1. Polygonaceae Juss.

    1. This family is accepted.


Melo, E. & França, F. (2009). Neotropical Polygonaceae.


Herbs, shrubs, lianas ( stem or tendril climbers ) or trees; without latex or exudate . Stipules usually present, connate to form a leaf sheath ( ochrea ), rarely absent (subfam. Eriogoneoideae), leaf sheath tubular, membranaceous or scarious , deciduous or persistent , with bilobed or fringed margins. Leaves simple , alternate (rarely opposite), usually spirally arranged; petiolate or subsessile, petioles often flattened; extrafloral nectaries sometimes present at petiole base; leaf-blades entire , pinnately veined; basally auriculate , cordate , hastate , sagittate , rounded to cuneate , margins entire , sometimes crenate . Flowers usually hermaphrodite , small, if unisexual then plants monoecious , polygamo- monoecious or dioecious ; inflorescence cymose, terminal , or in axillary racemes, corymbs, spikes and heads, sometimes in axillary fascicles; involucral bracts sometimes present, developed and showy, regular, 2-5- merous , cyclic to partially acyclic; hypanthium, when present, free , hypogynous disk or nectaries present between the androecial members; calyx and corolla distinct, or both sepal -like or petal -like, 2-6, free or joined, 1-2- whorled or spiralled, persistent in fruit and often accrescent ; stamens (2-)6(-9) to many (Symmeria Benth.), free or adnate to the perianth (usually more or less perigynous ), free or connate ; gynoecium (2-)3 carpelled, syncarpous, styles 2-3, free to partially jointed, apical, stigmas 2-3, ovary superior , unilocular, uniovulate, placentation basal , orthotropous. Fruit dry, indehiscent usually a trigonous or flattened nut or achene -like, sometimes enclosed by a fleshy hypanthium or perianth , 1 seeded. Seeds with ruminate (Coccoloba P. Browne) or not- ruminate endosperm , oily, starchy, cotyledons 2, embryo straight to curved.


General Description
Notes on delimitation
  • Traditionally the Polygonaceae were placed within the Caryophyllales on the basis of the unilocular ovary and single, basalovule. However, recent studies have revealed that the family lacks the P-type sieve-tube plastids, anatropous ovules, betalain pigments and perisperm characters that characterise the order Caryophyllales. Recent studies by the APG II (2003) still include the Polygonaceae within the Caryophyllales.
Number of genera
  • Antigonon (6 species).
  • Coccoloba (120 species).
  • Gymnopodium (3 species).
  • Leptogonum (one species endemic to Hispaniola).
  • Muehlenbeckia (9 species).
  • Neomillspaughia (2 species).
  • Persicaria (c. 5 species).
  • Podopterus (3 species).
  • Polygonum (c. 30 species).
  • Rumex (c. 15 species).
  • Ruprechtia (37 species).
  • Symmeria (1 species).
  • Triplaris (18 species).
  • While Coccoloba, Ruprechtia and Triplaris are endemic to the Neotropics, Rumex, Polygonum and Antigonon have weedy status, with species of knot-weed (Polygonum) being particularly invasive in Europe.
  • Antigononleptopus Hook. & Arn. originates from Mexico but is cultivated worldwide because of its showy flowers. Buckwheat, used in Japan for making pasta (soba, Fagopyrumesculentum Moench) is an increasingly popular, gluten-free alternative to wheat.


Distribution in the Neotropics
  • The Polygonaceae are cosmopolitan, with most genera and species occurring in northern temperate regions. 31 genera are found in the western hemisphere. 16 of these genera are restricted to western North America, with 3 disjunct to Chile and Argentina.

Of the 13 tropical and subtropical American genera:

  • Ruprechtia C.A.Mey., Triplaris Loefl., and Coccoloba P.Browne are fairly widespread in the Neotropics;
  • Neomillspaughia S.F.Blake, Podopterus Kunth, Gymnopodium Rolfe and Antigonon Endl. are restricted to Central America.
  • The monotypicLeptogonum Benth. is endemic to Hispaniola.
  • Symmeria Benth. is amphiatlantic.
  • Muehlenbeckia Meisn. is amphipacific.
  • Polygonum L., Rumex L., and Persicaria L. are cosmopolitan.
Other important characters
  • Flowers small, often unisexual (Coccoloba), sometimes with attractive bracts (Antigonon). Fruits with accrescentcalyx (Triplaris).
Distinguishing characters (always present)
  • Stems often with conspicuous swollen nodes.
  • Stipules present.
  • Ochreas are present in the Polygonoideae, absent in the Eriogonoideae (this subfamily is not represented in the Neotropics).
Key differences from similar families
  • Polygonaceae are characterised by the presence of the ochrea (absent from subfam. Eriogonoideae), and have leaves spirally alternate, swollen nodes and involucred inflorescence. Vegetatively they can be confused with Piperaceae (swollen nodes, leaves with irregular base) but they have a deciduousterminalstipule and very small flowers densely arranged in spikes.
Notable genera and distinguishing features
  • Coccoloba - erect or climbing woody plants, unisexual flowers and pedunculate fleshy fruits.
  • Ruprechtia - trees to shrubs, three-winged fruits, female partial inflorescences 2-3-flowered, male flowers pedicellate, twigs often solid.
  • Triplaris - shrubs to trees, three-winged fruits, female partial inflorescences 1-flowered, male flowers sessile, often associated with ants that live in its hollow branches.
  • Polygonum - erect herbs with flowers in spikes, closely allied to Persicaria.
  • Antigonon - climbing plants with showy bracts protecting inflorescences.


Useful tips for generic identification

See below.

Important literature

APG II, 2003. An update of the Angiosperm Phylogeny group classification for the orders and families of flowering plants: APG II. Botanical Journal of the Linnean Society 141(4): 399-436.

