Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide


Oryza longistaminata
(perennial wild rice)



Oryza longistaminata (perennial wild rice)


  • Last modified
  • 20 November 2019
  • Datasheet Type(s)
  • Invasive Species
  • Pest
  • Host Plant
  • Preferred Scientific Name
  • Oryza longistaminata
  • Preferred Common Name
  • perennial wild rice
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Spermatophyta
  •       Subphylum: Angiospermae
  •         Class: Monocotyledonae
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Oryza longistaminata (perennial wild rice); disseminules, lateral view. FNW taxon. USA.
CaptionOryza longistaminata (perennial wild rice); disseminules, lateral view. FNW taxon. USA.
Copyright©Julia Scher/Federal Noxious Weeds Disseminules/USDA APHIS ITP/ - CC BY-NC 3.0 US
Oryza longistaminata (perennial wild rice); disseminules, lateral view. FNW taxon. USA.
DisseminulesOryza longistaminata (perennial wild rice); disseminules, lateral view. FNW taxon. USA.©Julia Scher/Federal Noxious Weeds Disseminules/USDA APHIS ITP/ - CC BY-NC 3.0 US
Oryza longistaminata (perennial wild rice); invading a cultivated rice crop.
CaptionOryza longistaminata (perennial wild rice); invading a cultivated rice crop.
Copyright©Chris Parker/Bristol, UK
Oryza longistaminata (perennial wild rice); invading a cultivated rice crop.
HabitOryza longistaminata (perennial wild rice); invading a cultivated rice crop.©Chris Parker/Bristol, UK
Oryza longistaminata (perennial wild rice); Inflorescence, panicles 16-40 cm long.
CaptionOryza longistaminata (perennial wild rice); Inflorescence, panicles 16-40 cm long.
Copyright©Chris Parker/Bristol, UK
Oryza longistaminata (perennial wild rice); Inflorescence, panicles 16-40 cm long.
InflorescenceOryza longistaminata (perennial wild rice); Inflorescence, panicles 16-40 cm long.©Chris Parker/Bristol, UK


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Preferred Scientific Name

  • Oryza longistaminata A. Chev. & Roehr. 1914

Preferred Common Name

  • perennial wild rice

Other Scientific Names

  • Oryza barthii sensu Hutch. & Dalz. 1836, non A. Chev.
  • Oryza dewildemanii Vanderyst 1920
  • Oryza perennis Wild 1965
  • Oryza sylvestris A. Chev. 1911

International Common Names

  • English: rhizomatous wild rice
  • French: diga; riz sauvage; riz sauvage à rhizomes

Local Common Names

  • Germany: Reis, Wilder

EPPO code

  • ORYBA (Oryza barthii)
  • ORYLO (Oryza longistaminata)

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Plantae
  •         Phylum: Spermatophyta
  •             Subphylum: Angiospermae
  •                 Class: Monocotyledonae
  •                     Order: Cyperales
  •                         Family: Poaceae
  •                             Genus: Oryza
  •                                 Species: Oryza longistaminata

Notes on Taxonomy and Nomenclature

Top of page O. longistaminata is a member of the 'O. sativa' complex of rice species, sharing both the AA genome and chromosome number (2n = 24) with the cultivated species, O. sativa and O. glaberrima (Khush, 1997). The African cultigen O. glaberrima was domesticated from the annual wild rice O. barthii in the basin of the upper Niger river in West Africa. O. longistaminata is thought to have been the progenitor of O. barthii, having itself evolved from a common ancestor of O. rufipogon, the progenitor of O. sativa in Asia. The names of the wild rices have been widely misapplied and many publications have referred to the perennial form of wild rice in Africa as O. barthii. This confusion was discussed by Clayton (1968) whose nomenclature, which confirms O. longistaminata as the perennial and O. barthii as the annual species, is now followed by African regional flora.


Top of page O. longistaminata is an erect or spreading, robust perennial grass with extensive creeping, branched rhizomes. Glabrous, smooth culms are up to 250 cm tall, up to 2.5 cm diameter at the base, have up to 10 nodes, are erect but sometimes floating, weak and spongy with adventitious roots developing from lower nodes.

