Imperata cylindrica (commonly known as cogongrass or kunai grass ) is a species of perennial rhizomatous grass native to tropical and subtropical Asia, Micronesia, Melanesia, Australia, Africa, and Southern Europe. It has also been introduced to Latin America, the Caribbean, and the Southeastern United States. It is a highly flammable pyrophyte, and can spread rapidly by colonizing disturbed areas and encouraging more frequent wildfires.
Common names
The species is most commonly known in English as "cogongrass" (also "cogon grass"), from Spanish cogón, from the Tagalog and Visayan kugon. Other common names in English include kunai grass, blady grass, satintail, spear grass, sword grass, thatch grass, alang-alang, lalang grass, cotton wool grass, and kura-kura, among other names.
Description
It grows from 0.6 to 3 m (2 to 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.
Cogongrass has an extensive rhizome network, the biomass of which accounts for 60% of the total biomass of the plant. They can penetrate up to deep, but is typical in sandy soil.
Flammability
Cogongrass is a pyrophyte. It is highly flammable, even when still apparently green, particularly in tropical climates. It is not uncommon to see hillsides of cogongrass on fire. Cogongrass depends on regular fires to spread and maintain ecological dominance. Because of its density and high biomass, cogongrass provides a very high fuel load, enabling wildfires to burn faster, higher, and much hotter. This is hot enough to kill most competing plants, including trees. After a fire, cogongrass will recolonize the area using their rhizome network which was unaffected by the fire.
A common expression in the Philippines is ningas kugon ('cogon brush fire'). It is a figure of speech for quitters, specifically people who show a fervent interest in a new project but lose interest quickly, in reference to the propensity of cogongrass to catch fire and burn out quickly. Ningas kugon is somewhat related to procrastination in that people who start out strong on a project can end up procrastinating and never getting it done. They are ultimately distinct concepts, however—someone can exhibit short-lived enthusiasm and quit without procrastinating, and someone can procrastinate without ever having any enthusiasm for the task
Phytochemistry
The plant contains the triterpenoids arundoin, cylindrin and fernenol.
Cultivation and uses
It is used for thatching the roofs of traditional homes throughout south-east Asia.
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. It is used in traditional Chinese medicine.
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.
Imperata Cylindrica is a common medicinal spice that could be used to potentially human cervical cancer. This plant displayed dose-dependent cytotoxicity in vitro and in vivo in mice bearing tumors. Imperata C. was significantly seen to inhbit cell growth and attack against other cells.
Weed problems
The plant has become naturalized in the Americas, Northern Asia, Europe and Africa in addition to many islands and is listed as an invasive weed in some areas. In the U.S. it survives best in the Southeast (and, according to a 2003 survey, has overtaken more acreage in that region than the notorious kudzu), 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 pH from 4.0 to 7.5. It prefers full sun but will tolerate some shade. In Florida, I.cylindrica is found in areas where the soil has been disturbed, such as roadsides, building sites, timber harvesting areas, and borrow pits. It is able to invade both moist and dry upland pine forests. Once established it often forms dense monocultures.