It includes the former goosefoot family Chenopodiaceae and contains about 165 genera and 2,040 species,[2][3] making it the most species-rich lineage within its parent order, Caryophyllales.

[3] The flowers are solitary or aggregated in cymes, spikes, or panicles and typically perfect (bisexual) and actinomorphic.

One to five stamens are opposite to tepals or alternating, inserting from a hypogynous disc, which may have appendages (pseudostaminodes) in some species.

[3] In phytochemical research, several methylenedioxyflavonols, saponins, triterpenoids, ecdysteroids, and specific root-located carbohydrates have been found in these plants.

[5] The multiple origin of C4 photosynthesis in the Amaranthaceae is regarded as an evolutionary response to inexorably decreasing atmospheric CO2 levels, coupled with a more recent permanent shortage in water supply as well as high temperatures.

[6] The monophyly of this broadly defined Amaranthaceae has been strongly supported by both morphological and phylogenetic analyses.

[7] The family Amaranthaceae was first published in 1789 by Antoine Laurent de Jussieu in Genera Plantarum, p. 87–88.

The first publication of family Chenopodiaceae was in 1799 by Étienne Pierre Ventenat in Tableau du Regne Vegetal, 2, p. 253.

includes the former families Achyranthaceae Raf., Atriplicaceae Durande, Betaceae Burnett, Blitaceae T.Post & Kuntze, Celosiaceae Martynov, Chenopodiaceae Vent.

Molecular genetic studies revealed the traditional classification, based on morphological and anatomical characters, often did not reflect the phylogenetic relationships.

The former Amaranthaceae (in their narrow circumscription) are classified into two subfamilies, Amaranthoideae and Gomphrenoideae, and contain about 65 genera and 900 species in tropical Africa and North America.

[14] Current studies classified the species of former Chenopodiaceae to eight distinct subfamilies (the research is not yet completed): Polycnemoideae,[4][15] which are regarded as a basal lineage, Betoideae,[9] Camphorosmoideae,[13] Chenopodioideae,[12] Corispermoideae,[16] Salicornioideae,[10] Salsoloideae,[8] and Suaedoideae.

[4] Many of the species are halophytes, tolerating salty soils, or grow in dry steppes or semi-deserts.

Some species, such as spinach (Spinacia oleracea) or forms of beet (Beta vulgaris) (beetroot, chard), are used as vegetables.

Several amaranth species are also used indirectly as a source of soda ash, such as members of the genus Salicornia (see glasswort).