Leaf sheaths are pale-green to brownish, glabrous, nearly as long as the internodes, with 15 mm long auricles at the junction with the blade. The triangular ligule is often split down the middle, 0.8-5.5 cm long with an acute tip. Leaf blades are bright to dark green,10-75 cm long, 0.5-2.5 cm wide, are broadest below the middle, rough along the margins, otherwise smooth, glabrous with an indistinct mid-rib.

The panicle is 16-40 cm long, erect or slightly drooping with a tuft of hairs at the base of branches. Narrowly oblong spikelets, on 0.5-4 mm long pedicels, are 7-15 mm long, scabrid to hispid and shed when mature. Glumes are reduced to a narrow membranous rim. Sterile lemmas are 2-3.8 mm long, glabrous and smooth. Fertile lemmas are slightly shorter than the spikelet, stiffly hispid, with 6 stamens, a blackish stigma and awns 2.6-7.5 cm, usually pink or purplish when fresh. The seeds are 7.5-8.5 mm long, oblong, glabrous, light-brown and glossy.


Top of page Both O. longistaminata and O. barthii evolved in West Africa (Khush, 1997) and are restricted to the African continent.

Distribution Table

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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: 10 Jan 2020

Risk of Introduction

Top of page As O. longistaminata and O. barthii are restricted to Africa every effort should be made to prevent their inadvertent introduction to rice growing areas elsewhere in the world. This would be possible as contamination of grain shipments or exchange of rice germplasm. All consignments from infested areas should be carefully inspected. Both O. barthii and O. punctata are listed as economically important species which are a potential problem to USA agriculture and which should therefore be kept out of the country by plant quarantine procedures (Reed, 1977).


Top of page O. longistaminata occurs in swamp and floodplain grasslands, generally growing in shallow water, but also found along edges of rivers, dams or on river banks. It can be found from sea-level to a height of 1400 m (Clayton, 1970).

Hosts/Species Affected

Top of page As a weed of wetland habitats, O. longistaminata is only found as a problem in lowland rice crops.

Host Plants and Other Plants Affected

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Plant nameFamilyContext
Oryza sativa (rice)PoaceaeMain

Biology and Ecology

Top of page Little information has been published on the biology or ecology of the African wild rice species. O. longistaminata may be partially or completely sterile, but seed can be produced adding to weed problems (Parker and Dean, 1976). Seed will not germinate in the absence of adequate oxygen, such as under flooded conditions. O. longistaminata and O. barthii both display delayed germination over considerable periods when conditions for germination are otherwise favourable (Katayama, 1969), a trait that is presumably due to variable levels of dormancy in the samples tested. These species were dormant for at least 5 months after collection in a study conducted in Mali (WARDA, 1979). O. punctata may remain dormant for 1-5 years (Armstrong, 1968; Maijisu, 1970). There is some experimental evidence that O. barthii is allelopathic, reducing germination and establishment of O. sativa (Watanabe, 1989).

Notes on Natural Enemies

Top of page Pests and pathogens of O. longistaminata, such as rice yellow mottle sobemovirus (John et al., 1984), rice bacterial blight (Xanthomonas oryzae pv. oryzae) (Buddenhagen, 1982) and rice root nematode (Hirschmanniella spinicaudata) (Babatola, 1980), are also important economic pests of the rice crop.


Top of page Although there are numerous reports that wild rice species are widespread constraints to lowland rice production in many parts of Africa, there are few detailed studies of the actual yield losses caused. In Mali, populations of O. longistaminata have been reported to be as high as 150 plants per m² in fields in the Niger valley. A study of related species in Latin America indicated that 24 wild rice plants per m² caused yield losses of 75% (Fischer and Ramirez, 1993). In West Africa it is not uncommon for heavily infested fields to be abandoned (Davies, 1983). Yield losses have been estimated to be in the order of 85% in fields with severe infestations of O. longistaminata in Mali (IER, 1989), whereas in Senegal, yield losses of over 90% have been associated with infestations of O. barthii (Davies, 1983).

