Ischaemum rugosum Salisb.

Ischaemum rugosum has paired terminal spikes (IRRI).

Latin name

Ischaemum rugosum Salisb.



Common name

Wrinkle duck beak, saromacca grass


Andropogon arnottianus (Nees) Steudel, Colladoa distachia Cav., Ischaemum akoense Honda, I. segetum Trin., Meoschium arnottianum Nees, M. griffithii Nees & Arn., M. rugosum (Salisb.) Nees 

Geographical distribution

Asia: China.

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, Colombia, Ecuador, Fiji, Madagascar, Nicaragua, Peru, Venezuela, and West Africa.


An erect or ascending annual or perennial; up to 100 cm tall.

Stem: often purplish, usually has hairs at nodes, cylindrical.

Leaf: blades 10−30 cm long, glabrous or with scattered hairs on both surfaces; compressed sheaths rather loose and green or purplish, with hairs on margins; ligule membranous and fused with auricles.

Inflorescence: paired terminal spikes that are often strongly pressed against one another, thus appearing like a single spike. At maturity, it separates into two spike-like racemes. Spikelets paired, one is sessile, the other pedicelled; sessile spikelet yellowish green, up to 6 mm long, first glume prominently transversely wrinkled; awns spiral at base, dark colored. 

Biology and ecology

Propagates by seeds. Seeds do not germinate while submerged though, after emergence, they can grow easily under flooded conditions.

Ischaemum rugosum is found in wet conditions, especially in direct-seeded rice fields.

Agricultural importance

Ischaemum rugosum is a serious weed in lowland direct-seeded rice, where it emerges later than many weeds in the crop and is favored by shallow flooding.

Also an alternate host of Chaetocnema basalis (Baly), Cicadulina bipunctata (Melichar), Hysteroneura setariae (Thomas), Leptocorisa acuta (Thunberg), Nisia carolinensis Fennah, Orseolia oryzae (Wood-Mason), Pseudococcus saccharicola Takahashi, Sesamia inferens (Walker), and Tetraneura nigriabdominalis (Sasaki), and diseases caused by tungro virus. It is also a host of the nematode Meloidogyne sp.

Ischaemum rugosum is used as feed for animals. It also provides suitable material for mulch and compost.


Cultural control: hand weeding or hoeing.

Chemical control: Butachlor, thiobencarb, pendimethalin, or mixtures of thiobencarb or butachlor and propanil, cyhalofop, and fenoxaprop can give effective control. Molinate is not effective in controlling I. rugosum. 

Selected references

  • Akibo-Betts DT, Raymundo SA. 1978. Aphids as rice pests in Sierra Leone. Int. Rice Res. Newsl. 3:15-16.
  • Catindig JLA, Barrion AT, Litsinger JA. 1995. Suitability of ricefield plants to planthopper Nisia carolinensis Fennah. Int. Rice Res. Notes 20:27.
  • Gapasin RM, Barsalote EB, Lim JL. 1996. Survey and identification of plant parasitic nematodes associated with upland weeds and weed response to the rice root-knot nematode, Meloidogyne graminicola. Philipp. J. Weed Sci. 21:22-31.
  • Holm LG, Plucknett DL, Pancho JV, Herberger JP. 1977. The world's worst weeds: distribution and biology. Honolulu, Hawaii (USA): University of Hawaii Press. 609 p.
  • Noda K, Teerawatsakul M, Prakongvongs C, Chaiwiratnukul L. 1985. Major weeds in Thailand. National Weed Science Research Institute Project. Bangkok (Thailand): Department of Agriculture. 142 p.
  • Moody K. 1989. Weeds reported in rice in South and Southeast Asia. Manila (Philippines): International Rice Reseach 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.
  • Rivera CT, Ling KC, Ou SH. 1969. Suspect range of rice tungro virus. Philipp. Phytopathol. 5:16-17.
JLA Catindig, RT Lubigan, and D Johnson