Cyperus difformis L. - CYPERACEAE - Monocotyledon

Common name : small-floweed umbrella sedge.

Botany Biology Phenology Ecology Distribution Agricultural importance Chemical control

Botany :

Description :

Terrestrial, annual or perennial, tufted erect herb. Roots fibrous, white or brown. Stem triangular, solid, glabrous. Stipules absent. Leaves simple, not lobed or divided, alternate spiral, sessile, linear, more than 2 cm long/wide, margin entire, apex acute, base clasping, parallel-veined. Leaf sheath present, triangular or round in cross section. Flowers bisexual, grouped together in a terminal umbel, sessile, yellow, petals absent. Fruit a nut.

In tropical areas, C. difformis apparently can flower and produce seeds all year long if the soil moisture is sufficient. This plant reproduces by seeds which are produced in large quantities. One plant could complete the vegetative cycle in one month and produce a new generation of weeds during the second month, producing 50.000 seeds with about 60% germination.

Phenology :

Flowering and fruiting throughout the year.

Ecology :

The plant normally grows in flooded or in very moist soils. It is primarily a weed of paddy or flooded rice. It is frequently found in small pools, along rivers, canals and streams, in open wet places and in grassy swamps. It grows best in rich, fertile soils but can grown in poor sandy or clay soils of unused lands or in fallow rice fields.

Distribution :

S. Europe across to Japan, South Africa, Indian continent, S.E.Asia & Malesia to the Pacific. Introduced Central America.

Agricultural importance :

C. difformis is a widespread and serious weed of paddy rice. It is important because it produces abundant seed and rapidly becomes a dominant weed in the fields. Producing abundant plants per unit area, the plant form dense and solid mats of vegetation in the young rice crop. This weed appears to be more of a competitor for water and nutrients than for light. The ability of the plant to complete a vegetative and reproductive cycle within a month or so makes it especially competitive in a crop which requires at least 90 or more days to reach maturity.

Chemical control :

Post-emergence application of 2_4-D at 500 g/ha or Almix at 4 g/ha.

References :
-Holm L. G., Plucknett D. L., Pancho J. V., Herberger J. P. 1991. The world’s worst weeds. Distribution and Biology. East-West Center by the University Press. Hawaii.

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