Practical information to identify and manage non-native, invasive plants and animals
The Quiet Invasion:
A Guide to Invasive Species of the Galveston Bay Area
Cogongrass
Imperata cylindrica

USDA Symbol:IMCY
ITIS TSN:41788
Presence:Species of Concern
Habitat:Terrestrial
Native Range:Southeast Asia, Philippines, China, and Japan
Toxic Characteristics
Produces an herbicide-like toxin which prevents the growth of other plant species.
Geographic Distribution
Naturalized in the majority of southeastern U.S. states, from Florida to eastern Texas. Populations extend as far north as Virginia into Maryland and Oregon in the West.
Introduction Pathways
Brought to the United States in the early 1900s for erosion control and as an experimental forage. Spread by field machinery, and as its use as a packing material.
Specific Primary Habitats
Thrives in full sun, but will partially extend into a forest understory. While found in disturbed areas, it cannot tolerate continuously disturbed or inundated soil. It will occupy disturbed sand dunes, roadsides, and wetland fringes.
Identifying Characteristics
Grows as a tall, erect grass ranging 3 - 5 feet in height. Stems are tightly grouped at the base and spread out higher along the plant; rhizomes are white. Leaves are hairy at the base, up to 1 inches wide and taper towards the end. The midrib of the leaf is offset from the center. Leaf margins are finely toothed and are embedded with silica crystals. The inflorescence is 3 - 11 inches long and is cylindrical, white, and feathery, growing at the top of the culm.
Reproduction Characteristics
Reproduces via both seed production (up to 3000 seeds per plant) and new plant establishment through prolific rhizome production. Usually flowers in early spring, but flowering is also initiated by stress or disturbance at other times of the year.
Growth Characteristics
Cogongrass is very aggressive. Extensive growth occurs via rhizomes, which can remain dormant throughout the winter and later grow 5 - 10 feet the following growing season.
Ecological, Economic, or Social Impact
Cogongrass forms tall, dense stands, excluding nearly all native plants. Results in abrupt changes to wildlife cover and food sources. Its dense cover alters natural fire regimes, often causing more frequent and intense fires.
Control
An integrated approach is necessary for long-term control. For established populations, mow in the late spring, and apply a 2% solution of glyphosate (or a 1-1.5% solution of imazapyr where groundwater impacts are minimal) to new growth in the early fall.

Native Species Alternatives
Below is a list of alternative plants that are native to the area:
  • Big bluestem (Andropogon gerardii)
  • Sideoats grama (Bouteloua curtipendula)
  • Starrush whitetop (Rhynchospora colorata)
This species belongs to the following lists:
Images
To view a larger version of an image, click on the thumbnail.
Base stems of cogongrass. Photo courtesy of James H. Miller, USDA Forest Service, www.forestryimages.org; Image Number 0016150.
Base stems of cogongrass. Photo courtesy of James H. Miller, USDA Forest Service, www.forestryimages.org; Image Number 0016150.
Large infestation of cogongrass in mosaic forest/open field. Photo courtesy of Wilson Faircloth, USDA Agricultural Research Service, www.forestryimages.org; Image Number 1237047.
Large infestation of cogongrass in mosaic forest/open field. Photo courtesy of Wilson Faircloth, USDA Agricultural Research Service, www.forestryimages.org; Image Number 1237047.
Infestation of cogongrass in pine reforestation. Photo courtesy of Charles T. Bryson, USDA Agricultural Research Service, www.forestryimages.org; Image Number 1299003.
Infestation of cogongrass in pine reforestation. Photo courtesy of Charles T. Bryson, USDA Agricultural Research Service, www.forestryimages.org; Image Number 1299003.
Leaf blade of cogongrass showing off-center midrib. Photo courtesy of Ted Bodner, Southern Weed Science Society, www.forestryimages.org; Image Number 2307192.
Leaf blade of cogongrass showing off-center midrib. Photo courtesy of Ted Bodner, Southern Weed Science Society, www.forestryimages.org; Image Number 2307192.
Infestation of cogongrass in winter. Photo courtesy of James H. Miller, USDA Forest Service, www.forestryimages.org; Image Number 2307194.
Infestation of cogongrass in winter. Photo courtesy of James H. Miller, USDA Forest Service, www.forestryimages.org; Image Number 2307194.
Roots and rhizomes of cogongrass. Photo courtesy of James H. Miller, USDA Forest Service, www.forestryimages.org; Image Number 2307196.
Roots and rhizomes of cogongrass. Photo courtesy of James H. Miller, USDA Forest Service, www.forestryimages.org; Image Number 2307196.
Page Updated/Reviewed: 07/14/2010 8:32 AM
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