Although seed is shed at maturity, some wild rice seed may contaminate commercial rice grain (Parker and Dean, 1976), reducing its quality, as additional polishing may be required to remove the red pericarp of wild rice grains.

As well as the competitive effect on the crop, both O. longistaminata and O. barthii are alternative hosts of some important rice pests and pathogens including rice yellow mottle sobemovirus (John et al., 1984) and rice bacterial blight (Xanthomonas oryzae pv. oryzae) (Buddenhagen, 1982).


Top of page O. longistaminata is sometimes used to supplement cultivated rice as a food grain in the Niger Valley of Mali (Nyoka, 1983). As the seed is shed at maturity, it has to be collected from the soil surface after flood waters have receded. A full day is needed for one person to gather 2-3 kg. As it is a member of the primary gene pool, sharing the AA genome with O. sativa, the transfer of useful traits, including resistance genes, from O. longistaminata to the crop can be accomplished through conventional hybridization and selection procedures (Khush, 1997). Accessions of the species with immunity to rice yellow mottle sobemovirus, resistance to bacterial blight (Xanthomonas oryzae pv. oryzae) and rice blast (Magnaporthe grisea) have been described and have potential for use as parents in breeding programmes (Vales, 1985; Thottapilly and Rossel, 1993; Zhang et al., 1994).

Uses List

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Animal feed, fodder, forage

  • Forage

Genetic importance

  • Related to

Human food and beverage

  • Cereal

Similarities to Other Species/Conditions

Top of page Although all rice growing regions of the world have 'weedy' or wild rice problems, O. longistaminata is only likely to be confused with two other species within its range in Africa. Even so, it is the only rhizomatous form found on the continent. The annual species O. barthii has an extensive synonymy, having previously been referred to as O. sylvestris var. barthii, O. breviligulata, O. mezii, O. stapfi and O. perennis subsp. barthii. The species has a similar distribution to O. longistaminata and has been recorded in Burkina Faso, Côte d'Ivoire, Gambia, Guinea, Mali, Liberia, Mauritania, Niger, Nigeria, Senegal, Sierra Leone, Sudan, Tanzania, Uganda, Zambia and Zimbabwe(Clayton, 1970; Fernandes et al., 1971; Hepper, 1972).

Another African wild rice, O. punctata, is also distinguished from O. longistaminata by the absence of rhizomes. It is synonymous with O. schweinfurthiana, O. sativa var. punctata and O. eichingeri var. longistaminata, and is known from Angola, Côte d'Ivoire, Ghana, Kenya, Madagascar, Nigeria, Sudan, Swaziland, Tanzania, Uganda, Zanzibar and is also present in Thailand (Clayton, 1970; Fernandes et al., 1971; Hepper, 1972).

The annual O. punctata is distinguished from O. barthii by its small seeds <5 mm long). The spikelets of O. punctata are up to 6.2 mm long and they are approximately 2.5 times as long as they are wide. In O. barthii, the spikelets are somewhat larger (7-11 mm long). The seeds of both these wild rices are shed at maturity, unlike those of the cultivated forms O. glaberrima and O. sativa.

Red rice, weedy, shattering forms of O. sativa with a red pericarp or occasionally with black seeds have on rare occasions been introduced with planting seed into Africa, for example in Swaziland (Parker and Dean, 1976). These are sometimes referred to as O. rufipogon, although this is strictly a perennial species. The 'red rices' cause serious weed problems in the Americas (Holm et al., 1997). They lack rhizomes, but in common with O. longistaminata have very long ligules (1.25-3.0 cm) on lower leaves. In comparison, those of O. barthii and O. punctata are less than 10 mm long.

