Disclaimer:

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.

---

Common name: Indian swampweed

Synonyms and Other Names: East Indian hygrophila, Miramar weed, East Indian swampweed, Dwarf hygrophila, Justicia polysperma (Roxb.), Hemidelphis polysperma (Roxb.) Nees in Wall.

Taxonomy: available through www.itis.gov

Identification:

Stem/Roots: Hygrophila polysperma is a spiny dicotyledon plant. It is primarily a submersed rooted plant, but can be emersed in shallow areas with smaller, darker leaves (Cuda and Sutton 2000). Stems are creeping ascendant, brittle, and easily fragmented, and are 6 feet or longer (Ramey 2001). The emersed stems can be squarish.

Leaves: It has elliptical leaves that are up to 8 cm long and 2 cm wide, and taper to a sharp point (Langeland and Burks 1999). Attachment of leaves is sessile, with the bases joined at the nodes by ciliated flanges of tissue. The leaf arrangement is opposite.

Flowers: Flowers are small and are solitary in the uppermost leaf axils, and are nearly hidden by leaves. The calyx is 5-lobed, the corolla is bluish-white and 2-lipped, and there are 2 fertile stamens.

Fruit/Seeds: The fruit is a narrow capsule, which split lengthwise to release tiny round seeds.

Look-a-likes: Ludwigia repens creeping primrose-willow, Alternanthera philoxeroides alligatorweed, and Hygrophila costata lake hygro. The key difference is H. polysperma is mainly submersed.

Size: Stems 6 feet or longer (Ramey 2001).

Native Range: India, Malaysia, Bangladesh, Bhutan, Nepal, Cambodia, Laos, Myanmar, Thailand, and Vietnam (Angerstein and Lemke 1994, Nault and Mikulyuk 2009).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

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

Ecology: Hygrophila polysperma is a wetland plant that can occur as a submerged or an emersed plant. It inhabits lakes, streams, marshy areas, ditches, and rice-fields (de Thabrew 2014). This species can grow in water at depths up to 3 m and on stream banks as an emersed plant (Nault and Mikulyuk 2009). Hygrophila polysperma can inhabit habitats with a variety of environmental conditions. It favors warmer waters of 18-30°C but can tolerate water temperatures as low as 4°C (Kasselmann 1995, Ramey 2001, Rixon et al. 2005, US EPA 2008). It grows in waters with pH of 6.5-7.8 (Spencer and Bowes 1985, Doyle et al. 2003) and water hardness of 30-140 ppm (Nault and Mikulyuk 2009). This species has low light saturation and compensation points, so it is capable of photosynthesizing in low light levels (Doyle et al. 2003). Hygrophila polysperma exhibits low seasonality and can maintain shoot biomass year round (Spencer and Bowes 1985). Growth rate is dependent on water temperature and daylight (Nault and Mikulyuk 2009), and can increase dramatically in the presence of nutrient inputs (Sutton and Dingler 2000). This species can draw CO₂ from both the water and atmosphere (Doyle et al. 2003).

In North America, H. polysperma has a specific life cycle, starting with a rooted stage in hydro-soil in dense stands of shoots, some with large leaves reaching up to the canopy, and some emergent ones with smaller leaves. Shoots on moist banks are very small, and resemble the submerged form after banks are flooded. Shoots begin elongating in March as the water temperature rises, then they reach the surface in late spring. In summer, they break off into mats and float away, and take root as soon as they come into contact with soil. The whole shoot of the plant breaks off near the root crown in August and forms very dense floating mats, which can sink piece by piece, or all at once to form a new colony; new shoots regrow from the roots, and they grow slowly in winter (Hall et al. 2003).

Means of Introduction: Hygrophila polysperma was first introduced into Florida via the aquarium industry in the 1950s (Cuda and Sutton 2000). It was cultivated in Ohio at the end of WWII by an aquarium dealer (Reams 1953), but there is no indication that this species is still cultivated there.

Surveys conducted by Rixon et al. (2005) found that H. polysperma was available for purchase in 25% of the pet and aquarium stores surveyed near Lakes Erie and Ontario. Maki and Galatowitsch (2004) had evidence that H. polysperma is available for purchase from vendors across the U.S. with delivery service to Minnesota. In addition, it is sometimes sold under the incorrect name of Alternanthera sessilis.

Hygrophila polysperma spreads via vegetative fragmentation and has a high regrowth potential from stem fragments (Spencer and Bowes 1985).

Status: Established in Alabama, Florida, Kentucky, Mississippi, South Carolina, and Texas. Extirpated in Virginia due to freezing temperatures in the 1970s (Nault and Mikulyuk 2009).

