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.

Cabomba caroliniana
Cabomba caroliniana
(Carolina fanwort)
Native Transplant
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Cabomba caroliniana A. Gray

Common name: Carolina fanwort

Synonyms and Other Names: Cabomba (Portuguese-Brazil), Carolina water-shield, Fanwort, Fish grass, Green Cabomba, Washington grass, Washington-plant

Taxonomy: available through www.itis.govITIS logo

Identification: C. caroliniana is fully submerged except for occasional floating leaves and emergent flowers (Australian Department of the Environment and Heritage 2003). The roots grow on the bottom of water bodies and the stems can reach the surface. Parts of the plant can survive free-floating for six to eight weeks.  It is a perennial, growing from short rhizomes with fibrous roots. The branched stems can grow up to 10m long and are scattered with white or reddish-brown hairs.

The underwater leaves are divided into fine branches, resulting in a feathery fan-like appearance. These leaves are about 5cm across and secrete a gelatinous mucous which covers the submerged parts of the plant. The floating leaves, however, are small, diamond-shaped, entire, and borne on the flowering branches. The solitary flowers are less than 2cm across and range in colour from white to pale yellow and may also include a pink or purplish tinge. The flowers emerge on stalks from the tips of the stems (Australian Department of Environment and Heritage, 2003).

Submersed leaves: petiole to 4 cm; leaf blade 1-3.5 × 1.5-5.5 cm, terminal segments 3-200, linear to slightly spatulate, to 1.8 mm wide. Floating leaves: blade 0.6-3 cm × 1-4 mm, margins entire or notched to sagittate at base. Flowers 6-15 mm diam.; sepals white to purplish [yellow] or with purple-tinged margins, 5-12 × 2-7 mm; petals colored as sepals but with proximal, yellow, nectar-bearing auricles, 4-12 × 2-5 mm, apex broadly obtuse or notched; stamens 3-6, mostly 6; pistils 2-4, mostly 3, divergent at maturity; ovules 3. Fruits 4-7 mm. Seeds 1-3, 1.5-3 × 1-1.5 mm, tubercles in 4 longitudinal rows

The submersed leaves of Cabomba caroliniana are similar in form to those of Limnophila (Scrophulariaceae; introduced in southeastern United States). The latter has whorled leaves in contrast to the opposite leaves of Cabomba .

Size: Mature plant size is approximately 12-31 inches or more (30-80 cm or more) and may grow up to 10m long (Wilson et al. 2007).

Native Range: Cabomba caroliniana A. Gray is native to southern Brazil, Paraguay, Uruguay, northeast Argentina, southern and eastern USA.

Native range in USA: Connecticut, Massachusetts,  New Hampshire,  Rhode Island, Alabama,  Arkansas,  District of Columbia, Florida,  Illinois, Indiana, Kentucky, Louisiana, Maryland, Michigan,  Mississippi, Missouri, New Jersey,   New York, North Carolina, Ohio, Oklahoma, Pennsylvania, South Carolina,  Tennessee, Texas, Virgina

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 Cabomba caroliniana are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
CA199120082California Region; San Joaquin Delta
CT193720137Housatonic; Lower Connecticut; Pawcatuck-Wood; Quinebaug; Quinnipiac; Shetucket; Thames
DE189719904Brandywine-Christina; Broadkill-Smyrna; Chincoteague; Nanticoke
ME200820081New England Region
MA1895201912Blackstone; Cape Cod; Charles; Chicopee; Concord; Hudson-Hoosic; Merrimack River; Middle Connecticut; Miller; Narragansett; Nashua; Quinebaug
MI193520169Clinton; Huron; Kalamazoo; Lower Grand; Muskegon; Pere Marquette-White; St. Joseph; Thornapple; Upper Grand
NH195720203Merrimack River; Nashua; Piscataqua-Salmon Falls
NJ190120209Cohansey-Maurice; Crosswicks-Neshaminy; Hackensack-Passaic; Lower Delaware; Lower Hudson; Middle Delaware-Musconetcong; Mullica-Toms; Raritan; Sandy Hook-Staten Island
NY1947202015Bronx; Hackensack-Passaic; Hudson-Wappinger; Lower Hudson; Lower Hudson; Middle Delaware-Mongaup-Brodhead; Middle Hudson; Northeastern Lake Ontario; Northern Long Island; Oneida; Rondout; Sacandaga; Salmon-Sandy; Sandy Hook-Staten Island; Southern Long Island
OH193320183Cuyahoga; Southern Lake Erie; Upper Ohio-Beaver
OR196220103Alsea; Lower Columbia; Siltcoos
PA193820138Crosswicks-Neshaminy; Delaware; French; Lehigh; Lower Delaware; Middle Allegheny-Tionesta; Shenango; Upper Susquehanna-Lackawanna
RI193220153Blackstone; Massachusetts-Rhode Island Coastal; Narragansett
WA199420182Lower Columbia-Clatskanie; Pacific Northwest Region

Table last updated 11/24/2020

† Populations may not be currently present.

