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Redroot Amaranth

Amaranthus retroflexus L.

Associations

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In Great Britain and/or Ireland:
Foodplant / parasite
sorus of Albugo bliti parasitises live leaf of Amaranthus retroflexus

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Comments

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One of us (Clemants) does not recognize the following varieties.
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Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
bibliographic citation
Flora of China Vol. 5: 419 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
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Flora of China @ eFloras.org
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Wu Zhengyi, Peter H. Raven & Hong Deyuan
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Comments

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Amaranthus retroflexus, native to central and eastern North America, is a successful invasive species and has effectively colonized a wide range of habitats on all inhabited continents. Its variability is extremely wide; usually the species is easily recognized and its identification causes no specific problems. Infraspecific entities described within A. retroflexus are mostly ecologic variants of little or no taxonomic value. Two varieties are more easily recognized: the common var. retroflexus, with bracts about 1.5-2 times as long as tepals, and a more rare var. delilei (Richter & Loret) Thellung (= A. delilei Richter & Loret), with bracts 1-1.5 times as long as tepals.

Occasional forms morphologically intermediate between Amaranthus retroflexus and taxa of the A. hybridus aggregate (e.g., A. powellii and A. hybridus, in the strict sense) are known both in the Americas and the Old World. Usually such plants are treated as hybrids; in many cases they are probably just extremes of the natural variability of A. retroflexus. Putative hybrids of A. retroflexus were described from Europe as A. ×ozanonii Thellung (A. hybridus × A. retroflexus) and A. ×soproniensis Priszter & Karpáti (A. powellii × A. retroflexus) (see A. Thellung 1914-1919; S. Priszter 1958; P. Aellen 1959; F. Grüll and S. Priszter 1973).

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Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
bibliographic citation
Flora of North America Vol. 4: 422 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
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Flora of North America @ eFloras.org
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Flora of North America Editorial Committee
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Description

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Stem erect, light green, 20-80 cm tall, stout, branched or not, slightly obtusely angulate, densely pubescent. Petiole light green, 1.5-5.5 cm, hairy; leaf blade ovate-rhombic or elliptic, 5-12 × 2-5 cm, both surfaces shortly hairy, but densely hairy abaxially, base cuneate, margin entire and undulate, apex acute or notched, with a mucro. Complex thyrsoid structures terminal and axillary, erect, 2-4 cm in diam., including many spikes; terminal spikes longer than lateral ones. Bracts and bracteoles white, subulate, 4-6 mm, apex slenderly long pointed. Tepals white, oblong or oblong-obovate, 2-2.5 mm, membranous, with a green midvein, apex acute or notched, with a mucro. Stamens slightly longer than perianth. Stigmas 3, rarely 2. Utricles light green, ovoid, compressed, shorter than perianth, circumscissile. Seeds brown or black, subglobose, ca. 1 mm in diam., obtuse at margin. Fl. Jul-Aug, fr. Aug-Sep. 2n = 32*, 34*, 102*.
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cc-by-nc-sa-3.0
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Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
bibliographic citation
Flora of China Vol. 5: 419 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
source
Flora of China @ eFloras.org
editor
Wu Zhengyi, Peter H. Raven & Hong Deyuan
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eFloras.org
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Description

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Plants densely to moderately pubescent, especially distal parts of stem and branches. Stems erect, reddish near base, branched in distal part to simple 0.2-1.5(-2) m; underdeveloped or damaged plants rarely ascending to nearly prostrate. Leaves: petiole 1/2 to equaling blade; blade ovate to rhombic-ovate, 2-15 × 1-7 cm, base cuneate to rounded-cuneate, margins entire, plane or slightly undulate, apex acute, obtuse, or slightly emarginate, with terminal mucro. Inflorescences terminal and axillary, erect or reflexed at tip, green or silvery green, often with reddish or yellowish tint, branched, leafless at least distally, usually short and thick. Bracts lanceolate to subulate, (2.5-)3.5-5(-6) mm, exceeding tepals, apex acuminate with excurrent midrib. Pistillate flowers: tepals 5, spatulate-obovate, lanceolate-spatulate, not clawed, subequal or unequal, (2-)2.5-3.5(-4) mm, membranaceous, apex emarginate or obtuse, with mucro; style branches erect or slightly spreading,; stigmas 3. Staminate flowers few at tips of inflorescences; tepals 5; stamens (3-)4-5. Utricles broadly obovoid to broadly elliptic, 1.5-2.5 mm, shorter than or subequal to tepals, smooth or slightly rugose, especially near base and in distal part, dehiscence regularly circumscissile. Seeds black to dark reddish brown, lenticular to subglobose-lenticular, 1-1.3 mm, smooth, shiny.
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Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
bibliographic citation
Flora of North America Vol. 4: 422 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
source
Flora of North America @ eFloras.org
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Flora of North America Editorial Committee
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Description

