Amaranthus retroflexus

Classification System: APG IV

Superregnum: Eukaryota
Regnum: Plantae
Cladus: Angiosperms
Cladus: Eudicots
Cladus: Core eudicots
Ordo: Caryophyllales

Familia: Amaranthaceae s.l.
Cladus: Amaranthaceae s.str.
Subfamilia: Amaranthoideae
Genus: Amaranthus
Species: Amaranthus retroflexus
Subspecies: A. r. subsp. delilei – A. r. subsp. retroflexus
Name

Amaranthus retroflexus L., Sp. Pl. 2: 991. (1753)

Type locality: "Habitat in Pensylvania. Kalm."
Lectotype (designated by Townsend 1974): Cultivated material from Uppsala Botanic Garden. LINN LINN 1117.22.

Synonyms

Homotypic
Galliaria retroflexa (L.) Nieuwl., Amer. Midl. Naturalist 3: 278. (1914)
Heterotypic (ref. Govaerts 2019)
Amaranthus bullatus Besser ex Spreng., Syst. Veg., ed. 16 [Sprengel] 1: 928. (1824)
Amaranthus curvifolius Spreng., Syst. Veg., ed. 16 [Sprengel] 1: 928. (1824)
Amaranthus delilei Richt. & Loret, Bull. Soc. Bot. France 13: 316. (1868)
Amaranthus dubius E.H.L.Krause, Deutschl. Fl. (Sturm), ed. 2. 5: 141. (1901), nom. inval., quaelibet species dubia
Amaranthus johnstonii Kov., Nauch. Trud. Vissh Selskostop. Inst. Plovdiv 23(1): 50. (1978), nom. nov. (1978).
Amaranthus recurvatus Desf., Tabl. École Bot., ed. 3 (Cat. Pl. Horti Paris.) 39. (1829)
Amaranthus retroflexus subsp. delilei (Richt. & Loret) Tzvelev, Novosti Sist. Vyssh. Rast. 32: 183. (2000)
Amaranthus retroflexus var. rubricaulis Thell., in Asch. & Graebn., Syn. Mitteleur. Fl. [Ascherson & Graebner]. 5, Abt. 1: 260. (1914)
Amaranthus retroflexus f. rubricaulis Thell. ex Probst, Mitt. Naturf. Ges. Solothurn Heft 6: 26. (1920)
Amaranthus retroflexus var. salicifolius I.M.Johnst., J. Arnold Arbor. 25: 157. (1944)
Amaranthus rigidus Schult. ex Steud., Nomencl. Bot. [Steudel], ed. 2. 1: 70. (1840)
Amaranthus spicatus Lam., Fl. Franç. (Lamarck) 2: 192. (1779)
Galliaria scabra Bubani, Fl. Pyren. (Bubani) 1: 187. (1897)

Distribution
Native distribution areas:

Northern America
Mexico
Mexico Central, Mexico Gulf, Mexico Northeast, Mexico Southeast, Mexico Southwest

introduced elsewhere, nearly cosmopolitic

References: Brummitt, R.K. 2001. TDWG – World Geographical Scheme for Recording Plant Distributions, 2nd Edition
References
Primary references

Linnaeus, C. 1753. Species Plantarum. Tomus II: 991. Reference page.

Additional references

Townsend, C.C. 1974. Amaranthaceae. In: Ali, S.I. (ed.) Flora of West Pakistan. Vol. 71. 49 pp. Stewart Herbarium, Gordon College (u.a.), Rawalpindi. eFloras Reference page. : Amaranthus retroflexus

Links

Govaerts, R. et al. 2019. Amaranthus retroflexus in Kew Science Plants of the World online. The Board of Trustees of the Royal Botanic Gardens, Kew. Published online. Accessed: 2019 Aug. 20. Reference page.
Hassler, M. 2019. Amaranthus retroflexus. World Plants: Synonymic Checklists of the Vascular Plants of the World In: Roskovh, Y., Abucay, L., Orrell, T., Nicolson, D., Bailly, N., Kirk, P., Bourgoin, T., DeWalt, R.E., Decock, W., De Wever, A., Nieukerken, E. van, Zarucchi, J. & Penev, L., eds. 2019. Species 2000 & ITIS Catalogue of Life. Published online. Accessed: 2019 Aug. 20. Reference page.
International Plant Names Index. 2019. Amaranthus retroflexus. Published online. Accessed: Aug. 20 2019.
Tropicos.org 2019. Amaranthus retroflexus. Missouri Botanical Garden. Published online. Accessed: 20 Aug. 2019.

Vernacular names
dansk: Opret Amarant
Deutsch: Zurückgebogener Fuchsschwanz, Rauhhaariger Fuchssschwanz, Zurückgebogener Amarant
English: Red-root Amaranth, Redroot Pigweed, Red Rooted Pigweed, Common Amaranth, Common Tumble Weed
español: Abrebujo, Acederón, Atreu del Perú, Bledos, Breo, Jascas, Moco de Pavo
suomi: Viherrevonhäntä
français: Amarante réfléchie
italiano: Amaranto comune
日本語: アオゲイトウ
македонски: Обичен штир
norsk: Duskamarant
polski: Szarłat Szorstki
sardu: Amarantu
svenska: Svinamarant
中文: 反枝苋

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.[3]
Description

Amaranthus retroflexus, true to one of its common names, forms a tumbleweed.[3] 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[4] 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,[5] 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.[6] The leaves are high in calcium, iron, protein, and phosphorus.[6]

A. retroflexus was used for a multitude of food and medicinal purposes by many Native American groups in the US West.[7] 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[4] or toasted, and can be ground into flour and used for bread, hot cereal, or as a thickener.[8]
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,[9] 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.[10] However, when supplied in moderation, it is regarded as an exceptionally nutritious fodder.[11]
As a weed

A. retroflexus is a weed and has developed resistance against fomesafen in Northeast China.[12]
References

"Amaranthus retroflexus". Tropicos. Missouri Botanical Garden.
The Plant List
Louis Hermann Pammel (1903). Some Weeds of Iowa. Experiment Station, Iowa State College of Agriculture and the Mechanic Arts. page 470
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.
Plants for a future Archived January 15, 2009, at the Wayback Machine
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.
"Native American Ethnobotany Data Base, search of Amaranthus retroflexus". Retrieved March 6, 2022.
"Amaranthus retroflexus | Redroot Pigweed | Male Finger". Archived from the original on 2014-03-04. Retrieved 2014-02-28.
FEIS Ecology
van Wyk, Ben-Erik; van Heerden, Fanie; van Oudtshoorn, Bosch (2002). Poisonous Plants of South Africa. Pretoria: Briza. ISBN 978-1-875093-30-4.
Watt, John Mitchell; Breyer-Brandwijk, Maria Gerdina: The Medicinal and Poisonous Plants of Southern and Eastern Africa 2nd ed Pub. E & S Livingstone 1962
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.