Photograph of a field of cogongrass with feathery white inflorescences.

Cogongrass quick facts

Page snapshot: Quick facts about cogongrass (Imperata cylindrica), a globally distributed weed.


Topics covered on this page: What is cogongrass?; How is cogongrass identified?; Where did cogongrass come from?; How does cogongrass spread?; What are the impacts of cogongrass?; How can cogongrass be controlled?; Resources.

Credits: Funded by the National Science Foundation. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Page by Elizabeth J. Hermsen and Naomi Schulberg (2023).

Updates: Page last updated August 8, 2023.

Image above: a field of cogongrass. Photo by Karan A. Rawlins, University of Georgia (Bugwood.org photo number 5533095, licensed under a Creative Commons Attribution-Noncommercial 3.0 License).

What is cogongrass?

Cogongrass (Imperata cylindrica) is a tropical to subtropical grass that has an attractive white, plume-like inflorescence. This grass is considered to be one of the world's top ten worst weeds. In the U.S., the plant is listed federally as a noxious weed. Nevertheless, one cultivar, Japanese blood grass (Imperata cylindrica 'Rubra' or 'Red Baron'), is used as an ornamental plant.


Photograph of a field of cogongrass is Taiwan, where the grass is not native. The photo shows a field of grass with white, feathery inflorescences.

Photograph of cogongrass (Imperata cylindrica) in Taiwan, where it has been introduced. Photo by Cheng-Tao Lin (iNaturalist photo 22887263, Creative Commons Attribution 4.0 International license, image resized).

How is cogongrass identified?

Cogongrass is a perennial plant that spreads via pale and scaly rhizomes. It can reach 1.5 meters (about 5 feet) or more in height. The leaves are yellowish green and have a midvein that is slightly off-center in the leaf blade. The spikelets have conspicuous white hairs, which gives the inflorescences a feathery, plume-like appearance.


Photograph of a person holding segments of cogongrass rhizomes in a gloved hand. The rhizomes are straight and off-white with prominent nodes. The rhizomes are being held above a metal screen, which has apparently been used to sift them from the soil they were growing in.
Photograph showing a close-up of part of the blade of a cogongrass leaf with an obvious white, slight off-center midvein.

Leaf of cogongrass showing the light-colored, off-center midvein. Photo by elawrey (iNaturalist photo 5009793, Creative Commons Attribution 4.0 International license, image cropped).


Photograph of a mature white, feathery cogongrass inflorescence attached to a stalk, in a field of green and brown grass blades.

Cogongrass inflorescence with silvery white hairs, giving it a plume-like appearance. Photo by Chris Evans, University of Illinois (Bugwood.org photo number UGA2131097, licensed under a Creative Commons Attribution-Noncommercial 3.0 License, image cropped).

Where did cogongrass come from?

Cogongrass is native to parts of Europe, much of Africa, and southwest Asia. Today, it has spread widely beyond its native range to suitable areas of the Eastern Hemisphere and is distributed from around the Caspian Sea south and east as far as northeast China, the Koreas, and Japan, and south as far as Australia and New Zealand.

In the Americas, cogongrass is currently found in the southeastern U.S. from Virginia to Texas, in Oregon, and in southern and western Mexico. It also grows in Hawai'i. Cogongrass reached the United States in the early 1900s, first unintentionally as packing material and later as a forage grass. 


Photograph of cogongrass. The photo shows a large field of tall, green grasses with feathery while inflorescences.

Cogongrass (Imperata cylindrica) in Gauteng, South Africa. Photo by JMK (Wikimedia CommonsCreative Commons Attribution-ShareAlike 4.0 International license, image resized).

A map of the United States and Canada (excluding Hawaii). Several states in the Southeastern US are colored neon green to show the distribution of cogongrass, while the others are white. The green states are Texas, Louisiana, Mississippi, Alabama, Georgia, Florida, Tennessee, South Carolina, North Carolina, and Virginia.

Map of states where cogongrass has been reported. Map from EDDMapS. 2023. Early Detection & Distribution Mapping System. The University of Georgia - Center for Invasive Species and Ecosystem Health. Available online at http://www.eddmaps.org/; last accessed August 4, 2023. 

How does cogongrass spread?

Cogongrass spreads efficiently via rhizomes (horizontally growing underground stems) and, in some regions, may also reproduce by seed.


Photograph of a singule cogongrass plant against a blue background. Both root and shoot systems are shown, including a long rhizome extending horizontally from the base of the plant and to the right, where it curves upward.

What are the impacts of cogongrass?

Cogongrass is a weed of cultivated fields, disturbed areas (for example, roadsides), and natural areas like forests, wetlands, and savannas. Cogongrass can crowd out other plants to form monocultures (environments dominated by one type of organism) in pastures and wildlands. Cogongrass is fire-adapted and burns at high temperatures. Fire can promote the dominance of cogongrass, and cogongrass infestations can increase the risk of fire in infested areas. 

Because cogongrass is a poor forage grass, it is undesirable for grazing livestock. It can also infest cultivated fields, although cogongrass may be easier to manage in cultivated areas than in pastures and wildlands. 


Photograph of a field full of grass with white-cream, feather-like inflorescences, and trees in the background.
Photograph of a woodland that has been infested by cogongrass. The photo shows tall, yellowish-green grass growing among the bases of thin tree trunks. Some of the trunks have been scorched due to fire that burnt cogongrass in the past.

Cogongrass infestation. Original caption: "Burn marks on trees from extreme heat produced by flames fueled by cogongrass." Photo by Carey Minteer, University of Florida (Bugwood.org photo UGA536527, Creative Commons Attribution 3.0 United States license).

How is cogongrass controlled?

No single method can be used to control cogongrass, but methods can be used in tandem to prevent its spread. The age of the grass strongly determines which control methods will be most effective. 

Tilling is a good option for younger cogongrass infestations, which have less established rhizome mats. Frequent tillage prevents the re-emergence of cogongrass seedlings.

The use of herbicides is the most common control method. Herbicides containing glyphosate can be used, although repeated use over several years is needed. So far, cogongrass does not appear to have developed resistance to the herbicides that are used to manage it.


Photograph showing a man on a tractor plowing a field to control cogongrass.
Photograph of a man in a white shirt and jeans and beige hat spraying herbicide onto a field of grass.

Resources

Websites

Cogon grass (Imperata cylindrica) (Viriginia Invasive Species): https://www.invasivespeciesva.org/species/cogon-grass

Cogongrass control recommendations (University of Georgia’s Center of Invasive Species and Ecosystem Health). https://www.cogongrass.org/control/

Imperata cylindrica (Bugwood Wiki): https://wiki.bugwood.org/Imperata_cylindrica

Imperata cylindrica (Center for Aquatic and Invasive Plants, UF/IFAS): https://plants.ifas.ufl.edu/plant-directory/imperata-cylindrica/

Imperata cylindrica (Plants of the World Online, Royal Botanic Gardens Kew): https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:30138371-2

Articles & reports

Enloe, S., and N. Loewenstein. 2014. Alabama Cooperative Extension System. 2014. Cogongrass management FAQ. Alabama Cooperative Extension System, ANR-2230: 4 pages. PDF: https://www.aces.edu/wp-content/uploads/2018/12/ANR-2230.pdf

Articles

Hoyle, Z. 2014. Why is cogongrass so successful at invading the South? https://www.fs.usda.gov/features/why-cogongrass-so-successful-invading-south