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Annual herb, erect or with ascending branches, (6-) 15-80 (-100) cm, simple or branched (especially from the base to about the middle of the stem). Stem stout, sub-terete to angled, densely furnished with multicellular hairs. Leaves furnished with multicellular hairs along the lower surface of the primary venation and often the lower margins, long-petiolate (petioles up to c. 6 cm, in robust plants not rarely equalling the lamina), lamina ovate to rhomboid or oblong-ovate, (1-) 5-11 x (0.6-) 3-6 cm, obtuse to subacute at the mucronulate tip, shortly cuneate or attenuate into the petiole. Flowers in greenish or rarely somewhat pink-suffused, stout, axillary and terminal spikes, which are usually shortly branched to give a lobed appearance, more rarely with longer branches, the terminal inflorescence paniculate, very variable in size, male and female flowers intermixed, the latter generally much more plentiful except sometimes at the tip of the spikes. Bracts and bracteoles lanceolate-subulate, pale-membranous with a prominent green midrib excurrent into a stiff, colourless arista, longer bracteoles subequalling to twice as long as the perianth. Perianth segments 5, those of the male flowers 1.75-2.25 mm, lanceolate-oblong, blunt to subacute, those of the female flowers 2-3 mm, narrowly oblong-spathulate to spathulate, obtuse or emarginate, ± green-vittate along the midrib, which ceases below the apex or is excurrent in a short mucro. Stigmas 2-3, patent-flexuose or erect, c. 1 mm. Capsule subglobose, c. 2 mm, usually shorter than the perianth, circumscissile, with an indistinct neck, rugose below the lid. Seed black and shining, compressed, c. 1 mm, almost smooth centrally, faintly reticulate around the margins.
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Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
bibliographic citation
Flora of Pakistan Vol. 0: 12 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
source
Flora of Pakistan @ eFloras.org
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S. I. Ali & M. Qaiser
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Distribution

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St. Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Nunavut, Ont., P.E.I., Que., Sask.; Ala., Alaska, Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo.; introduced and naturalized nearly worldwide.
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copyright
Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
bibliographic citation
Flora of North America Vol. 4: 422 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
source
Flora of North America @ eFloras.org
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Flora of North America Editorial Committee
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Distribution

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Distribution: A native of N. America south to N. Mexico; introduced into the Old World as a weed, but in more temperate regions than many of its allies, occurring in S. and C. Europe, Mediterranean N. Africa and temperate Asia from Cyprus and Turkey to Iran, Siberia, Middle Asia, Mongolia, China and Japan. Also adventive in Australia and S. America (Bolivia etc.) and probably elsewhere. Generally occurs as a weed of cultivation, occurring as such in the cooler parts of Pakistan, ascending to 1820 m or more.
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Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
bibliographic citation
Flora of Pakistan Vol. 0: 12 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
source
Flora of Pakistan @ eFloras.org
editor
S. I. Ali & M. Qaiser
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eFloras.org
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Flowering/Fruiting

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Flowering summer-fall.
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Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
bibliographic citation
Flora of North America Vol. 4: 422 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
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Flora of North America @ eFloras.org
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Flora of North America Editorial Committee
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Habitat

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Banks of rivers, lakes, and streams, disturbed habitats, agricultural fields, railroads, roadsides, waste areas; 0-2500m.
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Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
bibliographic citation
Flora of North America Vol. 4: 422 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
source
Flora of North America @ eFloras.org
editor
Flora of North America Editorial Committee
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eFloras.org
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Habitat & Distribution

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Waste places, field margins, roadsides. Gansu, Hebei, Heilongjiang, Jilin, Liaoning, Nei Mongol, Ningxia, Shaanxi, Shandong, Shanxi, Xinjiang, Zhejiang [native origin uncertain; now cosmopolitan].
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cc-by-nc-sa-3.0
copyright
Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
bibliographic citation
Flora of China Vol. 5: 419 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
source
Flora of China @ eFloras.org
editor
Wu Zhengyi, Peter H. Raven & Hong Deyuan
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eFloras.org
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Synonym

