Amaranthus blitum L., Amaranthaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Other Latin names:  Amaranthus lividus L.

Common name(s): [more details]

Chinese: ao tou xian

English: Guernsey pigweed, livid amaranth, purple amaranth, slender amaranth

French: amarante livide

Spanish: bledo

Tahitian: upooti

Tongan: tupu‘a

Habit:  herb

Description:  "Monoecious annual herbs; stems sometimes tinged reddish or yellowish; erect, ascending, or prostrate, 0.6-6 (-9) dm long, unbranched or branched, striate, glabrous, rarely with unicellular to multicellular short hairs, especially above.  Leaves ovate to rhombic-ovate, blades 1-8 cm long, 0.6-6 cm wide, glabrous, rarely the lower surface with scattered multicellular hairs along the veins, apex usually broad, widely emarginate, petioles 0.5-10 cm long.  Flowers green, in slendere to stout axillary or terminal spikes, rarely panicles, both sexes mixed throughout the spikes, bracts and bracteoles whitish, deltate-ovate to lanceolate, membranous, tipped with a short yellow or reddish mucro; sepals 3 (4), lanceolate-oblong to spatulate, 0.7-2 mm long, apex subacute, mucronate, apex of pistillate flowers often more blunt; stigmas 2-3.  Fruit globose to pyriform, compressed, exceeding the sepals, 1.2-2.5 mm long, indehiscent or rupturing irregularly at maturity, the surface smooth, occasionally wrinkled upon drying.  Seeds dark brown to black, shiny, the margins duller, compressed, 1-1.8 mm long, faintly reticulate, minutely punctate-roughened"  (Wagner et al., 1999; p. 188).

Description from the Flora of China online.
Description from the Flora of North America online.

Habitat/ecology:  In Hawai‘i, "apparently sparingly naturalized in disturbed areas "(Wagner et al., 1999; p. 188).  In Papua New Guinea, "a weed of cultivation and plantations, to some extent grown in food gardens, the leaves being used as spinach" (Henty & Pritchard, 1975; p. 54); occurring as a weed along roads, in clearings and plantations, at 1200-2000 m altitude"  (Womersley, 1978; p.27). "Occasional in vegetable crops and disturbed places" (Whistler, 1988; p. 6). In New Zealand, "waste places, cultivated ground; uncommon" (Webb et al., 1988; p. 103).

