Imperata cylindrica, commonly known as blady grass, cogon grass //, kunai grass //, or Japanese bloodgrass, 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 east and southeast Asia, India, Micronesia, Melanesia, Australia, and eastern and southern Africa. 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.
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.
It is used as an ingredient in the skincare brand Kiehl's Since 1851 Ultra Facial Cream for its "high concentrations of potassium which provides an immediate and lasting hydrating effect... [it] helps skin to store and retain moisture efficiently – even in the driest weather conditions." Their website also states that indigenous native Australians may have used the plant as a substitute for salt due to its high saline content. 
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 burrow pits. It is able to invade both moist and dry upland pine forests. Once established it often forms dense monocultures.
In addition to outcompeting species for resources, the grass also exhibits allelopathic tendencies. The chemicals it releases as well as the dense mat of vegetation that usually accompanies a cogon grass invasion gives it an advantage over indigenous plants.
In the Southeastern United States, state governments have various eradication efforts in place, and deliberate propagation is prohibited by some authorities. Control is typically by the use of herbicides. Currently, the most effective herbicides used to control growth are glyphosate and imazapyr. Burnoff is seldom successful since the grass burns at a high temperature causing heat damage to trees which would ordinarily be undamaged by a controlled burn and recovers from a burn quickly. Quarantine and extermination of this plant is especially difficult because cogon grass establishes root systems as deep as four feet, and regrowth can be triggered by rhizome segments as small as one inch.
Cogon grass is difficult to contain mainly because it is highly adaptive to harsher environments, establishing itself on soils low in fertility. The grass also can grow on sand and clay, and consumers of it are few. The grass tends to be averse to dense shade, but reports indicate more shade-tolerant stains are developing.
Anecdotal and empirical evidence suggests that types of this grass are quite flammable even when apparently green, particularly in Southeast Asian climates. It is not uncommon to see hillsides of cogon grass on fire.
A common expression in the Philippines is ningas cogon ('cogon brush fire'). It is a figure of speech for procrastination, specifically people who show a fervent interest in a new project but lose interest quickly, in reference to the propensity of cogon grass to catch fire and burn out quickly.
Imperata cylindrica was first described by Linnaeus in 1759 under the basionym Lagurus cylindricus. They were renamed by the French entomologist and botanist Palisot de Beauvois to the current accepted name of Imperata cylindrica.
Other common names, used in English, include:
- cotton-wool grass
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- Long, Elizabeth A. "Identification and Control Methods for Cogongrass in Tennessee" (PDF). Tennessee invasives. University of Tennessee. Retrieved March 30, 2016.
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- 'Establishment of Stylo (Stylosanthes Guianensis) in Kunai (Imperata cylindrica) pastures and its Effect of Dry Matter Yield and Animal Production in the Markham Valley, Papua New Guinea by P.A. Chadhokar
- Fire leaves 20 without shelter
- Filipino Culture: What is Ningas Cogon
- The structures of arundoin, cylindrin and fernenol : Triterpenoids of fernane and arborane groups of imperata cylindrica var. koenigii. K. Nishimoto, M. Ito and S. Natori, Tetrahedron, 1968, Volume 24, Issue 2, Pages 735–752, doi:10.1016/0040-4020(68)88023-8
- Wunderlin, R. P., and B. F. Hansen. 2008. Imperata cylindrica. Atlas of Florida Vascular Plants (http://www.plantatlas.usf.edu/).[S. M. Landry and K. N. Campbell (application development), Florida Center for Community Design and Research.] Institute for Systematic Botany, University of South Florida, Tampa.
- "Hippeastrum petiolatum". Missouri Botanical Garden, http://www.tropicos.org/. Retrieved February 3, 2011. External link in
- Merriam-Webster Dictionary: Cogon
|Wikimedia Commons has media related to Imperata cylindrica.|
- US National Park Service - Description of Cogon Grass and control measures
- FAO information on Cogon
- Edible and medicinal uses, cultivation, etc.
- PLANTS Profile for Imperata cylindrica (cogongrass) | USDA PLANTS profile
- Murniati (2002) From Imperata cylindrica Grasslands to productive Agroforestry. PhD thesis Wageningen UR.
- Imperata cylindrica in West African plants – A Photo Guide.
- Species Profile- Cogongrass (Imperata cylindrica), National Invasive Species Information Center, United States National Agricultural Library. Lists general information and resources for Cogongrass.