Pacific Island Ecosystems at Risk (PIER)

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Ambrosia psilostachya
DC., Asteraceae
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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results:  High risk, score: 15 (Go to the risk assessment)

Other Latin names:  Ambrosia coronopifolia Torr. & A. Gray

Common name(s): [more details]

English: artemisia, cuman ragweed, Dunbible-weed, perennial ragweed, Roman wormwood, western ragweed

French: herbe à poux vivace

Habit:  herb

Description:  "Perennials,10-60 (-100+) cm. Stems erect. Leaves proximally opposite, distally alternate; petioles 0-25 mm (often ± winged); blades deltate to lanceolate, 20-60 (-140) x 8-35 (-50+) mm, pinnately toothed to 1-pinnately lobed, bases cuneate to truncate, ultimate margins entire or toothed, abaxial and adaxial faces hirsutulous to strigose and gland-dotted. Pistillate heads clustered, proximal to staminates; florets 1. Staminate heads: peduncles 0.5-2 mm; involucres obliquely cup-shaped, 2-4 (-5) mm in diameter, hirsutulous; florets 5-15 (-30+). Burs: bodies ± obpyramidal to globose, 2-3 mm, hirsutulous, spines or tubercles 0 or 1-6, mostly distal, stoutly conic to acerose, (0.1-) 0.5-1 mm, tips straight"  (Flora of North America online).

Known to hybridize with Ambrosia artemisiifolia.

Habitat/ecology:  "Disturbed sites, often wet, alkaline, clay soils; 0-2200 m"  (Flora of North America online).

Propagation:  Seed

Native range:  North America (GRIN).

Presence:

Pacific
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
New Caledonia
New Caledonia Archipelago
Île Grande Terre introduced
invasive
MacKee, H. S. (1994) (p. 31)
Voucher cited: MacKee 20601
Spontané
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) introduced
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
South Australia, Victoria
Naturalized
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
Canada (British Colombia)
Province of British Columbia
Canada (British Columbia) native
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Japan
Japan
Japan (country) introduced
Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 189)
Mexico
Mexico
Mexico (United Mexican States) native
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Taiwan
Taiwan Island
Taiwan Island introduced
Ching-I Peng, ed. (2013)
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)
Also reported from
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
Canada (except British Colombia)
Canada
Canada (country) 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)


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This page was created on 8 DEC 2009 and was last updated on 31 DEC 2011.