Cyperus iria (rice flatsedge)
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- Risk of Introduction
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- Growth Stages
- Biology and Ecology
- Notes on Natural Enemies
- Uses List
- Detection and Inspection
- Similarities to Other Species/Conditions
- Prevention and Control
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Cyperus iria L. (1753)
Preferred Common Name
- rice flatsedge
Other Scientific Names
- Chlorocyperus iria (L.) Rikli (1895)
International Common Names
- English: grasshopper's cyperus
Local Common Names
- Bangladesh: barachucha
- Brazil: tiririca-do-brejo
- Cambodia: kak kangkep
- India: morphula
- Indonesia: dekeng wangin; djekeng; nyur-nyuran; rumput jekeng kunyit; umbung
- Japan: kogomegeyatsuri
- Korea, DPR: chambang-donsani
- Malaysia: rumput menderong
- Nepal: chow; guchen; mothey; ochumani
- Pakistan: khana
- Philippines: alinang; ballayang; payong-payong; sirau-sirau; sudsud; taga-taga
- Thailand: kok huadaeng; yaa rangkaa khaao
- USA: rice flatsedge
- CYPIR (Cyperus iria)
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Monocotyledonae
- Order: Cyperales
- Family: Cyperaceae
- Genus: Cyperus
- Species: Cyperus iria
Notes on Taxonomy and NomenclatureTop of page
C. iria was first described by Linnaeus (1753). It originated in the Old World tropics and subtropics and is one of approximately 650 species in the genus Cyperus (Haines and Lye, 1983). Courtoisia, Kyllinga, Mariscus and Pycreus are included in the genus Cyperus (Haines and Lye, 1983) though they are often cited as genera in their own right. Under the classification of Lye (1981), C. iria is in the subgenus Cyperus which contains about 300 species, including the common and important sedge weeds C. rotundus and C. esculentus.
DescriptionTop of page The height of C. iria plants varies from 8 to 60 cm. The roots are numerous, short and yellowish-red. The culms are tufted, triangular, glabrous, green and 0.6-3.0 mm thick. The leaves are linear-lanceolate, usually all shorter than the culm, 1-8 mm wide, flat, and scabrid on the margin and major ribs; leaf sheaths are green to reddish-brown, membraneous and envelope the culm at the base.
The inflorescence is simple or compound, usually open, 1-20 cm long and 1-20 cm wide, with groups of spikes which are either sessile or on 0.5-15.0 cm long peduncles (rays). Inflorescence bracts (involucre) are leafy, three to five (occasionally seven), the lower one longer than the inflorescence, 5-30 cm long, 1-6 mm wide. The spikes are sessile or almost so, elongate, and rather dense. Spikelets are erect-spreading, crowded, 6-24-flowered, 2-13 mm long, 1.5-2.0 mm wide, golden to yellowish-green.
Glumes are broad-ovate, 1.0-1.6 mm long, golden-brown. There are two or three stamens. The style is 3-branched. The fruit is a small achene (nutlet), 1.0-1.5 mm long, 0.6-0.7 mm wide, obovate, triangular in cross section, dark-brown to almost black; the surface is almost smooth. These descriptions are based on Haines and Lye (1983) and Holm et al. (1977).
DistributionTop of page C. iria is most often found as a weed in Japan, the Pacific Islands and Australia to the south, and through India to the west. Outside Asia, it has been reported in southern and western Africa and in the USA (Holm et al., 1977). It has also been recorded in Kenya (Napper, 1966), Uganda (Haines and Lye, 1983; Napper, 1966) and Brazil (Lorenzi, 1982).
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.
