(incl. Chenopodiaceae)
Recent molecular phylogenetic research strongly suggests the inclusion of Chenopodiaceae in Amaranthaceae (APG 1998-2009). This taxonomy became widely accepted in recent times (see for instance van der Meijden 2005, Stace 2010) and is adopted here as well.
Polycnemum L. is only remotely related to most members of Amaranthaceae s.l. and is possibly better segregated (see for instance Kadereit & al. 2003). Polycnemum majus A. Braun is an extinct native species (Lawalrée 1953, Lambinon & al. 2004) and P. arvense L. was last seen an alien in Belgium in 1903 (Verloove 2006). Similarly, Einadia Raf. is here tentatively accepted as a distinct genus (pending additional studies) but it might well a member of Australian Chenopodium (Kadereit & al. 2010).
The generic limits of Chenopodium s.l. and related taxa have considerably changed as a result of recent molecular phylogenetic studies (see Fuentes-Bazan & al. 2012 for an overview). Dysphania R. Br. (for species with aromatic, glandular hairs) had already been segregated before on morphological grounds (Mosyakin & Clemants 2002) and this is confirmed by molecular data. Chenopodium, as traditionally understood, finally turns out to fall apart in six independent lineages and the Belgian representatives (native as well as non-native) should be classified as follows (5 lineages present):
Lipandra Moq. with a single, native species:
L. polysperma (L.) S. Fuentes, Uotila & Borsch (syn.: Chenopodium polyspermum L.)
Oxybasis Kar. & Kir., with 5 species (4 native, 1 non-native, preceded by an asterisk):
O. chenopodioides (L.) S. Fuentes, Uotila & Borsch (syn.: Chenopodium chenopodioides (L.) Aellen)
O. glauca (L.) S. Fuentes, Uotila & Borsch (syn.: Chenopodium glaucum L.)
* O. macrosperma (Hook. f.) S. Fuentes, Uotila & Borsch (syn.: Chenopodium macrospermum Hook. f.)
O. rubra (L.) S. Fuentes, Uotila & Borsch (syn.: Chenopodium rubrum L.)
O. urbica (L.) S. Fuentes, Uotila & Borsch (syn.: Chenopodium urbicum L.)
Blitum L., with a single native species and three non-native species (preceded by an asterisk):
Blitum bonus-henricus (L.) Reichenb. (syn.: Chenopodium bonus-henricus L.)
* Blitum capitatum L. (syn.: Chenopodium capitatum (L.) Ambrosi)
* Blitum nuttallianum Schult. (syn.: Monolepis nuttalliana (Schult.) E. Greene)
* Blitum virgatum L. (syn.: Chenopodium foliosum Aschers.)
Dysphania R. Brown, with nine non-native species (preceded by an asterisk):
* D. ambrosioides (L.) Mosyakin et Clemants (syn.: Chenopodium ambrosioides L.)
* D. botrys (L.) Mosyakin et Clemants (syn.: Chenopodium botrys L.)
* D. carinata (R. Brown) Mosyakin et Clemants (syn.: Chenopodium carinatum R. Brown)
* D. cristata (F. Muell.) Mosyakin et Clemants (syn.: Chenopodium cristatum (F. Muell.) F. Muell.)
* D. glomulifera (Nees) P.G. Wilson (syn.: Chenopodium myriocephalum (Benth.) Aellen)
* D. multifida (L.) Mosyakin et Clemants (syn.: Chenopodium multifidum L.)
* D. pseudomultiflora (J. Murr) Verloove et Lambinon (syn.: Chenopodium pseudomultiflorum (J. Murr) Uotila)
* D. pumilio (R. Brown) Mosyakin et Clemants (syn.: Chenopodium pumilio R. Brown)
* D. schraderiana (Schult.) Mosyakin et Clemants (syn.: Chenopodium schraderianum Schult.)
Chenopodiastrum S. Fuentes, Uotila & Borsch, with two native and one non-native species (preceded by an asterisk):
C. hybridum (L.) S. Fuentes, Uotila & Borsch (syn.: Chenopodium hybridum L.)
C. murale (L.) S. Fuentes, Uotila & Borsch (syn.: Chenopodium murale L.)
* C. simplex (Torrey) S. Fuentes, Uotila & Borsch (syn.: Chenopodium simplex (Torrey) Raf.)
The remaining species belong with Chenopodium s.str. In this new, narrower circumscription it is monophyletic.
In the key beneath this new generic circumscription for Chenopodium and related genera is applied.