Panicum repens - L.
Torpedo Grass
Other Common Names: torpedo grass
Taxonomic Status: Accepted
Related ITIS Name(s): Panicum repens L. (TSN 504106)
Unique Identifier: ELEMENT_GLOBAL.2.131742
Element Code: PMPOA4K1X0
Informal Taxonomy: Plants, Vascular - Flowering Plants - Grass Family
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Monocotyledoneae Cyperales Poaceae Panicum
Check this box to expand all report sections:
Concept Reference
Help
Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Panicum repens
Conservation Status
Help

NatureServe Status

Global Status: GNR
Global Status Last Changed: 22Mar1994
Rounded Global Status: GNR - Not Yet Ranked
Nation: United States
National Status: NNA

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Alabama (SNA), California (SNA), Florida (SNA), Hawaii (SNA), Louisiana (SNA), Mississippi (SNA), North Carolina (SNA), Texas (SNA)

Other Statuses

NatureServe Global Conservation Status Factors

Other NatureServe Conservation Status Information

Distribution
Help
U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
NOTE: The distribution shown may be incomplete, particularly for some rapidly spreading exotic species.

U.S. & Canada State/Province Distribution
United States ALexotic, CAexotic, FLexotic, HIexotic, LAexotic, MSexotic, NCexotic, TXexotic

Range Map
No map available.

Ecology & Life History Not yet assessed
Help
Economic Attributes Not yet assessed
Help
Management Summary Not yet assessed
Help
Population/Occurrence Delineation Not yet assessed
Help
Population/Occurrence Viability
Help
U.S. Invasive Species Impact Rank (I-Rank)
Help
Disclaimer: While I-Rank information is available over NatureServe Explorer, NatureServe is not actively developing or maintaining these data. Species with I-RANKs do not represent a random sample of species exotic in the United States; available assessments may be biased toward those species with higher-than-average impact.

I-Rank: High/Medium
Rounded I-Rank: High
I-Rank Reasons Summary: Panicum repens has long rhizomes and forms dense monocultures that displace native species. It is particularly problematic in and near wetlands along the gulf coast. Habitats it invades include coastal beaches, the shores of lakes and ponds, grassland, riparian habitats, wetland margins, shallow water bodies, marshes, coastal swales, and wet disturbed sites. It is also a problem in non-natural areas such as golf courses, citrus groves, sugarcane fields, and irrigation canals. Panicum repens spreads vegetatively and even small fragments can establish and quickly form dense stands. Panicum repens is common in Florida and along the gulf coast but rare in other southeastern states. It is also established on 4 Hawaiian islands. It is apparently not yet naturalized in California. Management of Panicum repens is difficult. Repeated herbicide treatment is necessary.
Subrank I - Ecological Impact: Medium/Low
Subrank II - Current Distribution/Abundance: High
Subrank III - Trend in Distribution/Abundance: High/Low
Subrank IV - Management Difficulty: High/Medium
I-Rank Review Date: 08Nov2008
Evaluator: Tomaino, A.
Native anywhere in the U.S?
Native Range: Southern Europe, tropical and southern Africa, Canary Islands, and Madeira Islands (Weber 2003). Exact native range obscure (USDA ARS 2008).

Download "An Invasive Species Assessment Protocol: Evaluating Non-Native Plants for their Impact on Biodiversity". (PDF, 1.03MB)
Provide feedback on the information presented in this assessment

Screening Questions

S-1. Established outside cultivation as a non-native? YES
Comments: Established outside cultivation in the U.S. (Kartesz 1999).

S-2. Present in conservation areas or other native species habitat? Yes
Comments: Invasive in natural areas in the southeastern U.S. (Weber 2003).

Subrank I - Ecological Impact: Medium/Low

1. Impact on Ecosystem Processes and System-wide Parameters:Low significance/Insignificant
Comments: No mention of changes in abiotic ecosystem processes or system-wide parameters found in the literature; assumption is that any alterations are not high or moderate.

