Pacific Island Ecosystems at Risk (PIER)

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Amaranthus spinosus
L., Amaranthaceae
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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results:  Reject, score: 18 (Go to the risk assessment).

Common name(s): [more details]

Bikol: kilitis

Bontoc: tadtad

Cebuano: kalitis

Chamorro: kuletes, kulites

Chinese: ci xian

English: carelessweed, edlebur, needle burr, prickly amaranth, prickly calalu, Prince-of-Wales-feather, spiny amaranth, spiny pigweed, thorny amaranth, thorny pigweed

Filipino: gitin-gitin

French: brède malabar à piquants, épinard cochon, épinard malabre, oseille, petit trèfle, trèfle

Hawaiian: pakai kukū, pukai kukū

Ifugao: alayon

Iloko: kalunai

Japanese: haribiyu

Pampangan: ayantoto

Spanish: bledo, bledo espinoso, blero, espinaca de Malabar, huisquilite, quelite espinoso, yuyo macho

Tagalog: orai

Habit:  herb

Description:  "Monoecious annual herbs; stems sometimes tinged with red, erect, sometimes ascending, 4-15 dm long, usually branched, striate, glabrous or pubescent with multi-cellular hairs, especially above, most leaf axils with a pair of divergent spines up to 2.5 cm long.  Leaves ovate to rhombic-ovate, elliptic, lanceolate-oblong, or lanceolate, blades 1-12 cm long, 0.89-6 cm wide, glabrous, lower surface occasionally sparsely pilose, especially along the veins, petioles 1-9 cm long.  Flowers green, in axillary clusters in the lower part of the plant and in unbranched or branched spikes in the upper part, the lower clusters entirely pistillate as are the lower flowers of the spikes, the upper flowers in the spikes staminate, bracts and bracteoles deltate-ovate, membranous, tipped with a pale or reddish awn; sepals 5, those of staminate flowers broadly lanceolate or lanceolate-oblong, 1.5-2.5 mm long, apex obtuse or acute, mucronulate; stigmas (2) 3.  Fruit ovoid, with a short inflated neck below the style base, ca. 1.5 mm long, regularly or irregularly circumscissile, rarely indehiscent, the upper part rugulose below the neck.  Seeds black, shiny, compressed, 0.8-1 mm long, inconspicuously reticulate"  (Wagner et al., 1999; pp. 188-189).

Habitat/ecology:  "The plant is found in cultivated fields, waste places, roadsides, garbage heaps, and abandoned fields.  The plant will grow both in dry and wet sites but prospers when soil moisture levels are below field capacity.  Waterlogging retards its growth.  Maximum growth is obtained on soils which are high in organic matter, loamy in texture, and which have sufficient nitrogen.  The  plants do not grow well in shade or cool temperatures, because spine development and flowering are suppressed under these conditions"  (Holm et al., 1977; pp. 119, 121).

In Hawai‘i, "occurring in low elevation, disturbed habitats" (Wagner et al.,1999; pp. 188-189).  In Fiji, "occurring sparsely near sea level as a naturalized weed of waste places near the shore" (Smith, 1981; p. 287).  In Samoa, "uncommon in disturbed places" (Whistler, 1988; p. 6). In Papua New Guinea, "a weed of gardens and agricultural land, sometimes appearing in pastures. From low altitudes to at least 1000 m" (Henty & Pritchard, 1975; p. 55); "occurring as a garden weed at 0-600(?) m altitude"  (Womersley, 1978; p. 27). Arid lowlands and moist uplands in the Galápagos Islands (McMullen, 1999; p. 232). "A common weed, especially of newly plowed or disturbed ground, found in all hot countries" (Stone, 1970; p. 268).

Propagation:  "Up to 235,000 seeds per plant have been recorded.  Seeds are spread by wind and water.  Some germinate soon, others over several months and still others remian viable in the soil for many years"  (Waterhouse, 1994; p. 20).

Native range:  Not known, but possibly the neotropics (Smith, 1981; p. 287). Tropical America (Waterhouse, 1994; p. 20).

