The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

Ludwigia hexapetala
Ludwigia hexapetala
(six petal water primrose)

Copyright Info
Ludwigia hexapetala (Hook. & Arn.) Zardini, H.Y. Gu & P.H. Raven

Common name: six petal water primrose

Synonyms and Other Names:  Ludwigia grandiflora ssp. hexapetala (Hook. & Arn.) G.L. Nesom & Kartesz

Taxonomy: available through www.itis.govITIS logo

Identification: According to:

Habit: Perennial, floating and emergent, herbacous forb






Size: 90-120 cm

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).


Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Ludwigia hexapetala are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
CA1902202023Butte Creek; Clear Creek-Sacramento River; Cottonwood-Tijuana; Coyote; Honcut Headwaters-Lower Feather; Honey-Eagle Lakes; Lower American; Lower Sacramento; Newport Bay; Russian; Sacramento-Stone Corral; Salinas; San Diego; San Joaquin Delta; San Luis Rey-Escondido; San Pablo Bay; Santa Clara; Santa Margarita; Tomales-Drake Bays; Upper Cache; Upper Cosumnes; Upper Putah; Ventura
GA202020201Lower Flint
LA201420162Boeuf; East Central Louisiana Coastal
MS200820081Upper Tombigbee
NC195720208Deep; Haw; Lower Cape Fear; New River; Upper Cape Fear; Upper Catawba; Upper Neuse; Upper Tar
OK194619461Lower Cimarron
OR200720183Lower Rogue; Middle Rogue; Upper Willamette
SC1981202016Black; Broad-St. Helena; Carolina Coastal-Sampit; Cooper; Enoree; Lake Marion; Lower Broad; Lower Catawba; Lower Savannah; Middle Savannah; Salkehatchie; Saluda; Santee; South Carolina Coastal; Tyger; Upper Broad
WA199420181Lower Columbia-Clatskanie

Table last updated 10/22/2021

† Populations may not be currently present.

Means of Introduction: The ornamental plant trade (Jacono 2014).

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

EcologicalEconomicHuman HealthOther

Ecological impacts

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.

Author: Pfingsten, I., Procopio, J., and Daniel, W.M.

Revision Date: 10/22/2021

Citation Information:
Pfingsten, I., Procopio, J., and Daniel, W.M., 2021, Ludwigia hexapetala (Hook. & Arn.) Zardini, H.Y. Gu & P.H. Raven: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=2979, Revision Date: 10/22/2021, Access Date: 10/23/2021

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.


The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2021]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [10/23/2021].

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