Pacific Island Ecosystems at Risk (PIER)

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Poa annua
L., Poaceae
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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results:  Reject, score: 26 (Go to the risk assessment).

Common name(s): [more details]

Chinese: zao shu he

English: annual bluegrass, annual meadowgrass, annual poa, annual wintergrass, goose grass, walkgrass, winter grass

French: pâturin annuel

Japanese: suzumeno-katabira

Spanish: cebadilla, champa, espiguilla, hierba de la perdiz, hierba de punta, pastito de invierno, pasto azul anual, pasto de la perdiz, pasto de las liendres, pata de gallina, pata de perdiz, pel de ca, pelosa, piagillo, piojillo, poa annual, zacate azul, zacate poa

Habit:  grass

Description:  "Bright green annuals; culms spreading or sometimes erect, rooting at modes and forming mats, 0.3-2 (-3.5) dm tall, strongly flattened.  Sheaths open ca. 1/2 their length, with overlapping margins; ligule 1-3 mm long, obtuse or truncate, often erose; blades lax, folded or flat, 1-10 cm long, 1-2.5 (-3) mm wide, margins scaberulous, otherwise glabrous.  Panicles open, pyramidal, 1.5-3.5 (-8) cm long, branches spreading, usually rigid; spikelets 3-6-flowered, (3-) 4-5.5 (-7) mm long, rachilla elongate; glumes glabrous, first glume narrowly lanceolate, 1.5-2.2 mm long, 1-nerved, apex acute, second glume oblanceolate to obovate, slightly longer than first glume, 1.8-2.7 mm long, 1-3-nerved, somewhat obtuse; lemmas 2.5-3.5 mm long, prominently 5-nerved, the nerves villous toward base, the margins scarious toward apex, pilose toward base; palea 1.5-2 mm long, 2-nerved, keeled, nerves villous, margins hyaline.  Caryopsis pale brown, ellipsoid, somewhat trigonal, ca. 1 mm long"  (Wagner et al., 1999; p. 1583).

Description from GrassBase.

Habitat/ecology:  "It invades gardens, lawns, foot paths, bowling greens, flower beds, golf courses, and cracks in sidewalks and pavement.  It can be found at the margins of ponds and streams as well as in agronomic and horticultural crops and pastures.  It occurs in areas of 90 to 430 mm annual precipitation; average minimum and maximum temperatures of 4.9 and 27.4° C, respectively; and soil pHs from 4.5 to 8.2.  It grows on a wide range of soils, tolerates trampling, and is a frequent weed in areas heavily trafficked by livestock or humans"  (Holm et al.,  1997; p. 587).  In Hawai‘i, "naturalized and relatively common, occurring in a variety of disturbed, usually mesic habitats, including roadsides, pastures, urban sites, and disturbed mesic and wet forest, 0-1,830 m" (Wagner et al., 1999; p. 1583).

Propagation:  Seed

Native range:  Europe (Wagner et al., 1999; p. 1583).

Presence:

Pacific
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
Australia (Pacific offshore islands)
Lord Howe Island
Lord Howe Island introduced
invasive
Orchard, Anthony E., ed. (1994) (p. 23)
"An introduced and now common weed, especially of cultivated ground, including lawns". Vouchers cited: A.C. Beauglehole 5423 (CANB, MEL), A.N. Rodd 1480 (K, NSW), L.M. Bingley 11 (K), J.C. Game 69/273e (K)
Australia (Pacific offshore islands)
Norfolk Islands
Norfolk Island introduced
invasive
Orchard, Anthony E., ed. (1994) (p. 12)
"An introduced and now common weed, especially of cultivated ground, including lawns". Voucher cited: R.D. Hoogland 11233 (CANB)
Chile (offshore islands)
Juan Fernández Islands
Isla Más a Tierra (Robinson Crusoe Island) introduced
Skottsberg, Carl (1953) (p. 215)
Chile (offshore islands)
Juan Fernández Islands
Isla Más a Tierra (Robinson Crusoe Island) introduced
invasive
Atkinson, Rachel/Sawyer, John (2011)
Chile (offshore islands)
Juan Fernández Islands
Isla Más a Tierra (Robinson Crusoe Island) introduced
invasive
Danton, Philippe/Perrier, Christophe/Martinez Reyes, Guido (2006) (p. 556)
Chile (offshore islands)
Juan Fernández Islands
Isla Más Afuera (Alejandro Selkirk Island) introduced
Skottsberg, Carl (1953) (p. 215)
Chile (offshore islands)
Juan Fernández Islands
Isla Más Afuera (Alejandro Selkirk Island) introduced
invasive
Atkinson, Rachel/Sawyer, John (2011)
Chile (offshore islands)
Juan Fernández Islands
Isla Más Afuera (Alejandro Selkirk Island) introduced
invasive
Danton, Philippe/Perrier, Christophe/Martinez Reyes, Guido (2006) (p. 556)
Ecuador (Galápagos Islands)
Isabela Group
Isabela Island introduced
cultivated
Charles Darwin Foundation (2008)
Ecuador (Galápagos Islands)
Isabela Group
Volcán Sierra Negra, Isabela Island introduced
invasive
Charles Darwin Foundation (2008)
French Polynesia
Society Islands
Tahiti Island introduced
invasive
Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013)
Adventice
State of Hawaii
Hawaiian Islands
Hawai‘i (Big) Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1583)
State of Hawaii
Hawaiian Islands
Kaua‘i Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1583)
State of Hawaii
Hawaiian Islands
Kure Atoll introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1583)
State of Hawaii
Hawaiian Islands
Kure Atoll introduced
invasive
Starr, Forest/Martz, Kim/Loope, Lloyd (2001) (p. 16)
Uncommon. Only found around quarters.
State of Hawaii
Hawaiian Islands
Lāna‘i Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1583)
State of Hawaii
Hawaiian Islands
Maui Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1583)
State of Hawaii
Hawaiian Islands
Maui Island introduced
invasive
Starr, Forest/Starr, Kim (2011) (p. 33)
East Maui. Voucher cited: Starr & Starr 090504-03 (BISH)
State of Hawaii
Hawaiian Islands
Moloka‘i Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1583)
State of Hawaii
Hawaiian Islands
O‘ahu Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1583)
Japan (offshore islands)
Ogasawara (Bonin) Islands
Bonin (Ogasawara) Islands   Kato, Hidetoshi (2007)
New Caledonia
New Caledonia Archipelago
Île Grande Terre introduced
MacKee, H. S. (1994) (p. 61)
Voucher cited: Cribs 847
New Zealand (offshore islands)
Kermadec Islands
Kermadec Islands introduced
invasive
Edgar, E./Connor, H. (2000) (p. 141)
"A weed of cultivated land and waste places".
Papua New Guinea
Papua New Guinea (eastern New Guinea Island)
Papua New Guinea (eastern New Guinea Island) introduced
cultivated
Henty, E. E. (1969) (p. 154)
Papua New Guinea
Papua New Guinea (eastern New Guinea Island)
Papua New Guinea (eastern New Guinea Island) introduced
invasive
Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 585)
Philippines
Philippine Islands
Philippine Islands introduced
invasive
Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 585)
United States (other Pacific offshore islands)
Midway Atoll
Midway Atoll introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1583)
United States (other Pacific offshore islands)
Midway Atoll
Sand Island introduced
invasive
Starr, Forest/Starr, Kim/Loope, Lloyd (2008) (pp. B-12)
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
Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 585)
Australia
Australia (continental)
Northern Territory introduced
invasive
Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 585)
Australia
Australia (continental)
Queensland introduced
invasive
Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 585)
Chile (continental)
Chile
Chile (Republic of) introduced
invasive
Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 585)
China
China
China (People's Republic of) introduced
invasive
Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 585)
China
China
Hong Kong native
Wu, Te-lin (2001) (p. 344)
Colombia
Colombia
Colombia (Republic of) introduced
invasive
Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 585)
Costa Rica
Costa Rica
Costa Rica (Republic of)   Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 285)
Ecuador (Mainland)
Ecuador
Ecuador (Republic of) (continental) introduced
invasive
Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 585)
El Salvador
El Salvador
El Salvador (Republic of)   Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 285)
Honduras
Honduras
Honduras (Republic of) introduced
invasive
Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 593)
Indonesia
Indonesia
Indonesia (Republic of) introduced
invasive
Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 585)
Japan
Japan
Japan (country) introduced
invasive
Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 585)
Japan
Japan
Japan (country) introduced
Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 192)
South Korea
South Korea
South Korea (Republic of) introduced
invasive
Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 585)
Malaysia
Malaysia
Malaysia (country of) introduced
invasive
Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 585)
Mexico
Mexico
Mexico (United Mexican States) introduced
invasive
Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 585)
New Zealand
New Zealand
New Zealand (country) introduced
invasive
Edgar, E./Connor, H. (2000) (p. 141)
"A weed of cultivated land and waste places".
Nicaragua
Nicaragua
Nicaragua (Republic of) introduced
invasive
Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 593)
Perú
Perú
Perú (Republic of) introduced
invasive
Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 585)
Taiwan
Taiwan Island
Taiwan Island introduced
invasive
Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 585)
Indian Ocean
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
La Réunion (France)
La Réunion Island
La Réunion Island introduced
invasive
Comité français de l'Union Internationale pour la Conservation de la Nature en France (2013)
Envahissant principalement dans les milieux perturbés.
Mauritius
Mautitius Islands (Mauritius and Rodrigues)
Mauritius Island   Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 285)


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This page was created on 24 JAN 2007 and was last updated on 10 MAY 2017.