Propagation:  Seed

Native range:  Europe, Africa and/or Asia; exact native range obscure; widely naturalized (GRIN).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
American Samoa Tutuila Islands	Tutuila Island		Swarbrick, John T. (1997) (p. 88)
American Samoa Tutuila Islands	Tutuila Island		Anon. (1988) (p. 1)
Australia (Pacific offshore islands) Lord Howe Island	Lord Howe Island	introduced invasive	Orchard, Anthony E., ed. (1994) (p. 18) "A weed of disturbed ground". Vouchers cited: J. Pickard 2952 (NSW), A.C. Beauglehole 5522 (MEL), J.D. McComish 198 (NSW)
Australia (Pacific offshore islands) Norfolk Islands	Norfolk Island	introduced	Orchard, Anthony E., ed. (1994) (p. 7) "A weed of disturbed ground". Vouchers cited: R.O. Gardner 5769 (AK), P.S. Green 2445 (K), P.S. Green 2444 (K)
Ecuador (Galápagos Islands) Isabela Group	Isabela Island	introduced invasive	Charles Darwin Foundation (2008) As Amaranthus lividus = Amaranthus blitum L. subsp. oleraceus (L.) Costea
Ecuador (Galápagos Islands) Isabela Group	Volcán Alcedo, Isabela Island	introduced invasive	Charles Darwin Foundation (2008)
Ecuador (Galápagos Islands) Isabela Group	Volcán Sierra Negra, Isabela Island	introduced invasive	Charles Darwin Foundation (2008) As Amaranthus lividus
Ecuador (Galápagos Islands) San Cristóbal Group	San Cristóbal Island	introduced invasive	Charles Darwin Foundation (2008) As Amaranthus lividus = Amaranthus blitum L. subsp. oleraceus (L.) Costea
Ecuador (Galápagos Islands) Santa Cruz Group	Santa Cruz Island	introduced invasive	Charles Darwin Foundation (2008) As Amaranthus lividus = Amaranthus blitum L. subsp. oleraceus (L.) Costea
French Polynesia Society Islands	Mehetia (Mahetia, Meetia) Island	introduced invasive	Florence, J. (2004) (pp. 61-62) subsp. polygonoides (C.H.B.A. Moquin-Tandon) R. Probst
French Polynesia Society Islands	Mehetia (Mahetia, Meetia) Island	introduced invasive	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013) As Amaranthus lividus C. Linnaeus. Voucher cited: J. Florence 10296 (PAP) Adventice
French Polynesia Society Islands	Tahiti Island	introduced invasive	Florence, J. (2004) (pp. 61-62) subsp. polygonoides (C.H.B.A. Moquin-Tandon) R. Probst
French Polynesia Society Islands	Tahiti Island	introduced invasive	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013) subsp. polygonoides (C.H. Moquin-Tandon) R. Probst. "Mauvaise herbe dans l'ombrière du jardin". Voucher cited: J. Florence 2814 (PAP) Adventice
French Polynesia Austral (Tubuai) Islands	Rimatara (Rimitara) Island	introduced invasive	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013) subsp. polygonoides (C.H. Moquin-Tandon) R. Probst Adventice
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 188) Sparingly naturalized.
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 188) Sparingly naturalized.
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 188) Voucher cited: K. Nagata 910 (BISH) Sparingly naturalized.
Japan (offshore islands) Ogasawara (Bonin) Islands	Bonin (Ogasawara) Islands	introduced	Kato, Hidetoshi (2007)
Marshall Islands Ralik Chain	Jaluit (Jãlwõj) Atoll	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 68) var. oleraceus
Niue Niue	Niue Island	invasive	Whistler, W. A. (1988) (p. 6) Voucher cited: Sykes 341
Papua New Guinea Papua New Guinea (eastern New Guinea Island)	Papua New Guinea (eastern New Guinea Island)	introduced invasive cultivated	Henty, E. E./Pritchard, G. H. (1975) (p. 54) From near sea level to over 2000 m.
Papua New Guinea Papua New Guinea (eastern New Guinea Island)	Papua New Guinea (eastern New Guinea Island)	introduced invasive	Womersley, John S., ed. (1978) (pp. 26-27)
Samoa Western Samoa Islands	Savai‘i Island		Whistler, W. A. (1988) (p. 6)
Samoa Western Samoa Islands	Upolu Island		Whistler, W. A. (1988) (p. 6)
Tonga Tongatapu Group	‘Eua Island		Yuncker, T. G. (1959) (p. 107) Voucher cited: Yuncker 15643
Tonga Tongatapu Group	Tongatapu Island		Whistler, W. A. (1992) (p. 2) Voucher cited: Soakai 970
Tuvalu Tuvalu (Ellis) Islands	Tuvalu Islands		Swarbrick, John T. (1997) (p. 88)
United States (other Pacific offshore islands) Midway Atoll	Midway Atoll	introduced invasive	Bruegmann, Marie M. (1999) (p. 1) subsp. polygonoides (Moq.) Probst; voucher cited: Bruegmann 2018 (BISH) Naturalized but rare.

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
China China	China (People's Republic of)	native	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) Fields, waste places.
China China	Hong Kong	native	Wu, Te-lin (2001) (p. 78)
Indonesia Indonesia	Indonesia (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Japan Japan	Japan	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Malaysia Malaysia	Malaysia (country of)		Waterhouse, D. F. (1993) (p. 63)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 103) As A. lividus L.
Singapore Singapore	Singapore (Republic of)	introduced invasive	Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. (2009) (p. 12) ssp. oleraceus (L.) Costea. Naturalised
Taiwan Taiwan Island	Taiwan Island	native	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) Fields, waste places.
Thailand Thailand	Thailand (Kingdom of)		Waterhouse, D. F. (1993) (p. 63)
Vietnam Vietnam	Vietnam (Socialist Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)

Control:  If you know of control methods for Amaranthus blitum, please let us know.