The Lazy Naturalist - Sarasota, Florida

Exploring Nature in Sarasota, South Central Florida, and Beyond

Cogon Grass (Imperata cylindrica)

by Artie Visual, Categories: Plants Tags:

This aggressive invader, with its deceptive beauty and relentless growth, has become a significant challenge for land managers and conservationists alike. Join me as we delve into the tale of Cogon Grass, exploring its origins, impact, and the ongoing efforts to curb its spread in the Sunshine State.

An Unwanted Arrival

Cogon Grass, native to Southeast Asia, was introduced to the United States in the early 20th century. It was initially brought over for use as packing material and later as forage for livestock and soil erosion control. However, what seemed like a beneficial plant quickly revealed its true nature as a voracious invader. Escaping cultivation, Cogon Grass spread rapidly across the southeastern U.S., establishing itself firmly in Florida’s landscapes.

The Anatomy of Cogon Grass

Cogon Grass is a perennial grass that can grow up to six feet tall. It is characterized by its sharp-edged leaves, which are green during the growing season and turn a distinctive yellow-brown in the fall. The leaves have a prominent, off-center midrib, and their margins are finely serrated, making them difficult to handle without gloves.

The plant produces fluffy, white seed heads that resemble cotton or dandelion tufts. These seeds are highly effective dispersers, carried by the wind to new locations where they can germinate and establish new colonies. However, the real secret to Cogon Grass’s invasive success lies underground. The plant has an extensive rhizome system that allows it to spread vegetatively. These rhizomes can form dense mats that crowd out native vegetation and are incredibly resilient, making the plant difficult to eradicate.

Ecological Impact

The impact of Cogon Grass on Florida’s ecosystems is profound and far-reaching. Its aggressive growth habit and ability to form dense monocultures significantly alter native habitats, leading to a cascade of ecological consequences.

Displacement of Native Species

One of the most immediate effects of Cogon Grass invasion is the displacement of native plant species. As the grass spreads, it forms dense mats that prevent sunlight from reaching other plants, effectively smothering them. This reduction in plant diversity affects the entire ecosystem, as native plants provide essential habitat and food sources for wildlife.

Alteration of Fire Regimes

Cogon Grass is highly flammable, and its presence can alter natural fire regimes. The grass burns hotter and more frequently than native vegetation, increasing the intensity and frequency of wildfires. These altered fire regimes can devastate native plant communities that are not adapted to such intense fires, leading to further ecological degradation.

Soil Degradation

The extensive rhizome system of Cogon Grass can lead to soil degradation. As the grass outcompetes native plants, it reduces the diversity of root systems that help maintain soil structure and health. This can lead to increased erosion and a decline in soil fertility, making it more difficult for native plants to reestablish.

Agricultural Impact

Beyond its ecological impact, Cogon Grass poses significant challenges for agriculture in Florida. The grass can invade pastures and croplands, reducing the productivity of these areas. Its sharp leaves can deter livestock from grazing, and its dense growth can outcompete crops for resources such as water and nutrients. The economic losses to farmers can be substantial, leading to increased costs for weed control and reduced yields.

Control and Management

Controlling Cogon Grass is a complex and ongoing battle that requires a combination of strategies. Given its resilience and ability to spread rapidly, effective management often involves an integrated approach that combines mechanical, chemical, and biological methods.

Mechanical Control

Mechanical control involves physically removing the grass and its rhizomes from the soil. This method can be effective for small infestations but is labor-intensive and requires repeated efforts to ensure all rhizomes are removed. Mowing can help reduce seed production, but it must be done frequently and followed by other control measures to prevent regrowth.

Chemical Control

Herbicides are commonly used to manage Cogon Grass infestations. Chemicals such as glyphosate and imazapyr can be effective in killing the grass and its rhizomes, but they must be applied carefully to avoid damaging non-target species. Repeated applications are often necessary, and follow-up treatments are crucial to prevent reinfestation.

Biological Control

Research into biological control methods for Cogon Grass is ongoing. Biological control involves introducing natural enemies of the grass, such as insects or pathogens, that can help reduce its population. While promising, this approach requires careful testing and monitoring to ensure that the introduced species do not become invasive themselves or negatively impact native species.

