Paspalum distichum L. Water Couch
Syst.Nat. Ed.10,2:855 (1759)

Conservation Code: Not threatened
Naturalised Status: Alien to Western Australia
Name Status: Current

Brief Description
Grazyna Paczkowska, Wednesday 1 December 1993

Tufted perennial, grass-like or herb, 0.05-0.5 m high. Fl. green/green-purple, Dec or Jan to Apr. Moist habitats, often saline.

Distribution

Beard’s Provinces: Northern Province, South-West Province.

IBRA Regions: Geraldton Sandplains, Jarrah Forest, Swan Coastal Plain, Victoria Bonaparte, Warren.

IBRA Subregions: Geraldton Hills, Northern Jarrah Forest, Perth, Southern Jarrah Forest, Victoria Bonaparte P1, Warren.

Local Government Areas (LGAs): Albany, Armadale, Augusta-Margaret River, Busselton, Capel, Donnybrook-Balingup, Gosnells, Greater Geraldton, Harvey, Kalamunda, Melville, Murray, Northampton, Perth, Rockingham, Serpentine-Jarrahdale, South Perth, Stirling, Wyndham-East Kimberley.

Management Notes (for the Swan NRM Region)
Kate Brown and Karen Bettink, Monday 18 July 2016

Alternative Names. Mercer grass, knotgrass, seashore paspalum, salt jointgrass, turfgrass.

General Biology. Growth form. Grass. Life form. Perennial, stoloniferous/rhizomatous. Reproduction. Stolon, rhizome, occasionally seed. Dispersal. Water. Photosynthetic Pathway. C4. Toxicity. Toxic to stock due to parasitic ergot fungus. Seedbank persistence. Possibly 2 years. Fire response. Resprouts from rhizomes.

Notes. Occurs in warm regions throughout the world, being most abundant in humid areas. Found on edges of wetlands, ponds and wet roadside drains. Has slow decomposition rates that can form permanent litter layers in wetlands. Eutrophication and disturbance exacerbates spread. Regeneration occurs mostly from rhizomes, although ecotypes have been known to reproduce readily from seed. Highest germination rates occur at temperatures between 28 and 35 degrees celsius. Seed has high viability. Alternating temperature and mositure breaks seed dormancy and results in high germination rates.

Additional information. History of use/introduction. Forage, rehabilitation of disturbed and contaminated sites, erosion control. Similar exotic species. Paspalum vaginatum.

Suggested method of management and control. Spray with 1% glyphosate 2-3 times over single growing season. Following any fire event is an optimal time to undertake control. 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 TypeJanFebMarAprMayJunJulAugSepOctNovDecComments
Dormant     YYYY    
Active GrowthYYYYO    YYY 
Germination        UUUU 
FloweringYYYY       Y 
FruitingYY           
Herbicide TreatmentYYYYO     YY 

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

 

References

  • Aguiar, F.C., Ferreira, M.T., Albuquerqu, A. & Bernez, I. (2005) Invasibility patterns of Knotgrass (Paspalum distichum) in Portuguese riparian habitats. Weed Technology, 19 (3): 509-516.
  • Botha, C.J., Kellerman, T.S. & Fourie, N. (1996) A tremorgenic mycotoxicosis in cattle caused by Paspalum distichum (l.) infected by Claviceps paspali. Journal of the South African Veterinary Association, 67 (1): 36-37.
  • Brown, K. & Brooks, K. (2002) Bushland Weeds: A Practical Guide to their Management. Environmental Weeds Action Network, Greenwood.
  • Hsiao, A.I. & Huang, W.Z. (1989) Effects of flooding on rooting and sprouting of isolated stem segments and on plant growth of Paspalum distichum L.. Weed Research, 29: 335-344.
  • Hussey, B.M.J., Keighery, G.J., Dodd, J., Lloyd, S.G. & Cousens, R.D. (2007) Western Weeds. A guide to the weeds of Western Australia. 2nd Edition. The Plant Protection Society of Western Australia, Victoria Park.
  • Kadono, Y. (1985) Distribution of tetraploid of Paspalum distichum L. ("Chikugo-suzumenohie") in irrigation reservoirs in the East Harima area, Hyogo Prefecture, southwestern Japan: Comparison with three aquatic grasses with similar ecological niche. Journal of Weed Science and Technology, 30 (1): 47-50.
  • Middleton, B.A., van der Valk, A.G., Mason, D.H., Williams, R.L. & Davis, C.B. (1991) Vegetation dynamics and seed banks of a monsoonal wetland overgrown with Paspalum distichum L. in northern India. Aquatic Botany, 40: 239-259.
  • Middleton, B.A., van der Valk, A.G., Willliams, R.L., Mason, D.H. & Davis, C.B. (1992) Litter decomposition in an Indian monsoonal wetland overgrown with Paspalum distichum. Wetlands, 12 (1): 37.
  • Moore, J.H. & Wheeler, J. (2008) Southern weeds and their control. DAFWA Bulletin 4744.
  • Okuma, M. & Chikura, S. (1984) Ecology and control of subspecies of Paspalum distichum L. "Chikugo suzumenohie" growing in creeks in the paddy area on the lower reaches of Chikugo River in Kyushu: Possibility of reproduction by seeds. Journal of Weed Science and Technology, 29 (1): 45-50.
  • Shu, W.S., Ye, Z.H., Lan, C.Y., Zhang, Z.Q. & Wong, M.H. (2002) Lead, zinc and copper accumulation and tolerance in populations of Paspalum distichum and Cynodon dactylon. Environmental Pollution, 120 (2): 445-53.
  • Snyder, S.A. (1992) Paspalum distichum. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer) URL: http://www.fs.fed.us/database/feis/ - Accessed January 2010.
  • USDA, ARS, National Genetic Resources Program (2009) Germplasm Resources Information Network - (GRIN). National Germplasm Resources Laboratory, Beltsville, Maryland. URL: https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysimple.aspx - Accessed October 2009.

Project information and acknowledgements