Impact of Introduction:

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

Ecological	Economic	Human Health	Other

Hygrophila polysperma forms dense monocultures that exclude native plants and is a superior competitor because of its low requirements for light and rapid growth (Spencer and Bowes 1985). It shades out native submerged plants and can displace native plants when it occupies the entire water column (Vandiver 1980; Owens et al. 2001; Ramey 2001). When H. polysperma was grown with Ludwigia repens, L. repens exhibited slower growth rates compared to when grown alone, suggesting that H. polysperma has superior competitive abilities (Doyle et al. 2003). Hygrophila polysperma has spread into areas formerly dominated by Hydrilla verticillata (Cuda and Sutton 2000).

Remarks: In India, H. polysperma seeds are used as a medicine (Spencer and Bowes 1985).

Many thanks to University and of Florida, Center for Aquatic and Invasive Plants for the superb photographs.

References: (click for full references)

Angerstein, M.B. and D.E. Lemke. 1994. First records of the aquatic weed Hygrophila polysperma (Acanthaceae) from Texas. Sida 16(2):365-371.

Cuda, J.P., and D.L. Sutton. 2000. Is the aquatic weed hygrophila, Hygrophila polysperma (Polemoniales: Acanthaceae), a suitable target for classical biological control? Pages 337-348 in Spencer, N.R, ed. Proceedings of the X International Symposium on Biological Control of Weeds, 4-14 July 1999. Montana State University. Bozeman, MT.

De Thabrew, W.V. 2014. A manual of water plants. Author House, Bloomington, Indiana, 290 pp.

Doyle, R.D., M.D. Francis, and R.M. Smart. 2003. Interference competition between Ludwigia repens and Hygrophila polysperma: two morphologically similar aquatic plant species. Aquatic Botany 77(3): 223-234.

Duke, D., P. O'Quinn and D.L. Sutton. 2000. Control of hygrophila and other aquatic weeds in the Old Plantation Water Control District. Aquatics 22(3):4-8.

(FLDEP) Florida Department of Environmental Protection, Bureau of Aquatic Plant Management. 1988-1994. Florida Aquatic Plant Surveys, electronic data. Bureau of Aquatic Plant Management, Florida Department of Environmental Protection, Tallahassee, FL.

FL DEP (Florida Department of Environmental Protection). 2007. Status of the aquatic plant maintenance program in Florida public waters. Annual Report Fiscal Year 2005-2006. Bureau of Invasive Plant Management. Available at http://www.floridainvasives.org/toolbox/reports/aquaticsfy05-06.pdf. Accessed 20 August 2014.

GISD (Global Invasive Species Database). 2005. Hygrophila polysperma (aquatic plant). IUCN Species Survival Commission, Invasive Species Specialist Group. Available at http://www.issg.org/database/species/ecology.asp?si=759&fr=1&sts=&lang=EN. Accessed 19 August 2014.

Great Lakes Panel on Aquatic Nuisance Species. 2012. Prohibited species in the Great Lakes region. Available at http://citeseerx.ist.psu.edu/viewdoc/download;jsessionid=C54210BC2F921B7F141EE55707B81327?doi=10.1.1.396.3017&rep=rep1&type=pdf. Accessed 11 August 2014. 

Hall, D.W., V.V. Vandiver, and C.J. Gray. 2003. East Indian Hygrophila, Hygrophila polysperma (Roxb.) T. Anderson. Florida Cooperative Extension Service: Institute of Food and Agricultural Sciences: University of Florida. Available at http://edis.ifas.ufl.edu/pdffiles/FW/FW01900.pdf. Accessed 20 August 2014.

Harman, W.N. 2011. Catskill Region Aquatic Nuisance Species Survey for the Catskill Center for Conservation and Development. SUNY Oneonta, Biological Field Station, Oneonta, NY. http://www.oneonta.edu/academics/biofld/PUBS/ANNUAL/2011/23%20Aquatic%20Survey%20CRISP.pdf.

Hook, M.W., and J.B. Nelson. 2011. Noteworthy Collections: South Carolina. Castanea 76(2):195-196.

Hussner, A, K. Van de Weyer, E.M. Gross, and S. Hilt. 2010. Comments on increasing number and abundance of non-indigenous aquatic macrophyte species in Germany. Weed Research  50: 519-526.

Kay, S.H., and S.T. Hoyle. 2001. Mail order, the internet, and invasive aquatic weeds. Journal of Aquatic Plant Management 39: 88-91.

Kasselmann, C. 1995. Aquarienpflanzen. Egen Ulmer GMBH and Co., Stuttgart, Germany.

Langeland, K.A., and K.C. Burks (eds.). 1999. Identification and biology of non-native plants in Florida’s natural areas. University of Florida, Gainesville, Florida.

Les, D.H. and R.P. Wunderlin. 1981. Hygrophila polysperma (Acanthaceae) in Florida. Florida Scientist 44(3): 189-192.

