Imperata cylindrica (L.) Beauv., Poaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results: 

High risk, score: 22 (Go to the risk assessment (Pacific))
Reject, score: 26 (Go to the risk assessment  (U.S. (Florida)))

Other Latin names:  Imperata arundinacea Cirillo

Common name(s): [more details]

Bikol: gogon, kógon

Bontoc: gaon, goon

Chinese: bai mao

English: Japanese blood grass, alang-alang, blady grass, cogon, cogon grass, cotton-wool grass, imperata, kunai grass, kura-kura, satintail

Fijian: gi

French: impérata cylindrique, impérate, paille de dys, paillotte

Ibatan: buchid

Ifugao: bulum

Iloko: kogon, panáu

Japanese: chi, chi-gaya, fushige-chi-gaya, tsubana

Kwara‘ae: fa‘i lai

Palauan: kasoring

Pampangan: ilib

Spanish: caminadora, carrizo, cisca, marciega, virora

Tagalog: kogon

Habit:  grass

Description: 

Genus:  "Rhizome subterranean; flowering culms of few internodes, tall; leaf-blades nearly all arising from near the base of the culm, very long, erect; inflorescence a much branched panicle, its branches ascending close to the main axis, the whole compact and cylindric at flowering; branchlets not jointed, spikelets paired or solitary, all alike, bisexual, if paired pedicels unequal, and bearing a few long fine hairs near the thickened top and many fine spreading white hairs also on the base of the spikelets, hairs twice as long as the glumes or more; glumes about equal, hairy on the back, thin; lower floret neuter, lemma much smaller than the glumes, no palea; upper floret hermaphrodite, lemma thin, not awned, palea present."

Key to species of Imperata:

Imperata cylindrica:  Stamens 2.  Panicle up to 30 x 2 cm.
Imperata conferta:  Samen 1.  Panicle up to 50 x 5 cm.

Species:  (var. major) (Nees) C.E. Hubbard ex Hubb. et Vaughan.  Rhizomatous perennial grass throwing up vertical flowering culms 30-200 cm tall, but commonly less than 100 cm; rhizome whitish, nodes long-hairy, the cataphylls straw-coloured, strongly striate, smooth and often 2-pointed, internodes 1.5 cm long; erect shoots with cataphylls at first similar to the rhizome, quickly changing to the foliage leaves;  sheaths smooth, striate, with a few marginal hairs towards the throat, 7.5 cm long, increasing upwards, overlapping; blades narrowed to both ends, broadest about the middle, the midrib broad at the base, acuminate, often inrolled, upper surface hairy towards the base or scabrid along the first 3-4 nerves either side of the midrib, otherwise smooth, hairless below, strongly scabrid along the margin, up to 180 cm long by 2.5 cm wide; ligule an acute membrane about 1.8 mm deep, backed by some fine hairs.  Inflorescence a loose strict subspiciform panicle up to 30 cm long by 2 cm across, densely white-hairy; branches of the panicle many, short, ascending, the lowest about 5 cm long; spikelets alike and mostly in pairs, one short-pedicelled, the other long-pedicelled, pedicels respectively 0.8 mm and 1.8 mm; callus of glumes with long silky hairs 2.5 cm long; lower glume obscurely 3-nerved, hyaline, delicate, lanceolate-acute, 2.8 mm long; upper glume narrower, obscurely 5-nerved, 2.6 mm long, fringed at the top; lower lemma delicately hyaline, denticulate, 1.6 mm long; palea nil; upper lemma similarly delicately hyaline and denticulate, 1.6 mm long; palea similar denticulate, deleicate and nyaline but much wider, wrapped around the stamens and pistil, 1.2 mm long; stamens 2, anthers 3 mm long at anthesis, orange; stigmata 2, purple, plumose" (Gilliland, 1971; pp. 220-221).

Description from GrassBase.