* HUCs are not listed for states where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).

Ecology: Cabomba is sensitive to drying out and requires permanent shallow water, usually less than 3 meters (but up to 10 meters) deep (Australian Department of the Environment and Heritage 2003). It grows rooted in the mud of stagnant to slow flowing water including streams, and smaller rivers (The Washington State Department of Ecology, 2003). It also grows in ponds, lakes, reservoirs, sloughs, ditches, and canals.

It can respond to wide fluctuations in water depths and is a water column feeder that grows well in silty substrate and exhibits reduced vigour in hard substrates. Growth of 50mm a day has been reported in Lake Macdonald in Queensland, Australia. It grows well in high nutrient environments with low pH, but in more alkaline waters it tends to lose its leaves. High calcium levels inhibit growth and unlike other aquatic weeds, cabomba can grow well in turbid water. It prefers a warm, humid climate with a temperature range of 13-27ºC but can survive when the surface of the water body is frozen (Australian Department of Environment and Heritage 2003). PH ranges 4.8~7.8, dCH soft ~ hard.

C. caroliniana flowers from May to September. In the southeastern U.S., C. caroliniana is self-pollinating and seeds readily germinate (The Washington State Department of Ecology 2003).

Means of Introduction: 1935, release from aquarium in Lake Michigan drainage (U.S. EPA 2008). Fanwort stems become brittle in late summer, which causes the plant to break apart, facilitating its distribution and invasion of new waterbodies. It produces seed but vegetative reproduction seems to be its main vehicle for spreading to new waters. Large numbers of plants are sent from Florida to the rest of the U.S. for commercial use. Fanwort is also grown commercially in Asia for export to Europe and other parts of the world. Small-scale, local cultivation occurs in some area and aquarists (aquarium release or escape) are probably responsible for some introductions.

Status: Established, widely distributed in many US states.

Impact of Introduction: An important aquarium plant. 

C. caroliniana is an extremely persistent and competitive plant.  In New England and parts of southeast United States, it is sometimes an aggressive weed. It can sometimes form dense growth in water bodies of the southeastern United States and can impede water flow in ditches and canals and interfere with recreational activities (Tarver et al. 1986). Once established, this plant can clog drainage canals and freshwater streams interfering with recreational, agricultural, and aesthetic uses.

In Australia, Cabomba is regarded as a "Weed of National Significance". It is one of the worst weeds in Australia because of its invasiveness, potential for spread, and economic and environmental impacts. It is choking waterways along Australia's east coast (Australian Department of the Environment and Heritage 2003). It is extremely persistent and can take over a water body, excluding native plant species. It can also have an impact on native animals - in northern Queensland platypus and water rat numbers are lower in infested creeks (Australian Department of the Environment and Heritage 2003). Cabomba grows quickly and produces a large amount of plant material. It can significantly reduce water storage capacity and taint drinking water supplies. Water treatment costs can be increased by up to $50 a megalitre (Australian Department of the Environment and Heritage 2003). Heavy infestations can also raise water levels to a point where overflows and heavy seepage losses occur. Cabomba's dense mass of underwater stems and leaves provide a hazard for recreational water users. When this vegetation dies off, decomposition causes dramatic oxygen reductions and foul smelling water.

Remarks: In parts of the southeastern United States, plants with purple-tinted flowers, possibly a response to some environmental factor, have been treated as Cabomba caroliniana var. pulcherrima. South American plants with yellow flowers have been called C . caroliniana var. flavida O/rgaard.

References: (click for full references)

Australian Department of the Environment and Heritage (ADEH). 2003. Weed Managment Guide: Cabomba- Cabomba caroliniana. CRC for Australian Weed Managment; Commonwealth Department of the Environment and Heritage. 6  pp.

Bultemeier, B. W., M.D. Netherland, J.A. Ferrell, and W. T. Haller. 2009. Differential herbicide response among three phenotypes of Cabomba caroliniana. Invasive Plant Science and Management 2(4): 352—359.

CSIRO Entomology. 2011. Biological control of Cabomba. Available http://www.csiro.au/science/ps2ku#a2. Accessed 16 April 2013.

