Virginia Invasive Species

Early Detection Species of Virginia

Cogon Grass (Imperata cylindrica)

What's the harm?

Cogon grass exudes substances into the soil that suppress other plants ability to grow, allowing it to form dense colonies wherever it establishes. Large infestations of this plant can alter the fire regime by causing more frequent and intense fires, injuring or destroying some native plants and potentially damaging property. It can displace native plants used by native animals, and has been known to displace some ground-nesting animals due to the dense ground cover it creates.

cogon grass

What is it?

Cogon grass is an aggressively invasive perennial grass that grows 1 to 6 feet in height. It typically occurrs in leaning mats when over 3 feet tall. Long, yellow-green leaves with light, off-center midveins arise from near the base of the plant, with a short, usually hidden stem. Senesced leaves appear light orange-brown in color. In flower, it produces a silver plume; seed heads form in late winter (south) to early summer (north). New plants arise from sprawling underground stems, called rhizomes.

cogon grass infloresence

Where's it from?

Cogon grass is native to East Africa and Asia. 

How did it get here?

Cogon grass has been introduced to the U.S. both accidentally and intentionally. It arrived as packing material in produce from Japan as well as in the ballast of ships. Cogon grass was introduced into Florida and Mississippi as forage and soil stablization. 

cogon grass leaning mat

Where is it now?

It is now invasive across the southeastern US, with a range spreading from as far west as eastern Texas and as far north as North Carolina. A single occurrence outside cultivation has been documented in Virginia, but it was not relocated in subsequent site visits.

Cogon grass is capable of invading a variety of sites, as it grows in full sunlight to partial shade and dry to wet soils. It is tolerant of drought and high salinity. Thus, it has been found growing in the southeastern US on sand dunes, along roadsides, in forests and open fields, and up to the edge of standing water.


How is it controled?

To achieve lasting control of cogon grass, a combination of chemical, mechanical, and prescribed fire methods is necessary. Control, then, is very expensive. Preventing establishment of cogon grass is the most cost-effective strategy. 

How do I report a sighting of these species?

You can choose from several ways to report sightings of an invasive species here >> 

How can I learn more?

Read more about cogon grass here >>