Alternanthera

''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'' (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 weeds.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 plants, most are terrestrial. They take many forms, from prostrate to erect to floating. The leaves are oppositely arranged. The inflorescence is a spike or a rounded head occurring in the leaf axils or the ends of branches. The flowers have 5 tepals. There are 3 to 5 stamens which are fused into a rim at the bases, and 5 pseudostaminodes, appendages between the stamens that are not true staminodes. The fruit is a utricle containing one seed.

The genus ''Alternanthera'' contains both terrestrial and aquatic species. The photosynthetic 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'' Suess.
*''Alternanthera albotomentosa'' Suess.
*''Alternanthera albida'' (Moq.) Griseb
*''Alternanthera albosquarrosa'' Suess.
*''Alternanthera albotomentosa'' Suess.
*''Alternanthera altacruzensis'' Suess.
*'' Alternanthera angustifolia'' R.Br. – narrow-leaf joyweed
*''Alternanthera aquatica'' (Parodi) Chodat
*''Alternanthera arequipensis'' Suess.
*''Alternanthera areschougii''
*''Alternanthera asterotricha'' Uline
*''Alternanthera axillaris'' (Willd.) DC.
*''Alternanthera bettzickiana'' – calico-plant
*''Alternanthera brasiliana'' (L.) Kuntze – Brazilian joyweed, ruby leaf
*'' Alternanthera caracasana'' Kunth – mat chaff-flower, washerwoman
*''Alternanthera corymbiformis''
*''Alternanthera crucis'' Bold. – West Indian joyweed
*''Alternanthera dentata'' – little ruby
*''Alternanthera denticulata'' – 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''
*''