Cogon grass
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 Cogon Grass (Imperata cylindrica) of the cultivar 'Red Baron', planted in Pittsburgh, Pennsylvania
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| Imperata cylindrica (L.) Beauv. |
Cogon Grass (Imperata cylindrica) is a species of grass in the genus Imperata. It is placed in the subfamily Panicoideae, supertribe Andropogonodae, tribe Andropogoneae.
It is a perennial rhizomatous grass native to southeast Asia (Japan and China south to the Philippines and New Guinea). It grows from 0.6-3 m (2-10 feet) 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 meters deep, but 0.4 m is typical in sandy soil.
Other common names include speargrass (Nigeria), blady grass (Australia), alang-alang, lalang (Malaysia), gi (Fiji), ngi, paille de dys, paillotte, impérata cylindrique, impérate, satintail, kasoring (Palau), cotton wool grass, cotranh (Viet Nam), illuk (Sri Lanka), yakha (Laos), kunai (New Guinea), silver spike (southern Africa), and Bai Mao Gen. The Tok Pisin name for (Imperata cylindrica) is Kunai grass, the name of a grass commonly found in Papua New Guinea.
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[edit] Cultivation and uses
It is used for thatching the roofs of traditional homes in Papua New Guinea.
It is planted extensively for ground cover and soil stabilization near beach areas and other areas subject to erosion. Other uses include paper-making, thatching and weaving into mats and bags. However, its most common usefulness may be seen in its medicinal properties which include astringent, febrifuge, diuretic, tonic and styptic action.
A number of cultivars have been selected for garden use as ornamental plants, including the red-leaved 'Red Baron' (also known as Japanese blood grass).
Young inflorescences and shoots may be eaten cooked, and the roots contain starch and sugars and are therefore easy to chew.
[edit] Weed problems
Following introduction by humans, it has invaded every continent except Antarctica, and is listed as an invasive weed in many areas. In the U.S. it survives best in the southeast, but has been reported to exist as far north as West Virginia and Oregon. Worldwide it has been observed from 45°N to 45°S. It grows on wet lands, dry lands, areas of high salinity, organic soils, clay soils and sandy soils of pHs from 4.0 to 7.5. It prefers full sun but will tolerate some shade.
It is an aggressive plant which is spread both through small seeds, which are easily carried by the wind, and rhizomes which can be transported by tilling equipment and in soil transport. The rhizomes create dense mats on the ground surface reducing the chances of the seeds of other plants reaching the soil and germinating successfully.
In the Southeastern United States, state governments have various eradication efforts in place. Control is typically by the use of herbicides. Burnoff is seldom successful since the grass burns quite hot causing heat damage to trees which would ordinarily be undamaged by a controlled burn and recovers from a burn quickly.
Silica crystals in its leaves deter all but the most desperate animals from eating its low food value leaves. The crystals cut the mouth (and do the same to the legs of unwary humans who run through fields of the stuff in shorts) and probably wear down teeth. It forms a very dense mat which prevents much competition from other plants. It may release an allelopathic phenoic chemical that may kill other plants or prevent seeds from germinating. The strong sharp tipped rhizomes penetrate the roots of other plants, perhaps to weaken them or leave them open to infection.
It is because of these reasons that the overall fodder value is very much reduced, and because of its ability to survive, it is considered to be an invasive pest in warmer climates.
[edit] Flammability
Anecdotal and empirical evidence suggests that types of this grass are quite flammable even when apparently green - particularly in Papua New Guinea climates. It is not uncommon to see hillsides of "Kunai" on fire.
