• Common Name : Thunessa

• Scientific Name : Cyperus iria

• Family : Cyperaceae

• Life cycle : Annual

• Place of collected : Faculty field, Puliyankulama, Anuradhapura

• Date of collected : 2009.07.30

• Morphological characters : Culms – solitary or a few together, erect, 8- 60 cm tall, slender or slightly thick, trigonous smooth

Roots – fibrous roots only . Leaves 2 or 3 to a culm, much shorter than culm; blades linear, 2-5 mm broad, weakly folded. Sheaths – dish or somewhat purplish brown . Inflorescence – branched, spikes about 2.5 cm long, about 10-12-flowered; spikelets 6 mm long, glumes spreading, scarcely imbricate, apex rounded with a tiny mucro, pale straw-colored, but green-carinate; achene narrowly obovoid, yellow-brown, trigonal, minutely apiculate

• Propagation : By Seeds.

• Agricultural importance : The mature plant grows higher than rice, so that it competes for sunlight, besides soil nutrients. Reduces yield.

• Uses : Can incorporate to the soil for organic matter.

• Control measures : Deep plowing and proper field level.Repeated tillage or soil disturbance Hand weeding. Chemical control-MCPA, Proponil.