A Naturalist’s Perspective

As a Florida naturalist, the presence of Cogon Grass in our landscapes is both a challenge and an opportunity. Its rapid spread and impact on native ecosystems highlight the importance of vigilance and proactive management. The story of Cogon Grass underscores the need for continued research and innovation in managing invasive species and protecting our natural heritage.

Educational Opportunities

The issue of Cogon Grass also presents an opportunity for education and community engagement. By raising awareness about the ecological and economic impacts of invasive species, we can foster a greater understanding of the challenges posed by plants like Cogon Grass. Educational programs and outreach efforts can help build support for control measures and encourage responsible practices among landowners and the general public.

The Future of Florida’s Ecosystems

Looking ahead, the battle against Cogon Grass will require ongoing effort and collaboration among government agencies, researchers, landowners, and the public. Integrated pest management strategies that combine mechanical, chemical, and biological control offer the best chance for long-term success. Restoration of damaged habitats and continued monitoring will also be essential to ensure the health and resilience of Florida’s ecosystems.

Conclusion

Cogon Grass, with its deceptive beauty and aggressive growth, is a formidable invader in Florida’s landscapes. Its impact on native ecosystems, agriculture, and fire regimes underscores the need for vigilant and proactive management. As we navigate the challenges posed by this invasive species, we are reminded of the intricate web of life that connects us all.

Through informed action, public awareness, and collaborative efforts, we can work to mitigate the impact of Cogon Grass and protect the rich biodiversity that makes Florida’s natural areas so unique. Whether admired from a distance or managed with care, Cogon Grass remains a vivid chapter in the ongoing narrative of Florida’s natural history—a symbol of both the resilience and fragility of our environment.

By understanding and addressing the challenges posed by invasive species, we can ensure that Florida’s ecosystems continue to thrive for generations to come. The battle against Cogon Grass may be challenging, but with concerted effort and dedication, we can reclaim our landscapes and foster a future where native plants and wildlife flourish.

Imperata cylindrica

Imperata cylindrica (commonly known as cogongrass /koʊˈɡoʊn/ or kunai grass /ˈkuːnaɪ/[1][3]) 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.[4]

Common names

The species is most commonly known in English as "cogongrass" (also "cogon grass"),[3] from Spanish cogón, from the Tagalog and Visayan kugon.[5] Other common names in English include kunai grass, blady grass, satintail, spear grass, sword grass, thatch grass, alang-alang, lalang grass, cotton wool grass, kura-kura,[3] keri[6] among other names.

Taxonomy

Imperata cylindrica was first described by Linnaeus in 1759 under the basionym Lagurus cylindricus.[7] They were renamed by the French entomologist and botanist Palisot de Beauvois to the current accepted name of Imperata cylindrica.

Description

Cogongrass grows from 0.2–3 m (1⁄2–10 ft) tall, its stalk is firm and has nodes covered with long white hairs.[8][9] Each clump that grows shares an extensive rhizome network, the biomass of which accounts for 60% of the total biomass of the plant. They can penetrate up to 1.2 m (4 ft) deep, but 0.4 m (1+1⁄2 ft) is typical in sandy soil.[8][10]

The leaves are about 2 cm wide in average and 12–80 centimetres (4+1⁄2–31+1⁄2 in) in length[9] 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.[8]

Its flowers small and gathered on pedicels 0.5–3 mm long from narrow panicles slightly above its stalks that grow tall as high as 28 cm.[9]

Phytochemistry

The plant contains the triterpenoids arundoin, cylindrin and fernenol.[11]

Ecology

As a weed

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 United States it survives best in the Southeast (and, according to a 2003 survey, has overtaken more acreage in that region than the notorious kudzu),[12] 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.[13]

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 cogongrass invasion gives it an advantage over indigenous plants.[14]

It spreads both through small seeds, which are easily carried by the wind, and rhizomes which can be transported by tilling equipment and in soil transport.

