Panicum repens (torpedo grass)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Plant Type
- Distribution Table
- History of Introduction and Spread
- Risk of Introduction
- Habitat List
- Host Plants and Other Plants Affected
- Biology and Ecology
- Latitude/Altitude Ranges
- Air Temperature
- Rainfall Regime
- Soil Tolerances
- Natural enemies
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Plant Trade
- Wood Packaging
- Impact Summary
- Impact: Biodiversity
- Social Impact
- Risk and Impact Factors
- Uses List
- Similarities to Other Species/Conditions
- Prevention and Control
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Panicum repens L. 1762
Preferred Common Name
- torpedo grass
Other Scientific Names
- Panicum aquaticum A.Rich. 1851
- Panicum arenarium Brot. 1804
- Panicum chromatostigma Pilg. 1902
- Panicum convolutum Beauv. ex Spreng. 1825
- Panicum hygrocharis Steud. 1854
- Panicum ischaemoides Retz. 1786
- Panicum leiogonum Delile 1812
- Panicum nyanzense K. Schum., 1897
International Common Names
- English: creeping panic
- Spanish: gramma del norte
- French: panic rampant
- Portuguese: escalracho
Local Common Names
- Argentina: paja voladora
- Bangladesh: baranda
- Brazil: capim-torpedo
- Brunei Darussalam: huma; kerunong
- Cambodia: chhlong
- Cuba: alpiste de tierra
- Egypt: beid el-homaar; neseela na'-ame; zommaar; zommeirentaya
- Germany: Torpedogras
- India: injipilla; karigaddi
- Indonesia: jajahean; lampuyangan; rumput jae-jae
- Indonesia/Java: suket balungan; suket lempuyangan
- Israel: dohan zohel
- Italy: panico strisciante
- Japan: haikibi
- Malaysia: kerunong padi; metubong; rumput kerbau; telur padi
- Mexico: zacate carrillo
- Myanmar: myet-kha
- Netherlands: victoriagras
- Pakistan: chimacara; surpurrcharela
- Philippines: luya-luyahan; maralaya
- Poland: proso rozlogowe
- Senegal: bamba subu; ekena; eselek
- South Africa: kruipgras
- Sri Lanka: etora
- Taiwan: pu-shu-tsao
- Thailand: ya-chan ka; yakhaemman; ya-onoi
- Turkey: tuylu dari
- USA/Hawaii: wainaku grass
- PANHY (Panicum hygrocharis)
- PANRE (Panicum repens)
Summary of InvasivenessTop of page
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Monocotyledonae
- Order: Cyperales
- Family: Poaceae
- Genus: Panicum
- Species: Panicum repens
Notes on Taxonomy and NomenclatureTop of page
DescriptionTop of page
Culms have bladeless scales at the base. Leaves are in two ranks, bright green to slightly glaucous, stiff, almost erect, 15-20 cm long, about 1 cm wide, tapering gradually to an acute tip, sparsely hairy on the upper surface, smooth and sometimes with a waxy bloom on the lower. Leaf sheaths have long white hairs along the margin. The ligule is a very short membrane, 0.5 mm long, fringed with long white hairs.
Robust rhizomes, up to 1 cm thick, grow horizontally at depths down to 20 cm or more and up to several metres distance. Nodes at 10-15 cm intervals tend to be swollen and each bears a viable but often dormant bud.
Panicles exserted 10-15 cm above foliage, about 10 (5-20) cm long, with 1-3 branches per node, usually quite stiffly erect. Spikelets 2-flowered pale green/glaucous, sometimes tinged with purple, oblong-ovate, acute or slightly acuminate, 2.5-3 mm long. Lower glume 1-3 nerved, broadly ovate one-fifth to one-third as long as the spikelet, upper glume and lower lemma similar, 7-nerved, as long as the spikelet. Upper lemma shorter, pale and glossy. Anthers three, yellow-orange, stigmas purple, caryopsis (seed) lanceolate, pale, white or straw-coloured.
