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.

Panicum repens
Panicum repens
(torpedo grass)

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Panicum repens L.

Common name: torpedo grass

Synonyms and Other Names: Panicum littorale, Panicum aquaticum, Panicum arenarium, Panicum chromatostigma, Panicum convolutum, Panicum hygrocharis, Panicum ischaemoides, Panicum leiogonum, Panicum nyanzense, couch panicum, dog-tooth grass, torpedograss, creeping panic, wainaku grass, quack grass, and bullet grass

Taxonomy: available through www.itis.govITIS logo

Identification: According to Langeland et al. 1998:

Habit: Panicum repens is a perennial, rhizomatous grass

Stems/Roots: sharp, torpedo-shaped growing tips (Haroun 1995; Hossain et al. 1997); stolons and rhizomes have brown/white- colored scales, bulbil-shaped nodes, and can grow to lengths of 20 ft.

Leaves: glabrous to hairy below, long hairy on top, 10 inches in length and 0.3 inches in width, with leaf blades that can be flat, folded, linear, or stiff; blades often have a wax-like coating.

Flowers: branches on inflorescences are usually ascending or erect; spikelets are glabrous, 0.08-0.12 inches in length and 0.04 inches in width.

Size: up to 3 ft tall (0.9 m) (Langeland et al. 1998)

Native Range: Panicum repens is native to Asia, Africa, and Europe (Hossain et al. 1999).

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 Panicum repens are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
AL187619872Mississippi Coastal; Mobile-Tensaw
FL1907201941Alafia; Apalachee Bay-St. Marks; Apalachicola; Aucilla; Big Cypress Swamp; Blackwater; Caloosahatchee; Chipola; Crystal-Pithlachascotee; Daytona-St. Augustine; Escambia; Everglades; Florida Southeast Coast; Hillsborough; Kissimmee; Lake Okeechobee; Little Manatee; Lower Chattahoochee; Lower Choctawhatchee; Lower Ochlockonee; Lower St. Johns; Lower Suwannee; Manatee; Myakka; Nassau; Oklawaha; Peace; Pensacola Bay; Perdido; Santa Fe; Sarasota Bay; South Atlantic-Gulf Region; Southern Florida; St. Andrew-St. Joseph Bays; St. Marys; Tampa Bay; Upper St. Johns; Upper Suwannee; Withlacoochee; Withlacoochee; Yellow
LA1971201214Atchafalaya - Vermilion; Bayou Sara-Thompson; Calcasieu-Mermentau; East Central Louisiana Coastal; Eastern Louisiana Coastal; Lake Maurepas; Lake Maurepas; Louisiana Coastal; Lower Grand; Lower Mississippi; Lower Mississippi Region; Lower Red-Ouachita; Toledo Bend Reservoir; West Central Louisiana Coastal
MS189620213Mississippi Coastal; Pascagoula; Upper Leaf
NC196919711Lower Cape Fear
SC198719872Congaree; Middle Savannah
TX197119952Lower West Fork Trinity; Sabine Lake

Table last updated 1/18/2022

† Populations may not be currently present.


Habitat: Panicum repens tends to grow on lagoon shores, moist sandy beaches, dunes, canals, ditches, gardens, fields, and on the marshy shores of lakes and ponds (Boules and El Hadidi 1984; Godfrey and Wooten 1979).

Life history: Panicum repens commonly forms dense covers in areas with specific biological, chemical, and physical soil factors, including muck soils (Chandrasena and Dhammika 1988; Toth 2007). Although P. repens has the ability to reproduce both by seed and by rhizomes, in the United States it is believed to only reproduce by rhizomes (Wilcut et al. 1988a) and commonly does not produce viable seed (Tarver et al. 1978; Wilcut et al. 1988); Weber 2003). In other areas in the word however, such as Portugal, P. repens spreads by seed (Moreira 1978; Sutton 1996).

Tolerances: Panicum repens can grow in various soil types, within a pH range between 4.2-6.7, and a temperature range between 30-35°C; continuous cold and frost conditions kill the plant (Wilcut et al. 1988a; Wilcut et al. 1988b).

Means of Introduction: It is widely reported that the introduction of Panicum repens in the United States was accidental, as it was introduced through the contaminated ballast water of sailing vessels (Langeland et al. 1998; Tabor 1952). From there, it was purposefully introduced to the United States from Africa and/or Asia through the United States Department of Agriculture for planting in pasturelands to provide forage for cattle (MacDonald 2008; USFWS 2017). Panicum repens has been continuously observed throughout Alabama and Florida since 1876 (Langeland et al. 1998). The consequent spread of P. repens appears be vegetatively due to the lack of viable seed production (Wilcut et al. 1988).

Status: Panicum repens became established in southern Florida during the early 1900s as it reproduced widely in pastures (Langeland et al. 1998).

Established in Florida, Mississippi, and Alabama

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

EcologicalEconomicHuman Health

Panicum repens is characterized as an invasive perennial grass in several wetland, terrestrial, and aquatic habitats throughout subtropical and tropical regions (Sutton 1996).

Panicum repens has been observed to overrun large grassland and marshland areas, dominating large areas of land across the world, and displacing native plants, including spikerush and beakrush in Florida (Hanlon and Brady 2005; Richardson et al. 1995; Tan et al. 2012).

Through the spread of rhizomes, P. repens can form dense swards that replace native species (Weber 2003). This has been the case in the Everglades, where several SAVs (Submerged Aquatic Vegetation) were unable to grow. In some cases, P. repens mats can become so dense that they obstruct water flow in canals and/or ditches (MacDonald et al. 2008; USFWS 2017). As a result of their density, P. repens mats can limit recreational use of shorelines surrounding lakes and/or ponds (MacDonald et al. 2008; USFWS 2017).

