Pacific Island Ecosystems at Risk (PIER)

  [   PIER species lists  ]   [   PIER home  ]

Cyperus difformis
L., Cyperaceae
Click on an image for links to BIGGER PICTURES


Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Common name(s): [more details]

Cebuano: gilamhon

Chinese: yi xing suo cao

English: dirty-Dora, one-arm sedge, rice sedge, small-flower umbrella plant, smallflower umbrella sedge, variable flat sedge

Filipino: baki-baki

French: souchet difforme

Iloko: ballayang

Japanese: tamagayatsuri

Spanish: cortadera, juncia de agua, lleivun, tiña

Habit:  sedge

Description:  "A tufted, smooth, annual or infrequently perennial sedge, 10 to 75 cm high; stems rather weak or tender, triangular, slightly winged, smooth, 1 to 3 mm thick; roots numerous, fibrous, reddish; leaves linear, few, weak, rather abruptly acuminate, smooth or slightly rough at the top, usually shorter than the plant is high (often two-thirds of the height), 2 to 5 mm wide, sometimes reduced to sheaths; sheaths tubular united, the lower sheaths straw-colored to brown; inflorescence in dense, globose, umbellate heads, simple or compound, 8 to 15 mm across, with numerous (more than 40) stellately spreading spikelets, the inflorescence rather loose, simple or compound, subtended by one, two, three, or four, variable, leaf-like bracts which are contracted or spreading, one may be almost erect, up to 25 cm long; the umbel rays 1 to 5 cm long, some sessile, some long peduncled; spikelets linear to oblong-linear, compressed but slightly swollen, obtuse, 2.5 to 8 mm long, 1 to 1.25 mm wide, 10 to 30 flowered, remarkable for the numerous, very small (0.6 to 0.8 mm), almost orbicular, concave, very obtuse glumes which occur in two opposite rows, closely packed, at first a rich brown, dirty green, or blackish, but becoming variegated by their pale yellow or almost white margins, with a green keel; stamens one or two; style branches tree; achenes elliptic to slightly obovate, acutely subequally triangular, lightly pitted, shining, straw-colored, yellowish brown or pale brown, about 6 mm long.  This species may be distinguished by the dense, globose heads composed of many radiating spikelets and by the many small orbicular, obtuse glumes which are a rich brown at first but later become variegated by their pale yellow or almost white margins"  (Holm et al., 1977; p. 236).

"Annuals, tufted, glabrous; culms up to 50 cm tall, sharply trigonal; leaves shorter than culm; bracteal leaves (some of them) longer than inflorescence; inflorescence umbellate, of rays to 5 cm long; spikes subglobose, dense, about 1-1.3 cm in diameter; spikelets with reddish markings on light brown; glumes rounded at apex; achenes trigonal"  (Stone, 1970; p. 168).

Habitat/ecology:  Usually a weed of wet places (Stone, 1970; p. 168).  "The plant normally grows in flooded or in very moist soils.  It is primarily a weed of paddy or flooded rice.  It is frequently found in small pools, along rivers, canals, and streams, in open wet places, and in grassy swamps.  It grows best in rich, fertile soils, but can grow in poorer sandy or clay soils of unused lands or in fallow rice fields.  It...has been reported from sea level to 1,400 m in Indonesia" (Holm et al., 1977; pp. 236, 239).

In Hawai‘i, "naturalized in wet sites, beach parks, urban sites, cultivated fields, and along roadsides, 0-50 m"  (Wagner et al., 1999; pp. 1395-1396).  In Fiji, "a naturalized adventive, occurring near sea level in wet places in the open, in swamps and pastures, along roadsides, and often abundantly in rice fields" (Smith, 1979; pp. 251-252).

Propagation:  Seed.  "Having heavy seed production and massive seedling densities, the plant quickly covers the ground and becomes dominant.  In tropical areas the plant apparently can flower and produce seeds all year long provided sufficient soil moisture is present" (Holm et al., 1977; p. 239).

Native range:  "Widespread in Eurasia from southern Europe through India and China to Japan and Malesia, and also in Australia and the Pacific Islands" (Smith, 1979; pp. 251-252).

Presence:

Pacific
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
Commonwealth of the Northern Mariana Islands (US)
Northern Mariana Islands
Northern Mariana Islands   Swarbrick, John T. (1997) (p. 90)
Commonwealth of the Northern Mariana Islands (US)
Northern Mariana Islands
Saipan Island introduced
Raulerson, L. (2006) (p. 13)
Cook Islands
Northern Cook Islands
Manihiki Atoll   McCormack, Gerald (2013)
?
Cook Islands
Northern Cook Islands
Nassau Island   National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (1985) (voucher ID: PTBG 41600)
Taxon name on voucher: Cyperus difformis
Cook Islands
Northern Cook Islands
Pukapuka Atoll   McCormack, Gerald (2013)
?
Cook Islands
Northern Cook Islands
Rakahanga Atoll   McCormack, Gerald (2013)
?
Cook Islands
Northern Cook Islands
Suwarrow (Taka) Atoll   McCormack, Gerald (2013)
?
Cook Islands
Southern Cook Islands
Mangaia Island   McCormack, Gerald (2013)
Cook Islands
Southern Cook Islands
Ma‘uke Island   McCormack, Gerald (2013)
Cook Islands
Southern Cook Islands
Palmerston (Avarau) Island   McCormack, Gerald (2013)
?
Cook Islands
Southern Cook Islands
Rarotonga Island   National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (1982) (voucher ID: PTBG 41599)
Taxon name on voucher: Cyperus difformis
Federated States of Micronesia
Chuuk Islands
Weno (Moen) Island introduced
Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 66)
Federated States of Micronesia
Kosrae Island
Kosrae Island introduced
invasive
Space, James C./Waterhouse, Barbara/Denslow, Julie S./Nelson, Duane/Waguk, Erick E. (2000) (p. Voucher specimen)
Voucher: BMW 5747 (BISH, BRI, GUAM)
Federated States of Micronesia
Kosrae Island
Kosrae Island native
Lorence, David H./Flynn, Timothy (2010) (p. 7)
Roadsides and wet areas.
Federated States of Micronesia
Kosrae Island
Kosrae Island   National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (1997) (voucher ID: PTBG 24666)
Taxon name on voucher: Cyperus difformis L.
Federated States of Micronesia
Kosrae Island
Kosrae Island   National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (1997) (voucher ID: PTBG 24879)
Taxon name on voucher: Cyperus difformis
Federated States of Micronesia
Kosrae Island
Kosrae Island   National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (2005) (voucher ID: PTBG 42636)
Taxon name on voucher: Cyperus difformis
Federated States of Micronesia
Pohnpei Islands
Pohnpei Island introduced
Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 66)
Federated States of Micronesia
Pohnpei Islands
Pohnpei Island native
Herrera, Katherine/Lorence, David H./Flynn, Timothy/Balick, Michael J. (2010) (p. 41)
Voucher cited: L. Stemmermann 2918A (BISH)
Federated States of Micronesia
Yap Islands
Yap (Waqab) Island   Swarbrick, John T. (1997) (p. 90)
Fiji
Fiji Islands
Rambi Island introduced
invasive
Smith, Albert C. (1979) (pp. 251-252)
Voucher cited: DA 5763
Fiji
Fiji Islands
Vanua Levu Island introduced
invasive
Smith, Albert C. (1979) (pp. 251-252)
Vouchers cited: Greenwood 479, DA 12045, Degener & Ordonez 14223
Fiji
Fiji Islands
Viti Levu Island introduced
invasive
Smith, Albert C. (1979) (pp. 251-252)
Vouchers cited: DA 94, DA 10557, DA 11873, DA 3831, DA 7527, DA 5663, DA 10573
French Polynesia
Society Islands
Tahiti Island introduced
invasive
Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013)
Voucher cited: J. Florence & W.R. Sykes 11437 (PAP)
Adventice
Guam
Guam Island
Guam Island introduced
invasive
Stone, Benjamin C. (1970) (p. 168)
Vouchers cited: Stone 4447 (GUAM), G.E.S. 45, G.E.S. 236, Moore 144, Fosberg 35566, Rodin 764
Guam
Guam Island
Guam Island introduced
Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 66)
State of Hawaii
Hawaiian Islands
Kaua‘i Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 1395-1396)
State of Hawaii
Hawaiian Islands
Maui Island introduced
invasive
Starr, Forest/Martz, Kim/Loope, Lloyd L. (2002) (pp. 19-20)
West Maui. Voucher cited: Starr & Martz 990724-1 (BISH)
Common
State of Hawaii
Hawaiian Islands
Maui Island introduced
invasive
Starr, Forest/Starr, Kim/Loope, Lloyd L. (2006) (p. 35)
East Maui. Voucher cited: Starr & Starr 030807-3 (BISH)
State of Hawaii
Hawaiian Islands
O‘ahu Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 1395-1396)
Voucher cited: Heller 2003 (BISH)
Japan (offshore islands)
Ogasawara (Bonin) Islands
Bonin (Ogasawara) Islands   Kato, Hidetoshi (2007)
Marshall Islands
Ralik Chain
Kili (Kõle) Atoll introduced
invasive
Vander Velde, Nancy/Vander Velde, Brian (2006) (p. 2)
"Rare; small patch alongside ocean road, just north of town".
Marshall Islands
Ratak Chain
Majuro (Mãjro) Atoll introduced
Vander Velde, Nancy (2003) (p. 37)
Rare
Palau
Palau (Belau ) (main island group)
Babeldaob Island introduced
Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 66)
Palau
Palau (Belau ) (main island group)
Babeldaob Island   Beleu National Museum (Republic of Palau. Koror.) (1976) (voucher ID: BNM 1157)
Taxon name on voucher: Cyperus difformis L.
Palau
Palau (Belau ) (main island group)
Malakal (Ngemelachel) Island introduced
Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 66)
Papua New Guinea