Plant TypeTop of page
Grass / sedge
DistributionTop of page
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.Last updated: 17 Feb 2021
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Cameroon||Present||Native||Original citation: Hepper and ed. (1972)|
|Central African Republic||Present||Native|
|Côte d'Ivoire||Present||Native||Original citation: Hepper and ed. (1972)|
|Egypt||Present||Native||Original citation: Täckholm (1974)|
|Ghana||Present||Native||Original citation: Hepper and ed. (1972)|
|Liberia||Present||Native||Original citation: Hepper and ed. (1972)|
|Mali||Present||Native||Original citation: Hepper and ed. (1972)|
|Niger||Present||Native||Original citation: Hepper and ed. (1972)|
|Nigeria||Present||Native||Original citation: Hepper and ed. (1972)|
|Senegal||Present||Native||Original citation: Hepper and ed. (1972)|
|Sierra Leone||Present||Native||Original citation: Hepper and ed. (1972)|
|Saudi Arabia||Present, Localized||Introduced|
|Sri Lanka||Present, Widespread||Introduced|
|Federal Republic of Yugoslavia||Present||Introduced|
|Northern Mariana Islands||Present||Introduced|
|-Mato Grosso do Sul||Present||Introduced|
|-Rio de Janeiro||Present||Introduced|
History of Introduction and SpreadTop of page
Risk of IntroductionTop of page
HabitatTop of page
A plant of generally wet places, both coastal and inland, occurring naturally along the edges of rivers, irrigation channels, lakes and brackish shorelines. It does not tolerate long-term submergence (Thayer and Haller, 1990), but may occur as a component of floating islands, in succession to, or as a co-dominant with e.g. Eichhornia crassipes or Cyperus papyrus. Natural habitats are often sandy, but it is able to persist in heavy soils that remain moist due to high rainfall, poor drainage or irrigation. It is most commonly a weed of perennial plantation crops in the humid tropics, but may also occur in moist sub-tropical situations (e.g. southern Europe) and as a weed in annual crops where tillage is not sufficiently deep and drainage is poor.
Habitat ListTop of page
|Terrestrial||Managed||Cultivated / agricultural land||Present, no further details||Harmful (pest or invasive)|
|Terrestrial||Managed||Managed forests, plantations and orchards||Present, no further details||Harmful (pest or invasive)|
|Terrestrial||Managed||Managed grasslands (grazing systems)||Present, no further details||Harmful (pest or invasive)|
|Terrestrial||Natural / Semi-natural||Riverbanks||Present, no further details||Harmful (pest or invasive)|
|Terrestrial||Natural / Semi-natural||Wetlands||Present, no further details||Harmful (pest or invasive)|
|Littoral||Coastal areas||Present, no further details|
Host Plants and Other Plants AffectedTop of page
|Ananas comosus (pineapple)||Bromeliaceae||Main|
|Arachis hypogaea (groundnut)||Fabaceae||Main|
|Camellia sinensis (tea)||Theaceae||Main|
|Capsicum annuum (bell pepper)||Solanaceae||Main|
|Cocos nucifera (coconut)||Arecaceae||Main|
|Coriandrum sativum (coriander)||Apiaceae||Main|
|Glycine max (soyabean)||Fabaceae||Main|
|Hevea brasiliensis (rubber)||Euphorbiaceae||Main|
|Hibiscus sabdariffa (Roselle)||Malvaceae||Main|
|Oryza sativa (rice)||Poaceae||Main|
|Saccharum officinarum (sugarcane)||Poaceae||Main|
|Zea mays (maize)||Poaceae||Main|
Biology and EcologyTop of page
Accessions from Egypt and India are diploid with a chromosome number of 2n = 36 (MOBOT, 2004).
Physiology and phenology
P. repens is a serious weed mainly on account of its perennial habit, including its ability to spread and persist by rhizomes in any moist situations where there is inadequate deep tillage. Once a new plant is established, rhizomes develop within a few weeks, growing horizontally for several metres, usually at 5-20 cm depth, but sometimes deeper. Hossain et al. (1996) reported rhizomes mostly in the top 30 cm but some down to 42 cm in a reddish soil in southern Japan. They also recorded that one rhizome node could give rise to over 20,000 new rhizome buds in 365 days. Most axillary buds on the rhizome remain dormant until there is fragmentation by cultivation. Pieces of rhizomes with six nodes are able to regenerate from 8-16 cm depth (Wilcut et al., 1988a). Under suitable conditions, new plants can develop from any single-node segment of rhizome. P. repens is resistant to fire (Weber, 2003).
Seeds are usually produced in considerable numbers but may be unimportant as a means of spread in some localities. Flowering and seed production are said to be rare, e.g. in Java, while Chandrasena and Dhammika (1988) show that different clones of the weed in Sri Lanka may differ significantly in flowering behaviour. Seeds are sometimes claimed to be non-viable but Moreira (1976a, 1978) has shown germination levels up to 100%. Dormancy may be high in young seed, but germination can be enhanced by chilling, nitrate and alternating temperatures, e.g. between 20 and 30°C. Populations in Florida, USA, do not produce viable seed (Weber, 2003).
