Amaranthus hybridus (smooth pigweed)
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- Habitat List
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- Biology and Ecology
- Natural enemies
- Notes on Natural Enemies
- Uses List
- Similarities to Other Species/Conditions
- Prevention and Control
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Amaranthus hybridus L. (1753)
Preferred Common Name
- smooth pigweed
Other Scientific Names
- Amaranthus chlorostachys Willd.
- Amaranthus frumentaceus Buch.-Ham. ex Roxb.
- Amaranthus incurvatus Timeroy ex Gren. & Godr.
- Amaranthus patulus Bertol. (1837)
International Common Names
- English: green amaranth; slim amaranth
- Spanish: bledo; quelite
- French: amarante hybride
- Portuguese: caruru-de-folha-larga
Local Common Names
- Brazil: caruru-branco; caruru-roxo
- Germany: Bastard - Amarant; Gruenaehriger Amarant; Gruenaehriger Fuchsschwanz
- Japan: honagaaogeito
- Netherlands: basterdamarant
- AMACH (Amaranthus hybridus)
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Dicotyledonae
- Order: Caryophyllales
- Family: Amaranthaceae
- Genus: Amaranthus
- Species: Amaranthus hybridus
Notes on Taxonomy and NomenclatureTop of page
A. hybridus has a chromosome number of 2n = 32 (Murray, 1940; Grant, 1959). It readily hybridizes with closely related species, but the F1 generation is highly sterile (Tucker and Sauer, 1958). Hybrids often have oddly shaped inflorescences. Brenan (1961) distinguished three subspecies of A. hybridus on the basis of the relative length of the bracts compared with the length of the sepals.
A. hybridus is sometimes confused with the cultivated species A. hypochondriacus and A. caudatus (love-lies-bleeding), both of which have long, thin often reddish inflorescences. However, Sauer (1967) contends that A. hypochondriacus was derived mainly from A. powellii, and A. caudatus mainly from A. quitensis. A. hybridus is thought to be the progenitor of A. cruentus, a cultivated grain and ornamental plant. Introgression has undoubtedly occurred among the weedy and domesticated amaranths. While this represents the current status of A. hybrudus in the strictest sense, it must be noted that the 'cultivated' A. cruentus often occurs as a weed and is sometimes referred to as 'A. hybridus' in weed literature. Hence it is likely that a number of the records in this data-sheet might refer more strictly to A. cruentus (or to other closely related species).
DescriptionTop of page
A. hybridus is an erect annual herbaceous plant which reproduces only by seeds. It produces a tap root and erect, often branched stems from 0.1 to 2.0 m in height. The stems are thick and often ribbed or tinged with red. Its leaves are alternate, long-stalked, and ovate to rhombic-ovate. Leaf and stem surfaces have small fine hairs. Flowers are numerous, green, and crowded into finger-like spikes forming a long, dense terminal panicle, with axillary spikes below. The terminal spike is often lax. Perianth segments 5, lanceolate, acute, 2–3 mm long, subtended by bracteoles somewhat longer, about 4 mm, with a long, sharp tip, causing the inflorescence to feel distinctly prickly. Stamens 5. At maturity, the entire plant may be reddish in colour. Seeds are round, dark brown, shiny, somewhat flattened, and 1.0 to 1.5 mm in diameter.
DistributionTop of page
A. hybridus is a native riverbank pioneer of eastern North America and parts of Mexico, Central America and northern South America (Sauer, 1967). It is much more common in the eastern than the western half of the USA. Its range has expanded to Africa, south-central Asia and Australia, possibly because of its use as a green vegetable.
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
HabitatTop of page
A. hybridus is found on a wide variety of soil types and textures. It is a common weed of cultivated fields, gardens, waste places, roadsides, riverbanks, and other open, disturbed habitats where annual weeds predominate. It is seldom found in closed or shaded communities (Weaver and McWilliams, 1980).