Habitat/ecology:  A common weed (C4 plant) in hot climatic conditions in several countries of Africa south of Sahara, South and South-east Asia. "Cogon grass invades a wide variety of natural habitats such as desert dunes, wetlands, savannahs and forests, where it out-competes wild plants..." (Randall & Marinelli, 1996; p. 149). "Its habitat includes the dry sand dunes of shores and deserts as well as swamps and river margins.  It grows in grasslands, in cultivated annual crops, and on plantations.  It quickly enters abandoned farmlands, and it may be seen on railroad and highway embankments and on both deforested and reforested areas.  It can withstand long dry spells on light soils and will tolerate waterlogging on heavy soils.  It becomes established most quickly on medium to good soils and is less frequently a pest on poor soils.  Although sometimes reported to be a weed of poor soils, it probably inhabits these areas because of lack of competition from better grasses which cannot be supported there.  The species makes it maximum development in wet areas of good soils.  If all other factors of the environment are suitable, it can occupy any soil type where sufficient moisture exists to support growth.  The plant grows at altitudes to 2,000 m in several parts of the world and to 2,700 m in Indonesia"  (Holm et al., 1977; p. 64).

"Imperata cylindrica grows in well lit regularly mown or burnt areas where there is little competition from taller plants.  It prefers loose, disturbed or sandy soils.  Dense masses compete with lower growing plants, burn readily, and recover vigorously from the rhizomes after mowing or fire.  It does not tolerate shade and ceases abruptly at the edge of rainforest or other heavy shade." (Swarbrick, 1997; p. 40). In Papua New Guinea, "a coloniser of disturbed land and a weed of plantations and fallow cultivation" (Henty & Pritchard, 1975; p. 42).

"The leaves are easily burnt in dry weather, but the underground rhizome is undamaged.  After a grass fire new growth is started immediately and is followed by gregarious flowering.  Other plants growing with it (such as tree and shrub seedlings) are frequently killed by a burn or repeated burning so that open stretches of Imperata cylindrica are often very persistent.  The roots also are highly competitive and exert a depressing effect on other plants" (Gilliland, 1971; pp. 220-221).

Propagation:  I. cylindrica may reproduce by seed and rhizomes. Flowering of I. cylindrica is usually initiated by stress, such as burning, cutting or drought. Numerous seeds produced (as many as 3,000 per plant) which can be wind-dispersed over long distances. Santiago (1965) reported that 95 percent can germinate within a week of harvest and seeds can remain viable for at least one year. I. cylindrica also reproduces Vegetatively. Eussen (1980) reported that a single rhizome node could lead to the production of 350 shoots in six weeks and ground cover of 4 square meters in 11 weeks.