BRANDBYGE, J. 1986. A revision of the genus Triplaris (Polygonaceae). Nord. Journ. Bot. 6(5).

BRANDBYGE, J. 1989. Polygonaceae. Flora of Ecuador. 38:39.

BUCHINGER, M. & SANCHEZ, E. 1959. Sinopsis preliminar de las especies argentinas del genero Coccoloba. Bol. Soc. Arg. Botanica, v.7, n.3/4, p.251-255.

BURGER, W. 1983. Polygonaceae. In: Burger. Flora Costaricensis. Fieldiana Botany. Field Museum of Natural History, n.s. 13, p.99-138.

CIALDELLA, A. M. 1989. Revisión de las espécies argentinas de Polygonum s.l. (Polygonaceae). Darwiniana 29(1-4):179-246.

CIALDELLA, A.M. 2001. Polygonaceae. In Spichiger & Ramella. Flora del Paraguay v. 33: 1-106.

HOWARD, R. A. 1960. Polygonaceae. In: Woodson (ed.). Flora of Panama. Annals of the Missouri Botanical Garden, 47: 340-357.

HOWARD, R. A. 1961. Studies in the Genus Coccoloba, X. New species and a summary of distribution in South America. Journ. Arn. Arb. 42(1): 87-95.

HOWARD, R. A. 1992. Collected notes on Coccoloba L. (Polygonaceae). Brittonia 44: 356-367.

MARTÍNEZ, R. V. 1997. Polygonaceae. In: Lleras & Taylor. Flórula de las reservas biologicas de Iquitos. Peru. Missouri Botanical Garden. Press. p.587-592.

MELO, E. 1996. Levantamento das espécies de Coccoloba (Polygonaceae) da restinga do estado da Bahia, Brasil. Sitientibus 15:49-59.

MELO, E. 1998. Levantamento da família Polygonaceae no estado da Bahia, Brasil: espécies do semi-árido. Rodriguesia 50(76/77):19-37.

MELO, E. 2000. Polygonaceae da Cadeia do Espinhaço, Brasil. Acta Bot. Bras. 14(3):273-300.

MELO, E. & F. FRANÇA. 2006. A familia Polygonaceae no semi-árido brasileiro. In A.M. Giulietti et al. (eds) Diversidade e Caracterização das fanerógamas do semi-árido brasileiro. In A. Giulietti  & L. Queiroz Instituto do Milênio do Semi-Árido, v. 1, p. 437-488.

PENDRY, C.A. 2004. Monograph of Ruprechtia (Polygonaceae). Systematic Botany Monographs 67: 1 - 113.


Polygonaceae, Hutchinson and Dalziel. Flora of West Tropical Africa 1:1. 1954

Herbs, shrubs or climbers, rarely trees: leaves alternate, with the base of the petiole often dilated into a membranous sheath (ochrea)
Flowers hermaphrodite, polygamous or dioecious, actinomorphic, small and inconspicuous
Sepals 3–6, imbricate, often enlarged and becoming membranous in fruit
Petals absent
Stamens usually 6–9, rarely more; filaments free or united at the base; anthers 2-celled, opening lengthwise
Disk annular or central
Ovary superior, sessile, 1-celled; styles 2–4, usually free; ovule solitary, basal, sessile or stalked
Fruit an indehiscent trigonous or 2-sided nut
Seeds with abundant mealy endosperm and often excentric embryo
Besides the above indigenous genera, Antigonon leptopus Hook. & Arn., a native of Mexico, is often met with; it is widely cultivated as an ornamental and is known as "Corallita."

Polygonaceae, I. Nogueira, S. Ortiz & J.A.R. Paiva. Flora Zambesiaca 9:3. 2006

Annual or perennial herbs, shrubs or climbers (more rarely trees), glabrous or hairy
Branches sometimes with tendrils
Leaves usually alternate and usually with sheathing stipules (ocreae)
Inflorescences capitate, racemose or ± umbellate, sometimes branched and paniculate, the flowers usually fascicled and subtended by bracts as well as the ocrea, with or without bracteoles
Flowers hermaphrodite, polygamous or unisexual, sometimes heterostylous, actinomorphic, pedicellate; pedicels usually articulated
Perianth sepaloid or petaloid of 3–6 free or connate segments (tepals), in 1 or 2 series, imbricate in bud, membranous, sometimes accrescent, sometimes armed with spines, prickles or teeth
Stamens (4)6–9, usually inserted at or near the base of the perianth segments; filaments filiform or dilated at the base, free or basally united; anthers dorsifixed, 2-thecous, opening lengthwise
Disk annular or composed of glands
Ovary superior, syncarpous, unilocular, sometimes falsely 3-locular, with a solitary basal orthotropous ovule; styles 2–3, free, or connate at the base; stigmas capitate, peltate or penicillate
Fruit a nut, indehiscent, hard, trigonous or lenticular, usually enclosed in the ± persistent perianth
Seed similar in shape to the nut, with abundant endosperm; testa membranous, smooth or not


Polygonaceae Juss. appears in other Kew resources:

First published in Gen. Pl. [Jussieu] 82. 1789 [4 Aug 1789] (1789)

Accepted by

  • APG IV (2016) http://dx.doi.org/10.1111/boj.12385


Flora of West Tropical Africa
[A] http://creativecommons.org/licenses/by-nc-sa/3.0

Flora Zambesiaca
Flora Zambesiaca
[B] http://creativecommons.org/licenses/by-nc-sa/3.0

Kew Names and Taxonomic Backbone
The International Plant Names Index and World Checklist of Selected Plant Families 2017. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
[C] © Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

Milliken, W., Klitgard, B. and Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics.
[D] http://creativecommons.org/licenses/by/3.0