2. Impact on Ecological Community Structure:Moderate significance
Comments: A perennial grass that grows to 1 meter tall and forms monocultures (Langeland and Burks 1998). "Forms thick dense stands that smother low plants" (Motooka et al. 2003).

3. Impact on Ecological Community Composition:High significance
Comments: Forms dense pure stands that replace native species (Weber 2003). In Lake Okeechobee, Florida, Panicum repens displaced 14,000 acres of native marsh (Langeland & Burks 1998). Smith et al. (2004) states that, "Since the 1970s, more than 6,000 ha of native plants, including spikerush (Eleocharis cellulosa) and beakrush (Rhynchospora spp.) and open water habitat have been displaced by Panicum repens in areas of Lake Okeechobee's marsh where inundation depths often are less than 50 cm." (Global Invasive Species Database 2006).


4. Impact on Individual Native Plant or Animal Species:Low significance/Insignificant
Comments: No mention of disproportionate impacts on particular native species found in the literature; assumption is that any impacts are not high or moderate.

5. Conservation Significance of the Communities and Native Species Threatened:High/Low significance
Comments: Invades grassland, riparian habitats, and coastal beaches in the southeastern U.S. (Weber 2003). Occurs on open, moist, sandy beaches and the shores of lakes and ponds, occasionally extending out into the water (Flora of North America Editorial Committee 2003). Invades wetland margins and shallow water bodies (Masterson 2007). In Florida, Panicum repens occurs in marshes, coastal swales, lake margins, and wet disturbed sites (Wunderlin and Hansen 2003). In Hawaii, it invades coastal sites, mesic to high-rainfall environments (Motooka et al. 2003). Some of these communities are likely to be of conservation significance or be habitat for species of conservation significance.


Subrank II. Current Distribution and Abundance: High

6. Current Range Size in Nation:Moderate significance
Comments: Mainly established along the gulf coast of the southeastern, U.S. and throughout Florida (J. Kartesz, unpublished data). Rare north of Florida but in a few scattered counties in Georgia, South Carolina, and North Carolina (Weakley 2008; J. Kartesz, unpublished data). In Hawaii, established on Oahu, Lanai, Hawaii (Motooka et al. 2003); and East Maui (Starr et al. 2002). In California, Panicum repens was introduced from Melaleuca stock received from Florida and is apparently not naturalized; it is an agricultural, garden or urban weed (Baldwin et al. 2008).


7. Proportion of Current Range Where the Species is Negatively Impacting Biodiversity:High significance
Comments: Listed as a category I plant in Florida meaning that it is altering native plant communities by displacing native species and changing community structures (FLEPPC 2007). Present in 57 of 67 Florida counties (Masterson 2007). In 1992, Panicum repens occurred in 70% of Florida's public waters (Langeland & Burks 1998). In the southeast, Panicum repens is rare north of Florida (Weakley 2008).

8. Proportion of Nation's Biogeographic Units Invaded:Moderate significance
Comments: Inferred from distribution as currently understood (J. Kartesz, unpublished data; TNC 2001).

9. Diversity of Habitats or Ecological Systems Invaded in Nation:Moderate significance
Comments: Invades grassland, riparian habitats, and coastal beaches in the southeastern U.S. (Weber 2003). Occurs on open, moist, sandy beaches and the shores of lakes and ponds, occasionally extending out into the water (Flora of North America Editorial Committee 2003). Invades wetland margins and shallow water bodies (Masterson 2007). In Florida, Panicum repens occurs in marshes, coastal swales, lake margins, and wet disturbed sites (Wunderlin and Hansen 2003). In disturbed coastal sands in the southeast U.S. (Weakley 2008). In Hawaii, it invades coastal sites, mesic to high-rainfall environments (Motooka et al. 2003), and moist disturbed habitats such as along ditches and roadsides in sugar cane fields (Wagner et al. 1999).

