Imperata cylindrica (Cogon Grass)

Scientific name

Imperata cylindrica (L.) Beauv.

Synonyms

Imperata arundinacea Cirollo; Lagurus cylindricusL.

Common names

Cogon grass, cotton wool grass, silver spike, sword grass, ialang, lusanke (Luganda), mtimbi (Kiswahili), ol'ungu (Maasai)

Family

Poaceae (Gramineae)

Origin

Pantropical - almost certainly found in all countries in the humid tropics

Naturalised distribution (global)

Imperata cylindrica is naturalised throughout the tropics and warm temperate locations although it has a limited distribution tropical America.

Introduced, naturalised or invasive in East Africa

Imperata cylindrica is invasive in parts of Kenya and Tanzania (A.B.R. Witt pers. obs.) and Uganda (Lyons and Miller 1999).

Habitat

Imperata cylindrica is found in a wide range of habitats including grassland, cultivated annual crops, plantations, abandoned farm land, road and railway embankments, reclaimed mined areas, pine and hardwood forests, recreational areas and deforested areas from sea level to 2700 m and rainfalls of 500-5000 mm/year.

Description

Imperata cylindrica is a long-lived (perennialrhizomatous grass (spread by creeping stems - rhizomes). Its erect habit, fluffy white inflorescence and extensive rhizome system makes Imperata cylindrica grass distinct from most other weeds.

It grows from 0.6-3 m tall. The leaves are about 2 cm wide near the base of the plant and narrow to a sharp point at the top; the margins are finely toothed and are embedded with sharp silica crystals. The main vein is a lighter colour than the rest of the leaf and tends to be nearer to one side of the leaf. The upper surface is hairy near the base of the plant while the underside is usually hairless. Roots are up to 1.2 m deep, but 0.4 m is typical in sandy soil.

Reproduction and dispersal

Imperata cylindrica is a prolific seed producer with one plant capable of producing up to 3000 seeds. These are dispersed by wind over long distances. It also spreads by rhizomes (root-like stems) which can be transported by tilling equipment and in soil transport.

Similar species

Imperata cylindrica may be confused with I. brasiliensis (Brazilian satintail). I. brasiliensis differs from I. cylindrica in terms of the number of stamens per flower; I. brasiliensis has one stamen whereas I. cylindrica has two.

Economic and other uses

Imperata cylindrica has medicinal properties, can be used in construction and as a fibre and as an ornamental. Young inflorescences and shoots may be eaten cooked, and the roots contain starch and sugars and are therefore easy to chew.

Environmental and other impacts

Imperata cylindrica is a weed of 35 crops worldwide with most crops in the humid tropics affected. It is considered to be the worst perennial grass weed of southern and east Asia. Millions of hectares of farmland are abandoned because of I. cylindrica grass in West and Central Africa each year. It is also thought to negatively impact upon biodiversity as it is an inferior forage grass. I. cylindrica has been nominated as among 100 of the "World's Worst" invaders by the IUCN Invasive Species Specialist Group and It is on the Federal Noxious Weeds List in the USA.

Management

The precise management measures adopted for any plant invasion will depend upon factors such as the terrain, the cost and availability of labour, the severity of the infestation and the presence of other invasive species. Some components of an integrated management approach are introduced below.

The best form of invasive species management is prevention. As Imperata cylindrica is so widespread this is unlikely to be possible in many instances.

If prevention is no longer possible, it is best to treat the weed infestations when they are small to prevent them from establishing (early detection and rapid response). Controlling the weed before it seeds will reduce future problems. Control is generally best applied to the least infested areas before dense infestations are tackled. Consistent follow-up work is required for sustainable management.

Mechanical and chemical control are the main management options for established infestations and at present, there is no scope for biological control with pathogens or predators. Details on possible control methods for I. cylindrica are available in the CABI Invasive Species Compendium. IRRI/NRI (1996) have produced a guide to the management of I. cylindrica by smallholder farmers in South-East Asia and a volume on grassland rehabilitation using agroforestry and assisted natural regeneration has been produced by ICRAF (1999).

Legislation

Not listed as a noxious weed by the state or governments in Kenya, Tanzania and Uganda.

References

CABI Invasive Species Compendium online data sheet. Imperata cylindrica (satintail). CABI Publishing 2011. www.cabi.org/ISC. Accessed March 2011.

Dickens, R. and Moore, G.M. (1974). Effects of light, temperature, KNO3, and storage on germination of cogon grass. Agronomy Journal 66: 187-188.

ICRAF (1999). Imperata Grassland Rehabilitation using Agroforestry and Assisted Natural Regeneration. Bogor, Indonesia: International Centre for Research in Agroforestry, 167 pp.

IRRI/NRI (1996). Imperata Management for Smallholders. Polembang, Indonesia: Indonesian Rubber Research Institute, and Chatham, UK: Natural Resources Institute.

Lyons, E.E. and Miller, S.E. (eds) (1999). Invasive Species in Eastern Africa: Proceedings of a Workshop held at ICIPE, July 5-6, 1999.

Editors

Agnes Lusweti, National Museums of Kenya; Emily Wabuyele, National Museums of Kenya, Paul Ssegawa, Makerere University; John Mauremootoo, BioNET-INTERNATIONAL Secretariat - UK.

Acknowledgments

This fact sheet is adapted from The Environmental Weeds of Australia by Sheldon Navie and Steve Adkins, Centre for Biological Information Technology, University of Queensland. We recognise the support from the National Museums of Kenya, Tropical Pesticides Research Institute (TPRI) - Tanzania and Makerere University, Uganda. This activity was undertaken as part of the BioNET-EAFRINET UVIMA Project (Taxonomy for Development in East Africa).

Contact

BioNET-EAFRINET Regional Coordinator: eafrinet@africaonline.co.ke