Pacific Island Ecosystems at Risk (PIER)

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Xanthium strumarium
L., Asteraceae
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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results:  Reject, score: 7 (Go to the risk assessment)

Other Latin names:  Xanthium occidentale Bertol.; Xanthium pensylvanicum Wallr.; Xanthium pungens Wallr.

Common name(s): [more details]

English: California bur, cocklebur, ditchbur, heartleaf cocklebur, Noogoora burr, sheepbur

Fijian: nggatima ni vavalangi, ovuka, qatima ni vavalagi

Hawaiian: kīkānia

Japanese: ōnamomi

Habit:  herb

Description:  "Plants 2-20 dm tall, appressed pubescent or subglabrous.  Leaf blades broadly ovate to reniform, 2-8 cm long, 1.5-10 cm wide, scabrous and glandular-dotted, margins coarsely and irregularly toothed, base usually cordate, petioles 1.5-10 cm long.  Heads in several to numerous short axillary inflorescencesBurs broadly cylindrical to ovoid, ellipsoid, or sometimes subglobose, (1-) 1.5-3.5 cm long, covered with stout, hooked prickles, terminated by 2 straight or incurved beaks" (Wagner et al., 1999; pp. 376-377).

Habitat/ecology:  "It is found along streams, rivers, in low-lying areas subject to flooding, and in waste places.  It frequents roadsides, railway banks, small streams, and riverbanks, as well as the edges of ponds and freshwater marshes and poorly managed or overgrazed pastures.  It cannot stand shading.  The weed can grow on a wide range of soils, from sands to heavy clays, and in a wide range of moisture supply.  On rich soils with high moisture and little competition from other plants, it grows tall and luxurious, forming pure stands.  In dry, poor soils, if the seedlings have become established, the plant may grow to only a few cm in height, persisting under drought, but still fruiting and setting seeds.  This ability to grow under a wide range of conditions results in a constant seed supply if the plant is not controlled" (Holm et al., 1977; p. 480).  "An extensive root system and rapid growth make these plants strong competitors with desirable forages and crops"  (Motooka et al., 2003).

"In Hawai‘i a common weed of low elevation, relatively dry, disturbed habitats" (Wagner et al., 1999; pp. 376-377). In Fiji, "occurring near sea level or at low elevations probably not exceeding 100 m as a naturalized weed in open places, cultivated areas, and grasslands, and along roadsides, sometimes locally abundant" (Smith, 1991; pp. 289-290).  In Australia, "riparian zones along river systems where it forms dense thickets.  Also invades grazing and cultivated lands, and seasonally wet areas" (Smith, 2002; pp. 67-68). "A weed of grazing land; the burrs are troublesome to livestock and the plants are harmful and even fatal if eaten" (Henty & Pritchard, 1975; p. 87).

Propagation:  "The spiny fruit...adhere to wool, fur, clothing, hay bales, mud, etc. The fruits float and are readily dispersed by water. Fruits are also spread in contaminated pasture seed" (Smith, 2002; pp. 67-68).  "As is true of X. spinosum, the two seeds in the fruit...germinate at different rates.  The lower seed germinates more readily than the upper seed, which has a seed coat of low permeability to oxygen.  Both seeds show dormancy, but the lower is less dormant than the upper" (Holm et al., 1977; p. 480).

Native range:  "Probably native to the New World, now a cosmopolitan weed"  (Wagner et al., 1999; pp. 376-377).

Presence:

Pacific
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
Cook Islands
Southern Cook Islands
Ma‘uke Island   McCormack, Gerald (2013)
Cook Islands
Southern Cook Islands
Rarotonga Island   McCormack, Gerald (2013)
Cook Islands
Southern Cook Islands
Rarotonga Island   National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (2002) (voucher ID: PTBG 333)
Taxon name on voucher: Xanthium strumarium
Fiji
Fiji Islands
Viti Levu Island introduced
invasive
Smith, Albert C. (1991) (pp. 289-290)
Vouchers cited: Greenwood 715, 715B; DA 10701; DA 10430; DA 9466; DA 10175; DA 10674; DA 9144; O. & I. Degener 31909; Greenwood 715A; DA 2808; DA 10813; DA 6088
French Polynesia
Gambier Islands
Mangareva (Gambier) Island introduced
invasive
Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013)
Adventice
French Polynesia
Marquesas Islands
Hiva Oa Island introduced
invasive
Lorence, David H./Wagner, Warren L. (2013)
French Polynesia
Marquesas Islands
Hiva Oa Island introduced
invasive
Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013)
Voucher cited: M.-H. Sachet 1208 (PAP)
Adventice
French Polynesia
Marquesas Islands
Hiva Oa Island   National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (2003) (voucher ID: PTBG 39536)
Taxon name on voucher: Xanthium strumarium
French Polynesia
Marquesas Islands
Nuku Hiva (Nukahiva) Island introduced
invasive
Lorence, David H./Wagner, Warren L. (2013)
French Polynesia
Marquesas Islands
Nuku Hiva (Nukahiva) Island introduced
invasive
Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013)
Adventice
French Polynesia
Society Islands
Moorea Island introduced
invasive
Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013)
Adventice
French Polynesia
Society Islands
Raiatea (Havai) Island introduced
invasive
Welsh, S. L. (1998) (p. 82)
Voucher cited: Moore 704
French Polynesia
Society Islands
Tahiti Island introduced
invasive
Welsh, S. L. (1998) (p. 82)
Voucher cited: Setchell & Parks 187
State of Hawaii
Hawaiian Islands
Hawai‘i (Big) Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 376-377)
var. canadense
State of Hawaii
Hawaiian Islands
Kaho‘olawe Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 376-377)
var. canadense
State of Hawaii
Hawaiian Islands
Kaua‘i Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 376-377)
var. canadense
State of Hawaii
Hawaiian Islands
Lāna‘i Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 376-377)
var. canadense
State of Hawaii
Hawaiian Islands
Ni‘ihau, Lehua Islet introduced
invasive
Wood, K. R./LeGrande, Maya (2006) (p. 21)
State of Hawaii
Hawaiian Islands
Maui Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 376-377)
var. canadense
State of Hawaii
Hawaiian Islands
Moloka‘i Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 376-377)
var. canadense
State of Hawaii
Hawaiian Islands
Ni‘ihau Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 376-377)
var. canadense
State of Hawaii
Hawaiian Islands
O‘ahu Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 376-377)
var. canadense
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. 39)
Vouchers cited: MacKee 31251, Sopéna in MacKee 34187
Papua New Guinea
Papua New Guinea (eastern New Guinea Island)
Papua New Guinea (eastern New Guinea Island)   Waterhouse, D. F. (1997) (p. 66)
Philippines
Philippine Islands
Philippine Islands introduced
invasive
Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 476)
United States (other Pacific offshore islands)
Midway Atoll
Midway Atoll introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 376-377)
var. canadense
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)
Northern Territory introduced
invasive
Smith, Nicholas M. (2002) (p. 67)
Australia
Australia (continental)
Queensland introduced
invasive
Smith, Nicholas M. (2002) (p. 67)
China
China
China (People's Republic of) introduced
invasive
Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 476)
Japan
Japan
Japan (country) introduced
invasive
Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 476)
South Korea
South Korea
South Korea (Republic of) introduced
invasive
Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 476)
Mexico
Mexico
Mexico (United Mexican States) introduced
Weber, Ewald (2003) (p. 457)
New Zealand
New Zealand
New Zealand (country) introduced
invasive
Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 227)
"Cultivated land".
Taiwan
Taiwan Island
Taiwan Island introduced
invasive
Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 476)
Taiwan
Taiwan Island
Taiwan Island uncertain if native
Ching-I Peng, ed. (2013)
"River banks, seacoasts, and waste fields throughout the lowland".
Thailand
Thailand
Thailand (Kingdom of) introduced
invasive
Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 476)

Control: 

Physical:  "Control measures should aim at preventing seed formation.  Small plants can be hand pulled or hoed.  Prescribed burning is also effective if the fire is hot enough"  (Weber, 2003; p. 457).  "Australian officials have imposed strict quarantines to keep uninfested areas clear of this weed.  Small infestations can be effectively cleared by hand pulling or hoeing with care to collect, remove and burn any burs.  Controlled burning my also be effective on larger areas"  (Motooka et al., 2003).

Chemical:  "An effective chemical control method is spraying 2,4-D or MCPA before flowering commences"  (Weber, 2003; p. 457).  "Sensitive to dicamba and metsulfuron.  Clopyralid, 2,4-D, glyphosate, triclopyr also effective"  (Motooka et al., 2003).

Biological:  "Several biocontrol insects and pathogens have been introduced in Australia with variable results"  (Motooka et al., 2003).


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This page was created on 1 JAN 1999 and was last updated on 11 FEB 2010.