In the Southeastern U.S., state governments have various eradication efforts in place, and deliberate propagation is prohibited by some authorities.[15] Cogongrass came to the Southeastern U.S. in the early 1900s as shipping material in crates.[16] Before it was named an invasive species in the area, it was cultivated for fodder for livestock and erosion control.[17] It failed to prevent erosion because of how weedy it was, and animals would not eat it as fodder.[18] It is now listed as a Federal Noxious Weed in some Southeastern states[19] and Arkansas.[20] In Mississippi it is mostly concentrated in the south of the state.[21]

Control is typically by the use of herbicides. Currently, the most effective herbicides used to control growth are glyphosate and imazapyr.[22] 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; it also recovers from a burn quickly. Quarantine and extermination of this plant is especially difficult because cogongrass establishes root systems as deep as four feet, and regrowth can be triggered by rhizome segments as small as one inch.[14]

Cogongrass is difficult to contain mainly because it is highly adaptive to harsher environments, establishing itself on soils low in fertility. The grass can also grow on sand and clay. It is not eaten by many species of animal, further contributing to containment difficulties. The grass tends to be averse to dense shade, but reports indicate more shade-tolerant strains are developing.[23][timeframe?]

The legume vine Mucuna pruriens is used in the countries of Benin and Vietnam as a biological control for Imperata cylindrica.[24]

Flammability

Green cogongrass on fire in Papua New Guinea.

Cogongrass is a pyrophyte. It is highly flammable, even when still apparently green,[25] particularly in tropical climates. It is not uncommon to see hillsides of cogongrass on fire.[26][27] 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.[4][28][29][10]

Uses

A Japanese bloodgrass cultivar, Imperata cylindrica 'Red Baron', grown as an ornamental

It is regarded as an excellent plant for thatching the roofs of traditional homes throughout south-east Asia, and is even grown as a crop for this purpose.[6][30]

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.[31]

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.[32]

Imperata Cylindrica is a common medicinal spice that could be used to potentially cure human cervical cancer. This plant displayed dose-dependent cytotoxicity in vitro and in vivo in mice bearing tumors. Imperata C. was significantly seen to inhibit cell growth and attack against other cells.[33]

In culture

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.[34] The concept is similar to, but distinct from, procrastination.[35]