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Amaranthus retroflexus var. salicifolius I. M. Johnston
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Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
bibliographic citation
Flora of North America Vol. 4: 422 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
source
Flora of North America @ eFloras.org
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Flora of North America Editorial Committee
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eFloras.org
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Common Names

provided by Fire Effects Information System Plants
rough pigweed
redroot pigweed
redroot amaranth
green amaranth
pigweed
wild beet
pigweed amaranth
canne
red-root pigweed
careless weed
license
cc-publicdomain
bibliographic citation
Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Cover Value

provided by Fire Effects Information System Plants
More info for the term: cover

The degree to which rough pigweed provides environmental cover for
wildlife species in several western states is as follows [7]:

North
Dakota Utah Wyoming

Pronghorn good poor poor
Elk poor poor
Mule deer good poor poor
White-tailed deer good poor
Small mammals fair fair
Small nongame birds fair fair
Upland game birds poor poor poor
Waterfowl fair poor poor
license
cc-publicdomain
bibliographic citation
Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Description

provided by Fire Effects Information System Plants
More info for the terms: fruit, herb, monoecious, utricle, woodland

Rough pigweed is an introduced, coarse, monoecious, annual herb with
taproots. It has an erect stem, 1 to 6.6 feet (0.3-2 m) tall, that is
commonly freely branched. Leaves are 0.8 to 3.9 inches (2-10 cm) long.
Inflorescences are usually densely crowded. There are often additional
dense clusters of flowers in the axils of upper leaves. The fruit is a
utricle [11,14,18,19,34].

Rough pigweed has a taproot. In pinyon-juniper (Pinus-Juniperus)
woodland in New Mexico, root depth averaged 39 inches (100 cm), with a
range of 3.9 to 95 inches (10-240 cm) [12].
license
cc-publicdomain
bibliographic citation
Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Distribution

provided by Fire Effects Information System Plants
Rough pigweed is found throughout North America, from Canada to Mexico,
and from the Atlantic to the Pacific coasts. It is also found
throughout much of the rest of the world, including Europe, South
America, Eurasia, and Africa. It is a native of tropical America
[11,14,18,19,27,35,43].
license
cc-publicdomain
bibliographic citation
Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Fire Ecology

provided by Fire Effects Information System Plants
More info for the term: fire regime

Rough pigweed seeds are an important part of the seedbank in many
habitats, even when plants are almost absent [16]. As an obligate
initial community species, rough pigweed needs bare, disturbed sites in
order to establish [26,38]. A fire which clears away competing
vegetation can allow the establishment of rough pigweed.

Rough pigweed seeds are very small [14], and easily blown by the wind
from off-site sources. Some seeds survive cattle digestion [4], and can
be carried by animals to burned areas.

FIRE REGIMES :
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page under
"Find FIRE REGIMES".
license
cc-publicdomain
bibliographic citation
Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Growth Form (according to Raunkiær Life-form classification)

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More info on this topic.

More info for the term: therophyte

Therophyte
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cc-publicdomain
bibliographic citation
Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Habitat characteristics

provided by Fire Effects Information System Plants
Rough pigweed grows in cultivated fields, gardens, orchards, fallow
land, stream valleys, shores, prairie ravines, roadsides, fence rows,
and waste places [17,34,35,43,47]. Its grows in dry to moist conditions
[7].

In Utah, rough pigweed demonstrated poor growth on gravel, dense clay,
and sodic-saline soils; fair growth on sandy, clay-loam, organic acidic,
and saline soils; and good growth on sandy loam, loam, and clay.
Optimum soil depth was 10 to 20 inches (25-50 cm) [7].

Recorded elevations for rough pigweed are [7]:

State Elevation (feet) Elevation (m)

Arizona 5,000-7,000 1,525-2,134
Colorado 4,700-9,200 1,433-2,804
Montana 2,300-9,000 700-2,743
Utah 4,400-4,700 1,341-1,433
Wyoming 4,300-7,800 1,310-2,377
license
cc-publicdomain
bibliographic citation
Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Habitat: Cover Types

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More info on this topic.