Native range:  Europe, Africa, Asia, Australia; also cultivated and naturalized (GRIN).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
American Samoa Tutuila Islands	Tutuila Island	introduced	Whistler, W. A. (1980) (p. 131) Not common. Voucher: Whistler W2931 (BISH 430412)
American Samoa Tutuila Islands	Tutuila Island		Bishop Museum (Honolulu) (1975) (voucher ID: BISH 430412) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Australia (Pacific offshore islands) Lord Howe Island	Lord Howe Island	probably introduced invasive	Orchard, Anthony E., ed. (1994) (p. 22) Var. major (Nees) C.E. Hubb. & R.E. Vaughn. Vouchers cited: A.C. Beauglehole 5757 (CANB, MEL); 1898, J.H. Maiden (K, NSW)
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Rota Island	introduced invasive	Space, James C./Waterhouse, Barbara/Denslow, Julie S./Nelson, Duane (2000) (p. 5)
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Tinian Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 45)
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Tinian Island	introduced	Meyer, Jean-Yves (2000) (p. 102) "Potential invader".
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Tinian Island	introduced	Fosberg, F. R./Sachet, M.-H. (1982) (p. 50) Voucher cited: Fosberg 59916 (US, BISH, POM, NY)
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Tinian Island		Bishop Museum (Honolulu) (1980) (voucher ID: BISH 588748) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Commonwealth of the Northern Mariana Islands (US) Saipan	Saipan Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 45)
Commonwealth of the Northern Mariana Islands (US) Saipan	Saipan Island	introduced	Meyer, Jean-Yves (2000) (p. 102) "Potential invader".
Commonwealth of the Northern Mariana Islands (US) Saipan	Saipan Island	introduced invasive	Space, James C./Falanruw, Marjorie (1999) (pp. 3, 9)
Commonwealth of the Northern Mariana Islands (US) Saipan	Saipan Island	introduced	Fosberg, F. R./Sachet, M.-H. (1982) (p. 50) Vouchers cited: Herbst & Falanruw 6894 (US), Herbst & Falanruw 6907 (US)
Federated States of Micronesia Yap Islands	Yap (Waqab) Island	introduced invasive	Meyer, Jean-Yves (2000) (p. 90)
Federated States of Micronesia Yap Islands	Yap (Waqab) Island	introduced invasive	Space, James C./Falanruw, Marjorie (1999) (pp. 3, 8)
Federated States of Micronesia Yap Islands	Yap (Waqab) Island		Bishop Museum (Honolulu) (1978) (voucher ID: BISH 432395) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Federated States of Micronesia Yap Islands	Yap (Waqab) Island		Bishop Museum (Honolulu) (1999) (voucher ID: BISH 660001) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Federated States of Micronesia Yap Islands	Yap (Waqab) Island		Bishop Museum (Honolulu) (1999) (voucher ID: BISH 660002) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Fiji Fiji Islands	Vanua Levu Island		Bishop Museum (Honolulu) (1969) (voucher ID: BISH 31696) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Fiji Fiji Islands	Viti Levu Island		Bishop Museum (Honolulu) (1954) (voucher ID: BISH 31698) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Fiji Fiji Islands	Viti Levu Island		Bishop Museum (Honolulu) (1927) (voucher ID: BISH 125050) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Fiji Fiji Islands	Viti Levu Island		Bishop Museum (Honolulu) (1953) (voucher ID: BISH 125051) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Fiji Fiji Islands	Viti Levu Island		Bishop Museum (Honolulu) (1953) (voucher ID: BISH 125052) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Fiji Fiji Islands	Viti Levu Island		Bishop Museum (Honolulu) (1940) (voucher ID: BISH 125053) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Guam Guam Island	Guam Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 45)
Guam Guam Island	Guam Island	introduced	Fosberg, F. R./Sachet, M.-H. (1982) (p. 50) Voucher cited: Falanruw 1299 (US, GUAM)
Guam Guam Island	Guam Island		Bishop Museum (Honolulu) (1983) (voucher ID: BISH 649453) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Guam Guam Island	Guam Island		Bishop Museum (Honolulu) (1983) (voucher ID: BISH 1000255) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Japan (offshore islands) Ogasawara (Bonin) Islands	Bonin (Ogasawara) Islands	introduced	Kato, Hidetoshi (2007)
New Caledonia New Caledonia Archipelago	Île Grande Terre		Bishop Museum (Honolulu) (1947) (voucher ID: BISH 125054) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
New Caledonia New Caledonia Archipelago	Île Grande Terre		Bishop Museum (Honolulu) (1992) (voucher ID: BISH 654835) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Palau Palau (Belau ) (main island group)	Babeldaob Island	introduced invasive	Space, James C./Falanruw, Marjorie (1999) (pp. 3, 8)
Palau Palau (Belau ) (main island group)	Babeldaob Island	introduced invasive	Space, James C./Waterhouse, Barbara/Miles, Joel E./Tiobech, Joseph/Rengulbai, Kashgar (2003) (pp. 7, 85) In vicinity of the airport. Also possibly at Ngardmau but not flowering (Joel Miles, pers. com.). Subject of an eradiction program.
Palau Palau (Belau ) (main island group)	Babeldaob Island		Bishop Museum (Honolulu) (1999) (voucher ID: BISH 660000) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Palau Palau (Belau ) (main island group)	Ngerkebesang Island	introduced invasive	Miles, Joel (year unknown) Suspected but non-flowering infestation.
Papua New Guinea Bougainville Islands	Bougainville Island		Foreman, D. B. (1971) (p. 25)
Papua New Guinea Papua New Guinea (eastern New Guinea Island)	Papua New Guinea (eastern New Guinea Island)	native invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Also naturalized.
Philippines Philippine Islands	Philippine Islands	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Philippines Philippine Islands	Philippine Islands	native invasive	Merrill, Elmer D. (1925) (p. 30) On open slopes, often gregariously occupying enormous areas. It ascends to 2,300 m altitude.
Samoa Western Samoa Islands	Savai‘i Island		Bishop Museum (Honolulu) (1929) (voucher ID: BISH 125044) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Samoa Western Samoa Islands	Savai‘i Island		Bishop Museum (Honolulu) (1924) (voucher ID: BISH 125045) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Samoa Western Samoa Islands	Savai‘i Island		Bishop Museum (Honolulu) (1929) (voucher ID: BISH 125046) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Samoa Western Samoa Islands	Savai‘i Island		Bishop Museum (Honolulu) (1975) (voucher ID: BISH 417549) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Samoa Western Samoa Islands	Savai‘i Island		Bishop Museum (Honolulu) (1975) (voucher ID: BISH 417589) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Samoa Western Samoa Islands	Savai‘i Island		Bishop Museum (Honolulu) (1973) (voucher ID: BISH 417804) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Samoa Western Samoa Islands	Upolu Island	introduced	Whistler, W. A. (1980) (p. 131)
Samoa Western Samoa Islands	Upolu Island		Bishop Museum (Honolulu) (1974) (voucher ID: BISH 418178) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Solomon Islands Solomon Islands	Guadalcanal Island		Bishop Museum (Honolulu) (1947) (voucher ID: BISH 402148) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Solomon Islands Solomon Islands	Solomon Islands		Whitmore, T. C. (1969) (p. 261)
Solomon Islands Solomon Islands	Solomon Islands	native	Hancock, I. R./Henderson, C. P. (1988) (p. 83)
Tonga Ha‘apai Group	Kao Island		Bishop Museum (Honolulu) (1953) (voucher ID: BISH 125042) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Tonga Ha‘apai Group	Kao Island		Bishop Museum (Honolulu) (1953) (voucher ID: BISH 125043) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Tonga Tongatapu Group	‘Eua Island		Bishop Museum (Honolulu) (1953) (voucher ID: BISH 125041) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Vanuatu New Hebrides Islands	Aneityum Island		Bishop Museum (Honolulu) (1955) (voucher ID: BISH 125057) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Vanuatu New Hebrides Islands	Aneityum Island		Bishop Museum (Honolulu) (1903) (voucher ID: BISH 125059) Taxon name on voucher: Imperata cylindrica (L.) Beauv.
Vanuatu New Hebrides Islands	Vanuatu (Republic of)	introduced invasive	Meyer, Jean-Yves (2000) (p. 106)
Wallis and Futuna Wallis and Futuna (Horne) Islands	Wallis and Futuna Islands	introduced invasive	Comité français de l'Union Internationale pour la Conservation de la Nature en France (2013) Naturalisée