Maki, K., and S. Galatowitsch. 20014. Movement of invasive aquatic plants into Minnesota (USA) through horticultural trade. Biological Conservation 118: 389-396.

Mississippi Museum of Natural Science. 2016. Mississippi Museum of Natural Science Herbarium (MMNS). Mississippi Department of Wildlife, Fisheries and Parks, Jackson, MS. https://www.mdwfp.com/seek-study/bio-collections/plants.aspx.

Mora-Olivo, A., T.F. Daniel, and M. Martinez. 2008. First record in the Mexican flora of Hygrophila polysperma (Acanthaceae), an aquatic weed. Revista Mexicana de Biodiversidad 79(1): 265-269.

Nault, M.E., and A. Mikulyuk. 2009. East Indian Hygrophila (Hygrophila polysperma): a technical review of distribution, ecology, impacts, and management. Wisconsin Department of Natural Resources Bureau of Science Services, Publication SS-1049 2009. Madison, Wisconsin, USA.

Owens, C.S., J.D. Madsen, R.M. Smart, and R.M. Stewart. 2001. Dispersal of native and nonnative aquatic plant species in the San Marcos River, Texas. Journals of Aquatic Plant Management 39: 75-79.

Osceola County. 2012. Hydrilla & Hygrophila Demonstration Project FAQ’s. University of Florida. Available at http://plants.ifas.ufl.edu/osceola/faq.html#benefitshydrilla. Accessed 20 August 2014.

Ramey, V. 2001. East Indian hygrophila (Hygrophila polysperma). Center for Aquatic and Invasive Plants, University of Florida, IFAS. Available at http://plants.ifas.ufl.edu/node/191. Accessed 19 August 2014.

Reams, Jr., W.M. 1953. The occurrence and ontogeny of hydathodes in Hygrophila polysperma T. Anders. New Phytologist 52(1):8-13.

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: 1365-1381.

Robinson, M. 2003. Potential invader, Eastern Indian Hygrophila: an exotic aquatic plant. Massachusetts Department of Conservation and Recreation Office of Water Resources, Lakes and Ponds Program. Available at http://www.mass.gov/eea/docs/dcr/watersupply/lakepond/factsheet/hygrophila.pdf. Accessed 20 August 2014.

Romanowski, N.2011. Wetland weeds: causes, cures, and compromises. CSIRO Publishing, Collingwood, Australia. p. 95-96.

Schmitz, D.C., and L.E. Nall. 1984. Status of Hygrophila polysperma in Florida. Aquatics 6(3):11-14. http://www.fapms.org/aquatics/issues/1984fall.pdf.

SC DNR (South Carolina Department of Natural Resources). 2010. Aquatic Nuisance Species Program Illegal Aquatic Plants: Hygrophila (Hygrophila polysperma). Available at http://www.dnr.sc.gov/invasiveweeds/img/hygrophila.pdf. Accessed 19 August 2014.

Spencer, W., and G. Bowes. 1985. Limnophila and Hygrophila: a review and physiological assessment of their weed potential in Florida. Journal of Aquatic Plant Management 23: 7-16.

Sutton, D.L. 1995. Hygrophila is replacing Hydrilla in South Florida. Aquatics 17(3):4,6,8,10.

Sutton, D.L., and P.M. Dingler. 2000. Influence of sediment nutrients on growth of emergent Hygrophila. Journal of Aquatic Plant Management 38: 55-61.

APHIS (Animal and Plant Health Inspection Service). 2012. Federal Noxious Weed List. United States Department of Agriculture. Available at http://www.aphis.usda.gov/plant_health/plant_pest_info/weeds/downloads/weedlist.pdf. Accessed 20 August 2014.

USDA NRCS (United States Department of Agriculture Natural Resources Conservation Service). 2014. Hygrophila polysperma Profile. PLANTS Database. Available at http://plants.usda.gov/core/profile?symbol=HYPO3. Accessed 20 August 2014.

US EPA (US Environmental Protection Agency). 2008. Predicting future introductions of nonindigenous species to the Great Lakes. National Center for Environmental Assessment, Washington, DC. Available http://www.epa.gov/ncea.

Van Dijk, G.M., D.D. Thayer, and W.T. Haller. 1986. Growth of Hygrophila and Hydrilla in flowing water. Journal of Aquatic Plant Management 24: 85-87.

Vandiver, V.V. 1980. Hygrophila. Aquatics 2: 4-11.

 

Other Resources:
Hygrophila polysperma - UF/IFAS Center for Aquatic and Invasive Plants

US Fish and Wildlife Service Ecological Risk Screening Summary for Hygrophila polysperma

Author: Thayer, D.D., I.A. Pfingsten, C.C. Jacono, and J. Li.

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.