Presence:

Pacific
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
Commonwealth of the Northern Mariana Islands (US)
Northern Mariana Islands
Agrigan (Agrihan) Island introduced
Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 69)
Commonwealth of the Northern Mariana Islands (US)
Northern Mariana Islands
Agrigan (Agrihan) Island introduced
invasive
Fosberg, F. R./Falanruw, M. V. C./Sachet, M.-H. (1975) (p. 23)
Voucher cited: Fosberg 31432 (US)
Commonwealth of the Northern Mariana Islands (US)
Northern Mariana Islands
Alamagan Island   Wagner, W. L./ Herbst, D. R./Weitzman, A./Lorence, D.H. (2013)
Commonwealth of the Northern Mariana Islands (US)
Northern Mariana Islands
Anatahan Island introduced
invasive
Fosberg, F. R./Falanruw, M. V. C./Sachet, M.-H. (1975) (p. 23)
Voucher cited: Kanehira 2147 (K)
Commonwealth of the Northern Mariana Islands (US)
Northern Mariana Islands
Maug Island   Wagner, W. L./ Herbst, D. R./Weitzman, A./Lorence, D.H. (2013)
Commonwealth of the Northern Mariana Islands (US)
Northern Mariana Islands
Pagan Island introduced
Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 69)
Commonwealth of the Northern Mariana Islands (US)
Northern Mariana Islands
Pagan Island introduced
invasive
Fosberg, F. R./Falanruw, M. V. C./Sachet, M.-H. (1975) (p. 23)
Voucher cited: Fosberg 31363 (US)
Commonwealth of the Northern Mariana Islands (US)
Northern Mariana Islands
Rota Island introduced
Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 69)
Commonwealth of the Northern Mariana Islands (US)
Northern Mariana Islands
Rota Island introduced
invasive
Space, James C./Waterhouse, Barbara/Denslow, Julie S./Nelson, Duane (2000) (p. Voucher specimen)
Voucher: BMW 5817 (BISH)
Commonwealth of the Northern Mariana Islands (US)
Northern Mariana Islands
Rota Island   National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (1966) (voucher ID: PTBG 26632)
Taxon name on voucher: Amaranthus spinosus
Commonwealth of the Northern Mariana Islands (US)
Northern Mariana Islands
Saipan Island introduced
Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 69)
Commonwealth of the Northern Mariana Islands (US)
Northern Mariana Islands
Tinian Island introduced
Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 69)
Commonwealth of the Northern Mariana Islands (US)
Northern Mariana Islands
Tinian Island   National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (1982) (voucher ID: PTBG 26475)
Taxon name on voucher: Amaranthus spinosus
Ecuador (Galápagos Islands)
Floreana Group
Floreana Island introduced
invasive
Charles Darwin Foundation (2008)
Ecuador (Galápagos Islands)
Isabela Group
Isabela Island introduced
invasive
Charles Darwin Foundation (2008)
Ecuador (Galápagos Islands)
Isabela Group
Volcán Sierra Negra, Isabela Island introduced
invasive
Charles Darwin Foundation (2008)
Ecuador (Galápagos Islands)
San Cristóbal Group
San Cristóbal Island introduced
invasive
Charles Darwin Foundation (2008)
Ecuador (Galápagos Islands)
Santa Cruz Group
Santa Cruz Island introduced
invasive
Charles Darwin Foundation (2008)
Federated States of Micronesia
Yap Islands
Ulithi Atoll introduced
invasive
Whistler, W. A./Steele, O. (1999) (p. 31)
Federated States of Micronesia
Yap Islands
Yap (Waqab) Island introduced
Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 69)
Fiji
Fiji Islands
Taveuni Island introduced
invasive
Smith, Albert C. (1981) (p. 287)
Voucher cited: DA 8881
Fiji
Fiji Islands
Vanua Levu Island introduced
invasive
Smith, Albert C. (1981) (p. 287)
Voucher cited: DA 9110
Fiji
Fiji Islands
Viti Levu Island introduced
invasive
Smith, Albert C. (1981) (p. 287)
Voucher cited: DA L.26246
French Polynesia
Tuamotu Archipelago
Makatea (Ma‘atea) Island introduced
invasive
Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013)
Adventice
French Polynesia
Austral (Tubuai) Islands
Raivavae (Raevavae) Island introduced
invasive
Florence, J. (2004) (pp. 65-66)
French Polynesia
Austral (Tubuai) Islands
Tubuai Island introduced
invasive
Florence, J. (2004) (pp. 65-66)
Guam
Guam Island
Guam Island introduced
invasive
Stone, Benjamin C. (1970) (p. 268)
Guam