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Afghanistan||Present||Holm et al., 1979|
|Brunei Darussalam||Present||Waterhouse, 1993|
|-Hong Kong||Present||Yip, 1976|
|-Jiangsu||Present||Jiang et al., 1989|
|India||Present||Present based on regional distribution.|
|-Andaman and Nicobar Islands||Present||Singh and Gangwar, 1986|
|-Assam||Present||Kurmi and Das, 1993|
|-Haryana||Present||Malik et al., 1981|
|-Himachal Pradesh||Present||Bansal and Singh, 1986|
|-Indian Punjab||Present||Sidhu et al., 1982|
|-Jammu and Kashmir||Present||Kaul, 1986|
|-Karnataka||Widespread||Sastry et al., 1980|
|-Kerala||Present||George et al., 1990|
|-Madhya Pradesh||Present||Sharma and Thakur, 1993|
|-Manipur||Present||Singh and Singh, 1988|
|-Meghalaya||Present||Neogi and Rao, 1982|
|-Odisha||Present||Jena and Patro, 1990|
|-Tamil Nadu||Present||Kandasamy and Palaniappan, 1990|
|-Uttar Pradesh||Present||Singh and Singh, 1985|
|-West Bengal||Present||Mukhopadhyay, 1982|
|Indonesia||Present||Kostermans et al., 1987|
|Japan||Widespread||Numata et al., 1975|
|-Honshu||Present||Numata et al., 1975|
|-Kyushu||Present||Numata et al., 1975|
|-Ryukyu Archipelago||Present||Numata et al., 1975|
|-Shikoku||Present||Numata et al., 1975|
|Korea, Republic of||Present||Park and Kim, 1971|
|Malaysia||Present||Barnes and Chan, 1990|
|Nepal||Present||Ranjit and Bhattarai, 1988|
|Philippines||Widespread||Moody et al., 1984|
|Sri Lanka||Present||Weerakoon and Gunewardena, 1983|
|Thailand||Present||Noda et al., 1985|
|Burkina Faso||Present||Clayton, 1972|
|Kenya||Present||Haines and Lye, 1983|
|Swaziland||Present||Holm et al., 1979|
|Tanzania||Present||Haines and Lye, 1983|
|Uganda||Present||Haines and Lye, 1983|
|USA||Present||Holm et al., 1979|
|-Louisiana||Present||Baker and Shrefler, 1983|
|-Mississippi||Present||Riley et al., 1986|
Central America and Caribbean
|Dominican Republic||Present||Holm et al., 1979|
|Puerto Rico||Present||Liu and Lozano, 1987|
|Trinidad and Tobago||Present||Holm et al., 1979|
|-Espirito Santo||Present||Lorenzi, 1982|
|-Mato Grosso do Sul||Present||Lorenzi, 1982|
|-Minas Gerais||Present||Lorenzi, 1982|
|-Rio de Janeiro||Present||Lorenzi, 1982|
|-Santa Catarina||Present||Lorenzi, 1982|
|-Sao Paulo||Present||Lorenzi, 1982|
|Colombia||Present||Häfliger et al., 1982|
|Ecuador||Present||Lopez et al., 1974|
|Venezuela||Present||Häfliger et al., 1982|
|Fiji||Present||Holm et al., 1979|
Risk of IntroductionTop of page None known.
HabitatTop of page C. iria is found in moist-to-wet soils, including river banks and ditches. It is an important weed of lowland and irrigated ricefields but is less important in the upland crop.
Hosts/Species AffectedTop of page C. iria is principally a weed of rice around the world but Holm et al. (1977) also noted its occurrence in bananas, cassava, groundnuts, maize, pastures, pineapples, sweet potatoes, tea and vegetables.
Host Plants and Other Plants AffectedTop of page
|Oryza sativa (rice)||Poaceae||Main|
Growth StagesTop of page Vegetative growing stage
Biology and EcologyTop of page C. iria is an annual sedge, sometimes behaving as a perennial. It propagates from seed (achenes or nutlets); a large plant can produce up to 5000 progeny (Holm et al., 1977). Forty percent of fresh seeds can germinate immediately and most dormant seeds can germinate only following a short period of after-ripening (Chozin and Nakagawa, 1988). Storage in darkness at low temperature, or in submerged soil, causes seeds to enter secondary dormancy. Light is required for optimum germination but germination in darkness, in upland soil, can be stimulated by alternating temperatures (20/35°C). Seeds of C. iria germinate at 15-40°C but an alternating temperature regime of 20/30°C is optimum. Seeds germinate well on the soil surface but few emerge from depths below 1 cm (Chozin and Nakagawa, 1988). C. iria is somewhat less able to germinate under water than C. difformis. Civico and Moody (1979) show that it may germinate under 1 cm of water but early development is suppressed at depths of 2.5 cm or more.
