fixing legume, it has been used as forage for livestock, as a cover crop to improve soil fertility, and occasionally for erosion control and habitat restoration in tropical regions.

Risks & Threats:
Vigna luteola is naturalized on Kauaʻi, Oʻahu, and Maui, and is potentially naturalizing on Hawaiʻi Island. It possesses traits that are cause for concern, including rapid vegetative growth, prolific seed production, nitrogen fixation, and the ability to spread into wetlands, coastal habitats, and other disturbed areas. Dense mats of vegetation can smother native plants, alter habitat structure, and facilitate further ecosystem changes, potentially degrading sensitive tropical island ecosystems. Because of these invasive characteristics, planting Vigna luteola is not recommended. Choose a low-risk or native alternative when suitable options are available. Where this species is already widespread, avoid planting it in new locations and manage existing populations near natural areas to help minimize further spread and ecological impacts.

High Risk Traits:

• Elevation range exceeds 1000 m, demonstrating environmental versatility
  
• Thrives in tropical climates
  
• Naturalized on Kauai and Oahu (Hawaiian Islands); widely introduced and naturalized elsewhere
  
• An aggressive weedy vine that may impact rice, other agricultural crops and young trees
  
• Other Vigna species have become weeds
  
• Tolerates many soil types (not substrate limited)
  
• Climbing vine; can potentially smother young trees
  
• Reproduces by seeds and vegetatively by rooting at nodes and internodes
  
• Self-compatible, but dependent on bees and other pollinators for seed set
  
• Rapidly reaches maturity (as quickly as 90 days from planting)
  
• Seeds dispersed by water, in cattle dung and intentionally planted by people
  
• Prolific seed production and potentially long-lived seed bank
  
• May tolerate burning, grazing and flooding (conflicting accounts)

Low Risk Traits:

• Despite reports of weediness, valued as a palatable pasture livestock forage (and unlikely to become weedy or problematic in regularly grazed pastures)
  
• Unarmed (no spines, thorns, or burrs)
  
• Herbicides may provide effective control