Cyperus difformis L., Cyperaceae

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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, 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 (2011) ?
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 (2011) ?
Cook Islands Northern Cook Islands	Rakahanga Atoll		McCormack, Gerald (2011) ?
Cook Islands Northern Cook Islands	Suwarrow (Taka) Atoll		McCormack, Gerald (2011) ?
Cook Islands Southern Cook Islands	Mangaia Island		McCormack, Gerald (2011)
Cook Islands Southern Cook Islands	Ma‘uke Island		McCormack, Gerald (2011)
Cook Islands Southern Cook Islands	Palmerston (Avarau) Island		McCormack, Gerald (2011) ?
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. (2011) 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) Bonin (Ogasawara) 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 (main island group)	Babeldaob Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 66)
Palau Palau (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 (main island group)	Malakal 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)		Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 238)
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)		Hafliger, E. (1092) (p. 15)
Cambodia Cambodia	Cambodia (Kingdom of)	probably native	Waterhouse, D. F. (1993) (pp. 64, 77)
Chile (continental) Chile	Chile (Republic of)	introduced invasive	Belov, Michail (2011)
China China	China (People's Republic of)		Li-ying, Li/Ren, Wang/Waterhouse, D. F. (1997) (p. 172)
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)		Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 238-239)
South Korea South Korea	South Korea (Republic of)		Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 238)
Malaysia Malaysia	Malaysia (country of)	probably native	Waterhouse, D. F. (1993) (pp. 64, 77)
Mexico Mexico	Mexico (United Mexican States)	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 238-239)
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
Taiwan Taiwan	Taiwan Island		Li-ying, Li/Ren, Wang/Waterhouse, D. F. (1997) (p. 172)
Thailand Thailand	Thailand (Kingdom of)	probably native	Waterhouse, D. F. (1993) (pp. 64, 77)
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
Mauritius Mautitius Islands (Mauritius and Rodrigues)	Mauritius Island		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 114)

Additional information:
Photos and other information from Chileflora.

Additional online information about Cyperus difformis is available from the Hawaiian Ecosystems at Risk project (HEAR).

Information about Cyperus difformis as a weed (worldwide references) may be available from the Global Compendium of Weeds (GCW).

Taxonomic information about Cyperus difformis may be available from the Germplasm Resources Information Network (GRIN).

References:

Beleu National Museum (Republic of Palau. Koror.). 1976. Voucher specimen #BNM1157(Vann, J.E. A-06).

Belov, Michail. 2011. Chileflora (online resource).

Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. 2009. A checklist of the total vascular plant flora of Singapore: native, naturalised and cultivated species. Raffles Museum of Biodiversity Research, National University of Singapore. 273 pp.

Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. 2011. Base de données botaniques Nadeaud de l'Herbier de la Polynésie Française (PAP). (online resource).

Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce. 1987. A geographical checklist of the Micronesian monocotyledonae. Micronesica 20:1-126.

Hafliger, E. 1092. Monocot Weeds 3. CIBA-GEIGY Ltd., Basle, Switzerland. 132 pp. plus plates.

Hancock, I. R./Henderson, C. P. 1988. Flora of the Solomon Islands. Research Bulletin No. 7. Ministry of Agriculture and Lands, Honiara. 203 pp.

Herrera, Katherine/Lorence, David H./Flynn, Timothy/Balick, Michael J. 2010. Checklist of the vascular plants of Pohnpei with local names and uses. Allertonia, in press. National Tropical Botanical Garden, Lawai, Hawai‘i. 146 pp.

Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. 1977. The world’s worst weeds: distribution and biology. East-West Center/University Press of Hawaii. 609 pp.

Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. 1979. A geographical atlas of world weeds. John Wiley & Sons, New York. 391 pp.

Kato, Hidetoshi. 2007. Herbarium records of Makino Herbarium, Tokyo Metropolitan University. Personal communication.

Li-ying, Li/Ren, Wang/Waterhouse, D. F. 1997. The distribution and importance of arthropod pests and weeds of agriculture and forestry plantations in southern China. ACIAR, Canberra, Australia. 185 pp.

Lorence, David H./Flynn, Timothy. 2010. Checklist of the plants of Kosrae. Unpublished checklist. National Tropical Botanical Garden, Lawai, Hawai‘i. 26 pp.

McCormack, Gerald. 2011. Cook Islands Biodiversity Database, Version 2007.2. Cook Islands Natural Heritage Trust, Rarotonga.

Merrill, Elmer D. 1925. An enumeration of Philippine flowering plants, vol. 1 [reprint]. Bureau of Printing, Manila. 463 pp.

Raulerson, L. 2006. Checklist of Plants of the Mariana Islands. University of Guam Herbarium Contribution 37:1-69. .

Smith, Albert C. 1979. Flora Vitiensis nova: a new flora of Fiji. National Tropical Botanical Garden, Lawai, Kauai, Hawaii. Volume 1. 494 pp.

Space, James C./Waterhouse, Barbara/Denslow, Julie S./Nelson, Duane/Waguk, Erick E. 2000. Invasive plant species on Kosrae, Federated States of Micronesia.  USDA Forest Service, Honolulu. 43 pp.

Starr, Forest/Martz, Kim/Loope, Lloyd L. 2002. New plant records from the Hawaiian archipelago. In: Evenhuis, Neal L. and Eldredge, Lucius G., eds. Records of the Hawaii Biological Survey for 2000. Part 2: Notes. Bishop Museum Occasional Papers. 69:16-27.

Starr, Forest/Starr, Kim/Loope, Lloyd L. 2006. New plant records from the Hawaiian Archipelago. In: Evenhuis, Neal L. and Eldredge, Lucias G., eds. Records of the Hawaii Biological Survey for 2004-2005. Part 1: Articles. Bishop Museum Occasional Papers 87:31-43.

Stone, Benjamin C. 1970. The flora of Guam. Micronesica 6:1-659.

Swarbrick, John T. 1997. Weeds of the Pacific Islands. Technical paper no. 209. South Pacific Commission, Noumea, New Caledonia. 124 pp.

Topp, J. M. W. 1988. An annotated check list of the flora of Diego Garcia, British Ocean Territory. Atoll Research Bulletin No. 313. Smithsonian Institution, Washington. 21 pp.

U.S. Dept. Agr., Agr. Res. Serv. 2011. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

Vander Velde, Nancy. 2003. The vascular plants of Majuro Atoll, Republic of the Marshall Islands. Smithsonian Institution, Atoll Research Bulletin No. 503:1-141.

Vander Velde, Nancy/Vander Velde, Brian. 2006. Plants of Kili Island, Marshall Islands. Unpublished checklist. 12 pp.

Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. 1999. Manual of the flowering plants of Hawaii. Revised edition. Bernice P. Bishop Museum special publication. University of Hawai‘i Press/Bishop Museum Press, Honolulu. 1919 pp. (two volumes).

Waterhouse, D. F. 1993. The major arthropod pests and weeds of agriculture in Southeast Asia. The Australian Centre for International Agricultural Research, Canberra. 141 pp.

Whistler, W. Arthur. 1996. Botanical survey of Diego Garcia, Chagos Archipelago, British Indian Ocean Territory. Isle Botanica. 49 pp.

Wu, Te-lin. 2001. Check List of Hong Kong Plants. Hong Kong Herbarium and the South China Institute of Botany. Agriculture, Fisheries and Conservation Department Bulletin 1 (revised). 384 pp.

Zhengyi, Wu/Raven, Peter H./Deyuan, Hong. 2011. Flora of China (online resource).