Family: Fabaceae

Origin, Description & Uses
Common vetch (Vicia sativa) is an annual climbing legume native to Europe that has been widely introduced around the world as a valuable fodder crop. It has slender, trailing or climbing stems with paired leaflets ending in branched tendrils that help it scramble over surrounding vegetation. The plant produces pink, purple, or reddish flowers followed by elongated seed pods. Because it grows quickly and enriches the soil by fixing nitrogen, common vetch has long been cultivated for livestock forage, hay, green manure, cover cropping, erosion control, and, in some regions, as a minor food crop. In Hawaiʻi, it has become naturalized, primarily in dry to moist pastures between 860 and 2,130 meters on Kauaʻi, Maui, and Hawaiʻi Island, where it was first collected on Hawaiʻi Island in 1909.

Risks & Threats
Although valued in agriculture, common vetch is naturalized in Hawaiʻi and possesses traits that are cause for concern. It reproduces readily by seed, grows rapidly, and can form dense patches that compete with desirable pasture species and native vegetation. Its ability to thrive in disturbed habitats, combined with nitrogen-fixing capabilities that can alter soil conditions, increases its potential to spread into natural ecosystems. These characteristics could detrimentally impact tropical island ecosystems if the species continues to expand its range. Because common vetch is already established in parts of Hawaiʻi, landowners and land managers should avoid planting it in or near natural areas and help prevent its spread into regions where it is not yet widespread. When suitable, choose a low-risk or native alternative for forage, cover cropping, or soil improvement to help protect Hawaiʻi’s unique ecosystems.

High Risk Traits:

• Elevation range exceeds 1000 m, demonstrating environmental versatility
  
• Able to grow in temperate and tropical climates
  
• Naturalized in the Hawaiian Islands (Kauai, Maui, Hawaii) and elsewhere
  
• A weedy plant and potential agricultural and environmental weed
  
• Other Vicia species are invasive
  
• Seeds may be toxic
  
• Tolerates many soil types
  
• Climbing plant (can possibly smother or suppress other vegetation)
  
• Reproduces by seeds
  
• Hybridizes with other Vicia species
  
• Self-compatible
  
• Reaches maturity in <1 year (annual)
  
• Seeds dispersed by birds and other animals (internally), by adhering to boots in mud, by water, and intentionally by people
  
• Prolific seed production with some subspecies
  
• Seeds for a persistent seed bank
  
• Able to tolerate mowing at certain growth stages

Low Risk Traits:

• Although weedy, regarded as a desirable plant for weed suppression or soil fertility in certain situations
  
• Unarmed (no spines, thorns, or burrs)
  
• Provides fodder for livestock
  
• Not reported to spread vegetatively
  
• Herbicides provide effective control