Family: Fabaceae

Origin, Description & Uses
Mimosa pigra (catclaw mimosa) is a thorny, fast-growing shrub or small tree native to tropical and subtropical regions of the Americas. It is recognized for its sensitive, fern-like leaves that fold when touched, along with its prickly stems and rounded pink to purple flower heads. The species has been introduced to many tropical regions as an ornamental plant and has also been used for hedging, erosion control, and occasionally as a source of fuelwood. However, its dense growth habit and sharp thorns can make it difficult to manage once established.

Risks & Threats
Although Mimosa pigra is currently not known to be naturalized in the Hawaiian Islands, it possesses several traits that are cause for concern and could negatively impact tropical island ecosystems if introduced. This species is considered one of the world’s worst invasive plants in some tropical regions, where it forms dense, impenetrable thickets that displace native vegetation, reduce biodiversity, obstruct waterways, and limit access for people and wildlife. It produces abundant long-lived seeds and can spread rapidly in wet and disturbed habitats such as floodplains, wetlands, and pastures. Its thorny growth also interferes with agriculture and land management. Because of these invasive characteristics, planting Mimosa pigra is not recommended in Hawaiʻi. Whenever possible, choose a low-risk or native alternative better suited for tropical island environments.

High Risk Traits:

• Grows in tropical/subtropical climates; invasive in Australia, Thailand, Florida
  
• Naturalized and forms dense, impenetrable thickets
  
• Agricultural & environmental weed (threatens cattle, wetlands, irrigation)
  
• Congeneric weed (Mimosa pudica is a major pest)
  
• Produces spines/thorns
  
• Unpalatable to grazing animals
  
• Wide soil tolerance (clays to sands)
  
• Self-compatible; no specialist pollinators needed
  
• Flowers within 3–12 months
  
• Prolific seeds (up to 12,000/m²)
  
• Persistent seed bank (>2 years)
  
• Water-dispersed seeds (floating pods)
  
• Animal-dispersed (sticks to fur, clothing, machinery; survives gut)
  
• Resprouts after fire or cutting

Low Risk Traits:

• Not allelopathic, parasitic, or toxic (to animals or humans)
  
• Not a climber, grass, or aquatic plant
  
• No vegetative fragmentation
  
• Not wind- or bird-dispersed
  
• No reproductive failure in native range