The weed can occur in a wide range of soil types and is not sensitive to pH between 4.2 and 6.7 (Wilcut et al., 1988a) or to moderate-to-high salinity (up to 10,000 p.p.m.) (Peng et al., 1977; Peng and Twu, 1979; Nemoto et al., 1987). Although adapted to wet conditions and presumably needing these for active growth, it can, once established, survive moderately prolonged drought conditions, particularly where there is a high water table. Optimum temperatures for growth are 30-35°C and it is killed by persistent frost (Wilcut et al., 1988b). It prefers open sunny conditions but persists in semi-shaded plantation crop situations.
Latitude/Altitude RangesTop of page
|Latitude North (°N)||Latitude South (°S)||Altitude Lower (m)||Altitude Upper (m)|
Air TemperatureTop of page
|Parameter||Lower limit||Upper limit|
|Mean annual temperature (ºC)||19||27|
|Mean maximum temperature of hottest month (ºC)||25||31|
|Mean minimum temperature of coldest month (ºC)||16||22|
RainfallTop of page
|Parameter||Lower limit||Upper limit||Description|
|Dry season duration||0||7||number of consecutive months with <40 mm rainfall|
Rainfall RegimeTop of page
Soil TolerancesTop of page
- seasonally waterlogged
Special soil tolerances
Natural enemiesTop of page
Notes on Natural EnemiesTop of page
Means of Movement and DispersalTop of page
P. repens spreads by means of rhizomes. Seed is rarely produced.
P. repens is planted in grazing land and may invade adjacent areas if not carefully managed. A careful impact assessment should be made before introducing the species as forage to a new area.
Plant TradeTop of page
|Plant parts liable to carry the pest in trade/transport||Pest stages||Borne internally||Borne externally||Visibility of pest or symptoms|
|Bulbs/Tubers/Corms/Rhizomes||Pest or symptoms usually visible to the naked eye|
|True seeds (inc. grain)||Pest or symptoms not visible to the naked eye but usually visible under light microscope|
Wood PackagingTop of page
|Wood Packaging not known to carry the pest in trade/transport|
|Loose wood packing material|
|Processed or treated wood|
|Solid wood packing material with bark|
|Solid wood packing material without bark|
Impact SummaryTop of page
|Fisheries / aquaculture||Negative|
ImpactTop of page
P. repens may act as an alternative host to rice leafhopper, Ustilago and Pyricularia spp. (Holm et al., 1977).
Impact: BiodiversityTop of page
Social ImpactTop of page
Risk and Impact FactorsTop of page
- Proved invasive outside its native range
- Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
- Has high reproductive potential
- Has propagules that can remain viable for more than one year
- Damaged ecosystem services
- Ecosystem change/ habitat alteration
- Negatively impacts agriculture
- Negatively impacts tourism
- Reduced amenity values
- Reduced native biodiversity
- Competition - monopolizing resources
- Pest and disease transmission
- Difficult/costly to control
UsesTop of page
Uses ListTop of page
Animal feed, fodder, forage
- Fodder/animal feed
- Erosion control or dune stabilization
Similarities to Other Species/ConditionsTop of page
Prevention and ControlTop of page
Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.Cultural
The use of leguminous smothering crops is important and effective in plantation crops in sufficiently humid climatic conditions, e.g. in oil palm or rubber. In Florida wetlands, maintenance of high water levels favours indigenous species and reduces spread of P. repens (David, 1999).
Among traditional weeding methods, hoeing and hand-weeding are ineffective, owing to strong and rapid regrowth from the underground rhizome system. Tillage can be effective but it must be deep enough to disturb as many of the rhizomes as possible, and persistent enough and under the right climatic and soil conditions to result in good desiccation. One or two cultivations under wet conditions may serve only to spread the problem.