Chromosome numbers vary in C. iria (n=56, 64) and intraspecific variation in genotype and phenotype occurs (Bir et al., 1992). Natural hybridization can occur between C. iria and C. microiria (Chozin and Yasuda, 1991) to produce progeny of new-type plants of similar dormancy to the parents, showing clear segregation in spikelet characteristics and floret morphology. C. iria has Kranz-type leaf anatomy and, like C. rotundus, has two layers of bundle sheath cells (Lin et al., 1982). This is indicative of C4 photosynthesis which is generally not a characteristic of weeds growing in wet habitats.
Notes on Natural EnemiesTop of page Phoma cyperi sp. nov. is described from C. iria in India where it shows specificity towards nut sedges and produces at least one phytotoxin (Upadhyay et al., 1990). Cuscuta chinensis uses C. iria for mechanical support but, although haustoria are produced on the leaf lamina, there is no vascular contact between host and parasite (Mohanty and Rath, 1987). For pests and diseases of rice which also occur on C. iria, see Economic Impact.
ImpactTop of page
C. iria is rated by Holm et al. (1977) as one of the three most important weeds of rice in Sri Lanka, India and the Philippines. It is a principal weed in Indonesia and Japan and a common weed in Fiji, Thailand and the USA. It is principally a weed of rice around the world but Holm et al. (1977) also noted its occurrence in bananas, cassava, groundnuts, maize, pastures, pineapples, sweet potatoes, tea and vegetables. It is difficult to separate the competitive effects of C. iria from those of other components of the weed flora but the weed caused 40% yield reductions in rice (Ampong-Nyarko and DeDatta, 1991).
The costs of controlling C. iria, whether manual, mechanical or chemical, are significant. C. iria is a host for several pests of rice. In Cuba, it is a host of the rice nematodes Pratylenchus zeae and Hirschmanniella spinicaudata (Fernandez and Ortega, 1982). Criconemella onoensis is a rice nematode which uses C. iria as a host in the southern USA. Complete control of the weed is necessary before nematicides (e.g. fensulfothion) can be effective in increasing rice yields (Hollis, 1972).
Arthropod rice pests which use C. iria as a host plant include Scotinophara latiuscula (Barrion and Litsinger, 1987), Nisia atrovenosa (Cruz and Dela-Cruz, 1986), Lissorhoptrus brevirostris (Meneses-Carbonell and Carbonell, 1985), Nymphula depunctalis (Pillai and Nair, 1979), Baliothrips biformis and B. holorphnus (Ananthakrishnan and Kandasamy, 1977).
Pathogens of rice that have been reported on C. iria include Pyricularia oryzae [Magnaporthe grisea] (Singh and Singh, 1988), Rhizoctonia solani (Gokulapalan and Nair, 1983) and Acrocylindrium oryzae [Sarocladium oryzae] (Balakrishnan and Nair, 1981). Also the nematode Pratylenchus zeae (Waterhouse, 1994).
Uses ListTop of page
Detection and InspectionTop of page The experienced eye can detect seeds of C. iria as a contaminant of crop seed.
Similarities to Other Species/ConditionsTop of page C. iria is distinguished by its yellowish-red, fibrous roots; yellowish, usually open inflorescence; and by the lowest bract of the flower always being longer than the inflorescence (Holm et al., 1977). However, as a seedling or non-flowering plant, it closely resembles many immature, annual Cyperus spp. In a key to seedling Cyperaceae, Kostermans et al. (1987) use the coleoptile, seed, first leaf blade and first leaf sheath as diagnostic characters. It is sometimes possible to distinguish seedlings of C. iria from those of C. difformis by the mild aroma released when C. iria is crushed.