This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

More info for the term: cover

Rough pigweed occurs in most SAF Cover Types.
license
cc-publicdomain
bibliographic citation
Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Habitat: Ecosystem

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More info on this topic.

This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

Rough pigweed occurs in most ecosystems
license
cc-publicdomain
bibliographic citation
Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Habitat: Plant Associations

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More info on this topic.

This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

Rough pigweed occurs in most Kuchler Plant Associations.
license
cc-publicdomain
bibliographic citation
Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Habitat: Rangeland Cover Types

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More info on this topic.

This species is known to occur in association with the following Rangeland Cover Types (as classified by the Society for Range Management, SRM):

More info for the term: cover

Rough pigweed occurs in most SAF Cover Types.
license
cc-publicdomain
bibliographic citation
Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Importance to Livestock and Wildlife

provided by Fire Effects Information System Plants
More info for the terms: fresh, presence

Rough pigweed affects the kidneys of swine and cattle when animals
consume large quantities of fresh material for 5 to 10 days. Cattle
have developed perirenal edema and toxic nephrosis after ingesting rough
pigweed. The toxicant has not been identified, although oxalates and/or
phenolics have been suspected [37]. Additionally, rough pigweed
accumulates nitrates, which causes poisoning in most livestock species
when ingested in large quantities either fresh or in hay [6,21,44]. The
excess nitrates cause cattle to bloat [41]. In the Midwest, pigs have
been poisoned by rough pigweed growing under drought stress. In drought
conditions, rough pigweed accumulation of nitrates accelerates [28,49].

In Nebraska, cattle consumed immature leaves and tops of rough pigweed
in fields seeded to big bluestem (Andropogon gerardii var. gerardii).
By mid-July of the first year of the study, nitrate concentration had
reached toxic levels (10,000 ppm). In the second year, nitrate levels
exceeded the toxic level at the beginning of the grazing season [23].

Sheep in Texas were maintained for varying lengths of time on rough
pigweed pasture supplemented with wheat and alfalfa hays [15].

Scaled quail in Texas made use of rough pigweed seeds. When available,
seeds averaged 0.9 percent of food eaten. In the highest recorded use,
rough pigweed seeds made up 3.6 percent of food eaten. Percent use was
greater than rough pigweed presence [1].
license
cc-publicdomain
bibliographic citation
Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Life Form

provided by Fire Effects Information System Plants
More info for the term: forb

Forb
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bibliographic citation
Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Management considerations

provided by Fire Effects Information System Plants
More info for the terms: cover, forb, grassland, seed

Rough pigweed is a useful component of patchwork vegetation for scaled
quail habitat, providing both food and cover [1].

Rough pigweed is difficult to eradicate when once established [34]. A
survey of weeds in spring annual crops throughout Manitoba over a 4-year
period showed 83 weed species. Rough pigweed was the third most common
dicotyledonous weed [40]. In Kansas, it was the most abundant forb weed
in the seedbank [24].

Rough pigweed can be controlled with herbicides [30].

Cultivation reduces longevity of rough pigweed seed, apparently by
increasing soil aeration, exposing the seeds to light, and generally
improving conditions for germination. High soil temperatures favor
germination and reduce rough pigweed seed survival [8].

Rough pigweed showed no establishment in intact prairie vegetation in an
Illinois study. It did, however, establish in gaps in prairie
vegetation. Flowering and seed set increased with increasing gap size
[26].

An investigation was conducted in Nebraska as to the effect of cattle
grazing in controlling rough pigweed and other weeds in seeded
grassland. Cattle consumed immature rough pigweed, but nitrate
accumulation limited grazing rough pigweed as a weed control practice
[23].
license
cc-publicdomain
bibliographic citation
Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Nutritional Value

provided by Fire Effects Information System Plants
Rough pigweed seeds with hulls contain 18.0 percent protein [29].