Habitat ListTop of page
Hosts/Species AffectedTop of page
A. hybridus is a common weed of many field and horticultural row crops throughout the temperate areas of the world.
Host Plants and Other Plants AffectedTop of page
|Beta vulgaris (beetroot)||Chenopodiaceae||Main|
|Glycine max (soyabean)||Fabaceae||Main|
|Nicotiana tabacum (tobacco)||Solanaceae||Other|
|Phaseolus vulgaris (common bean)||Fabaceae||Main|
|Pisum sativum (pea)||Fabaceae||Other|
|Solanum tuberosum (potato)||Solanaceae||Other|
|Sorghum bicolor (sorghum)||Poaceae||Main|
|Triticum aestivum (wheat)||Poaceae||Other|
|Zea mays (maize)||Poaceae||Main|
Biology and EcologyTop of page
A. hybridus is a summer annual herbaceous weed that reproduces solely by seed with maximum emergence in late spring or early summer (Weaver and McWilliams, 1980; Anderson, 1994). Plants which emerge in late May generally begin to flower in late July or early August, and produce ripe seed by the beginning of September (Weaver, 1984). Its small seeds are easily dispersed by wind, and germinate primarily from the top 2 cm of soil in disturbed habitats. Germination is stimulated by light and/or high temperatures, with greatest germination occurring at alternating temperatures of 20/35°C in the light (Weaver and McWilliams, 1980; Weaver, 1984).
A. hybridus possesses the C4 pathway of photosynthesis, a low carbon dioxide compensation point, little photorespiration, and its optimum temperature for net photosynthesis lies between 30 and 40°C (Patterson, 1976). Separate male and female flowers occur on the inflorescence, and pollination is generally by wind. A single vigorous plant may produce as many as 100,000 seeds. Seed longevity has not been reported, but seeds of the closely related species A. retroflexus and A. powellii, can remain viable for many years when buried in soil.
Natural enemiesTop of page
|Natural enemy||Type||Life stages||Specificity||References||Biological control in||Biological control on|
Notes on Natural EnemiesTop of page
A. hybridus is a host plant for a variety of insect pests and diseases which attack crops, however damage is rarely severe enough to serve as biological control.
ImpactTop of page
A. hybridus is a principal weed in a variety of field and vegetable row crops, and has been reported to substantially reduce yields of maize, soyabeans, cotton, sugarbeet, sorghum and peas (Holm et al., 1977; Weaver and McWilliams, 1980). It can also reduce harvesting efficiency because of increased lodging of weed infested crops (Nave and Wax, 1971).
A. hybridus accumulates nitrates in its tissues and has caused poisoning of cattle (Ferreira et al., 1991).
A. hybridus is an alternative host for members of the parasitic nematode genus Meloidogyne and for tobacco mosaic virus (Holm et al., 1977; Tedford and Fortnum, 1988). It also serves as a host for Colletotrichum capsici, which causes anthracnose on tomato fruit and cotton seedlings (McLean and Roy, 1991).
Amaranthus species have been reported to cause allergic reactions in humans, primarily due to wind-borne pollen (Weber et al., 1978; Mitchell and Rook, 1979).
UsesTop of page
A. hybridus has been reported to be a highly nutritious herbage and a potentially valuable forage crop (Mugerwa and Bwabye, 1974). It is used as a green vegetable in parts of South Africa, India, Mexico and the southern USA (Holm et al., 1977; Sealy et al., 1990). Hauptli and Jain (1978) suggested that it could be used as breeding material for recombining desirable yield characteristics in the cultivated grain amaranths.
Leaves and young seedlings are cooked like spinach and added to soups, etc. Leaves have a mild flavour. Seeds can be used raw or cooked as a cereal substitute. An astringent medical tea can be made from the leaves.
Uses ListTop of page
Animal feed, fodder, forage
- Fodder/animal feed
- Related to
Human food and beverage
Similarities to Other Species/ConditionsTop of page
A. hybridus is similar in appearance to A. retroflexus and A. powellii, particularly in the vegetative state. Flowering plants of A. retroflexus differ in having shorter, thicker branches on the terminal inflorescence, sepals rounded or blunt and often reflexed, bracteoles less distinctly spiny. A. powelli also has a somewhat thicker inflorescence, the bracteoles are longer (up to 6 mm), and stamens usually 3, not 5.
A. caudatus and A. hypochondriacus are ornamental, domesticated plants, with larger terminal inflorescences, often bright red in colour, with a utricle equalling or exceeding the bract and sepals in length. The utricle of A. hybridus, A. retroflexus, and A. powellii is shorter than the bracts and sepals. The seeds of the weedy amaranths are usually dark brown, whereas many forms of the cultivated grain amaranths have ivory seeds.