A very experienced eye is required to distinguish the seeds of C. iria from those of other Cyperus species.
Prevention and ControlTop of page Cultural Control
The principles of good weed management in rice, such as those advocated by Ampong-Nyarko and DeDatta (1992), are applicable to C. iria in rice and other crops. These include the need to prepare clean seedbeds, prevent seed production, establish a healthy and vigorous crop and avoid contamination of crop seed at harvest. C. iria is susceptible to many of the usual methods of weed control in rice and other crops. These include hand-pulling, manual and mechanical tillage and trampling in puddled fields. Flooding has a major suppressive effect during the early growth stages of C. iria (Civico and Moody, 1979) but established plants are difficult to control in this way and can tolerate 90 cm of floodwater for four days (Singh et al., 1983).
At present there are no biological control agents for C. iria but Phoma cyperi sp. nov., a pathogen of C. iria, may have some potential.
A number of herbicides are approved for use in rice but their use is dictated by the conditions used to grow the crop, e.g. whether the crop is irrigated, rainfed lowland, upland and deepwater. C. iria is susceptible to the herbicides commonly used in rice: bensulfuron, bentazone, bifenox + 2,4-D, butachlor, butralin, 2,4-D, MCPA, molinate, oxadiazon, pendimethalin, piperophos + dimethametryn, pretilachlor + antidote (e.g. fenclorim), propanil, thiobencarb, thiobencarb + 2,4-D. Cinmethylin and fluorodifen were also active against C. iria (Ampong-Nyarko and DeDatta, 1991). Paraquat and glyphosate can both be used as non-selective, post-emergence herbicides against C. iria, for example in land preparation using zero-tillage.
Integrated Weed Management
Integrated weed management is recommended for cost-effective weed control; combinations of treatments such as: planting clean seed into a weed-free seedbed; sowing crop at optimum spacing; good water control; applying appropriate herbicides or cultivations; and harvesting crop grain which is not contaminated by weeds may be combined for an effective integrated control strategy.
ReferencesTop of page
Ampong-Nyarko K; DeDatta SK, 1991. A Handbook for Weed Control in Rice. Manila, Philippines: International Rice Research Institute.
Anon, 1968. Weeds found in Cultivated land in Taiwan, Volumes 1 & 2. Taipei, Taiwan: College of Agriculture, National Taiwan University.
Barnes DE; Chan LG, 1990. Common Weeds of Malaysia and their Control. Kuala Lumpur, Malaysia: Ancom Berhad Persiaran Selangor.
Barrion AT; Litsinger JA, 1987. The bionomics, karyology and chemical control of the node-feeding black bug, Scotinophara latiuscula Breddin (Hemiptera: Pentatomidae) in the Philippines. Journal of Plant Protection in the Tropics, 4(1):37-54
Chozin MA; Nakagawa K, 1988. Autecological studies on Cyperus iria L. and C. microiria Steud., annual cyperaceous weeds. I. Seed dormancy, germination, and seedling emergence. Weed Research, Japan, 33(1):23-30
Clayton WD, 1972. Gramineae. In: Hutchinson J, Dalziel JM, Hepper FN, 1972. Flora of West Tropical Africa. Vol 3. Part 2. London, UK: Crown Agents, 349-512.
Cruz CG; Dela-Cruz CG, 1986. Host plant range of the planthopper Nisia atrovenosa. International Rice Research Newsletter, 11(2):26-27.
Haines RW; Lye KA, 1983. The Sedges and Rushes of East Africa. Nairobi, Kenya: East African Natural History Society.
Hollis JP, 1972. Nematicide-weed interaction in rice fields. Plant Disease Reporter, 56(5):420-424.
HSfliger E; Kühn U; HSmet-Ahti L; Cook CDK; Faden R; Speta F, 1982. Monocot Weeds 3. Basle, Switzerland: Documenta Ciba-Geigy.
