Pacific Island Ecosystems at Risk (PIER)

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Emex australis
Steinh., Polygonaceae
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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results: 

Reject, score: 8 (Go to the risk assessment (Australia)).
High risk, score: 17 (Go to the risk assessment (Pacific)).

Common name(s): [more details]

English: Cape-spinach, cathead, devil's thorn, doublegee, prickly jack, southern three-corner-jack, spiny emex, three-corner Jack

Habit:  herb

Description:  "A herb; stem branched, 3 lin. in diameter, ribbed when dry, glabrous; leaves ovate or oval, with the outer basal angles rounded, obtuse, cuneate into the 2 in.-long petiole, 3 in. long, 2 in. wide, entire or obscurely crenate, glabrous; outer fruiting perianth 6 lin. long, less indented between the angles than in E. spinosa L., spines spreading; inner segments broadly ovate, mucronate, strongly reticulately nerved."

"This species differs from E. spinosa Campd. in the larger, less rugose outer fruiting perianth with longer spinescent segments, and the inner erect segments being broader and more rounded" (Thiselton-Dyer, 1912; pp. 481-481).

Habitat/ecology:  In New Caledonia, "espèce envahissante récoltée une seule fois et peut-être pas établie en Nouvelle-Calédonie" (MacKee, 1994; p. 116). In Western Australia, "a widespread agricultural and wasteland weed" (Hussey et al., 1997).

Propagation:  Seed

Native range:  Southern Africa (Hussey et al., 1997).

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
Parker, James L./Parsons, Bobby (2012) (pp. 72-73)
Vouchers cited: J. Parker & R. Parsons BIED148 (BISH), R.A. Goff s.n. (BISH #63678), H. Kennedy & S. Ishikawa 3910 (BISH)
New Caledonia
New Caledonia
New Caledonia Islands   Swarbrick, John T. (1997) (p. 92)
New Caledonia
New Caledonia Archipelago
Île Grande Terre introduced
invasive
Tassin, Jacques (2005)
New Caledonia
New Caledonia Archipelago
Île Grande Terre introduced
MacKee, H. S. (1994) (p. 116)
Voucher cited: MacKee 35455
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
National Herbarium of New South Wales (2013)
South Australia, Victoria, Western Australia
Naturalised
Australia
Australia (continental)
New South Wales introduced
invasive
National Herbarium of New South Wales (2013)
Naturalised
New Zealand
New Zealand
New Zealand (country) introduced
invasive
Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 966)
"Coastal areas, mainly in waste and cultivated land on light sandy soils, sometimes in rough pasture".
Taiwan
Taiwan Island
Taiwan Island   Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 141)


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This page was created on 22 SEP 2002 and was last updated on 19 OCT 2011.