''Alternanthera'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of flowering plants in the family

Amaranthaceae Amaranthaceae is a family of flowering plants commonly known as the amaranth family, in reference to its type genus ''Amaranthus''. It includes the former goosefoot family Chenopodiaceae and contains about 165 genera and 2,040 species, making i ...

. It is a widespread genus with most species occurring in the

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

Americas,Sánchez-Del Pino, I., et al. (2012)
Molecular phylogenetics of ''Alternanthera'' (Gomphrenoideae, Amaranthaceae): resolving a complex taxonomic history caused by different interpretations of morphological characters in a lineage with C₄ and C₃–C₄ intermediate species.
''Botanical Journal of the Linnean Society'' 169(3), 493-517.''Alternanthera''.
Flora of North America. and others in Asia, Africa, and Australia. Plants of the genus may be known generally as joyweeds, or Joseph's coat.''Alternanthera''.
Integrated Taxonomic Information System (ITIS). Several species are notorious

noxious weed A noxious weed, harmful weed or injurious weed is a weed that has been designated by an agricultural or other governing authority as a plant that is injurious to agricultural or horticultural crops, natural habitats or ecosystems, or humans or li ...

s.Tanveer, A., et al. (2013)
A review on genus ''Alternanthera'' weeds implications.
''Pak. J. Weed Sci. Res'' 19(1), 53-58.

Description

These are annual or perennial herbs or subshrubs. While some of the better-known species are

aquatic plant Aquatic plants are plants that have adapted to living in aquatic environments ( saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes. A macrophyte is a plant that ...

s, most are terrestrial. They take many forms, from prostrate to erect to floating. The leaves are oppositely arranged. The

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are forme ...

is a spike or a rounded head occurring in the leaf axils or the ends of branches. The flowers have 5

tepal A tepal is one of the outer parts of a flower (collectively the perianth). The term is used when these parts cannot easily be classified as either sepals or petals. This may be because the parts of the perianth are undifferentiated (i.e. of very ...

s. There are 3 to 5

stamen The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the fila ...

s which are fused into a rim at the bases, and 5 pseudostaminodes, appendages between the stamens that are not true

staminode In botany, a staminode is an often rudimentary, sterile or abortive stamen, which means that it does not produce pollen.Jackson, Benjamin, Daydon; ''A Glossary of Botanic Terms with their Derivation and Accent''; Published by Gerald Duckworth & C ...

s. The fruit is a utricle containing one seed. The genus ''Alternanthera'' contains both terrestrial and aquatic species. The

photosynthetic Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in ...

pathway varies in this genus: Some species undergo C₃ carbon fixation, one clade of 17 species has acquired the C₄ pathway, and yet other species have an intermediate C₃-C₄ pathway. Chinthapalli, B., et al. (2001)
Phospho''enol''pyruvate carboxylase purified from leaves of C₃, C₄, and C₃-C₄ intermediate species of ''Alternanthera'': Properties at limiting and saturating bicarbonate.
''Photosynthetica'' 38(3), 415-19.

Species

It is not yet clear how many species belong in the genus. Estimates range between 80 and 200.''Alternanthera''.
The Plant List. Species include:GRIN Species Records of ''Alternanthera''.
Germplasm Resources Information Network (GRIN). *'' Alternanthera acaulis'' Andersson *''

Alternanthera adscendens ''Alternanthera'' is a genus of flowering plants in the family Amaranthaceae. It is a widespread genus with most species occurring in the tropical Americas,Sánchez-Del Pino, I., et al. (2012)Molecular phylogenetics of ''Alternanthera'' (Gomphren ...

'' Suess. *''

Alternanthera albotomentosa ''Alternanthera'' is a genus of flowering plants in the family Amaranthaceae. It is a widespread genus with most species occurring in the tropical Americas,Sánchez-Del Pino, I., et al. (2012)Molecular phylogenetics of ''Alternanthera'' (Gomphren ...

'' Suess. *''

Alternanthera albida ''Alternanthera'' is a genus of flowering plants in the family Amaranthaceae. It is a widespread genus with most species occurring in the tropical Americas,Sánchez-Del Pino, I., et al. (2012)Molecular phylogenetics of ''Alternanthera'' (Gomphren ...

'' (Moq.) Griseb *''

Alternanthera albosquarrosa ''Alternanthera'' is a genus of flowering plants in the family Amaranthaceae. It is a widespread genus with most species occurring in the tropical Americas,Sánchez-Del Pino, I., et al. (2012)Molecular phylogenetics of ''Alternanthera'' (Gomphren ...

'' Suess. *''

Alternanthera altacruzensis ''Alternanthera'' is a genus of flowering plants in the family Amaranthaceae. It is a widespread genus with most species occurring in the tropical Americas,Sánchez-Del Pino, I., et al. (2012)Molecular phylogenetics of ''Alternanthera'' (Gomphren ...

'' Suess. *''

Alternanthera angustifolia ''Alternanthera angustifolia'' (narrow-leaf joyweed) is a small herb in family Amaranthaceae found widely in inland Australia from northern Western Australia, the Northern Territory, South Australia, New South Wales to Queensland ) , nickn ...

'' R.Br. – narrow-leaf joyweed *''

Alternanthera aquatica ''Alternanthera'' is a genus of flowering plants in the family Amaranthaceae. It is a widespread genus with most species occurring in the tropical Americas,Sánchez-Del Pino, I., et al. (2012)Molecular phylogenetics of ''Alternanthera'' (Gomphren ...