Subrank III. Trend in Distribution and Abundance: High/Low

10. Current Trend in Total Range within Nation:High/Moderate significance
Comments: Can be dispersed long distances via movement of infected nursery stock. Also, occurs in disturbed areas; assumption is that disturbed areas are not declining or remaining stable and therefore this species' total range is not declining or remaining stable.

11. Proportion of Potential Range Currently Occupied:Low significance
Comments: Inferred from USDA (1990) and J. Kartesz, unpublished data.

12. Long-distance Dispersal Potential within Nation:Moderate significance
Comments: Can be dispersed long distances via movement of infected nursery stock. In California, Panicum repens was introduced from Melaleuca stock received from Florida (Baldwin et al. 2008). Fragments are buoyant for extended periods; fragments can readily root when they encounter sediment that is exposed or covered by shallow water and once established Panicum repens can thrive in water up to 75 cm deep (Smith et al. 2004 in Global Invasive Species Database 2006).

13. Local Range Expansion or Change in Abundance:High/Low significance
Comments: Small fragments can establish and produce dense clonal stands through vegetative growth (Hossain et al. 1999, Brecke et al. 2001 in Masterson 2007). Fragments are buoyant for extended periods; fragments can readily root when they encounter sediment that is exposed or covered by shallow water and once established Panicum repens can thrive in water up to 75 cm deep (Smith et al. 2004 in Global Invasive Species Database 2006). Also, Panicum repens occurs in disturbed areas and assumption is that disturbed areas are not decreasing or remaining stable and therefore this species' local range is not decreasing or remaining stable.

14. Inherent Ability to Invade Conservation Areas and Other Native Species Habitats:Medium/Low significance
Comments: No mention of invasion of undisturbed habitats found in the literature; assumption is that it rarely or seldom invades undisturbed habitats.

15. Similar Habitats Invaded Elsewhere:Low significance
Comments: Worldwide, it is one of the most invasive grasses in terrestrial, wetland, and aquatic habitats of the tropics and subtropics (Sutton 1996 in Masterson 2007).

16. Reproductive Characteristics:High/Moderate significance
Comments: Reproduces mainly by rhizome extension and fragmentation (Holm et al. 1977). Rhizomes may reach 6 m in length or more (Weber 2003). Quickly produces dense monocultures (Masterson 2007). Small fragments can establish and produce dense clonal stands through vegetative growth (Hossain et al. 1999, Brecke et al. 2001 in Masterson 2007). Tillage encourages growth (Motooka et al. 2003). Rhizome fragments buried 50 cm deep can send up new shoots (Hossain et al. 1999, Brecke et al. 2001 in Masterson 2007). Because of the lack of apical dominance, each node can produce axillary buds along entire rhizome (Wilcut et al. 1988 in Masterson 2007). A single culm emerging from a single rhizome bud produced approximately 23,000 rhizome buds in a single year (Hossain et al. 2001 in Masterson 2007). In Florida, Panicum repens does not appear to produce viable seed (Weber 2003). It is tolerant of flooding, drought, and salt (Holm et al. 1977; Weber 2003).


Subrank IV. General Management Difficulty: High/Medium

17. General Management Difficulty:High significance
Comments: Recommended control for large infestations is with herbicides (Weber 2003). Repeated treatments are required (Motooka et al. 2003). Panicum repens was not adversely affected by the herbicide imazapyr (Jenkins et al. 2004 in Global Invasive Species Database 2006). Little or no long-term control was achieved at 16 of 26 herbicide treatment sites; however, where fire reduced plant biomass before herbicide was applied, Panicum repens was controlled for two years and native species became dominant (Hanlon and Langeland 2000 in Global Invasive Species Database 2006). To control Panicum repens, a sufficient amount of herbicide must be absorbed by the rhizomes (Williams et al. 2003 in in Global Invasive Species Database 2006). Difficult to eradicate because of vigorous vegetative regrowth (Weber 2003). Small patches can be dug out but rhizomes must be completely removed (Weber 2003). Small fragments can establish and produce dense clonal stands through vegetative growth (Hossain et al. 1999, Brecke et al. 2001 in Masterson 2007). Spread is stimulated by tilling and fertilization (Langeland and Burks 1998). Management in flood control systems in Florida, from 1980-1988, cost $2-2.5 milllion a year (Masterson 2007). Biological control may be feasible but requires more study (Cuda et al. 2007).