Prevention and Control

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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 Control

As the wild rices do not germinate in the absence of adequate oxygen, they are only weed problems if they are allowed to germinate and establish in drained soil prior to flooding or in the case of O. longistaminata, when the weed regenerates from rhizomes. The annual species' are therefore not serious weeds of transplanted rice, provided clean seed is used and adequate water control is employed (Parker and Dean, 1976). Seedlings of the rice crop and wild rices are morphologically similar. Planting the crop in rows can therefore help to identify any wild rice plants developing in the inter-rows. In India, purple-leaved rice cultivars were developed so that crop and weedy rices could be readily distinguished to facilitate hand weeding (Malik and Moorthy, 1996). Use of a short-term rice cultivar, which matures before the wild rice plants have begun to shed seed, results in more contamination of the harvested grain, but reduces the long term problem by breaking the cycle of introduction of new weed seed into the soil (Parker and Dean, 1976).

A traditional control measure for O. longistaminata, practised in Mali, has been the rotational 'underwater' mowing of plants on fallow areas of the Niger floodplain (Nyoka, 1983). This provides adequate suppression of the weed to allow production of a rice crop in the subsequent rainy season although the technique is very labour intensive. The rhizome system of O. longistaminata is relatively shallow, so only shallow tillage is needed to sever it from adventitious roots. Repeated dry-season tillage can therefore lead to the desiccation and death of the rhizome system. Timing in relation to soil moisture can be critical. Although a single ploughing prior to flooding failed to control the weed in trials conducted in Mali (WARDA, 1979), 'undercutting' with a blade set shallowly in the soil was effective if carried out twice prior to planting. Tillage has also been shown to influence O. barthii populations (Davies, 1983). A stale seedbed technique using rotary cultivations was shown to be particularly effective, leading to reduced levels of infestation and increased rice yields in Senegal.

Chemical Control

The herbicide dalapon has given satisfactory control of both O. longistaminata and O. barthii on fallow land (Boeken, 1972). Pre-sowing applications of glyphosate or use of the herbicide on fallow land provide effective control of both species (Aubin et al., 1974; Diarra, 1978; Davies, 1983).


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Armstrong K, 1968. Weed control on a Swaziland rice and sugar-cane estate. Proceedings of the 9th Weed Control Conference, 9:687-693.

Aubin JP; Deuse J; Guilloux P; Reynard A, 1975. A contribution to the study of glyphosate, a systemic herbicide for control of rhizomatous wild rice (Oryza longistaminata) in irrigated rice crops in the valley and delta of the Senegal river. 2éme Symposium sur le Desherbage des Cultures Tropicales, organized by COLUMA. Paris, France: Comité Frantaise de Lutte contre les Mauvaises Herbes, 93-103.

Babatola JO, 1980. Studies on the weed hosts of the rice root nematode, Hirschmanniella spinicaudata Sch. Stek. 1944. Weed Research, 20(1):59-61

Boeken GB, 1972. The control of wild rice in Senegal. Bulletin des Recherches Agronomiques de Gembloux, Hors Ser., Vol. Extraordinaire:554-564

Buddenhagen I, 1982. Bacterial blight of rice appears to be indigenous on wild rice species in West Africa. International Rice Research Newsletter, 7(1):5

Clayton WD, 1968. Studies in the Gramineae: XVII. Kew Bulletin, 21:485-488.

Clayton WD, 1970. Gramineae (Part 1). In: Milne-Redhead E, Polhill RM, eds. Flora of Tropical East Africa. London, UK: Crown Agents for Oversea Governments and Administrations.

Davies ELP, 1984. Mechanical and chemical methods for the control of annual wild rice (Oryza barthii). Tropical Pest Management, 30(3):319-320

Diarra A, 1978. Observations on wild rice and a study of control methods, Mopti 1977. 3éme Symposium sur le Desherbage des Cultures Tropicales. Paris, France: COLUMA, 1:228-243.

Fernandes A; Laurnet E; Wild H, 1971. Flora Zambesiaca, Volume 10, Part 1. London, UK: Crown Agents.

Fischer AJ; Ramirez A, 1993. Red rice (Oryza sativa): competition studies for management decisions. International Journal of Pest Management, 39(2):133-138

Hepper FN, 1972. Flora of West Tropical Africa, Volume 3, Part 2. London, UK: Crown Agents.

