''Amaranthus retroflexus'' is a species of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

in the family Amaranthaceae with several

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often con ...

s, including red-root amaranth, redroot pigweed, red-rooted pigweed, common amaranth, pigweed amaranth, and common tumbleweed. Outside of its native range, it is considered a weed. Although it may be toxic if eaten uncooked, or in excess by livestock, it can be consumed as a vegetable or as fodder.

Description

''Amaranthus retroflexus,'' true to one of its common names, forms a tumbleweed. It is an erect, annual herb growing to . The

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

are nearly 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 Monoecy (; adj. monoecious ) is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant. It is a monomorphic sexual system comparable with gynomonoecy, andromonoecy and trimonoecy, and contras ...

, with individuals bearing both male and female flowers. The

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

is a large, dense cluster of flowers interspersed with spiny green

bract In botany, a bract is a modified or specialized leaf, associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves in size, color, shape or texture. They also lo ...

s. The fruit is a capsule less than long with a "lid" which opens to reveal a tiny black seed.

Distribution and habitat

It may be native to the

Neotropics The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In biogeog ...

or Central and Eastern North America, but is widespread as an

introduced species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived ther ...

on most continents in a great number of habitats. One common name is "pigweed" because it grows where hogs are pasture-fed.

As a weed

''A. retroflexus'' is a

weed A weed is a plant considered undesirable in a particular situation, growing where it conflicts with human preferences, needs, or goals.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. Pla ...

outside its native range and has developed resistance against fomesafen in

Northeast China Northeast China () is a geographical region of China, consisting officially of three provinces Liaoning, Jilin and Heilongjiang. The heartland of the region is the Northeast China Plain, the largest plain in China with an area of over . The regi ...

Potential toxicity

No species of genus ''Amaranthus'' is known to be poisonous to humans, but the leaves of ''A. retroflexus'' contain oxalic acid and may contain

nitrate Nitrate is a polyatomic ion with the chemical formula . salt (chemistry), Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are solubility, soluble in wa ...

s if grown in nitrate-rich soils. Like many other species of ''Amaranthus'', this plant may be harmful and even deadly when fed to

cattle Cattle (''Bos taurus'') are large, domesticated, bovid ungulates widely kept as livestock. They are prominent modern members of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Mature female cattle are calle ...

and pigs in large amounts over several days. Such forage may cause fatal

nephrotoxicity Nephrotoxicity is toxicity in the kidneys. It is a poisonous effect of some substances, both toxic chemicals and medications, on kidney function. There are various forms, and some drugs may affect kidney function in more than one way. Nephrotoxin ...

,FEIS Ecology
/ref> 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.

Uses

Culinary

This plant is eaten as a vegetable in different places of the world. The water should be discarded after boiling due to the presence of oxalic acid and possibly nitrates. The young shoots and leaves can be eaten raw. The leaves are high in calcium, iron, protein, and

phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...

. ''A. retroflexus'' was used for a multitude of food and medicinal purposes by many Native American groups in the western United States. It is among the species consumed as a vegetable in Mexican markets as ''Quelite quintonil''. It is used in the

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

n state of

Kerala Kerala ( , ) is a States and union territories of India, state on the Malabar Coast of India. It was formed on 1 November 1956, following the passage of the States Reorganisation Act, by combining Malayalam-speaking regions of the erstwhile ...

to prepare a popular dish known as '' thoran'' by combining the finely cut leaves (''cheera'' ) with grated

coconut The coconut tree (''Cocos nucifera'') is a member of the palm tree family (biology), family (Arecaceae) and the only living species of the genus ''Cocos''. The term "coconut" (or the archaic "cocoanut") can refer to the whole coconut palm, ...

chili pepper Chili peppers, also spelled chile or chilli ( ), are varieties of fruit#Berries, berry-fruit plants from the genus ''Capsicum'', which are members of the nightshade family Solanaceae, cultivated for their pungency. They are used as a spice to ...

s, garlic, turmeric and other ingredients. The seeds are edible raw or toasted, and can be ground into flour and used for bread, hot cereal, or as a thickener.

As fodder

When supplied in moderation (circumventing its toxicity to livestock), it is regarded as an exceptionally nutritious fodder.Watt, John Mitchell; Breyer-Brandwijk, Maria Gerdina: The Medicinal and Poisonous Plants of Southern and Eastern Africa 2nd ed Pub. E & S Livingstone 1962

References

External links

*
Jepson Manual Treatment
*
Amaranthus retroflexus L.
Medicinal Plant Images Database (School of Chinese Medicine, Hong Kong Baptist University) * {{Taxonbar, from=Q157663 retroflexus Flora of Northern America Flora of Southern America Plants described in 1753 Taxa named by Carl Linnaeus Kerala cuisine Plants used in Native American cuisine Invasive plant species in Japan