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.
† 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).
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...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).
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.
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.