The nutritional components of immature rough pigweed browse are [29]:

Component Percent

Ash 18.8
Crude Fiber 10.8
N-free Extract 43.2
Protein 25.7


The use that various animals can make of protein in rough pigweed browse
is [29]:

Percent
Animal Digestible Protein

Cattle 19.7
Goats 20.5
Horses 19.3
Rabbits 18.5
Sheep 20.9

The food value of rough pigweed for wildlife species in several western
states is rated as follows [7]:

North
Dakota Utah Wyoming

Pronghorn good fair poor
Elk fair poor
Mule deer good good poor
White-tailed deer good poor
Small Mammals fair good
Small nongame birds good good
Upland game birds good fair good
Waterfowl good poor fair

In Minnesota, rough pigweed harvested from late June to mid-July showed
a nutrient composition and digestibility for sheep equivalent to that of
high-quality alfalfa (Medicago sativa). Rough pigweed contained
adequate minerals to meet the requirements of ruminants. However, it
must be utilized at relatively early stages of maturity. Nitrate
concentration, which has been implicated in livestock poisoning, is
highest in rough pigweed just before bloom. Calcium to potassium ratio
in rough pigweed is such that it should not be fed as the sole ration
[25].
license
cc-publicdomain
bibliographic citation
Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Occurrence in North America

provided by Fire Effects Information System Plants
AL AK AZ AR CA CO CT DE FL GA
ID IL IN IA KS KY LA ME MD MA
MI MN MS MO MT NE NV NH NJ NM
NY NC ND OH OK OR PA RI SC SD
TN TX UT VT VA WA WV WI WY AB
BC MB NB NS ON PE PQ SK MEXICO
license
cc-publicdomain
bibliographic citation
Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Other uses and values

provided by Fire Effects Information System Plants
More info for the term: fresh

Young leaves of rough pigweed are used as salad greens when the plant is
only a few inches tall, before the stem becomes woody. Fresh young
plants can also be used as a potherb. Seeds are edible whole or ground
into meal. However, because rough pigweed concentrates nitrates, it
should be used in moderation, particularly when taken from
nitrate-fertilized areas [9].
license
cc-publicdomain
bibliographic citation
Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Palatability

provided by Fire Effects Information System Plants
Rough pigweed is probably unpalatable when mature because of the stiff,
spine-like bracts in the flower clusters.

In Utah, rough pigweed was rated as having fair palatability for cattle
and horses, and good palatability for sheep [7].

In Minnesota, rough pigweed was as palatable to sheep as oats (Avena
sativa) [25].
license
cc-publicdomain
bibliographic citation
Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Phenology

provided by Fire Effects Information System Plants
More info on this topic.

Rough pigweed normally begins growth in late spring and matures in late
summer or early fall [44]. It blooms in the Great Plains from July to
October [14], and in the central and northeastern United States and
adjacent Canada from August to October [11]. It blooms in southern
California from June to November [27], in Montana from June to October,
in North Dakota and Wyoming from July to September [7] and in the
Carolinas from July until frost [31].
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Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Plant Response to Fire

provided by Fire Effects Information System Plants
More info for the term: seed

When rough pigweed is killed by fire, the population must establish from
seed. If a fire in the spring kills rough pigweed plants but
conditions continue to be favorable, seeds from the seedbank will
germinate [44]. Late in the growing season, a fire will prepare the
seedbed for establishment of rough pigweed from seed the next spring.
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Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Post-fire Regeneration

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Ground residual colonizer (on-site, initial community)
Initial-offsite colonizer (off-site, initial community)
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Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Regeneration Processes

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More info for the term: seed

Rough pigweed regenerates from seed each year. Plants can result from
germination of newly released seed, or from germination of seed carried
over in the seedbank from previous years. Seeds may germinate any time
soil moisture is adequate during the growing season [44].

Rough pigweed seeds harvested in Mississippi showed 94 percent viability
at time of harvest. After burial in soil for 30 months, seeds showed 7
percent viability. Seeds put in dry, low-temperature storage for 30
months had 98 percent viability [8].

Some seeds of rough pigweed remained viable after 24 hours of rumen
digestion, 8 weeks ensiling, or both [4].
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Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Regional Distribution in the Western United States

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More info on this topic.

This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
4 Sierra Mountains
5 Columbia Plateau
6 Upper Basin and Range
7 Lower Basin and Range
8 Northern Rocky Mountains
9 Middle Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
13 Rocky Mountain Piedmont
14 Great Plains
15 Black Hills Uplift
16 Upper Missouri Basin and Broken Lands
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Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Successional Status

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More info on this topic.

More info for the term: competition

Obligate Initial Community Species

Rough pigweed, an early successional species, extracts more nitrogen
from and grows faster on the nitrogen-poor soils of recently abandoned
fields than mid- and late successional species [38].

