Family: Fabaceae

Origin, Description & Uses
Onobrychis viciifolia, commonly known as sainfoin or esparcet, is a perennial legume native to Central and Southeastern Europe. It is a deep-rooted, drought-tolerant plant that produces attractive pink flower spikes and is commonly grown in temperate regions as a high-quality forage crop for livestock. Sainfoin is valued for its nutritious, protein-rich hay and its ability to improve soil fertility through nitrogen fixation, making it useful in pasture systems and ecological farming. Its flowers are also beneficial for pollinators such as bees.

Risks & Threats
Sainfoin is generally considered a low-risk species because it has limited ability to spread aggressively outside of cultivation and is not known to be invasive in tropical island environments. It does not typically form dense, persistent wild populations, and its establishment is usually dependent on deliberate planting. While any introduced plant carries a small possibility of escape under favorable conditions, Onobrychis viciifolia currently shows minimal traits of concern for naturalization or ecosystem disruption in Hawaiʻi. As a result, it is considered a low threat compared to many other introduced forage or ornamental species.

High Risk Traits:

• Broad climate suitability
  
• Naturalized in regions with temperate and Mediterranean climates, but no evidence in Hawaiian Islands to date
  
• Reported to be a crop weed, but impacts generally unspecified
  
• Potentially allelopathic to certain plants
  
• Tolerates many soil types
  
• Reproduces by seeds and by rhizomes
  
• Self-compatible forms exist, but seed set is low
  
• Reaches maturity in second growing season
  
• Seeds dispersed by external attachment to animals and internally by passing through animals, as well as intentionally cultivated by humans
  
• Seeds able to be stored for extended periods but seed bank reported to be transient (longevity unknown)
  
• Able to regrow slowly after cutting or browsing

Low Risk Traits:

• Generally regarded as a desirable pasture plant, with relatively poor competitive ability, despite reports of weediness
  
• Unarmed (no spines, thorns, or burrs)
  
• Provides fodder for livestock
  
• Grows in full sunlight (may limit ability to spread under dense vegetation)
  
• Primarily self-incompatible, although self-fertile forms exist (with low seed set)