ENSR International. 2005. Rapid Response Plan for Fanwort (Cabomba caroliniana) in Massachusetts. Massachutes Department of Conservation and Recreation. 22 pp.

Ensbey, R. and E. van Oosterhout. 2010. Cabomba. 6 pp.

Falck, M. and S. Garske. 2003. Invasive Non-native Plant Management During 2002. Great Lakes Indian Fish & Wildlife Commission (GLIFWC), Odanah, WI. 68 pp.

Forest Health Staff. 2006. Carolina Fanwort; Cabomba caroliniana Gray. U.S. Department of Agriculture 1 pp.

Gleason, H.A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York.

Global Invasive Species Database. National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG) http://www.issg.org/database/species/ecology.asp?si=402&fr=1&sts=sss  

Godfrey, R. K. and J. W. Wooten. 1981. Aquatic and Wetland Plants of Southeastern United States. Dicotyledons. The University of Georgia Press, Athens, Georgia.  

Great Lakes Panel on Aquatic Nuisance Species (GLPANS). 2008. Prohibited species in the Great Lakes region. Research Coordination Committee, GLPANS. Available: http://www.glc.org/ans/pdf/08-11-26-Great%20Lakes%20Reg%20Species%20List-complete.pdf

Hamel, K. 2013. Cabomba caroliniana (Fanwort) - Technical Information. Department of Ecology, State of Washington. Available http://www.ecy.wa.gov/programs/wq/plants/weeds/aqua006.html. Accessed 16 April 2013.

Hanlon, C. 1990. A Florida native - Cabomba (fanwort). Aquatics 12(4): 4-6.

Hogsden, K.L., E.P.S. Sager, T.C. Hutchinson. 2007. The impacts of the non-native macrophyte Cabomba caroliniana on littoral biota of Kasshabog Lake, Ontario. Journal of Great Lakes Research 33:497-504.

Hotchkiss, N. 1972. Common Marsh, Underwater and Floating-leaved Plants of the United States and Canada. Dover Publications, Inc., New York.

Hudon, C. and R. Carignan. 2008. Cumulative impacts of hydrology and human activities on water quality in the St. Larence River (Lake Saint-Pierre, Quebec, Canada). Canadian Journal of Aquatic Sciences 65:1165—1180.

Idaho Invasive Species Council Technical Committee, The (IISCTC) . 2007. Idaho Aqautic Nuisance Species Plant. 139 pp.

ITIS (Integrated Taxonomic Information System), 2004. Online Database Cabomba carolinianahttp://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=18408

Lui, K., M. Butler, M. Allen, E. Snyder, J. da Silva, B. Brownson, and A. Ecclestone. 2010. Field Guide to Aqautic Invasive Species: Identification, collection and reporting of aquatic invasive in Ontario waters. Minstry of Natural Resources, Ontario, Canada. 201 pp.

Madsen, J. D. 1999. A Quantitative Approach to Predict Potential Nonindigenous Aquatic Plant Species Problems. 2 pp.

Marson, D., B. Cudmore, D.A.R. Drake, and N.E. Mandrak. 2009. Summary of a survey of aquarium owners in Canada. Canadian Manuscript Report of Fisheries and Aquatic Sciences 2905: iv + 20 p

Mikulyuk, A. and M. Nault. 2011. Cabomba caroliniana (Carolina fanwort). Available http://www.cabi.org/isc/?aqb=yes&compid=5&dsid=107743&loadmodule=datasheet&page=481&site=144. Accessed 16 April 2013.

Minnesota Department of Natural Resources (MN DNR) 2013a. Grass carp (Ctenopharyngodon idella). Available http://www.dnr.state.mn.us/invasives/aquaticanimals/grasscarp/index.html. Accessed 16 April 2013.

Minnesota Department of Natural Resources (MN DNR). 2013b. Minnesota invasive species laws. Available http://www.dnr.state.mn.us/invasives/laws.html. Accessed 16 April 2013.

Morrison, W.E. and M.E. Hay. 2011. Induced chemical defenses in a freshwater macrophyte suppress
herbivore fitness and the growth of associated microbes. Oecologia 165:427-436.

New York Department of Environmental Conservation (NY DEC). 2013. Triploid Grass Carp in New York Ponds: What is a grass carp? Available http://www.dec.ny.gov/outdoor/7973.html. Accessed 16 April 2013.

New York Invasive Species Council (NYISC). 2010. Final report: a regulatory system for non-native species. Department of Environmental Conservation, Albany, NY. 131 pp.

