Polygonum aviculare L., Polygonaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  yes

Common name(s): [more details]

Chinese: bian xu

English: doorweed, hogweed, ironweed, knotgrass, knotweed, prostrate knotweed, wireweed, yard knotweed

French: centinode, herbe aux cochons, renouée des oiseaux, trainasse

Japanese: michi-yanagi, niwayanagi

Spanish: alambrillo, caminadora, centinodia, cien nudos, coloradilla, corredora, correguela de los caminos, gonorrea, herbe de las calenturas, hierba de chivo, huichun, huichuri, lengue de pajaro, pasto del pollo, sangrina, sanguinaria, sanguinaria mayor, verdolaga

Habit:  herb

Description:  "Glabrous, taprooted annual or short-lived perennial herbs; stems usually prostrate and often rooting at the nodes, or erect with ascending lateral branches.  Leaves few to numerous, widely spaced to crowded, linear to narrowly oblong or narrowly elliptic, (0.2-) 0.3-1.5 (-2.5) cm long, 0.1-0.6 cm wide, petioles short, jointed to the blade, ocreae hyaline, laciniate, 5-10 mm long.  Flowers 1-3, axillary, pedicels filiform, shorter than the ocreae so that the flower and fruit are erect; tepals green, apex whitish tinged reddish purple, sometimes not opening and perhaps the flower cleistogamous, 3 tepals arranged over the angle of the nut and the inner 2 on the nut faces.  Nuts dark brown, trigonous, ca. 2-3 mm long, the surface minutely papillose, appearing striate, dull"  (Wagner et al., 1999; p. 1063).

Habitat/ecology:  "A common weed in trampled areas such as footpaths and animal trails, in lawns, along the edges and in cracks of sidewalks and other paved surfaces, along roadsides, and especially in fields of cereal crops.  It is found on dark and sandy loam soils rich in N but also grows well on infertile soil.  It grows in soils with pHs of 5.6 to 8.4.  A variable species with many growth forms and varieties.  In full sunlight, plants remain prostrate and can form dense mats of wiry stems or the main stem remains flat and the branches may be somewhat erect.  In partial shade, it is nearly erect, reaching 30 to 40 cm tall.  It invades bare ground and competes well with grasses"  (Holm et al., 1997; p. 598).

In Hawai‘i, "sparingly naturalized in pastures and other disturbed areas, 1,000-2,080 m"  (Wagner et al., 1999; p. 1063).

Propagation:  Seed, dispersed by birds, mammals and water (Weber, 2003; p. 339).

Native range:  "Widespread in temperate regions of the world, perhaps native to Europe"  (Wagner et al., 1999; p. 1063).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced	Skottsberg, Carl (1953) (p. 216)
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 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)
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1063) Voucher cited: Ewart III 196 (BISH)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1063)
New Zealand (offshore islands) Kermadec Islands	Kermadec Islands	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 971) "Cultivated ground, waste places, railway tracks, roadsides and other modified habitats, also poor and open pastures and riverbeds". Casual

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		Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 596)
Australia Australia (continental)	Australia (continental)		Hafliger, Toni J./Wolf, Matthias (1988) (p. 279)
Australia Australia (continental)	Northern Territory		Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 596)
Australia Australia (continental)	Queensland		Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 596)
Central America Central America (Pacific rim)	El Salvador (Republic of)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 287)
Central America Central America (Pacific rim)	Guatemala (Republic of)	introduced invasive	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 596)
Central America Central America (Pacific rim)	Honduras (Republic of)	introduced invasive	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 596)
China China	China (People's Republic of)	invasive	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) "Near fields, roadsides, waste places; sea level to 4200 m".
China China	China (People's Republic of)		Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 596)
Japan Japan	Japan		Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 596)
Japan Japan	Japan	introduced	Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 181) var. condensatum Beck. and var. monospeliensie Thiband.
South Korea South Korea	South Korea (Republic of)		Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 596)
Mexico Mexico	Mexico (United Mexican States)	introduced invasive	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 596)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 971) "Cultivated ground, waste places, railway tracks, roadsides and other modified habitats, also poor and open pastures and riverbeds".
South America (Pacific rim) South America (Pacific rim)	Chile (Republic of)	introduced invasive	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 596)
South America (Pacific rim) South America (Pacific rim)	Colombia	introduced invasive	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 596)
South America (Pacific rim) South America (Pacific rim)	Ecuador (Republic of) (continental)	introduced invasive	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 596)
South America (Pacific rim) South America (Pacific rim)	Perú (Republic of)	introduced invasive	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 596)

Control:  "Specific control methods for this species are not available.  Plants may be cut before fruit formation to prevent seed dispersal.  Seedlings can be hand pulled, larger plants treated with herbicide"  (Weber, 2003; p. 339).