References

  1. ^ a b "Imperata cylindrica". Germplasm Resources Information Network. Agricultural Research Service, United States Department of Agriculture. Retrieved 2016-04-03.
  2. ^ "Imperata cylindrica (L.) Raeusch". Plants of the World Online. Royal Botanic Gardens, Kew. 2024. Retrieved 3 June 2024.
  3. ^ a b c "Imperata cylindrica (cogongrass)". Centre for Agriculture and Bioscience International (CABI). Retrieved November 16, 2016.
  4. ^ a b Pillion, Dennis (13 August 2017). "This 'vicious' invasive plant burns hot enough to kill trees and stabs them with its roots". Alabama Local. Retrieved 3 July 2019.
  5. ^ "Merriam-Webster Dictionary: Cogon". Merriam-webster.com. 2018-07-19. Retrieved 2018-07-26.
  6. ^ a b Djawanai, Stephanus (1983). Ngadha Text Tradition: The Collective Mind of the Ngadha People, Flores. Pacific Linguistics Series D – No. 55. Canberra: Australian National University. p. 25. doi:10.15144/PL-D55. hdl:1885/145062. ISBN 978-0-85883-283-1.
  7. ^ "Imperata cylindrica - Species Details". Atlas of Florida Plants. Retrieved 2024-05-27.
  8. ^ a b c "Imperata cylindrica". Smithsonian Marine Station. Smithsonian Institution. Retrieved 31 March 2016.
  9. ^ a b c Middleton, D.J.; Leong-Škorničková, J.; Lindsay, S. (2019). Flora of Singapore. Vol. 7: Poales. pp. 360–362. ISBN 978-981-14-3024-4.
  10. ^ a b Sellers, B. A.; Ferrell, J. A.; MacDonald, G. E.; Enloe, S. F.; Flory, S. L. (2002). "Cogongrass (Imperata cylindrica) Biology, Ecology, and Management in Florida Grazing Lands". Publication #SS-AGR-52. Agronomy Department, UF/IFAS Extensio.
  11. ^ 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
  12. ^ "Aggressive weed becoming a menace worse than kudzu, UF researcher says". Archived from the original on 2008-05-17.
  13. ^ "Cogongrass". Invasive Non-native Plants. Florida Department of Agriculture and Consumer Services. Archived from the original on 2013-12-02. Retrieved 2013-11-25.
  14. ^ a b Long, Elizabeth A. "Identification and Control Methods for Cogongrass in Tennessee" (PDF). Tennessee invasives. University of Tennessee. Archived from the original (PDF) on April 12, 2016. Retrieved March 30, 2016.
  15. ^ Mazhukhina, Karina (August 27, 2021). "Avoid this plant at your local garden center. It's 'world's most invasive weed'".
  16. ^ Dickens, Ray (1974). "Cogongrass in Alabama after Sixty Years". Weed Science. 22 (2). Cambridge University Press (CUP): 177–179. doi:10.1017/s004317450003681x. ISSN 0043-1745. S2CID 86848569.
  17. ^ Hubbard, C.E. (1944). Imperata cylindrica: Taxonomy, distribution, economic significance and control. Imperial Agricultural Bureaux Joint Publication No. 7. Oxford & Aberystwyth, U.K.: Imperial Forestry Bureau & Imperial Bureau of Pastures and Forage Crops.
  18. ^ "Cogongrass Resources | National Invasive Species Information Center".
  19. ^ "Cogongrass biology and management in the southeastern U.S. University of Florida, Southern Regional Extension Forestry, 2018 Candice Prince, Gregory MacDonald, Stephen Enloe, and David Coyle".
  20. ^ "Arkansas Invasive Pests | Cogongrass". Archived from the original on 2021-09-18. Retrieved 2020-10-30.
  21. ^ Associated Press (2020-12-16). "Cogongrass: Mississippi fights to control one of world's most invasive weeds". Al.com. Retrieved 2021-01-02.
  22. ^ Dozier, Hallie; Gaffney, James F.; McDonald, Sandra K.; Johnson, Eric R. R. L.; Shilling, Donn G. (1998-01-01). "Cogongrass in the United States: History, Ecology, Impacts, and Management". Weed Technology. 12 (4): 737–743. doi:10.1017/S0890037X0004464X. JSTOR 3989097. S2CID 55181258.
  23. ^ "Imperata cylindrica | UF/IFAS Center for Aquatic and Invasive Plants". plants.ifas.ufl.edu. Retrieved 2016-03-31.
  24. ^ "Factsheet - Mucuna pruriens". www.tropicalforages.info. Archived from the original on 2008-05-15. Retrieved 2008-05-21.
  25. ^ "Species Description: Imperata cylindrica (L.) Beauv". Archived from the original on 2010-07-28. Retrieved 2010-12-16.
  26. ^ "'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" (PDF). Archived from the original (PDF) on 2018-03-30. Retrieved 2018-07-26.
  27. ^ "Fire leaves 20 without shelter". Postcourier.com.pg. Archived from the original on 2012-03-08. Retrieved 2018-07-26.
  28. ^ Stocker, Randall; Hupp, Karen V.S. (2008). "Fire and Nonnative Invasive Plants in the Southeast Bioregion". Wildland Fire in Ecosystems: Fire and nonnative invasive plants. Rocky Mountain Research Station, Forest Service, USDA. p. 103. ISBN 9780160814655.
  29. ^ Lippincott, C.L. (2000). "Effects of Imperata cylindrica (L.) Beauv. (Cogongrass) invasion on fire regime in Florida sandhill (USA)". Natural Areas Journal. 20 (2): 140–149.
  30. ^ Holm, LeRoy G.; Plucknett, Donald L.; Pancho, Juan V.; Herberger, James P. (1977). The World's Worst Weeds: distribution and biology. Honolulu: University Press of Hawaii. p. 70. ISBN 0-8248-0295-0.
  31. ^ "Imperata". Acupuncturetoday - traditional Chinese medicine (tcm). Retrieved 22 Dec 2014.
  32. ^ "Imperata cylindrica". PFAF. Retrieved 2016-03-31.
  33. ^ Nayim, Paul; Mbaveng, Armelle T.; Sanjukta, Mukherjee; Rikesh, Jain; Kuete, Victor; Sudhir, Krishna (2021-07-15). "CD24 gene inhibition and TIMP-4 gene upregulation by Imperata cylindrica's root extract prevents metastasis of CaSki cells via inhibiting PI3K/Akt/snail signaling pathway and blocking EMT". Journal of Ethnopharmacology. 275: 114111. doi:10.1016/j.jep.2021.114111. ISSN 0378-8741. PMID 33848610. S2CID 233233738.
  34. ^ "Filipino Culture: What is Ningas Cogon". Archived from the original on 2011-01-15. Retrieved 2010-12-16.
  35. ^ "Little-Known Power of Ningas Kugon to Create Breakthroughs". 22 June 2022.
source: https://en.wikipedia.org/wiki/Imperata_cylindrica

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