Cyperus rotundus L.
Nut Grass

Sp.Pl. 1:45 (1753)
Conservation Code
Not threatened
Naturalised Status
Alien to Western Australia
Name Status

Rhizomatous and tuberous, perennial, grass-like or herb (sedge), 0.15-0.6 m high. Fl. green-brown, Apr to Jul. Wet sand. Disturbed sites.

Grazyna Paczkowska, Descriptive Catalogue, 4 November 1993


IBRA Regions
Carnarvon, Dampierland, Geraldton Sandplains, Jarrah Forest, Murchison, Pilbara, Swan Coastal Plain, Victoria Bonaparte.
IBRA Subregions
Chichester, Dandaragan Plateau, Eastern Murchison, Fitzroy Trough, Geraldton Hills, Hamersley, Keep, Northern Jarrah Forest, Perth, Pindanland, Roebourne, Wooramel.
Local Government Areas (LGAs)
Ashburton, Broome, Carnarvon, Chittering, Derby-West Kimberley, East Pilbara, Gingin, Greater Geraldton, Karratha, Stirling, Wanneroo, Wiluna, Wyndham-East Kimberley.

Management Notes (for the Swan NRM Region)

Alternative Names. Coco-grass, Purple Nut Sedge.

General Biology. Growth form. Sedge. Life form. Perennial. Reproduction. Primarily tubers and rhizome, occasionally seed. Dispersal. Soil, water (flooding), wind, nursery stock. Seedbank persistence. Seed viability low, dormant tubers can remain viable for up to 10 years.

Notes. Can displace native plants and change the availability of food or shelter for native animals. Although relatively small in size it is highly competitive for resources. Has rapid growth, is able to produce an extensive system of rhizomes and tubers and can quickly form dense colonies. Most seed produced is not viable. Hundreds of tubers can be produced in one season at the tips of the rhizome. Tubers require a chilling period to break dormancy and produce a primary small basal bulb beneath the soil surface. Cultivation stimulates growth. Tubers are vulnerable to drying and die at low moisture content levels. Plants are susceptible to shading, which reduces vegetative growth and tuber production. Grows well across a range of soil types, soil moisture, pH and elevations, and grows best in moist fertile soils. Tubers can lie dormant in the soil for up to 10 years until stimulated to sprout. Predicted to increase in abundance with elevated CO2 levels. Has allelopathic properties. Intolerant of dense shade.

Additional information. Origin. Pilbara and Kimberley Regions of Western Australia. History of use/introduction. Nursery stock, ship ballasts, contaminated seed/crops.

Suggested method of management and control. Difficult to control once established. Hand remove small/isolated plants ensuring all tubers and rhizomes are removed. Responds differently to glyphosate depending on growth stage. Apply glyphosate at label rate before the fifth leaf stage - after this time herbicide is not translocated to tubers. Repeated applications are usually required for effectiveness. Read the manufacturers' labels and material safety data sheets before using herbicides. For further information consult the Australian Pesticides and Veterinary Medicines Authority to determine the status of permits for your situation or state.

Management Calendar

Calendar Type Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Comments
Germination Y               Y Y Y Y  
Active Growth Y Y Y Y Y       Y Y Y Y  
Flowering       Y Y Y Y            
Fruiting           Y Y Y          
Manual Removal O O O O O O O O O O O O  
Herbicide Treatment Y Y             Y Y Y Y  

Legend: Y = Yes, regularly, O = Occasionally, U = Uncertain, referred by others but not confirmed.



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