Papua New Guinea (eastern New Guinea Island)
Papua New Guinea (eastern New Guinea Island) native
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Philippines
Philippine Islands
Philippine Islands probably native
Waterhouse, D. F. (1993) (pp. 64, 77)
Philippines
Philippine Islands
Philippine Islands   Merrill, Elmer D. (1925) (p. 104)
In open wet places, ascending to 2,000 m; a characteristic rice-paddy weed.
Solomon Islands
Solomon Islands
Solomon Islands   Swarbrick, John T. (1997) (p. 90)
Solomon Islands
Solomon Islands
Solomon Islands native
Hancock, I. R./Henderson, C. P. (1988) (p. 62)
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)
Australia (continental) native
U.S. Dept. Agr., Agr. Res. Serv. (2013)
South Australia, Victoria, Western Australia
Australia
Australia (continental)
New South Wales native
U.S. Dept. Agr., Agr. Res. Serv. (2013)
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) probably native
Waterhouse, D. F. (1993) (pp. 64, 77)
Central America
Central America (Pacific rim)
Costa Rica (Republic of) introduced
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Naturalized
Central America
Central America (Pacific rim)
Nicaragua (Republic of) introduced
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Naturalized
Central America
Central America (Pacific rim)
Panama (Republic of) introduced
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Naturalized
China
China
China (People's Republic of) native
Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013)
Grasslands at mountain slopes, shallow water, water margins, lake margins, wet places in grasslands, along trails, paddy fields; below 100-2000 m. Anhui, Chongqing, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Liaoning, Nei Mongol, Ningxia, Shaanxi, Shandong, Shanxi, Sichuan, Xinjiang, Yunnan, Zhejiang.
China
China
Hong Kong native
Wu, Te-lin (2001) (p. 309)
In wet grassland and along streams.
Indonesia
Indonesia
Indonesia (Republic of) probably native
Waterhouse, D. F. (1993) (pp. 64, 77)
Japan
Japan
Japan (country) native
U.S. Dept. Agr., Agr. Res. Serv. (2013)
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) probably native
Waterhouse, D. F. (1993) (pp. 64, 77)
Mexico
Mexico
Mexico (United Mexican States) introduced
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Naturalized
Negara Brunei Darussalam
Brunei
Brunei (Negara Brunei Darussalam) probably native
Waterhouse, D. F. (1993) (pp. 64, 77)
Singapore
Singapore
Singapore (Republic of) probably native
Waterhouse, D. F. (1993) (pp. 64, 77)
Singapore
Singapore
Singapore (Republic of) uncertain if introduced
invasive
Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. (2009) (p. 31)
Weed of uncertain origin
South America (Pacific rim)
South America (Pacific rim)
Chile (Republic of) introduced
invasive
Belov, Michail (2013)
South America (Pacific rim)
South America (Pacific rim)
Perú (Republic of) introduced
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Naturalized
Taiwan
Taiwan Island
Taiwan Island native
Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013)
Grasslands at mountain slopes, shallow water, water margins, lake margins, wet places in grasslands, along trails, paddy fields; below 100-2000 m.
Thailand
Thailand
Thailand (Kingdom of) probably native
Waterhouse, D. F. (1993) (pp. 64, 77)
United States (west coast)
United States (west coast states)
USA (Oregon) introduced
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Naturalized
United States (west coast)
United States (west coast states)
USA (California) introduced
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Naturalized
Vietnam
Vietnam
Vietnam (Socialist Republic of) probably native
Waterhouse, D. F. (1993) (pp. 64, 77)
Indian Ocean
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
British Indian Ocean Territory
Chagos Archipelago
Diego Garcia Island   Topp, J. M. W. (1988) (p. 18)
British Indian Ocean Territory
Chagos Archipelago
Diego Garcia Island introduced
invasive
Whistler, W. Arthur (1996) (p. 23)
British Indian Ocean Territory
Chagos Archipelago
Diego Garcia Island   National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (1995) (voucher ID: PTBG 23870)
Taxon name on voucher: Cyperus difformis
Comoros
Comoro Islands
Comoro Islands native
U.S. Dept. Agr., Agr. Res. Serv. (2013)
La Réunion (France)
La Réunion Island
La Réunion Island native
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Mauritius
Mautitius Islands (Mauritius and Rodrigues)
Mauritius Island   Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 114)
Seychelles
Seychelles Islands
Seychelles Islands native
U.S. Dept. Agr., Agr. Res. Serv. (2013)
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
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Naturalized
United States (continental except west coast)
United States (other states)
USA (Florida) introduced
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Naturalized


Need more info? Have questions? Comments? Information to contribute? Contact PIER! (pier@hear.org)

  [   PIER species lists  ]   [   PIER home  ]

This page was created on 1 JAN 1999 and was last updated on 9 JAN 2011.