Many other Amaranthus species are superficially similar. Of those included as data-sheets in this compendium, A. spinosus has spines, A. viridis has much smaller flowers, A. bitum has indented leaf tips, and A graecizans and A. blitoides have axillary inflorescences. Further species can occur as weeds on a local basis and reference to local floras is therefore recommended.
Prevention and ControlTop of page
Seedlings of A. hybridus can be controlled by cultivation, but older plants often recover from mechanical damage by producing axillary branches and inflorescences.
A. hybridus is readily controlled by almost all the standard soil-applied and foliar-applied herbicides used for controling broadleaved weeds, including atrazine, simazine, metribuzin, linuron, bromoxynil, 2,4-D, dicamba, imazethapyr, thifensulfuron-methyl, rimsulfuron, nicosulfuron, acifluorfen, fomesafen and pendimethalin (Weaver and McWilliams, 1980; Manley et al., 1996; Robinson et al., 1996). Its pattern of intermittent germination throughout the growing season, however, make the application of residual soil-applied herbicides, or sequential post-emergence treatments, necessary in heavily infested fields. Lorenzi (1984) indicates that A. hybridus is only moderately susceptible to oxyfluorfen, butylate or vernolate.
Populations of A. hybridus resistant to triazine herbicides have been reported in the USA, France, Switzerland, Italy, Spain, Israel and South Africa (Heap, 1997). Populations resistant to the imidazolinone herbicides have been found in the USA (Heap, 1997).
Reputed biological control agents for A. hybridus are the pathogenic bacterium, Erwinia carotovora var. rhapontici [Erwinia rhapontici], (Gonzalez-Mendoza and Rodriguez, 1990), and insects Herpetogramma bipunctalis and Conotrachelus seniculus (Perez Panduro et al., 1990), all in Mexico.
ReferencesTop of page
Aellen P, Akeroyd JR, 1993. Amaranthus L. In: Tutin TG, Burges NA, Chater AO, Edmondson JR, Heywood VH, Moore DM, Valentine DH, Walters SM, Webb DA, eds. Flora Europaea. Volume 1. Psilotaceae to Platanaceae. 2nd edition. Cambridge, UK: Cambridge University Press, 130-132.
Brenan JPM, 1961. Amaranthus in Britain. Watsonia, 4:261-280.
Chirila C, Pintilie C, 1985. The principal weeds and their control (XVIII). Wild pigweed (Amaranthus retroflexus L.), field pigweed (Amaranthus hybridus L.) and creeping pigweed (Amaranthus blitoides S. Wats.). Productia Vegetala, Cereale si Plante Tehnice, 37(7):28-31
Ferreira JLM, Riet-Correa F, Schild AL, Méndez MDC, 1991. Poisoning of cattle by Amaranthus spp. (Amaranthaceae) in Rio Grande de Sul, southern Brazil. Pesquisa Veterinária Brasileira, 11(3/4):49-54; 22 ref.
Gonzalez Mendoza L, Rodriguez MM de L, 1990. Isolation, identification and pathogenicity of bacteria of Amaranthus hybridus L. and possibilities of their biological control. Revista Chapingo, 15:67-68.
Grant WF, 1959. Cytogenetic studies in Amaranthus. III. Chromosome numbers and phylogenetic aspects. Canadian Journal of Genetics and Cytology, 1:313-328.
Heap IM, 1997. International Survey of Herbicide-Resistant Weeds. Annual Report, Weed Science Society of America.
Hutchinson J, Dalziel JM, 1954. Flora of West Tropical Africa, Volume 1, Part 1 (revised by Keay RWJ). London, UK: Crown Agents.
Lorenzi H, 1982. Weeds of Brazil, terrestrial and aquatic, parasitic, poisonous and medicinal. (Plantas daninhas de Brasil, terrestres, aquaticas, parasitas, toxicas e medicinais.) Nova Odessa, Brazil: H. Lorenzi, 425 pp.
Lorenzi H, 1984. Manual de Identificacao e Controle de Plantas Danhinas. Odessa, Brazil: H. Lorenzi.