In Michigan, an agricultural field was rototilled and abandoned in
March. By May, seedlings of several annuals had emerged. Dominant
species during the first growing season included rough pigweed. In
similar adjacent fields that had been abandoned for 5 and 15 years,
rough pigweed was not present. [16].

During the 1934 drought, rough pigweed grew thickly where windblown dust
had covered considerable portions of prairies in Kansas and Nebraska.
Rough pigweed and other ruderals normally not found in prairies became
widely distributed when released from their usual competition with
grasses. However, with the end of drought and the return of grasses,
rough pigweed nearly disappeared in many prairies [45].
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Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Taxonomy

provided by Fire Effects Information System Plants
The currently accepted scientific name of rough pigweed is Amaranthus
retroflexus L. [11,14,18,20]. It is a member of the pigweed family
(Amaranthaceae). There are no recognized subspecies, varieties, or
forms.
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bibliographic citation
Walsh, Roberta A. 1993. Amaranthus retroflexus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Comprehensive Description

provided by North American Flora
Amaranthus retroflexus L. Sp. PI. 991. 1753
Amaranthus spicatus Lam. Fl. Fr. 2: 192. 1778. Amaranthus recurvatus Desf. Cat. Hort. Par. ed. 3. 390. 1829. Amaranthus Delilei Richt. & Loret, Bull. Soc. Bot. Fr. 13: 316. 1866. Galliaria scabra Bubani, Fl. Pyren. 1: 187. 1897. Galliaria retroflexa Nieuwl. Am. Midi. Nat. 3: 278. 1914.
Stems stout, green or whitish, 3-30 dm. high, erect or ascending, usually much branched but often simple, abundantly villous, at least above, often densely so about the inflorescence; leaves numerous, the petioles 1.5-8 cm. long, slender, usually villous, the blades 3-12 cm. long, 1.5-7 cm. wide, ovate, rhombic-ovate, or the upper, and rarely the lower, lanceolate, plane or sometimes slightly crispate, acute to obtuse and often emarginate at the apex, acute or obtuse at the base, papillose on both surfaces, glabrate above, more or less villous or puberulent beneath, pale-green, prominently nerved, the veins white beneath; flowers monoecious, in dense, obtuse, terminal or axillary, usually paniculate, densely crowded, erect spikes 5-20 cm. long and 8-20 mm. thick, dense clusters often present also in the axils of the upper leaves; bracts ovate, tapering into a stout subulate green tip, usually twice as long as the sepals, at least in age, 1-nerved, sparsely villous; sepals of the staminate flowers ovate-oblong to lanceolate, acute or acutish, scarious, 1-nerved, the nerve shortly excurrent; sepals of the pistillate flowers 3 mm. long, linear-oblong, rounded to truncate at the apex, usually emarginate, often mucronate, scarious and whitish except for the green midnerve, the bases thickened in age; stamens 5; style-branches 3, rather short; utricle subglobose, more or les rugulose on the upper half, circumscissile at the middle, shorter than the sepals; seed rotund, 1 mm. broad, dark reddish-brown, lustrous.
Type locality: Pennsylvania.
Distribution: A common weed in waste ground, from southern Canada, throughout the United States, to northern Mexico; naturalized in Europe, Asia, and Africa.
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bibliographic citation
Paul Carpenter Standley. 1917. (CHENOPODIALES); AMARANTHACEAE. North American flora. vol 21(2). New York Botanical Garden, New York, NY
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Amaranthus retroflexus

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Amaranthus retroflexus is a species of flowering plant in the family Amaranthaceae with several common names, including red-root amaranth, redroot pigweed, red-rooted pigweed, common amaranth, pigweed amaranth, and common tumbleweed.[4]

Description

Amaranthus retroflexus, true to one of its common names, forms a tumbleweed.[4] It is native to the tropical Americas, but is widespread as an introduced species on most continents in a great number of habitats. This is an erect, annual herb reaching a maximum height near 3 m (9.8 ft). The leaves are nearly 15 cm (5.9 in) long on large individuals, the ones higher on the stem having a lance shape and those lower on the plant diamond or oval in shape. The plant is monoecious, with individuals bearing both male and female flowers. The inflorescence is a large, dense cluster of flowers interspersed with spiny green bracts. The fruit is a capsule less than 2 mm (0.079 in) long[5] with a "lid" which opens to reveal a tiny black seed. Another of A. retroflexus's common names is "pigweed" because it grows where hogs are pasture-fed.