18. Minimum Time Commitment:Moderate significance
Comments: Difficult to eradicate because of vigorous vegetative regrowth (Weber 2003). Small fragments can establish and produce dense clonal stands through vegetative growth (Hossain et al. 1999, Brecke et al. 2001 in Masterson 2007). Management in flood control systems in Florida, from 1980-1988, cost $2-2.5 milllion a year (Masterson 2007).

19. Impacts of Management on Native Species:High/Low significance
Comments: Herbicides may impact non-target species.

20. Accessibility of Invaded Areas:Insignificant
Comments: A serious weed of citrus groves and golf courses in Florida (Langeland and Burks 1998). Frequently a problem in sod production (MacDonald et al. 2008). Replaces more desirable forage species (Masterson 2007). Also a problem in flood control, navigation, and irrigation (Willard et al. 1998). Assumption is accessibility problems are rare.
Authors/Contributors
Help

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

References
Help
  • Baldwin, B.G., S. Boyd, D.J. Keil, R.W. Patterson, T.J. Rosatti and D.H. Wilken eds. 2008. Jepson Flora Project: Jepson Online Interchange for California Floristics. Regents of the University of California, Berkeley. Online. Available:
    http://ucjeps.berkeley.edu/interchange/ (accessed 2008).

  • Cuda, J.P., J.C. Dunford, and J.M. Leavengood. 2007. Invertebrate fauna associated with torpedograss, Panicum repens (Cyperales: Poaceae), in Lake Okeechobee, Florida, and prospects for biological control. Florida Entomologist 90(1): 238-248.

  • Flora of North America Editorial Committee. 2003a. Flora of North America North of Mexico. Vol. 25. Magnoliophyta: Commelinidae (in part): Poaceae, part 2. Oxford Univ. Press, New York. xxv + 781 pp.

  • Florida Exotic Pest Plant Council (FLEPPC). 2007. Florida Exotic Pest Plant Council's 2007 List of Invasive Species. Online. Available: http://www.fleppc.org/list/07list_ctrfld.pdf (accessed 2008).

  • Global Invasive Species Database. 2006. Panicum repens Online. Available: http://www.invasivespecies.net/database/species/management_info.asp?si=777&fr=1&sts= (accessed 4 November 2008).

  • Holm, L.G., P. Donald, J.V. Pancho, and J.P. Herberger. 1977. The World's Worst Weeds: Distribution and Biology. The University Press of Hawaii: Honolulu, Hawaii. 609 pp.

  • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

  • Kartesz, J.T. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. First edition. In: Kartesz, J.T., and C.A. Meacham. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden, Chapel Hill, N.C.

  • Langeland, K.A. and K.C. Burks. 1998. Identification and Biology of Non-Native Plants in Florida's Natural Areas. University of Florida. 165 pp. [http://aquat1.ifas.ufl.edu/identif.html]

  • MacDonald, G., J. Ferrell, B. Sellers, K. Langeland, T. Duperron-Bond, and E. Ketterer-Guest. 2008. Torpedo grass Panicum repens non-native to Florida. Excerpted from the Invasive species management plans for Florida. University of Florida, IFAS Extension, Circular. 257. Online. Available: http://aquat1.ifas.ufl.edu/node/308 (accessed 4 November 2008).

  • Masterson, J. 2007. October 5 last update. Panicum repens species report. Smithsonian Marine Station. Online. Available: http://www.sms.si.edu/irLspec/Panicum_repens.htm (accessed 4 November 2008).