Older herbicides used for control of P. repens include dalapon and asulam and these may still have applicability in particular situations, e.g. in sugarcane (Peng et al., 1977; Yeh and Wang, 1980) and along irrigation channels (Panchal, 1981). MSMA was reported by Coats (1974) to be inferior to asulam for control of P. repens in turf, but MSMA has been tested with some success in tea (e.g. Soedarsan et al., 1974). Quinclorac has also been shown to be an effective treatment in turf (Busey, 2003). Otherwise the herbicide of choice where crop safety allows, is glyphosate. Split doses a few weeks apart have given better results than a single application (Chandrasena, 1990). At lower doses activity may be decreased in hard water (Ca 5 mM) or in the presence of iron salts (Shilling et al., 1990a) or in mixtures with triazine or urea herbicides, whereas activity may be enhanced by various additives including ammonium sulphate, kaolin and surfactants (Kathiravetpillai and Punyasiri, 1989; Shilling et al., 1990b; Reddy and Singh, 1992). Fluazifop-butyl was not fully effective in Florida citrus (Singh et al., 1985) and Seth and Madin (1984) found glyphosate superior to fluazifop-butyl. However, working with fluazifop-P-butyl, Chandrasena (1989, 1991) was able to improve performance with surfactant and oil additives. In pot experiments Parker (1982) found both fluazifop-butyl and sethoxydim to have activity at least equal to that of glyphosate. These two graminicides should be of value in broad-leaved crops. Imazapyr has given longer-lasting control than glyphosate in irrigation channels (Nir, 1988).
ReferencesTop of page
Chandrasena JPNR, 1989. Fluazifop-butyl activity on perennial torpedograss (Panicum repens L.). Proceedings, 12th Asian-Pacific Weed Science Society Conference Taipei, Taiwan; Asian-Pacific Weed Science Society, No. 1:159-164
Chandrasena JPNR, 1991. Enhancement of fluazifop-P toxicity to torpedograss (Panicum repens L.) by surfactant and oil-additive. BIOTROP Special Publication, No. 40:133-143; [a symposium on aquatic weed management held in Bogor, Indonesia, 15-17 May 1990].
Chandrasena JPNR; Dhammika WHY, 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
Cope TA, 1982. Poaceae. In: Nasir E, Ali SI, eds. Flora of Pakistan. Kew, UK: Royal Botanic Gardens.
David PG, 1999. Response of exotics to restored hydroperiod at Dupuis Reserve, Florida. Restoration Ecology, 7(4):407-410.
FLEPPC, 2004. Invasive plant list of Florida Exotic Pest Plant Council. World wide web page at http://www.fleppc.org.
Fröman B; Persson S, 1974. An Illustrated Guide to the Grasses of Ethiopia. Assella, Ehiopia: Chilalo Awraja Development Unit.
Ghaly FM, 2002. Role of natural vegetation in improving salt affected soil in northern Egypt. Soil and Tillage Research, 64, (3-4):173-178.
Gibbs Russell GE; Watson L; Koekemoer M; Smook L; Barker NP; Anderson HM; Dellwitz MJ, 1990. Grasses of Southern Africa. Memoirs of the Botanical Survey of South Africa No 58. Pretoria, South Africa: National Botanic Grdens/ Botanical Research Institute.
Hepper FN, ed. , 1972. Flora of West Tropical Africa, Volume III (Part 2), 2nd edn. London, UK: Crown Agents.
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Hossain MA; Ishimine Y; Akamine H; Muruyama S, 1996. Growth and development characteristics of torpedo grass (Panicum repens L.) in Okinawa Island southern Japan. Weed Research, Japan, 41:323-331.
Kaushal Kumar; Kumar K; Singh VK; Govil JN; Singh G, 2002. Ethnopharmacognostical studies on Panicum repens L. In: Recent Progress in Medicinal Plants. Vol 1: Ethnomedicine and pharmacognosy. Houston, USA: Sci Tech Publishing.
LOPP, 2004. World wide web page at http://www.sfwmd.gov/org/wrp/wrp_okee/2_wrp_okee_inlake/2_wrp_okee_inlake.html.
Lorenzi H, 1982. Weeds of Brazil, terrestrial and aquatic, parasitic, poisonous and medicinal. (Plantas daninhas de Brasil, terrestres, aquaticas, parasitas, toxicas e medicinais.) Nova Odessa, Brazil: H. Lorenzi, 425 pp.
Meikle RD, 1977. Flora of Cyprus. Kew, UK: Bentham-Moxon Trust.
MOBOT, 2004. Tropicos Plant Nomenclature Database, Missouri Botanical Garden. World Wide Web page http://www.mobot.org/.
Moreira I, 1978. Propagation of Panicum repens by seed. Weeds and herbicides in the Mediterranean Basin: Proceedings of the Mediterranean Herbicide Symposium, Madrid, 1978. Ministerio de Agricultura. Madrid Spain, Vol. I:1-7
Moreira IR dos S, 1976. Aspects of the biology of rhizomatous weeds Cynodon dactylon (L.) Pers. and Panicum repens (L.). Aspectos da biologia de infestantes rizomatosas Cynodon dactylon (L.) Pers. e Panicum repens (L.). Universidade Tecnica, Lisbon. Portugal, Vol. 1, Vol. 2:pp.;pp.
