Ludwigia grandiflora thrives in slow-flowing rivers, drainage ditches, lakes, and ponds. Its ability to produce both floating and emergent stems allows it to survive in moist to wet soil (Stiers et al., 2014). L. grandiflora can grow on nutrient poor soils such as gravel, sand bars, and mud (EPPO, 2011). They have adventitious roots that are capable of absorbing oxygen allowing them to colonize environments with low or variable dissolved oxygen (Rejamánková, 1992). L. grandiflora reproduces primarily through vegetative fragmentation achieving densities as high as 2 kg dry weight/ m2  (Dandelot et al., 2005). L. grandiflora grows quickly and forms dense mats that can crowd out native species and contribute to reduced flow and hyper-sedimentation (Dandelot et al., 2008).

L. grandiflora produces unpalatable compounds that cause herbivores and pathogens to avoid them (Dandelot et al., 2008). They also showed evidence of allelopathic abilities when grown with watercress (Dandelot et al., 2008). Red swamp crayfish (Procambarus clarkii) were found to consume large quantities of L. grandiflora in France (Lambert et al., 2009).

Potential pathway(s) of introduction: Hitchhiking/Fouling.
Ludwigia grandiflora has primarily spread throughout its native range by vegetative fragmentation or escape from water gardens. However, the closest known populations of L. grandiflora to the Great Lakes are in Eastern Pennsylvania and Southeastern New York (EDDmaps, 2019). L. grandiflora is a popular plant for recreational culture, however it is not readily available through retailers in the Great Lakes. This species is commonly misidentified and may be sold under another name.

Ludwigia grandiflora has a high probability of establishment if introduced to the Great Lakes (Confidence level: High).

This species has a high level of polymorphism and phenotypic plasticity which has allowed it to establish in a broad range of environments (Ruaux et al., 2009). L. grandiflora is reported to survive and reproduce under high levels of pollution, increased salinity, and drought (Dandelot et al., 2008). L. grandiflora can survive low temperatures of 4-8°C with submersed fragments remaining viable even after freezing. L. grandiflora has high fecundity, especially when reproducing through vegetative fragmentation (Dandelot et al., 2005).

Summary of species impacts derived from literature review. Click on an icon to find out more...

Environmental	Socioeconomic

Ludwigia grandiflora has the potential for high socioeconomic impact if introduced to the Great Lakes.
    Dense monotypic stands of L. grandiflora interfere with flood control efforts and drainage systems causing flooding and impeding navigation and recreational boating (CABI, 2019). L. grandiflora can outcompete native grasses in wet meadows which reduces grazing space for livestock (Dutarte, 2004). Dense mats of L. grandiflora may also reduce the perceived aesthetic of water bodies it inhabits (CABI, 2019).

There is little or no evidence to support that Ludwigia grandiflora  has the potential for significant beneficial impact if introduced to the Great Lakes.
    L. grandiflora is sometimes employed as an ornamental plant in water gardens. However, it is not a popular garden plant in the Great Lakes region, and L. grandiflora is not easily found through garden stores or online retailers.

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.

Control
Biological
    Procambarus clarkii are a predator of L. grandiflora, but current P. clarkii populations in the Great Lakes are unlikely to prevent establishment of this species.

Physical
    Manual removal of L. grandiflora may be effective for eradicating small isolated populations, but there is a risk of spreading plant fragments which may allow existing populations to spread even further (EPPO, 2011)
   
Chemical
    Herbicides may be used to control Ludwigia grandiflora (EPPO, 2011).

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.