Family: Fabaceae

Origin, Description & Uses
Desmanthus virgatus, commonly known as slender mimosa, is a fast-growing, perennial legume native to tropical and subtropical regions of the Americas. This shrubby plant typically reaches 3–6 feet tall and has delicate, fern-like leaves and small, ball-shaped white to pale green flowers followed by narrow seed pods. Slender mimosa is valued as a forage plant for livestock because of its high protein content and ability to fix nitrogen, improving soil fertility. It has also been used for erosion control, cover cropping, and in some areas as an ornamental plant due to its airy foliage and drought tolerance.

Risks & Threats
Although slender mimosa is not currently known to be naturalized in the Hawaiian Islands, it possesses traits that raise concern for tropical island ecosystems. It produces abundant seeds, tolerates drought and poor soils, and readily colonizes disturbed sites such as roadsides and pastures. In other tropical regions, it has spread beyond cultivation and can outcompete native vegetation. As a nitrogen-fixing species, it may also alter soil chemistry, giving it an advantage over native plants adapted to nutrient-poor conditions. These characteristics could allow it to spread and disrupt fragile island habitats. Because of these risks, Plant Pono recommends choosing a low-risk or native alternative better suited to Hawaii’s unique ecosystems.

High Risk Traits:

• Naturalized beyond native range (Hawaii, Florida, many tropical countries)
  
• Garden/amenity/disturbance weed (common garden weed in Australia)
  
• Agricultural weed (serious weed in sugarcane; troublesome in cultivated fields)
  
• Congeneric weed (D. illinoensis is a weed in soybean fields)
  
• Tolerates wide range of soils (sand to clay; pH 5-8)
  
• Nitrogen-fixing woody plant (competitive advantage in poor soils)
  
• Produces viable seed
  
• Short generation time (can behave as an annual)
  
• Intentional dispersal by people (planted for forage and soil conservation)
  
• Seeds survive gut passage (dispersed by ruminants)
  
• Prolific seed production (~244,000 seeds/kg)
  
• Forms persistent seed bank (hard seed coat dormancy >1 year)
  
• Tolerates disturbance (resprouts after fire, grazing, or mutilation)

Low Risk Traits:

• No spines, thorns, or burrs
  
• Not allelopathic
  
• Palatable to grazing animals (high-quality forage)
  
• Non-toxic to animals
  
• Non-toxic to humans
  
• Shade intolerant (limits forest invasion)
  
• No vegetative fragmentation (spread by seed only; slow vegetative spread)
  
• No wind or water dispersal
  
• No external animal dispersal (internal dispersal only)