Amaranthus deflexus L., Amaranthaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Common name(s): [more details]

English: Argentine amaranth, deflexed amaranth, large-fruit amaranth, low amaranth, perennial pigweed, prostrate amaranth, spreading amaranth

Habit:  herb

Description:  "Plants short-lived perennial or annual, pubescent in distal parts of plant or becoming glabrescent at maturity. Stems ascending or prostrate, profusely branched basally, radiating from rootstock, mostly 0.2-0.5 m. Leaves: petiole 1/2 as long as to equaling blade; blade rhombic-ovate or ovate to lanceolate, 1-2 x 0.5-1 cm, base tapering or cuneate, margins entire, plane or slightly undulate, apex subacute, obtuse, or retuse or shallowly emarginate, mucronulate. Inflorescences terminal, erect, compact, pyramidal panicles and also some axillary clusters, green or silvery green, occasionally tinged with red, leafless at least distally. Bracts of pistillate flowers linear, 0.5-1 mm, 1/2 as long as tepals. Pistillate flowers: tepals 2-3, narrowly elliptic or oblanceolate, not clawed, equal or subequal, 1.2-2 mm, apex broadly acute; style branches erect; stigmas 3. Staminate flowers clustered at tips of inflorescences; tepals 2-3; stamens 2-3. Utricles marked with 2(-3) green lines that intersect at apex and divide fruit into halves or quarters, slightly to distinctly inflated, ellipsoid, 2-3 mm, distinctly longer than tepals, smooth (in dry plants wrinkled or rugose), indehiscent. Seeds very dark brown to black, 1-1.2 mm in diameter, shiny, filling only proximal portion of fruit"  (Flora of North America online).

Description from Flora of New Zealand.

Habitat/ecology:  In North America, "ballast heaps, railroads, other disturbed habitats; 0-500 m"  (Flora of North America online).  In New Zealand, "waste places, especially on shingle or gravel, particularly around settled areas"  (Webb et al., 1988; p. 104).

Propagation:  Seed

Native range:  Bolivia (possibly), southern Peru, Argentina; naturalized worldwide (GRIN).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced invasive	Atkinson, Rachel/Sawyer, John (2011)
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced invasive	Danton, Philippe/Perrier, Christophe/Martinez Reyes, Guido (2006) (p. 551)
Chile (offshore islands) Juan Fernández Islands	Isla Más Afuera (Alejandro Selkirk Island)	introduced invasive	Atkinson, Rachel/Sawyer, John (2011)
Chile (offshore islands) Juan Fernández Islands	Isla Más Afuera (Alejandro Selkirk Island)	introduced invasive	Danton, Philippe/Perrier, Christophe/Martinez Reyes, Guido (2006) (p. 551)

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)	New South Wales	introduced invasive	National Herbarium of New South Wales (2011) Naturalised
Japan Japan	Japan (country)	introduced	Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 182)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 104)
Perú Perú	Perú (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
United States (west coast) United States (west coast states)	USA (Oregon)	introduced	Flora of North America Editorial Committee, eds. (2011)
United States (west coast) United States (west coast states)	USA (California)	introduced	Flora of North America Editorial Committee, eds. (2011)

Also reported from
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
United States (continental except west coast) United States (other states)	United States (other states)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011) Ala., Fla., Ga., La., Mass., N.J., N.Y., Pa., Tenn., Va.

Additional information:
Fact sheet from the University of California.

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

Information about Amaranthus deflexus as a weed (worldwide references) may be available from the Global Compendium of Weeds (GCW).

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

References:

Atkinson, Rachel/Sawyer, John. 2011. Naturalized species in the Juan Fernández Archipelago, Chile. Unpublished spreadsheet.

Danton, Philippe/Perrier, Christophe/Martinez Reyes, Guido. 2006. Nouveau catalogue de la flore vaculaire de l'archipel Juan Fernández (Chile) [Nuevo catálogo de la flora vacular del Archipélago Juan Fernández (Chile)]. Acta Bot. Gallica 153(4):399-587.

Flora of North America Editorial Committee, eds. 2011. Flora of North America North of Mexico (online edition).

Mito, Toshikazu/Uesugi, Tetsuro. 2004. Invasive alien species in Japan: the status quo and the new regulation for prevention of their adverse effects. Global Environmental Research 8(2)/2004: 171-191.

National Herbarium of New South Wales. 2011. PlantNet: New South Wales Flora online. The Plant Information Network System of the Botanic Gardens Trust Version 2.0. Online resource.

U.S. Dept. Agr., Agr. Res. Serv. 2011. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

U.S. Dept. Agr., Nat. Res. Cons. Serv. 2011. The PLANTS Database. National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

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.