Ambrosia artemisiifolia L., Asteraceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Other Latin names:  Ambrosia elatior L.

Common name(s): [more details]

Chinese: tun cao

English: Roman wormwood, annual ragweed, bitterweed, common ragweed, ragweed, short ragweed

French: ambroisie annuelle, petit herbe à poux

Japanese: buta-kusa

Spanish: ambrosia de hojas de ajenjo, artemisia de terra

Habit:  herb

Description:  "Erect, taprooted annual herbs; stems 3-10 dm long, branched at least above, ± hirsute.  Leaves pinnatifid or bipinnatifid, the lobes lanceolate, blades narrowly to broadly ovate or elliptic, 4-10 (-30) cm long, 4-7 (-15) cm wide, upper surface hirsutulous, lower surface strigose and often hirsute on the veins.  Staminate involucre 1.5-2 mm high; pistillate involucre 3-5 mm high in fruit with a single series of short, sharp, erect spines near or above the middle."  (Wagner et al., 1999; p. 256).

Description from the Flora of China online.
Description from the Flora of North America online.

Known to hybridize with Ambrosia psilostachya.

Habitat/ecology:  In Hawai‘i, "naturalized in low elevation, dry, disturbed habitats, especially along roadsides and in pastures, 0-900m" (Wagner et al., 1999; p. 256).

Propagation:  Seed

Native range:  United States and southern Canada (Wagner et al., 1999; p. 256).

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	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 256)
State of Hawaii Hawaiian Islands	Lāna‘i Island	introduced	Wester, Lyndon (1992) (p. 127)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 256)
State of Hawaii Hawaiian Islands	Moloka‘i Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 256)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 256)

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)	Australia (continental)	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)
Central America Central America (Pacific rim)	Guatemala (Republic of)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 21)
China China	China (People's Republic of)	introduced invasive	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) "Introduced noxious weed of wet to dry soils; below 1000 m. Widely distributed in China".
China China	China (People's Republic of)	introduced invasive	Li-ying, Li/Ren, Wang/Waterhouse, D. F. (1997) (pp. 172, 178)
China China	Hong Kong	introduced invasive	Wu, Te-lin (2001) (p. 274) In wasteland.
Japan Japan	Japan	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
New Zealand New Zealand	New Zealand (country)	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 209) "Waste places, cultivated land. Ragweed is only known in N.Z. as a casual and seed impurity".
South America (Pacific rim) South America (Pacific rim)	Chile (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
South America (Pacific rim) South America (Pacific rim)	Colombia		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 21)
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	Ching-I Peng, ed. (2013) "A widely naturalized weed along freeways, open construction sites and waste places in lowlands".

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Mauritius Mautitius Islands (Mauritius and Rodrigues)	Mauritius Island	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized

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)
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 Ambrosia artemisiifolia, please let us know.