Cyperus esculentus L., Cyperaceae

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Present on Pacific Islands?  no

Primarily a threat at high elevations?  no

Risk assessment results:  Reject, score: 19 (Go to the risk assessment).

Common name(s): [more details]

Chinese: you suo cao

English: chufa, earth almond, nutgrass, tigernut, watergrass, yellow nut grass, yellow nutsedge

French: amande de terre, choufa, souchet comestible

Korean: gireumgol

Spanish: cebollín, chufa, chufa commún, coco, coquillo, coquillo amarillo, coquito, coyolillo, juncia, juncia avellanada

Habit:  sedge

Description:  "Perennials with fibrous roots, stolons filiform, elongate, covered with pale brown scales, terminated by a small tuber; culms solitary, slender, trigonous, smooth, (10-) 25-50 cm tall, thickened at base with a small corm-like enlargement clothed with brown fibers.  Leaves basal, several per culm, blades linear, 3-6 mm wide, shorter than to longer than the culm; sheaths reddish brown; ligule absent.  Inflorescence an open umbelliform corymb, simple or partially compound, 4-7 cm long and as wide, primary rays slender, 5-8, spreading, 1-4 cm long, spikes ovoid, loosely bearing 5-14 spikelets; involucral bracts 3-6, leaf-like, spreading, the lower 1-2 surpassing the inflorescence; spikelets 8-16-flowered, yellowish brown or pale brown, linear-oblong to oblong, slightly compressed, 5-12 mm long, ca. 2 mm wide, rachilla winged; glumes yellowish brown or reddish brown, upper margins membranous, hyaline, ovate or ovate-elliptic, 1.6-2.2 mm long, 7-nerved, apex and keel obtuse; stigmas 3.  Achenes grayish brown, glossy, obovate or oblong-obovate, obtusely trigonous, 1.5-1.8 mm long, minutely puncticulate.  Separation of this species from the very similar Cyperus rotundus is often difficult.  Cyperus eesculentus is generally larger than C. rotundus, and the glumes of the former are yellow rather than reddish brown in the latter.  The most reliable character, however, is the presence of a short ligule on the leaves of C. rotundus; this is absent on the leaves of C. esculentus"  (Wagner et al., 1999; p. 1396).

Habitat/ecology:  "The weed is found on low ground, moist fields, in heavily irrigated crops, along river banks and roadsides, and in ditches.  It tolerates high soil moisture much better than does C. rotundus.  The species grows very well on all soil types, including black peat soils, and performs equally well at pH ranges from 5 to 7.  It is quite intolerant of shade"  (Holm et al., 1977; pp. 125-133).

In New Zealand, "a weedy plant, troublesome overseas in gardens and cultivated land" (Healy & Edgar, 1980; p. 186).

Propagation:  Seed

Native range:  "Southern Europe, Mediterranean region, South Africa, North America, and the Andean region of South America" (Wagner et al., 1999; p. 1396).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive	Strong, Mark T./Wagner, Warren L. (1997) (p. 41) Voucher cited: Stemmermann 6889 (BISH)
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive	Wood, K. R. (2006) (p. 17) Voucher cited: K.R. Wood & S. Perlman 5103 (AD, BISH, F, K, MO, NY, PTBG, US)

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	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
Australia Australia (continental)	Queensland	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
British Columbia (province of Canada) Province of British Columbia	Canada (British Columbia)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Cambodia Cambodia	Cambodia (Kingdom of)		Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 127)
Central America Central America (Pacific rim)	Costa Rica (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	Nicaragua (Republic of)		Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 127, 133)
Central America Central America (Pacific rim)	Panama (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
China China	China (People's Republic of)	introduced invasive cultivated	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) var. sativus Boeckeler. Cultivated in Guangxi, Heilongjiang, Liaoning, Xinjiang, and Yunnan; collected as a naturalized plant in Shandong and perhaps elsewhere.
Indonesia Indonesia	Indonesia (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013) Java
Japan Japan	Japan	introduced	Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 193)
Mexico Mexico	Mexico (United Mexican States)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Healy, A. J./Edgar, E. (1980) (p. 186) Voucher cited: G. S. Harris (CHR 83385)
South America (Pacific rim) South America (Pacific rim)	Chile (Republic of)		Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 127)
South America (Pacific rim) South America (Pacific rim)	Colombia	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
South America (Pacific rim) South America (Pacific rim)	Ecuador (Republic of) (continental)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
South America (Pacific rim) South America (Pacific rim)	Perú (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Taiwan Taiwan Island	Taiwan Island	introduced invasive cultivated	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) var. sativus Boeckeler. Cultivated and naturalized.
Thailand Thailand	Thailand (Kingdom of)		Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 133)
United States (west coast) United States (west coast states)	USA (Oregon)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
United States (west coast) United States (west coast states)	USA (California)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
United States (west coast) United States (west coast states)	USA (Washington)	native	U.S. Dept. Agr., Agr. Res. 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
Comoros Comoro Islands	Comoro Islands	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Mauritius Mautitius Islands (Mauritius and Rodrigues)	Mauritius Island		McIntyre, Guy (1991) (p. 47)

Also reported from
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Canada Canada	Canada	native	U.S. Dept. Agr., Agr. Res. Serv. (2013) New Brunswick, Ontario, Quebec
United States (continental except west coast) United States (other states)	United States (other states)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
United States (continental except west coast) United States (other states)	USA (Florida)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)

Control:  If you know of control methods for Cyperus esculentus, please let us know.