Amaranthaceae Juss., nom. cons., sec. Müller & Borsch (2005)

Amaranthaceae Juss., nom. cons., sec. Müller & Borsch (2005)

Synonymy

Amaranthaceae Juss., nom. cons., sec. Müller & Borsch (2005), Gen. Pl.: 87. 1789

Introduction

Amaranthaceae belong to a clade together with Chenopodiaceae. Support for the monophyly of the "Amaranthaceae-Chenopodiaceae alliance" is found consistently in all molecular phylogenetic analyses (Manhart & Rettig 1994; Downie & al. 1997; Cuénoud & al. 2002; Kadereit & al. 2003; Müller & Borsch 2005a; Schäferhoff & al. 2009; Brockington & al. 2009). The family circumscription of the Amaranthaceae in the sense of Schinz (1893) was upheld by Townsend (1993) and confirmed as monophyletic with high statistical confidence by Kadereit & al. (2003) and Müller & Borsch (2005a). Following this concept the Amaranthaceae predominantly occur in tropical and subtropical regions with most of the species diversity in the Neotropics, Eastern and Southern Africa and Australia (Müller & Borsch 2005a,b; Sanchez del-Pino & al. 2009). Subfamily Gomphrenoideae has been revealed as monophyletic and nested within the Amaranthoideae and is characterized by unilocular anthers (Sanchez del-Pino & al. 2009), and metareticulate pollen (Borsch & Barthlott 1998; in core Gomphrenoideae except Iresine R. Br., Irenella Suess. and Woehleria Griseb.). In contrast, subfamily Amaranthoideae is largely paraphyletic. The genera Bosea and Charpentiera were found as successive sisters to the remainder of the Amaranthaceae (Müller & Borsch 2005a). The Celosioideae (corresponding to the celosioid clade) are the only natural tribe in the pre-phylogenetic classification of the family and further major lineages are constituted by the amaranthoid clade (Amaranthus, Chamissoa and relatives), the aervoid clade (Aerva, Ptilotus and relatives) and the achyranthoid clade (Achyranthes, Centemposis, Cyathula, Pupalia, Sericocoma and many other African genera; Müller & Borsch 2005b).
The Angiosperm Phylogeny Group (1998) proposed to apply the name Amaranthaceae to the complete Amaranthaceae-Chenopodiaceae alliance, essentially adopting the family concept of Baillon (1887) and Mallingson (1922). The broad family circumscription was also adopted in subsequent versions of the APG classification (APG II 2003; APG III 2009). However, since recent phylogenetic analyses rather indicate the monophyly of the core Chenopodiaceae but are just not yet conclusive about the position of the subfamily Polycnemoideae, the widely used family name Chenopodiaceae is maintained (see introduction to the family Chenopodiaceae). The four genera of the well-supported polycnemoid lineage (Hemichroa R. Br., Nitrophila S. Watson, Polycnemum L., Surreya R. Masson & G. Kadereit) that corresponds to the subfamily Polycnemoideae share petaloid tepals, two large bracteoles supporting the flower, an androecium that is basally united into a tube and bilocular anthers with the Amaranthaceae sensu Schinz (1893), Masson & Kadereit (2013). We are therefore provisionally treating this subfamily under the Amaranthaceae along with Endlicher (1837), Moquin-Tandon (1849) and Scott (1977).