Identification: According to:
Habit: Perennial, floating and emergent, herbacous forb
Native Range: Ludwigia hexapetala is native to South America.
There is questions if the species is native to the southeastern US. Its earliest records date to South Carolina in 1844 and Georgia in 1864; its unclear if these records reflect a lack of early collections or introductions (Jacono 2014).
† Populations may not be currently present.
Impact of Introduction:
Summary of species impacts derived from literature review. Click on an icon to find out more...
Ludwigia hexapetala can grow as impenetrable mats at the water surface, blocking incoming sunlight, decreasing dissolved oxygen, and reducing available habitat for waterfowl (Grewell et al. 2016). It impeded access of waterfowl, fish, and turtles to a wetland pond complex in Eugene, Oregon (Alkhadher 2016) and reduced over 90% of foraging habitat for the Giant Garter Snake, Thamnophis gigas, in Sacramento, California (Moffitt and Gill 2017). Through allelopathic chemicals, L. hexapetala caused a decrease in the relative growth rate of Ceratophyllum demersum and an increase in the length of lateral branches of Myriophyllum aquaticum. High densities of L. hexapetala decreased root length of Mentha aquatica via allelopathy (Thouvenot et al. 2013), while low and high densities of M. aquatica increased biomass of L. hexapetala (Thiébaut et al. 2019).
Economic and human health impacts
Ludwigia hexapetala inhibits access to waterways for boating, fishing, hunting, and swimming, and it impedes important water conveyance systems including water supply canals and wetland preserves for urban and industrial water use and agricultural irrigation (Grewell et al. 2016). Dense mats of L. hexapelata inhibit the effective application of larvicides for mosquito control. In the Laguna de Santa Rosa sub-basin of California’s Russian River watershed, a record number of adult mosquitoes were trapped adjacent to dense patches of L. hexapetala, coinciding with the arrival of the West Nile Virus, a mosquito-vectored disease (Meisler 2009).
References: (click for full references)
Alkhadher, M. 2016. South American aquatic weed is here to stay at Eugene’s Delta Ponds, but city succeeds in substantially knocking it back. The Register-Guard. Eugene, OR. http://registerguard.com/rg/news/local/34662990-75/story.csp. Created on 08/11/2016. Accessed on 08/11/2016.
Grewell, B.J., M.D. Netherland, and M.J. Skaer Thomason. 2016. Establishing research and management priorities for invasive water primroses (Ludwigia spp.). U.S. Army Corps of Engineers, Engineer Research and Development Center, Vicksburg, MS. https://apps.dtic.mil/sti/pdfs/AD1002917.pdf.
Jacono, C. 2014. A note on Florida's latest waterprimrose, Ludwigia hexapetala. Aquatics 36(1):15-16. https://plants-archive.ifas.ufl.edu/wp-content/uploads/files/caip/pdfs/LudwigiaHexapetala-fromAquaticsSpring2014.pdf.
Meisler, J. 2009. Lessons from Ludwigia control in Sonoma County. Cal-IPC News. Berkeley, CA. 17 (2):4-5. https://www.cal-ipc.org/docs/resources/news/pdf/Cal-IPC_News_Summer09.pdf.
Moffitt, L., and N.S. Gill. 2017. Mitigated Negative Declaration: Restoration of Priority Freshwater Wetlands for Endangered Species at the Cosumnes River Preserve. County of Sacramento, Sacramento, CA. http://deltaconservancy.ca.gov/wp-content/uploads/2017/09/AI-8.4-Prop-1-1608_CEQA_Initial-Study-Mitigated-Negative-Declaration-DK-CI.pdf.
Thiébaut, G., L. Thouvenot, and H. Rodríguez-Pérez. 2018. Allelopathic effect of the invasive Ludwigia hexapetala on growth of three macrophyte species. Frontiers in Plant Science 9(1835):1-10. https://doi.org/10.3389/fpls.2018.01835.
Thiébaut, G., H. Rodriguez-Perez, and O. Jambon. 2019. Reciprocal interactions between the native Mentha aquatica and the invasive Ludwigia hexapetala in an outdoor experiment. Aquatic Botany 157:17-23. https://doi.org/10.1016/j.aquabot.2019.05.005.
Thouvenot, L., C. Puech, L. Martinez, J. Haury, G. Thiébaut. 2013. Strategies of the invasive macrophyte Ludwigia grandiflora in its introduced range: Competition, facilitation or coexistence with native and exotic species? Aquatic Botany 107:8-16. https://doi.org/10.1016/j.aquabot.2013.01.003.
This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.