Amaranthus hybridus L., Amaranthaceae

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Present on Pacific Islands?  yes

Threat only at high elevations?  no

Common name(s): [more details]

English: green amaranth, green pigweed, hybrid amaranth, prince's feather, red root, slim amaranth, smooth amaranth, smooth pigweed

Fijian: ndriti

Japanese: hosoaogeito

Spanish: amaranto, bledo, blero, lero, moco de pavo, penacho, quelite, visnaga, yuyo, yuyo hembra

Habit:  herb

Description:  "Monoecious annual herbs 10-20 (-30) dm tall; stems often tinged reddish, erect, occasionally ascending, branched, striate, glabrous to moderately pubescent with multicellular hairs.  Leaves lanceolate to ovate or rhombic, blades 3-19 (-30) cm long, 1.5-8 (-12) cm wide, lower surface glabrous or sparsely pilose along the margins and veins, petioles 0.5-15 cm long.  Flowers yellowish green, reddish, or purple, in axillary and terminal spikes, both sexes mixed throughout the spikes, bracts and bracteoles deltate-ovate, tipped with a long, pale brown to reddish awn; sepals 5, 1.5-3.5 mm long, lanceolate or oblong, apex acute, often awn-tipped, sometimes the apex of pistillate flowers blunt, only the midrib green; stigmas (2) 3.  Fruit subglobose to ovoid, sometimes with a short, inflated or narrow and smooth neck below base of style, 2-3 mm long, dehiscent with a circumscissile lid, the lid smooth.  Seeds black, sometimes shiny, compressed, 0.8-1.3 mm long, faintly reticulate near the margins."  (Wagner et al., 1999; p. 188)

Subsp. hybridus: "The bracteoles of the pistillate flowers are usually 1.5-2 times longer than the sepals and the fruit has a distinct inflated neck" (Wagner et al.,1999; p. 188).

See also A. cruentus.

Habitat/ecology:  In Hawai‘i, "sparingly naturalized at low elevations" (Wagner et al.,1999; p. 188).

Propagation:  "Reproducing from its many seeds, hundreds of which may be produced by each flowering branch, the plant makes rapid early growth, competing quickly with crops"  (Holm et al., 1977; p. 114).

Native range:  "Apparently indigenous to mild, moist regions from eastern North America to northern South America, the species has now acquired a broad distribution as a naturalized weed" (Smith, 1981; pp. 288-289).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Fiji Fiji Islands	Ovalau Island	introduced invasive cultivated	Smith, Albert C. (1981) (pp. 288-289) Voucher cited: Seemann 367 Garden escape.
Fiji Fiji Islands	Viti Levu Island	introduced invasive cultivated	Smith, Albert C. (1981) (pp. 288-289) Voucher cited: DA 12182 Garden escape.
French Polynesia Society Islands	Tahiti Island	introduced cultivated	Florence, J. (2004) (p. 65) subsp. cruentus (L.) A. Thellung var. paniculatus (L.) A. Thellung
French Polynesia Tubuai (Austral) Islands	Tubuai (Tupuai) Island	introduced cultivated	Florence, J. (2004) (p. 65) subsp. cruentus (L.) A. Thellung var. paniculatus (L.) A. Thellung
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 188) subsp. hybridus Sparingly naturalized.
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 188) subsp. hybridus Sparingly naturalized.
Kiribati Line Islands	Teraina (Washington) Island	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)

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. 116-118)
Chile (continental) Chile	Chile (Republic of)	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 116-118)
Colombia Colombia	Colombia (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Costa Rica Costa Rica	Costa Rica (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
El Salvador El Salvador	El Salvador (Republic of)	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 116-118)
Guatemala Guatemala	Guatemala (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Indonesia Indonesia	Indonesia (Republic of)	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 116-118)
Japan Japan	Japan (country)	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 116-118)
Mexico Mexico	Mexico (United Mexican States)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 106)
Nicaragua Nicaragua	Nicaragua (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Panama Panama	Panama (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Perú Perú	Perú (Republic of)	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 116-118)
Thailand Thailand	Thailand (Kingdom of)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 19)
United States (west coast) United States (west coast states)	USA (California)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)

Additional information:  Additional online information about Amaranthus hybridus is available from the Hawaiian Ecosystems at Risk project (HEAR).

Taxonomic information about Amaranthus hybridus may be available from the Germplasm Resources Information Network (GRIN).

References:

Charles Darwin Research Station. 2005. CDRS Herbarium records.

Florence, J. 2004. Flore de la Polynésie française, Vol. 2. Paris. IRE Editions, Publications Scientifiques, Collection Faune et Flore Tropicales 41. 503 pp.

Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. 1977. The world’s worst weeds: distribution and biology. East-West Center/University Press of Hawaii. 609 pp.

Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. 1979. A geographical atlas of world weeds. John Wiley & Sons, New York. 391 pp.

Smith, Albert C. 1981. Flora Vitiensis nova: a new flora of Fiji. National Tropical Botanical Garden, Lawai, Kauai, Hawaii. Volume 2. 810 pp.

Thaman, R. R./Fosberg, F. R./Manner, H. I./Hassall, D. C. 1994. The flora of Nauru. Smithsonian Institution, Washington. Atoll Research Bulletin 392:1-223.

U.S. Dept. Agr., Agr. Res. Serv. 2007. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. 1999. Manual of the flowering plants of Hawaii. Revised edition. Bernice P. Bishop Museum special publication. University of Hawai‘i Press/Bishop Museum Press, Honolulu. 1919 pp. (two volumes).

Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. 1988. Flora of New Zealand, Volume IV: Naturalised pteridophytes, gymnosperms, dicotyledons. Botany Division, DSIR, Christchurch. 1365 pp.