Culinary use

Southern Kerala-style traditional thoran made with cheera (A. retroflexus) leaves

This plant is eaten as a vegetable in different places of the world. No species of genus Amaranthus is known to be poisonous,[6] but the leaves contain oxalic acid and may contain nitrates if grown in nitrate-rich soils, so the water should be discarded after boiling. The young shoots and leaves can be eaten raw.[7] The leaves are high in calcium, iron, protein, and phosphorus.[7]

A. retroflexus was used for a multitude of food and medicinal purposes by many Native American groups in the US West.[8] It is among the species consumed as a vegetable in Mexican markets as Quelite quintonil.

It is used in the Indian state of Kerala to prepare a popular dish known as thoran by combining the finely cut leaves with grated coconut, chili peppers, garlic, turmeric and other ingredients.

The seeds are edible raw[5] or toasted, and can be ground into flour and used for bread, hot cereal, or as a thickener.[9]

Use as fodder

Like many other species of Amaranthus, this plant may be harmful and even deadly when fed to cattle and pigs in large amounts over several days. Such forage may cause fatal nephrotoxicity,[10] presumably because of its high oxalate content. Other symptoms, such as bloat or methylglobineamia in the most severe cases, might reflect its high nitrate content.[11] However, when supplied in moderation, it is regarded as an exceptionally nutritious fodder.[12]

As a weed

A. retroflexus is a weed outside its native range and has developed resistance against fomesafen in Northeast China.[13]

References

  1. ^ NatureServe (5 May 2023). "Amaranthus retroflexus". NatureServe Network Biodiversity Location Data accessed through NatureServe Explorer. Arlington, Virginia: NatureServe. Retrieved 17 May 2023.
  2. ^ "Amaranthus retroflexus". Tropicos. Missouri Botanical Garden.
  3. ^ The Plant List
  4. ^ a b Louis Hermann Pammel (1903). Some Weeds of Iowa. Experiment Station, Iowa State College of Agriculture and the Mechanic Arts. page 470
  5. ^ a b Elias, Thomas S.; Dykeman, Peter A. (2009) [1982]. Edible Wild Plants: A North American Field Guide to Over 200 Natural Foods. New York: Sterling. p. 72. ISBN 978-1-4027-6715-9. OCLC 244766414.
  6. ^ Plants for a future Archived January 15, 2009, at the Wayback Machine
  7. ^ a b Benoliel, Doug (2011). Northwest Foraging: The Classic Guide to Edible Plants of the Pacific Northwest (Rev. and updated ed.). Seattle, WA: Skipstone. p. 95. ISBN 978-1-59485-366-1. OCLC 668195076.
  8. ^ "Native American Ethnobotany Data Base, search of Amaranthus retroflexus". Retrieved March 6, 2022.
  9. ^ "Amaranthus retroflexus | Redroot Pigweed | Male Finger". Archived from the original on 2014-03-04. Retrieved 2014-02-28.
  10. ^ FEIS Ecology
  11. ^ van Wyk, Ben-Erik; van Heerden, Fanie; van Oudtshoorn, Bosch (2002). Poisonous Plants of South Africa. Pretoria: Briza. ISBN 978-1-875093-30-4.
  12. ^ Watt, John Mitchell; Breyer-Brandwijk, Maria Gerdina: The Medicinal and Poisonous Plants of Southern and Eastern Africa 2nd ed Pub. E & S Livingstone 1962
  13. ^ Huang, Zhaofeng; Cui, Hailan; Wang, Chunyu; Wu, Tong; Zhang, Chaoxian; Huang, Hongjuan; Wei, Shouhui (2020). "Investigation of resistance mechanism to fomesafen in Amaranthus retroflexus L.". Pesticide Biochemistry and Physiology. Elsevier. 165: 104560. doi:10.1016/j.pestbp.2020.104560. ISSN 0048-3575. PMID 32359536. S2CID 216246076.

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Amaranthus retroflexus: Brief Summary

provided by wikipedia EN

Amaranthus retroflexus is a species of flowering plant in the family Amaranthaceae with several common names, including red-root amaranth, redroot pigweed, red-rooted pigweed, common amaranth, pigweed amaranth, and common tumbleweed.

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