  • Motooka, P., L. Castro, D. Nelson, G. Nagai, and L. Ching. 2003. Weeds of Hawaii's pastures and natural areas: an identification and management guide. College of Tropical Agriculture and Human Resources, University of Hawaii, Honolulu. 184 pp. [http://www.hear.org/bibliography/references/2557_motooka_2003/]

  • Pacific Island Ecosystems at Risk (PIER). 2007. 30 December last update. Panicum repens. United States Department of Agriculture Forest Service Institute of Pacific Island Forestry. Online. Available: http://www.hear.org/Pier/species/panicum_repens.htm (Accessed 4 November 2008).

  • Starr, F., K. Martz, and L. L. Loope. 2002. New records from the Hawaiian Archipelago. Bishop Museum Occasional Papers 69: 16-27.

  • The Nature Conservancy. 2001. Map: TNC Ecoregions of the United States. Modification of Bailey Ecoregions. Online . Accessed May 2003.

  • USDA Agricultural Research Service. 1990. USDA Plants Hardiness Zone Map. Misc. Publ. Number 1475.

  • USDA, ARS, National Genetic Resources Program. 2008 last update. Germplasm Resources Information Network (GRIN). National Germplasm Resources Laboratory, Beltsville, MD. Online. Available: http://www.ars-grin.gov/cgi-bin/npgs/html/index.pl (Accessed 2008).

  • Wagner, W.L., D.R. Herbst, and S.H. Sohmer. 1999. Manual of the flowering plants of Hawaii. Revised edition. Volumes 1 and 2. Univ. Hawaii Press and Bishop Museum Press, Honolulu. 1919 pp.

  • Weakley, A. S. 2008. Flora of the Carolinas, Virginia, Georgia, northern Florida, and surrounding areas. Working Draft of 7 April 2008. University of North Carolina Herbarium (NCU), North Carolina Botanical Garden, University of North Carolina at Chapel Hill. Online. Available: http://herbarium.unc.edu/flora.htm (Accessed 2008).

  • Weber, E. 2003. Invasive plant species of the world: a reference guide to environmental weeds. CABI Publishing, Cambridge, Massachusetts. 548 pp.

  • Willard, T.R., D.G. Shilling, W.T. Haller, K.A. Langeland. 1998. Physico-chemical factors influencing the control of torpedograss with glyphosate. J. Aquat. Plant Manage. 36: 11-15.

  • Wunderlin, R.P. and B.F. Hansen. 2003. Guide to the Vascular Plants of Florida. 2nd edition. University Press of Florida, Tampa. 788 pp.

Use Guidelines & Citation

Use Guidelines and Citation

The Small Print: Trademark, Copyright, Citation Guidelines, Restrictions on Use, and Information Disclaimer.

Note: All species and ecological community data presented in NatureServe Explorer at http://explorer.natureserve.org were updated to be current with NatureServe's central databases as of March 2019.
Note: This report was printed on

Trademark Notice: "NatureServe", NatureServe Explorer, The NatureServe logo, and all other names of NatureServe programs referenced herein are trademarks of NatureServe. Any other product or company names mentioned herein are the trademarks of their respective owners.

Copyright Notice: Copyright © 2019 NatureServe, 2511 Richmond (Jefferson Davis) Highway, Suite 930, Arlington, VA 22202, U.S.A. All Rights Reserved. Each document delivered from this server or web site may contain other proprietary notices and copyright information relating to that document. The following citation should be used in any published materials which reference the web site.

Citation for data on website including State Distribution, Watershed, and Reptile Range maps:
NatureServe. 2019. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available http://explorer.natureserve.org. (Accessed:

Citation for Bird Range Maps of North America:
Ridgely, R.S., T.F. Allnutt, T. Brooks, D.K. McNicol, D.W. Mehlman, B.E. Young, and J.R. Zook. 2003. Digital Distribution Maps of the Birds of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Bird Range Maps of North America:
"Data provided by NatureServe in collaboration with Robert Ridgely, James Zook, The Nature Conservancy - Migratory Bird Program, Conservation International - CABS, World Wildlife Fund - US, and Environment Canada - WILDSPACE."

