Family: Cyperaceae

Synonyms: Cyperus complanatus Forsk, Cyperus holoshoenoides Jan, Cyperus oryzetorum Steud., Cyperus protractus Lk

Common names: smallflower, souchet difforme, tiña, junquinho.

Erect sedge, smooth, densely tufted annual sedge that can grow as tall as 75 cm. The stem is sharply triangular at the top; 1 4 mm thick. Roots are numerous, fibrous and reddish. There are 3 to 4 {{basal}} leaves, with tubular sheaths, united at the base, the lower ones are straw coloured to brown. The blade is rather flaccid, linear, abruptly acuminate, smooth, usually shorter than the flowering stem, 10 40 cm long, 2 3 mm wide. The inflorescence is a dense, {{globose}}, simple or compound umbel, 5 to 15 mm in diameter, subtended by two to four (usually three) leaf like bracts 15 30 cm long and 6 mm wide. Primary rays of the umbels are 2 4 cm long; secondary rays about 1 cm long, some sessile, some long peduncled. Fruits are brownish achenes, elliptical to slightly obovate, lightly pitted, about 0.6 mm long.

This sedge is well adapted to moist lowland soils or flooded areas. Common weed of rice fields nearly everywhere in the world.  It is normally propagated by seeds and adapted to moist lowland soils or flooded areas. It is a heavy seed producer and can complete one life cycle in about 30 days.

Through high seed production and short life cycle, this weed can spread rapidly to become a dominant weed in a rice field.

The weed has currently been controlled through the post-emergence use of phenoxyacetic and, more recently, sulphonyl urea herbicides. Biotypes of C. difformis have been found resistant to the herbicide bensulfuron in rice in USA (1993) and Australia (1994).

Countries: Burundi, China,  Congo (Democratic), Egypt, Ghana, Iran, Nepal, Niger, Thailand

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