Kurmi K; Das GR, 1993. Effect of herbicides on weed control in transplanted rice. Integrated weed management for sustainable agriculture. Proceedings of an Indian Society of Weed Science International Symposium, Hisar, India, 18-20 November 1993 Hisar, Haryana, India; Indian Society of Weed Science, 3:27-29
Linnaeus C, 1753. Species plantarum vol. I. Holmiae.
Lopez A; Salazar E; Veloz A, 1974. Behaviour of various herbicides for weed control in rice sown broadcast with pre-germinated seed. Asociacion Latinoamericana de Malezas "ALAM" [y] Sociedad Colombiana de Control de Malezas y Fisiologia Vegetal "COMALFI". Resumenes de los Trabajos en el II Congreso ALAM y VI Seminario, COMALFI, Cali, 1974., 50-51
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.
Lye KA, 1981. Studies in African Cyperaceae 18. Two new subgenera of Cyperus. Nordic Journal of Botany, 1:57-61.
Malik RK; Bhan VM; Katyal SK; Balyan RS; Singh BV, Weed management problems in rice-wheat cropping system adoption of weed control technology in north western India. Abstracts of papers, annual conference of Indian Society of Weed Science, 1981., 33
Meneses-Carbonell R; Carbonell RM, 1985. Rice water weevil host plants in Cuba. International Rice Research Newsletter, 10(1):21-22.
Minh Si H, 1969. Weeds in South Vietnam. Saigon, Vietnam: Agricultural Research Institute, Ministry of Land Reform and Development of Agriculture and Fisheries.
Moody K; Munroe CE; Lubigan RT; Paller EC Jr, 1984. Major Weeds of the Philippines. Los Baños, Philippines: Weed Science Society of the Philippines, University of the Philippines at Los Baños.
Mukhopadhyay SK, 1982. Noxious aquatic vegetation of West Bengal. Abstracts of papers, Annual Conference of Indian Society of Weed Science, December 27-30, 1982. Haryana, India: Indian Society of Weed Science.
Napper DM, 1966. Cyperaceae of East Africa - IV. Cyperus L. Journal of the East African Natural History Society, 26(1):1-24.
Noda K; Teerawatsakul M; Prakongvongs C; Chaiwiratnukul L, 1985. Major Weeds in Thailand. Bangkok, Thailand: Department of Agriculture.
Park JK; Kim DS, 1971. Distribution of weeds and their competition with rice in Korea. Proceedings of the Asian-Pacific Weed Science Society Conference, 3.
Ranjit JD; Bhattarai AN, 1988. Crop Weeds and their Control in Nepal. Kathmandu, Nepal: Winrock International/USAID.
Sidhu M; Gogia BK; Kumar A, unda. Changes in weed flora of paddy fields of Patiala District (Punjab) during eleven years. Abstracts of papers, annual conference of Indian Society of Weed Science, 1982., 1
Singh RK; Singh RP, 1985. Effect of water management practices on relative composition of weed flora in rice. Abstracts of papers, Annual Conference of Indian Society of Weed Science.
Upadhyay RK; Strobel GA; Hess WM, 1990. Phoma cyperi sp.nov., a new pathogen of Cyperus iria, its vegetative and reproductive structures and production of phytotoxins. Canadian Journal of Botany, 68(10):2059-2064
Wang Z; Xin M; Ma D, 1990. Farmland Weeds in China. Agricultural Publishing House, 506 pp.
Waterhouse DF, 1993. The Major Arthropod Pests and Weeds of Agriculture in Southeast Asia. ACIAR Monograph No. 21. Canberra, Australia: Australian Centre for International Agricultural Research, 141 pp.
Waterhouse DF, 1994. Biological Control of Weeds: Southeast Asian Prospects. Canberra, Australia: ACIAR Monograph No 26.
Wozniak H, 1976. Studies on the weed flora in important rice growing areas of the Republic of Cuba. Part I. The weed flora on the rice fields. Beitrage zur Tropischen Landwirtschaft und Veterinarmedizin, 14(4):349-359
Distribution MapsTop of page
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