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia Australia (continental)	New South Wales	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Australia Australia (continental)	Australia (continental)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013) South Australia, Tasmania, Victoria, Western Australia
Australia Australia (continental)	Northern Territory	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Australia Australia (continental)	Queensland	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Cambodia Cambodia	Cambodia (Kingdom of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
China China	China (People's Republic of)	native	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) River and seashore sands, disturbed grassy places, cultivations. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Liaoning, Nei Mongol, Shaanxi, Shandong, Shanxi, Sichuan, Xinjiang, Xizang, Yunnan, Zhejiang.
Indonesia Indonesia	Indonesia (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Japan Japan	Japan	native	U.S. Dept. Agr., Agr. Res. Serv. (2013) Hokkaido, Honshu, Kyushu, Shikoku
Japan Ryukyu Islands	Ryukyu Islands	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
North Korea North Korea	North Korea (Democratic People's Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
South Korea South Korea	South Korea (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Malaysia Malaysia	Malaysia (country of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Negara Brunei Darussalam Brunei	Brunei (Negara Brunei Darussalam)		Waterhouse, D. F. (1993) (pp. 66, 77)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Edgar, E./Connor, H. (2000) (p. 605) "Open gullies, sunny places on hills, flats on volcanic soil near coast".
Singapore Singapore	Singapore (Republic of)		Waterhouse, D. F. (1993) (pp. 66, 77)
Singapore Singapore	Singapore (Republic of)	uncertain if introduced invasive	Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. (2009) (p. 50) Weed of uncertain origin
South America (Pacific rim) South America (Pacific rim)	Chile (Republic of)	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 65)
South America (Pacific rim) South America (Pacific rim)	Colombia	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 65)
Taiwan Taiwan Island	Taiwan Island	native	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) River and seashore sands, disturbed grassy places, cultivations.
Thailand Thailand	Thailand (Kingdom of)	native invasive	Waterhouse, D. F. (1993) (p. 66)
Thailand Thailand	Thailand (Kingdom of)	native invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Also naturalized
United States (west coast) United States (west coast states)	USA (Oregon)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
Vietnam Vietnam	Vietnam (Socialist Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia (Indian Ocean offshore islands) Christmas Island Group	Christmas Island	probably introduced invasive	Swarbrick, J. T. (1997) (pp. 40, 116)
Australia (Indian Ocean offshore islands) Cocos (Keeling) Islands	Cocos (Keeling) Islands	introduced invasive	Orchard, Anthony E., ed. (1993) (p. 38)
Mauritius Mautitius Islands (Mauritius and Rodrigues)	Mauritius Island		Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 70)
French Territory of Mayotte Mayotte Islands	Mayotte Island	introduced invasive	Comité français de l'Union Internationale pour la Conservation de la Nature en France (2013)
Seychelles Seychelles Islands	Seychelles Islands	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized

Also reported from
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
United States (continental except west coast) United States (other states)	United States (other states)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
United States (continental except west coast) United States (other states)	USA (Florida)	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 65)

Comments:  On U.S. Federal and State of Hawai‘i noxious weed lists.

Fosberg et al. (1987; p. 45) list I. cylindrica as being present in Saipan, Tinian and Guam and I. conferta as being present in Saipan, Tinian, Rota, Guam, Palau and Yap. Yuncker (1959, p. 64) lists it as being present in Tonga, but it is apparently I. conferta.

Control: 

Physical: In small areas, dig and remove all plants and underground stems. Repeat treatments will probably be necessary.

Flattening foliage with rollers or boards can help to suppress I. cylindrica if used in combination with a legume cover crop (Bourgoing and Boutin 1987; Cox and Johnson 1991).

Chemical: Glyphosate is applied typically at a dose rate of 1.8 kg a.e./ha to actively growing foliage of I. cylindrica from where it is absorbed and translocated to the rhizomes, causing death of most of the plant within 2-4 weeks. A little regrowth is almost inevitable and this should be treated with spot applications. Glyphosate can be applied in volume rates ranging from 20 l/ha (using spinning disc sprayers) to 600 l/ha (using hand-held hydraulic sprayers). Glyphosate should be applied 6-8 hours before rain falls and washes it off the weed. Burning several months before treatment enhances uptake of the herbicide.

Biological: Biological control information from the publication "Biological control of invasive plants in the eastern United States".