Pandey AK; Prakash V; Singh RD; Mani VP, 2002. Studies on crop-weed competition and weed dynamics in maize under mid-hill conditions of N-W Himalayas. Indian Journal of Weed Science, 34(1/2):63-67; 7 ref.
Peng SY; Twu LT, 1979. Studies on the regenerative capacity of rhizomes of torpedo grass (Panicum repens Linn.) Part 1. Characteristics in sprouting of rhizomes and resistance to herbicides and environmental adversities. Journal of the Agricultural Association of China, No. 107:61-74
Perera KADN; Chandrasena JPNR; Tillekeratne LMV, 1989. Further studies on allelopathic effects of torpedograss (Panicum repens L.). Proceedings, 12th Asian-Pacific Weed Science Society Conference Taipei, Taiwan; Asian-Pacific Weed Science Society, No. 2:433-439
PIER, 2004. Pacific Islands Ecosystem at Risk (PIER). Institute of Pacific Islands Forestry. http://www.hear.org/pier/species/.
Retana-Sánchez K; Agüero-Alvarado R; Montiel-Longhi M; Brenes-Prendas S, 2013. First report of Panicum repens L., as a potential weed in Costa Rica. (Primer reporte de Panicum repens L. como potencial maleza en Costa Rica.) Agronomía Mesoamericana, 24(1):189-193. http://www.redalyc.org/revista.oa?id=437
Seth AK; Madin RW, 1984. Current status of weed control practices in tropical plantations with special references to South-East Asia. Proceedings, 7th Australian Weeds Conference, 1984, Volume 2, 24-38.
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Shukla U, 1996. The Grasses of North-Eastern India. Jodhpur, India: Scientific Publishers, 325 pp.
Thayer PL; Haller WT, 1990. Fungal pathogens, Phoma and Fusarium, associated with declining populations of torpedograss growing under high water stress. Proceedings of the 8th international symposium on aquatic weeds, Uppsala, Sweden, 13-17 August 1990., 209-214; 6 ref.
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Cuong N L, Cohen M B, 2002. Field survey and greenhouse evaluation of non-rice host plants of the striped stem borer, Chilo suppressalis (Lepidoptera: Pyralidae), as refuges for resistance management of rice transformed with Bacillus thuringiensis toxin genes. Bulletin of Entomological Research. 92 (3), 265-268. DOI:10.1079/BER2002163
Fröman B, Persson S, 1974. An Illustrated Guide to the Grasses of Ethiopia., Assella, Ehiopia: Chilalo Awraja Development Unit.
Gibbs Russell GE, Watson L, Koekemoer M, Smook L, Barker NP, Anderson HM, Dellwitz MJ, 1990. Grasses of Southern Africa. In: Memoirs of the Botanical Survey of South Africa No 58, Pretoria, South Africa: National Botanic Grdens/ Botanical Research Institute.
Kiran G G R, Rao A S, 2013. Survey of weed flora in transplanted rice in Krishna agroclimatic zone of Andhra Pradesh, India. Pakistan Journal of Weed Science Research. 19 (1), 45-51. http://www.wssp.org.pk/4-19-1-45-51.pdf
Munirathnam P, Kumar K A, 2014. Survey of weed flora in major crops of Nandyal region in Kurnool district of Andhra Pradesh. Journal of Research ANGRAU. 42 (3/4), 142-146. http://www.angrau.ac.in/journalofresearchangrau.php
Pandey A K, Prakash V, Singh R D, Mani V P, 2002. Studies on crop-weed competition and weed dynamics in maize under mid-hill conditions of N-W Himalayas. Indian Journal of Weed Science. 34 (1/2), 63-67.
PIER, 2004. Pacific Islands Ecosystem at Risk (PIER)., Institute of Pacific Islands Forestry. http://www.hear.org/pier/species/
Retana-Sánchez K, Agüero-Alvarado R, Montiel-Longhi M, Brenes-Prendas S, 2013. First report of Panicum repens L., as a potential weed in Costa Rica. (Primer reporte de Panicum repens L. como potencial maleza en Costa Rica.). Agronomía Mesoamericana. 24 (1), 189-193. http://www.redalyc.org/revista.oa?id=437
Shukla U, 1996. The Grasses of North-Eastern India., Jodhpur, India: Scientific Publishers. 325 pp.
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