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

Filipino: gitin-gitin

French: épinard cochon, épinard malabre, brède malabar à piquants, 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	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
Commonwealth of the Northern Mariana Islands (US) Saipan	Saipan Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 69)
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	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 121-123)
Japan Japan	Japan	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		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.