Guam Island
Guam Island introduced
Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 69)
Guam
Guam Island
Guam Island   National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (1966) (voucher ID: PTBG 26631)
Taxon name on voucher: Amaranthus spinosus
State of Hawaii
Hawaiian Islands
Hawai‘i (Big) Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 188-189)
State of Hawaii
Hawaiian Islands
Kaho‘olawe Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 188-189)
State of Hawaii
Hawaiian Islands
Kaua‘i Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 188-189)
State of Hawaii
Hawaiian Islands
Kure Atoll introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 188-189)
State of Hawaii
Hawaiian Islands
Kure Atoll introduced
Starr, Forest/Martz, Kim/Loope, Lloyd (2001) (p. 8)
Previously reported, not observed in this survey.
State of Hawaii
Hawaiian Islands
Lāna‘i Island introduced
invasive
Oppenheimer, Hank L. (2003) (p. 5)
Voucher cited: Oppenheimer H40124 (BISH, PTBG)
State of Hawaii
Hawaiian Islands
Maui Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 188-189)
State of Hawaii
Hawaiian Islands
Moloka‘i Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 188-189)
State of Hawaii
Hawaiian Islands
O‘ahu Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 188-189)
Japan (offshore islands)
Ogasawara (Bonin) Islands
Bonin (Ogasawara) Islands introduced
Kato, Hidetoshi (2007)
Kiribati
Tungaru (Gilbert) Islands
Tarawa Atoll introduced
invasive
Whistler, W. A./Steele, O. (1999) (p. 31)
Marshall Islands
Ralik Chain
Kwajalein (Kuwajleen) Atoll introduced
Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 69)
Marshall Islands
Ralik Chain
Kwajalein (Kuwajleen) Atoll introduced
invasive
Whistler, W. A./Steele, O. (1999) (p. 31)
Vouchers cited: Wagner 3382, Fosberg 31174. Not seen on this survey and may no longer be present.
Marshall Islands
Ralik Chain
Kwajalein (Kuwajleen) Atoll introduced
invasive
Fosberg, F. R. (1955) (p. 9)
Voucher cited: Fosberg 31174 (US)
Nauru
Nauru Island
Nauru Island introduced
invasive
cultivated
Thaman, R. R./Fosberg, F. R./Manner, H. I./Hassall, D. C. (1994) (p. 85)
Voucher cited: Hassall 140 (SUVA)
New Caledonia
New Caledonia
New Caledonia Islands   Swarbrick, John T. (1997) (p. 88)
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. 11)
Voucher cited: MacKee 8233
Palau
Palau (Belau ) (main island group)
Angaur (Ngeaur) Island introduced
Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 69)
Papua New Guinea
Bismarck Archipelago
Bismarck Archipelago invasive
Peekel, P. G. [translated by E. E. Henty] (1984) (p. 165)
Common weed throughout the tropics. In many places planted as a vegetable.
Papua New Guinea
Papua New Guinea (eastern New Guinea Island)
Papua New Guinea (eastern New Guinea Island) invasive
Henty, E. E./Pritchard, G. H. (1975) (p. 55)
From low altitudes to at least 1000 m.
Papua New Guinea
Papua New Guinea (eastern New Guinea Island)
Papua New Guinea (eastern New Guinea Island)   Waterhouse, D. F. (1997) (p. 59)
Papua New Guinea
Papua New Guinea (eastern New Guinea Island)
Papua New Guinea (eastern New Guinea Island) introduced
invasive
Womersley, John S., ed. (1978) (p. 27)
Philippines
Philippine Islands
Philippine Islands introduced
invasive
Waterhouse, D. F. (1993) (pp. 63, 76)
Philippines
Philippine Islands
Philippine Islands probably introduced
invasive
Merrill, Elmer D. (1923) (p. 128)
A weed in open waste places, gregarious and abundant along sand bars and margins of streams; probably introduced.
Samoa
Western Samoa Islands
Upolu Island   Whistler, W. A. (1988) (p. 6)
Solomon Islands
Solomon Islands
Solomon Islands   Swarbrick, John T. (1997) (p. 88)
Solomon Islands
Solomon Islands
Solomon Islands native
Hancock, I. R./Henderson, C. P. (1988) (p. 46)
United States (other Pacific offshore islands)
Johnston Atoll
Johnston Island introduced
invasive
Amerson, A. Binion, Jr./Shelton, Philip C. (1976) (p. 55)
United States (other Pacific offshore islands)
Midway Atoll
Midway Atoll introduced
invasive
Starr, Forest/Martz, Kim/Loope, Lloyd L. (2002) (p. 17)
Voucher cited: Starr & Martz 990507-2 (BISH)