'' (Parodi) Chodat *''

Alternanthera arequipensis ''Alternanthera'' is a genus of flowering plants in the family Amaranthaceae. It is a widespread genus with most species occurring in the tropical Americas,Sánchez-Del Pino, I., et al. (2012)Molecular phylogenetics of ''Alternanthera'' (Gomphren ...

'' Suess. *'' Alternanthera areschougii'' *'' Alternanthera asterotricha'' Uline *'' Alternanthera axillaris'' (Willd.) DC. *''

Alternanthera bettzickiana ''Alternanthera bettzickiana'', commonly known as calico-plant, is a species of flowering plant in the family Amaranthaceae. It is commonly used as an ornamental edging plant. Native to South America, its cultivar 'Red' is similar in appearance ...

'' – calico-plant *'' Alternanthera brasiliana'' (L.) Kuntze – Brazilian joyweed, ruby leaf *''

Alternanthera caracasana ''Alternanthera caracasana'' is a species of flowering plant in the family Amaranthaceae known by the common names khakiweed, washerwoman and mat chaff flower. It is native to Central and South America but is well-known elsewhere as a noxious we ...

'' Kunth – mat chaff-flower, washerwoman *'' Alternanthera corymbiformis'' *'' Alternanthera crucis'' Bold. – West Indian joyweed *'' Alternanthera dentata'' – little ruby *''

Alternanthera denticulata ''Alternanthera denticulata'' (common name lesser joyweed) is a small prostrate white-flowering herb in the Amaranthaceae family. It is native to all states and territories of Australia, New Guinea, and the North Island of New Zealand. It is al ...

'' – lesser joyweed *'' Alternanthera echinocephala'' (Hook.f.) Christoph. – spiny-headed chaff flower,, p. 144 sea-urchin joyweed *'' Alternanthera ficoidea'' – parrot leaf, sanguinarea *'' Alternanthera filifolia'' (Hook.f.) J.T. Howell *'' Alternanthera flavescens'' – yellow joyweed *'' Alternanthera flavicoma'' *'' Alternanthera galapagensis'' *'' Alternanthera grandis'' *'' Alternanthera hassleriana'' Chodat – Hassler's alternanthera *'' Alternanthera helleri'' (B.L.Rob.) J.T.Howell *'' Alternanthera littoralis'' P.Beauv. *'' Alternanthera maritima'' (Mart.) A.St.-Hil. – seaside joyweed *'' Alternanthera mexicana'' *'' Alternanthera nahui'' *'' Alternanthera nana'' – downy joyweed, hairy joyweed *'' Alternanthera nesiotes'' *'' Alternanthera nodiflora'' – common joyweed *'' Alternanthera olivacea'' *'' Alternanthera paronichyoides'' A.St.-Hil. – smooth joyweed *'' Alternanthera philoxeroides'' (Mart.) Griseb. – alligator weed *'' Alternanthera pubiflora'' *''

Alternanthera pungens ''Alternanthera pungens'' is a creeping, prostrate perennial pioneer plant of the family Amaranthaceae, spreading by seed and vegetatively, with roots often developing at the nodes of spreading stems. A plant of roadsides, path verges and waste ...

'' *'' Alternanthera reineckii'' Briq. *'' Alternanthera sessilis'' (L.) DC. – rabbit-meat, sessile joyweed *'' Alternanthera snodgrassii'' *'' Alternanthera subscaposa'' *'' Alternanthera tenella'' Colla *'' Alternanthera versicolor'' R.Br.

Ecology

Many species have been reported as noxious weeds, including ''A. angustifolia'', ''A. caracasana'', ''A. denticulata'', ''A. nana'', ''A. nodiflora'', ''A. paronychioides'', ''A. philoxeroides'', ''A. sessilis'', ''A. tenella'', and ''A. triandra''. The most important species is

alligator weed ''Alternanthera philoxeroides'', commonly referred to as alligator weed, is a native species to the temperate regions of South America, which includes Argentina, Brazil, Paraguay and Uruguay. Argentina alone hosts around 27 species that fall wi ...

(''A. philoxeroides''), a South American aquatic plant that has spread to other continents. It is a weed of many kinds of

agricultural crops A crop is a plant that can be grown and harvested extensively for profit or subsistence. When the plants of the same kind are cultivated at one place on a large scale, it is called a crop. Most crops are cultivated in agriculture or hydroponics ...

, it is an

invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species adv ...

that degrades native habitat, and its dense mats of vegetation clog waterways, slowing shipping and increasing

flood A flood is an overflow of water ( or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are an area of study of the discipline hydrol ...

ing. ''Alternanthera'' plants are known to produce

allelopathic Allelopathy is a biological phenomenon by which an organism produces one or more biochemicals that influence the germination, growth, survival, and reproduction of other organisms. These biochemicals are known as allelochemicals and can have ben ...

compounds that injure other plants, including crops.

Biological pest control Biological control or biocontrol is a method of controlling pests, such as insects, mites, weeds, and plant diseases, using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also i ...

agents now in use to reduce alligator weed infestations include the alligator weed flea beetle (''Agasicles hygrophila''), the alligator weed thrips (''Amynothrips andersoni''), and the alligator weed stem borer (''Arcola malloi'').

Uses

''A. philoxeroides'' and ''A. sessilis'' are eaten as

vegetable Vegetables are parts of plants that are consumed by humans or other animals as food. The original meaning is still commonly used and is applied to plants collectively to refer to all edible plant matter, including the edible flower, flowers, ...

s in parts of Asia. Some ''Alternanthera'' are used as

ornamental plant Ornamental plants or garden plants are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars that ...

References

{{Taxonbar, from=Q2840398 Amaranthaceae genera