Family: Onagraceae

Origin, Description & Uses
Ludwigia repens (creeping primrosewillow, red ludwigia) is a semi-aquatic plant native to the southern United States, Central America, and the Caribbean. It typically grows in wetlands, along streambanks, and in shallow water, where it forms low, spreading mats. This species is known for its attractive reddish-green foliage and small yellow flowers, making it popular in freshwater aquariums and water gardens. Its ability to grow both submerged and emergent adds to its appeal for ornamental use.

Risks & Threats
Although Ludwigia repens is not currently known to be naturalized in the Hawaiian Islands, it possesses traits that raise concern. It can grow rapidly, reproduce vegetatively from fragments, and thrive in a variety of wet habitats—characteristics that increase its potential to spread beyond cultivation. In similar environments elsewhere, species in the Ludwigia genus have formed dense mats that outcompete native vegetation, alter water flow, and degrade aquatic ecosystems. If introduced into Hawaiʻi’s sensitive wetlands and waterways, it could detrimentally impact native species and habitat quality. For these reasons, it is recommended to choose low-risk or native aquatic plants when suitable alternatives are available.

High Risk Traits:

• Able to grow in tropical and subtropical climates
  
• Naturalized in New Zealand and Australia
  
• Potential environmental weed
  
• Other Ludwigia species are invasive
  
• Able to smother water surfaces
  
• Reproduces by seeds and vegetatively
  
• Readily hybridizes with other Ludwigia species
  
• Self-compatible
  
• Can spread vegetatively by stolons and stem fragments
  
• Able to reach maturity in 1 growing season
  
• Seeds dispersed by water, wind, birds (e.g. ducks), machinery, footwear, clothing and mud
  
• Distributed as an aquarium plant
  
• Seeds can become a contaminant of rice and possibly other aquatic crops
  
• Viable seeds passed by feral pigs
  
• Able to resprout and spread after cutting

Low Risk Traits:

• Unarmed (no spines, thorns or burrs)
  
• Palatable to pigs and humans
  
• Non-toxic
  
• Aquarium species
  
• Seeds may not form a persistent seed bank
  
• Herbicides may provide effective control