United States (other Pacific offshore islands)
Midway Atoll
Sand Island introduced
invasive
Starr, Forest/Starr, Kim/Loope, Lloyd (2008) (pp. B-3)
Vanuatu
New Hebrides Islands
Vanuatu (Republic of) introduced
invasive
Shine, C./Reaser, J. K./Gutierrez, A. T., eds. (2003) (p. 179)
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)
Queensland introduced
invasive
Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 121-123)
Cambodia
Cambodia
Cambodia (Kingdom of) introduced
invasive
Waterhouse, D. F. (1993) (pp. 63, 76)
Central America
Central America (Pacific rim)
El Salvador (Republic of)   Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 121-123)
Central America
Central America (Pacific rim)
Honduras (Republic of)   Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 20)
Central America
Central America (Pacific rim)
Nicaragua (Republic of)   Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 121-123)
China
China
China (People's Republic of) probably introduced
invasive
Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013)
"Waste places, gardens".
China
China
China (People's Republic of)   Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 20)
China
China
Hong Kong native
Wu, Te-lin (2001) (p. 78)
Indonesia
Indonesia
Indonesia (Republic of) introduced
invasive
Waterhouse, D. F. (1993) (pp. 63, 76)
Japan
Japan
Japan (country) introduced
invasive
Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 121-123)
Japan
Japan
Japan (country) introduced
Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 182)
North Korea
North Korea
North Korea (Democratic People's Republic of)   Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 20)
South Korea
South Korea
South Korea (Republic of)   Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 20)
Malaysia
Malaysia
Malaysia (country of) introduced
invasive
Waterhouse, D. F. (1993) (pp. 63, 76)
Mexico
Mexico
Mexico (United Mexican States)   Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 121-123)
New Zealand
New Zealand
New Zealand (country) introduced
invasive
Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 108)
"Known from Whangarei only".
Singapore
Singapore
Singapore (Republic of) introduced
invasive
Waterhouse, D. F. (1993) (pp. 63, 76)
Singapore
Singapore
Singapore (Republic of) introduced
invasive
Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. (2009) (p. 12)
Naturalised
South America (Pacific rim)
South America (Pacific rim)
Colombia (Republic of)   Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 121-123)
South America (Pacific rim)
South America (Pacific rim)
Perú (Republic of)   Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 121-123)
Taiwan
Taiwan Island
Taiwan Island introduced
invasive
Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 121-123)
Thailand
Thailand
Thailand (Kingdom of) introduced
invasive
Waterhouse, D. F. (1993) (pp. 63, 76)
Vietnam
Vietnam
Vietnam (Socialist Republic of) introduced
invasive
Waterhouse, D. F. (1993) (pp. 63, 76)
Indian Ocean
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
Australia (Indian Ocean offshore islands)
Christmas Island Group
Christmas Island introduced
invasive
Orchard, Anthony E., ed. (1993) (p. 16)
Maldives
Maldive Islands
Malè Atoll   Fosberg, F. R. (1957) (p. 18)
Mauritius
Mautitius Islands (Mauritius and Rodrigues)
Mauritius Island introduced
invasive
Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 121-123)

Comments:  Listed as present in the Cook Islands by Swarbrick (1997) but not known to Bill Sykes and no specimen known.

Control: 

Chemical: "Sensitive to hormone type herbicides, especially when young.  Sensitive to glyphosate"  (Motooka et al., 2003).

Biological:  "Mass rearing and release, as required, of the weevil Hypolixus trunculatus is reported to provide good control in Thailand but, of course, this  is augmentative rather than classical biological control"  (Waterhouse, 1994; p. 19).  Waterhouse (1994, pp. 21-24) also lists natural enemies of the species.


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This page was created on 26 JUL 2002 and was last updated on 21 JUN 2010.