Panicum repens has proven to be a useful species for the restoration of saline soils due to its high salt tolerance (Ghaly 2002). The species is also commonly used as a source of ethno-medicines in India (Kaushal 2002). Additionally, it was found that using an ethanolic extract of P. repens had favorable natriuretic, kaliuretic, and diuretic impacts on rats (Hozaien et al. 2018).

Remarks: Reduction of P. repens before the flooding period in the region would allow for the colonization and establishment of SAVs in the Everglades (Toth 2007).

Panicum repens is widely distributed in the canal banks, gardens, and fields of the Mediterranean (Boules and El Hadidi 1984).

References: (click for full references)

Chandrasena, J. P. N. R., and W. H. Y. Dhammika. 1988. Studies on the biology of Panicum repens L. 1 comparative morphological development of three selections from different geographical localities in Sri Lanka, Tropical Pest Management, 34(3):291-297, DOI:10.1080/09670878809371259.

Ghaly, F. M. 2002. Role of natural vegetation in improving salt affected soil in northern Egypt. Soil and Tillage Research, 64, (3-4):173-178.  

Godfrey, R.K., and J.W. Wooten. 1979. Aquatic and Wetland Plants of Southeastern United States, Monocotyledons. University of Georgia, Athens, GA.

Hanlon, C. and M. Brady. 2005. Mapping the Distribution of Torpedograss and Evaluating the Effectiveness of Torpedograss Management Activities in Lake Okeechobee, Florida. Journal of Aquatic Plant Management. 43. 24-29.

Haroun, S. A. 1995. Cytological abnormality control seed set in Panicum repens L. in Egypt. Cytologia, 60(4), 347-351.

Hossain, M.A., Y. Ishimine, H. Akamine, and S. Murayama. 1997. Growth and development characteristics of torpedograss (Panicum repens L.) in Okinawa island, southern Japan. Journal of Weed Science and Technology, 41, 323-331.  

Hossain, M. A., Y. Ishimine, S. Murayama and S. M. Uddin. 1999. Effect of burial depth on emergence of Panicum repens. Weed Science 47:651-656

Hozaien, H., W. El-Tantawy, A. Temraz, O. El-Gindi, and K. Taha. 2018. Diuretic activity of ethanolic extract of Panicum repens L. roots and rhizomes. Natural Product Research. 33. 1-2. 10.1080/14786419.2018.1437440.

Kaushal, K. 2002. Ethnopharmacognostical studies on Panicum repens L. Recent progress in medicinal plants: Ethnomedicine and pharmacognosy 1:337-344.

Langeland, K., B. Smith, and C. Hanlon. 1998. Torpedograss—forage gone wild. Wildland Weeds, 1(3), 4-6.

MacDonald, G.E., J.A. Ferrell, B. Sellers, K.A. Langeland, T.D. Bond, and E.K. Guest. 2008. Invasive species management plans for Florida. University of Florida Institute of Food and Agricultural Sciences Extension Circular, Gainesville, FL.

Moreira, I. 1978. Propagation of Panicum repens by seed. Weeds and herbicides in the Mediterranean Basin. Proc. Mediterr. Herb. Symp., Madrid, Spain. Ministerio de Agricultura. Vol. 1: 1-7.

Richardson, J. R., T. T. Harris and K A. Williges. 1995. Vegetation correlations with various environmental parameters in the Lake Okeechobee marsh ecosystem. Archiv fuir Hydrobiologie Beiheft Ergebnisse der Limnologie 45:41-46.

Sutton, D. 1996. Growth of Torpedograss from rhizomes planted under flooded conditions. J. Aquatic Plant Manage. 34:50-53.

Tabor, P. 1952. Cogongrass in Mobile County, Alabama. Agronomy Journal 44:50.

Tan, D. T., P. Q. Thu, and B. Dell. 2012. Invasive Plant Species in the National Parks of Vietnam. Forests. 3(4):997-1016. https://doi.org/10.3390/f3040997

Tarver, D.P., J.A. Rogers, M.J. Mahler, and R.L. Lazor. 1988. Aquatic and Wetland Plants of Florida. Bureau of Aquatic Plant Management, Florida Department of Natural Resources.

Toth, L. 2007. Establishment of Submerged Aquatic Vegetation in Everglades Stormwater Treatment Areas: Value of Early Control of Torpedograss (Panicum repens). J. Aquat. Plant Manage. 45. 17-20.

United States Fish and Wildlife Service (USFWS). 2017. Torpedograss (Panicum repens): Ecological Risk Screening Summary. 3-10 pp. https://www.fws.gov/fisheries/ANS/erss/highrisk/ERSS-Panicum-repens-Final-Jan2020.pdf. Created on 11/01/2021. Accessed on 06/15/2021.

Weber, E. 2003. Invasive plant species of the world: a reference guide to environmental weeds. 1st edition. CAB Publishing, Wallingford, UK.

Wilcut, J. W., B. Truelove, D. E. Davis, and J. C. Williams. 1988. Temperature factors limiting the spread of cogongrass (Imperata cylindrica) and torpedograss (Panicum repens). Weed Science, 36: 49-55 pp.

Wilcut, J. W., R. Dute, B. Truelove, and D. E. Davis. 1988. Factors limiting the distribution of cogongrass Imperata cylindrica and torpedograss, Panicum repens. Weed Science, 36(5): 577-582 pp.

Author: Wishah, L., and C.R. Morningstar

Revision Date: 9/9/2021

Citation Information:
Wishah, L., and C.R. Morningstar, 2022, Panicum repens L.: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=1124, Revision Date: 9/9/2021, Access Date: 1/18/2022

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. [2022]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [1/18/2022].

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