CogonGrass_illustration.jpg

Cogon Grass: Imperata cylindrica

Appearance:

Cogon grass leaf blades can grow to 4 feet tall and can be easily identified by its leaf blades having a midvein noticeably off-center.

Look for first

  • Off-center midrib on leaf blades, more apparent towards the tip of the blade
leaves Leaves: Leaf sheaths relatively short, glabrous or pubescent; ligule a membrane, 0.5-1 mm long. Leaf blades erect, narrow and pubescent at base, flat and glabrous above, to 1.2 m (4 ft) tall and to 2 cm (< 1 in) wide, with whitish midvein noticeably off-center; blade margins scabrous, blade tips sharp pointed.
flowers Flowers: Inflorescence a narrow, dense terminal panicle, white silky and plumelike, to 21 cm (8 in) long and 3.5 cm (1.5 in) wide. Spikelets crowded, paired on unequal stalks, with each spikelet surrounded by long white hairs

Habitat:

Note the flowering plant at the center backCogon grass is considered to be one of the top 10 worst weeds in the world and has extensively invaded north and central Florida disturbed areas and pinelands.  This perennial grass from Southeast Asia was introduced into the U.S. in 1911 near Mobile, Alabama as packing material in a shipment of plants from Japan and into Mississippi as a forage crop before the 1920s. Later it was introduced into Florida for forage and soil stabilization. Cogon grass was then found to be unsuitable for forage and its ability to rapidly spread and displace desirable vegetation outweighed any soil erosion control considerations.  Cogon grass has extensively invaded disturbed areas such as roadsides and fallow pastures throughout north and central Florida but also relatively undisturbed sandhill and pine flatwoods.

Distribution

Commonly found in humid tropics but has spread to warm temperate zones worldwide. Found throughout the southeastern U.S. and widely established in Florida.

Behavior:

Portion of a leaf blade, showing the off-center midrib and the scabrous leaf marginsCogon grass forms dense stands that displace native plant communities.  Because of its rough edges and silica bodies found throughout the leaves, it is mostly unpalatable to native wildlife species. Because of its dense, thick growth pattern, cogon grass degrades native gopher tortoise and indigo snake habitats in Florida.

Cogon grass stands can create a severe fire hazard especially when mixed in with other volatile fuels such as young pine trees. Fires occurring in cogon grass infested woods have significantly increased native tree mortality.

Why Cogon Grass must be managed

Cogon grass forms dense stands resulting in the almost total displacement of native plants that are important to wildlife. Cogon grass stands also represent a significant fire hazard on public conservation lands and agricultural forests.

Additional Information:

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Cogon grass (Imperata cylindrica)


Image Credit: LeRoy G. Holm



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