Polygonaceae, Gen. Pl.: 82. 1789, nom. cons., sec. APG III (2009)
- Type: Polygonum
The Polygonaceae are a morphologically diverse clade containing more than 50 genera and 1200 species. The family is a monophyletic group with the morphological synapomorphies of an ocrea, orthotropous ovules, trigonal (usually) achenes, and quincuncial aestivation (Judd & al. 2007). Polygonaceae are distributed worldwide and present in almost all ecosystems ranging from tropical rainforests to the alpine and tundra (Brandbyge 1993; Sanchez & al. 2009). Burke & Sanchez (2011), based on phylogenetic data, recognized three subfamilies: Polygonoideae Eaton, Eriogonoideae Arn., and Symmerioideae Meisn. Polygonoideae were considered non-monophyletic in previous studies (Lamb Frye & Kron 2003, Sanchez & Kron 2008), but a new circumscription by Sanchez & al. (2011) supported a monophyletic subfamily including the type genus Polygonum and other genera such as Atraphaxis, Fagopyrum, Fallopia, Koenigia, Muehlenbeckia, Oxyria, Persicaria, Rheum, and Rumex; whereby Eriogonoideae was expanded to include currently recognized Antigonon, Coccoloba, Ruprechtia, Triplaris, and other members of the woody genera previously in Polygonoideae (Sanchez & Kron 2009, Burke & al. 2010). It is important to mention that much work is still needed within the tribe Eriogoneae (or Eriogonoideae s.str.), since most of the recognized genera have no support as being monophyletic (Kempton 2012). Symmerioideae is monotypic and the only species recognized is Symmeria paniculata Benth.; this subfamily shows a unique trans-Atlantic disjunction in the Amazon Basin and western Africa, which needs further study (Burke & Sanchez 2011).