Family: Fabaceae

Origin, Description & Uses
Stylosanthes scabra is native to South Tropical America, where it grows in seasonally dry grasslands, savannas, and open disturbed areas. It is a hardy, deep-rooted perennial legume with a shrubby growth form and small yellow flowers typical of the bean family. Like other stylo species, it is valued for its ability to fix nitrogen in the soil, improving fertility and supporting pasture productivity in low-input agricultural systems. It has been widely introduced in tropical regions for use as forage for livestock, soil stabilization, erosion control, and as a cover crop in degraded or marginal lands. In Hawaiʻi, this species is now naturalized on Kauaʻi, Oʻahu, Molokaʻi, Lānaʻi, Maui, and Hawaiʻi Island, where it persists in dry to mesic pastures, roadsides, and other disturbed sites.

Risks & Threats
Stylosanthes scabra is considered a low-risk naturalized species in Hawaiʻi, and it does not currently show strong evidence of aggressive invasive behavior. However, because it is already established across multiple islands, it has the potential to continue spreading in dry, disturbed lowland habitats, especially in pasture systems where it was originally introduced. As a nitrogen-fixing legume, it may subtly alter soil nutrient dynamics and plant community composition over time, which can favor other weedy or non-native species in some settings. While it can provide useful forage and soil improvement benefits, its continued spread in natural or semi-natural dry ecosystems should still be monitored. In areas where conservation of native dryland vegetation is a priority, land managers are encouraged to observe its behavior and prioritize native or non-invasive alternatives when appropriate.

High Risk Traits:

• Naturalized beyond native range (Australia)
  
• Naturalized on Kaua'i, O'ahu, Moloka'i, Lāna'i, Maui, and Hawai'i
  
• Tolerates shade and persists under low light
  
• Grows on a wide range of soils
  
• Nitrogen-fixing (alters soil fertility)
  
• Highly self-pollinating (98.2%)
  
• Produces >11,000 seeds per square meter
  
• Seeds survive passage through animal guts
  
• Resprouts after fire and heavy grazing
  
• Widely introduced as a forage crop outside native range

Low Risk Traits:

• Not a documented agricultural or environmental weed
  
• Lacks spines, thorns, or burrs
  
• Not allelopathic, parasitic, or toxic
  
• Not unpalatable to grazing animals
  
• No vegetative reproduction
  
• No long-lived persistent seed bank