Lugo Mde L, Gonzßlez A, Talbert RE, 1995. Smooth pigweed (Amaranthus hybrid[u]s L.) interference with snap bean (Phaseolus vulgaris L.) quality. Journal of Agriculture of the University of Puerto Rico, 79(3-4):173-179; 6 ref.
Mamarot J, Rodriguez A, 1997. Sensibilité des Mauvaises Herbes aux Herbicides. 4th edition. Paris, France: Association de Coordination Technique Agricole.
Manley BS, Wilson HP, Hines TE, 1996. Smooth pigweed (Amaranthus hybridus) and livid amaranth (A. lividus) response to several imidazolinone and sulfonylurea herbicides. Weed Technology, 10(4):835-841; 22 ref.
Mitchell J, Rook A, 1979. Botanical Dermatology: plants and plant products injurious to the skin. Vancouver, Canada: Greengrass.
Mugerwa JS, Bwabye R, 1974. Yield, composition and in vitro digestibility of Amaranthus hybridus subspecies incurvatus. Tropical Grasslands, 8:49-53.
Murray MJ, 1940. The genetics of sex determination in the family Amaranthaceae. Genetics, 25:409-431.
Nave WR, Wax LM, 1971. Effect of weeds on soybean yield and harvesting efficiency. Weed Science, 19:533-535.
Oyelola O, Banjoko I, Ajishin I, 2014. Nutritional content of common Amaranthus hybridus vegetable (Efo Tete) in Nigeria (828.4), The FASEB Journal, 28(1)
Patterson DT, 1976. C4 photosynthesis in smooth pigweed [Amaranthus hybridus]. Weed Science, 24(1):127-130
Perez Panduro A, Solis Aguilar JF, Trujillo Arriaga J, Romero Rosales F, 1990. Biological agents for population regulation of Tithonia tubaeformis (Jacq) Cass (Asteraceae), Amaranthus hybridus L. and A. spinosus L. (Amaranthaceae) in Chapingo, State of Mexico and Tecalitlan, Jalisco. Revista Chapingo, 15(67-68):126-129
Portillo HE, Pitre HN, Meckenstock DH, Andrews KL, 1996. Oviposition preference of Spodoptera latifascia (Lepidoptera: Noctuidae) for sorghum, maize and non-crop vegetation. Florida Entomologist, 79(4):552-562; 25 ref.
Rambakudzibga AM, 1991. Allelopathic effects of aqueous wheat (Triticum aestivum L.) straw extracts on the germination of eight arable weeds commonly found in Zimbabwe. Zimbabwe Journal of Agricultural Research, 29(1):77-79.
Sauer JD, 1967. The grain amaranths and their relatives: A revised taxonomic and geographic survey. Annals of the Missouri Botanic Garden, 54:103-137.
Sealy RL, McWilliams EL, Novak J, Fong F, Kenerley CM, Simon JE, 1990. Vegetable amaranths: cultivar selection for summer production in the south. In: Janick J, ed. Advances in new crops. Proceedings of the First National Symposium 'New Crops: Research, Development, Economics', Indianapolis, USA. Oregon, USA: Timber Press, 396-398.
Tackholm V, 1974. Students' Flora of Egypt. 2nd edition. Cairo, Egypt: University of Cairo.
Townsend CC, 1985. Amaranthaceae. In: Polhill RM, ed. Flora of Tropical East Africa. Rotterdam, Netherlands: A.A. Balkema, 1-2, 20-24, 35-36.
Townsend CC, 1988. Amaranthaceae. In: Launert E, ed. Flora Zambesiaca. Volume 9, Part 1. London, UK: Flora Zambesiaca Management Committee, 28-133.
Tucker JM, Sauer JD, 1958. Aberrant Amaranthus populations of the Sacramento-San Joaquin Delta, California. Madrono, 14:252-261.
Weber RW, Mansfield LE, Nelson HS, 1978. Cross-reactivity among weeds of the amaranth and chenopod families. Journal of Allergy and Clinical Immunology, 61:172.
Wells MJ, Balsinhas AA, Joffe H, Engelbrecht VM, Harding G, Stirton CH, 1986. A catalogue of problem plants in South Africa. Memoirs of the botanical survey of South Africa No 53. Pretoria, South Africa: Botanical Research Institute.
Distribution MapsTop of page
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