Diagnostic Tool


Cyperus iria

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Latin name | Family l Common name | Synonyms | Geographical distribution | Morphology | Biology and ecology | Agricultural importance| Management | Selected references


Cyperus iria is a tufted weed with a yellowish brown to greenish crowded inflorescence (IRRI).

Full fact sheet

Latin name

Cyperus iria L. triangle


Cyperaceae triangle

Common name

Rice flatsedge and umbrella sedge triangle


Chlorocyperus iria (L.) Rikl, Cyperus microiria Steud., C. microlepis Baker, C. panicoides Lam., C. santonici Rottb. triangle

Geographical distribution

Asia: China (including Taiwan), Japan, and Korea.

South and Southeast Asia: Bangladesh, Cambodia, India, Indonesia, Lao PDR, Malaysia, Myanmar, Nepal, Pakistan, Philippines, Sri Lanka, Thailand, and Vietnam.

Rest of the world: Australia, Fiji, Swaziland, West Africa. triangle


A tufted annual herb, or occasionally perennial, with fibrous roots, 15—75 yellowish red roots; 10—70—cm tall.

Stem: sharply 3 angled, tufted, smooth, 5—80—cm high.

Leaf: basal, rough to touch in upper part, linear, flaccid, with gradually tapering point and 3—8—mm wide; sheath reddish or purplish brown, enveloping the stem at base.

Inflorescence: simple or compound umbel composed of numerous erect-spreading 3—10—mm—long flattened spikelets.

Fruit: three-angled, 1.0—1.5—mm nut with slightly concave sides, and shiny dark brown to black. triangle

Biology and ecology

Thrives in wetland rice, dryland annual crops, and plantation crops.

Multiplies rapidly: can produce 3,000—5,000 seeds per plant, seedlings emerge immediately after rice is sown; flowers month later and can establish second generation in the same season. Flowers throughout the year. triangle

Agricultural importance

An important and widespread weed in South and Southeast Asia.

Ovipositional host of the insects Creatonotus gangis Linnaeus, Leptocorisa acuta (Thunberg), Marasmia exigua (Butler), Mythimna separata (Walker), Nilaparvata lugens (Stål), Nisia carolinensis Fennah, Pseudococcus saccharicola Takahashi, Recilia dorsalis (Motschulsky), Spodoptera mauritia acronyctoides (Guenee), and Stenchaetothrips biformis (Bagnall), diseases Pyricularia oryzae, Rhizoctonia solani, and Sarocladium oryzae, and nematodes Circonemella onoensis, Hirschmanniella oryzae, and Pratylenchus indicus. triangle


Cultural control: hand weeding at earlier stage of growth to prevent flowering and seed production; rotary weeding in transplanted rice during the seedling stage.

Chemical control: Butachlor or oxadiazon after harrowing and sowing of rice and chlorimuron, propanil, or MCPA after emergence. triangle

Selected references

  • Galinato MI, Moody K, Piggin CM. 1999. Upland rice weeds of South and Southeast Asia. Manila (Philippines): International Rice Research Institute. 156 p.
  • Gokulapalan C, Nair MC. 1983. Collateral hosts of Rhizoctonia solani Kuhn causing sheath blight of rice. Int. Rice Res. Newsl. 8:10.
  • Kern JH. 1974. Cyperaceae. Flora Malesiana Ser. 1 7(3): 435-753.
  • Merrill ED. 1976. A flora of Manila. Manila (Philippines): Department of the Interior, Bureau of Science. 491 p.
  • Moody K. 1989. Weeds reported in rice in South and Southeast Asia. Manila (Philippines): International Rice Research Institute. 442 p.
  • Pancho JV, Obien SR. 1995. Manual of ricefield weeds in the Philippines. Muñoz, Nueva Ecija (Philippines): Philippine Rice Research Institute. 543 p.
  • Venkitesan TS, Satyakumar Charles J. 1979. The rice root nematode in lowland paddies in Kerala, India. Int. Rice Res. Newsl. 4:21. triangle


JLA Catindig, RT Lubigan, and D Johnson triangle