O’Sullivan, C., B. Rounsefell, A. Grinham, W. Clarke, J. Udy. 2010. Anaerobic digestion of harvested aquatic weeds: water hyacinth (Eichhornia crassipes), cabomba (Cabomba caroliniana), and salvinia (Salvinia molesta). Ecological Engineering 36:1459-1468.

Ontario's Invasive Species Awareness Program (OISAP). 2013. Fanwort (Cabomba caroliniana). Available http://www.invadingspecies.com/invaders/plants-aquatic/fanwort/. Accessed 16 April 2013.

Ørgaard, M. 1991. The genus Cabomba (Cabombaceae) - a taxonomic study. Nordic Journal of Botany 11: 179-203

Pennsylvania Department of Conservation and Natural Resources (PA DCNR). 2011. Carolina Fanwort. Cabomba caroliniana A. Gray. 2 pp.

Radford, A.E., H.E. Ahles, and C.R. Bell. 1968. Vascular Flora of the Carolinas. The University of North Carolina Press, Chapel Hill.

Riemer, D.N. and R.D. Ilnicki. 1968. Overwintering of Cabomba in New Jersey. Weed Science 16:101-102.

Rixon, C. A. M., I. C. Duggan, N. M. N. Bergeron, A. Ricciardi, and H. J. Macisaac. 2005. Invasion risks posed by the aquarium trade and live fish markets on the Laurentian Great Lakes. Biodiversity and Conservation 14(6): 1365-1381.

Schooler, S., M. Jullen, G.C. Walsh. 2006. Predicting the response of Cabomba caroliniana populations to biological control agent damage. Australian Journal of Entomology 45:327-330.

Shiels, A. L. and M. A. Hartle. n.d. Pond Owner's Guide to the Use of Triploid Grass Carp in Pennsylvania. Pennsylvania Fish & Boat Commission. Available http://fishandboat.com/images/pages/forms/pfbc_tgc002.pdf. Accessed 16 April 2013.

Tarver, D. P., J. A. Rogers, M. J. Mahler, and R. L. Lazor. 1986. Aquatic and Wetland Plants of Florida. Third Edition. Florida Department of Natural Resources, Tallahassee, Florida.  

Tilt, K. 2013. Plant Identification Resource: Cabomba caroliniana. Auburn University Horticulture Department. Available http://www.ag.auburn.edu/hort/landscape/dbpages/434.html. Accessed 16 April 2013.

USDA-GRIN (Germplasm Resources Information Network). 2003. Cabomba caroliniana. National Genetic Resources Program [Online Database] National Germplasm Resources Laboratory, Beltsville, Maryland.

U. S. Environmental Protection Agency (U.S. EPA) 2008. Predicting future introductions of nonindigenous species to the Great Lakes. Washington DC. 138 pp.

Washington State Department of Ecology, 2003. Technical Information About Cabomba Caroliniana (Fanwort). Water Quality Program: Non-Native Freshwater Plants.

Wiersema, J. H. 1997. Cabombaceae. In: Flora of North America. Volume 3. Magnoliophyta: Magnoliidae and Hamamelidae. Oxford University Press, Oxford. pp. 78-80.  

Wilson, C.E., S.J. Darbyshire, R. Jones. 2007. The biology of invasive alien plants in Canada. 7. Cabomba caroliniana A. Gray. Canadian Journal of Plant Science 87:615-638.

Wisconsin Department of Natural Resources (WI DNR). 2012. Fanwort (Cabomba caroliniana). Available http://dnr.wi.gov/topic/invasives/fact/fanwort.html. Accessed 16 April 2013.

Zhang, X., Z., Yang, and C., Jiakuan. 2003. Fanwort in Eastern China: An Invasive Aquatic Plant and Potential Ecological Consequences. AMBIO: A Journal of the Human Environment, 32:158-159.

Other Resources:

Flora of North America.  2008.  efloras.org

For more detailed control information, please view this Rapid Response Guide from the Massachusetts Department of Conservation and Recreation: http://www.mass.gov/dcr/watersupply/lakepond/downloads/rrp/fanwort.pdf

For more information on grass carp, please visit:
Department of Ecology, State of Washington

Michael Porter’s article Controlling Aquatic Vegetation with Grass Carp

US Fish and Wildlife Service Ecological Risk Screening Summary for Cabomba caroliniana

Author: Larson, J. L. Cao, L. Berent, and S. Iott

Revision Date: 7/25/2016

Citation Information:
Larson, J. L. Cao, L. Berent, and S. Iott, 2020, Cabomba caroliniana A. Gray: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=231, Revision Date: 7/25/2016, Access Date: 11/25/2020

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. [2020]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [11/25/2020].

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