Citation for Mammal Range Maps of North America:
Patterson, B.D., G. Ceballos, W. Sechrest, M.F. Tognelli, T. Brooks, L. Luna, P. Ortega, I. Salazar, and B.E. Young. 2003. Digital Distribution Maps of the Mammals of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Mammal Range Maps of North America:
"Data provided by NatureServe in collaboration with Bruce Patterson, Wes Sechrest, Marcelo Tognelli, Gerardo Ceballos, The Nature Conservancy-Migratory Bird Program, Conservation International-CABS, World Wildlife Fund-US, and Environment Canada-WILDSPACE."

Citation for Amphibian Range Maps of the Western Hemisphere:
IUCN, Conservation International, and NatureServe. 2004. Global Amphibian Assessment. IUCN, Conservation International, and NatureServe, Washington, DC and Arlington, Virginia, USA.

Acknowledgement Statement for Amphibian Range Maps of the Western Hemisphere:
"Data developed as part of the Global Amphibian Assessment and provided by IUCN-World Conservation Union, Conservation International and NatureServe."

NOTE: Full metadata for the Bird Range Maps of North America is available at:
http://www.natureserve.org/library/birdDistributionmapsmetadatav1.pdf.

Full metadata for the Mammal Range Maps of North America is available at:
http://www.natureserve.org/library/mammalsDistributionmetadatav1.pdf.

Restrictions on Use: Permission to use, copy and distribute documents delivered from this server is hereby granted under the following conditions:
  1. The above copyright notice must appear in all copies;
  2. Any use of the documents available from this server must be for informational purposes only and in no instance for commercial purposes;
  3. Some data may be downloaded to files and altered in format for analytical purposes, however the data should still be referenced using the citation above;
  4. No graphics available from this server can be used, copied or distributed separate from the accompanying text. Any rights not expressly granted herein are reserved by NatureServe. Nothing contained herein shall be construed as conferring by implication, estoppel, or otherwise any license or right under any trademark of NatureServe. No trademark owned by NatureServe may be used in advertising or promotion pertaining to the distribution of documents delivered from this server without specific advance permission from NatureServe. Except as expressly provided above, nothing contained herein shall be construed as conferring any license or right under any NatureServe copyright.
Information Warranty Disclaimer: All documents and related graphics provided by this server and any other documents which are referenced by or linked to this server are provided "as is" without warranty as to the currentness, completeness, or accuracy of any specific data. NatureServe hereby disclaims all warranties and conditions with regard to any documents provided by this server or any other documents which are referenced by or linked to this server, including but not limited to all implied warranties and conditions of merchantibility, fitness for a particular purpose, and non-infringement. NatureServe makes no representations about the suitability of the information delivered from this server or any other documents that are referenced to or linked to this server. In no event shall NatureServe be liable for any special, indirect, incidental, consequential damages, or for damages of any kind arising out of or in connection with the use or performance of information contained in any documents provided by this server or in any other documents which are referenced by or linked to this server, under any theory of liability used. NatureServe may update or make changes to the documents provided by this server at any time without notice; however, NatureServe makes no commitment to update the information contained herein. Since the data in the central databases are continually being updated, it is advisable to refresh data retrieved at least once a year after its receipt. The data provided is for planning, assessment, and informational purposes. Site specific projects or activities should be reviewed for potential environmental impacts with appropriate regulatory agencies. If ground-disturbing activities are proposed on a site, the appropriate state natural heritage program(s) or conservation data center can be contacted for a site-specific review of the project area (see Visit Local Programs).

Feedback Request: NatureServe encourages users to let us know of any errors or significant omissions that you find in the data through (see Contact Us). Your comments will be very valuable in improving the overall quality of our databases for the benefit of all users.