Holm LG; Doll J; Holm E; Pancho JV; Herberger JP, 1997. World Weeds: Natural Histories and Distribution. New York, USA: John Wiley & Sons Inc.

IER, 1989. Internal Report: Commission technique specialisee de productions vivrieres et oleagineuses, Malherbologie campagne 1988-89. Bamako, Mali: Institut d'Economie Rurale.

John VT; Thottapilly G; Awoderu VA, 1984. Occurrence of rice yellow mottle virus in some Sahelian countries in West Africa. FAO Plant Protection Bulletin, 32(3):86-87

Katayama T, 1969. Botanical studies in the genus Oryza. Part II. Germination Behavior. Memoirs of the Faculty of Agriculture. Kagoshima University, 7:89-119.

Khush GS, 1997. Origin, dispersal, cultivation and variation of rice. Plant Molecular Biology, 35:25-34.

Liberia; West Africa Rice Development Association, 1979. Annual research report May 1979. Annual research report May 1979. West Africa Rice Development Association. Monrovia Liberia, Vol. 3 Special Research Projects:201 pp.

Maijisu B, 1970. A potentially dangerous weed of rice in East Africa. East African Agriculture and Forestry Research Organisation Newsletter. Nairobi, Kenya: EAAFRON.

Malik RK; Moorthy BTS, 1996. Present status and management of weeds in rice in south Asia. In: Auld BA, Kim KU, eds. Weed Management in Rice. Plant Production and Protection Paper 139. Rome, Italy: FAO, 125-139.

Nyoka GC, 1983. Weed problems and control practices in deepwater and floating rice in Mali. In: Deat M, Marnotte P, eds. Proceedings of the Second Biannual Conference. Abidjan, Côte d'Ivoire: West African Weed Science Society, 146-157.

Parker C; Dean ML, 1976. Control of wild rice in rice. Pesticide Science, 7(4):403-416

Reed CF, 1977. Economically important foreign weeds. Potential problems in the United States. Agriculture Handbook No. 498. United States Department of Agriculture. Washington D.C., USA: USDA-ARS.

Thottapilly G; Rossel HW, 1993. Evaluation of resistance to rice yellow mottle virus in Oryza species. Indian Journal of Virology, 9(1):65-73.

Tropicos, 1998. Nomenclatural Data Base. Missouri Botanical Garden. World Wide Web page at

Vales M, 1985. Study of complete resistance to Pyricularia oryzae of Oryza sativa Oryza longistaminata hybrids and their Oryza longistaminata parent. Agronomie Tropicale Riz et Riziculture et Cultures Vivrieres Tropicales, 40(2):148-156

Watanabe N, 1989. An assessment of allelopathic effects of Oryza and Leersia genotypes. Research Bulletin of the Faculty of Agriculture, Gifu University, 54:19-22.

Zhang Q; Wang CL; Shi AN; Bai JF; Ling SC; Li DY; Chen CB; Pang HH, 1994. Genetic studies on resistance to bacterial blight (Xanthomonas oryzae pv. oryzae in nine rice cultivars. Scientia Agricultura Sinica, 27(5):1-9.

Distribution References

Anon, 1971. Flora Zambesiaca., 10 (1) [ed. by Fernandes A, Laurent E, Wild H]. London, UK: Crown Agents.

Clayton WD, 1970. Gramineae (Part 1). In: Flora of Tropical East Africa, [ed. by Milne-Redhead E, Polhill RM]. London, UK: Crown Agents for Oversea Governments and Administrations.

Hepper FN, 1972. Flora of West Tropical Africa., 3 (2) London, UK: Crown Agents.

Tropicos, 1998. Nomenclatural Data Base., Missouri Botanical Garden.

Links to Websites

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GISD/IASPMR: Invasive Alien Species Pathway Management Resource and DAISIE European Invasive Alien Species Gateway source for updated system data added to species habitat list.

Distribution Maps

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