The Polygonaceae are a family of flowering plants known informally as the knotweed family or smartweed—buckwheat family in the United States. The name is based on the genus Polygonum, and was first used by Antoine Laurent de Jussieu in 1789 in his book, Genera Plantarum.[2] The name refers to the many swollen nodes the stems of some species have. It is derived from Greek; poly means many and goni means knee or joint.

The Polygonaceae comprise about 1200 species[3] distributed into about 48 genera.[4] The largest genera are Eriogonum (240 species), Rumex (200 species), Coccoloba (120 species), Persicaria (100 species) and Calligonum (80 species).[5][6] The family is present worldwide, but is most diverse in the North Temperate Zone.

Several species are cultivated as ornamentals.[7] A few species of Triplaris provide lumber.[3] The fruit of the sea grape (Coccoloba uvifera) is eaten, and in Florida, jelly is made from it and sold commercially.[8] The seeds of two species of Fagopyrum, known as buckwheat (sarrasin in French), provide grain (its dark flour is known as blé noir (black wheat) in France). The petioles of rhubarb (Rheum rhabarbarum and hybrids) are a food item. The leaves of the common sorrel (Rumex acetosa) are eaten in salads or as a leaf vegetable.[9]

Polygonaceae contain some of the worst weeds, including species of Persicaria, Rumex and Polygonum, such as Japanese knotweed.[3]

Polygonum persicaria bgiu
Persicaria maculosa
Scientific classification
Kingdom: Plantae
Clade: Angiosperms
Clade: Eudicots
Order: Caryophyllales
Family: Polygonaceae



Polygonaceae are very well-defined and have long been universally recognized. In the APG III system, the family is placed in the order Caryophyllales.[1] Within the order, it lies outside of the large clade known as the core Caryophyllales.[10] It is sister to the family Plumbaginaceae, which it does not resemble morphologically.[11]

Polygonum plebeium W IMG 0462
Polygonum plebeium or small knotweed

The last comprehensive revision of the family was published in 1993 by John Brandbyge as part of The Families and Genera of Vascular Plants.[6] Brandbyge followed earlier systems of plant classification in dividing Polygonaceae into two subfamilies, Eriogonoideae and Polygonoideae. Since 1993, the circumscriptions of these two subfamilies have been changed in light of phylogenetic studies of DNA sequences.[12] Genera related to Coccoloba and Triplaris were moved from Polygonoideae to Eriogonoideae. The genus Symmeria does not belong to either of these subfamilies because it is sister to the rest of the family.[13] Afrobrunnichia might constitute a new subfamily as well.[14]

Brandbyge wrote descriptions for 43 genera of Polygonaceae in 1993.[6] Since then, a few more genera have been erected, and some segregates of Brunnichia, Eriogonum, and Persicaria have been given generic status in major works.[5][13][15] Some of the genera were found not to be monophyletic and their limits have been revised. These include Ruprechtia, Eriogonum, Chorizanthe, Persicaria, Aconogonon, Polygonum, Fallopia, and Muehlenbeckia.


Most Polygonaceae are perennial herbaceous plants with swollen nodes, but trees, shrubs and vines are also present. The leaves of Polygonaceae are simple, and arranged alternately on the stems. Each leaf has a peculiar pair of fused, sheathing stipules known as an ochrea. Those species that do not have the nodal ocrea can be identified by their possession of involucrate flower heads. The flowers are normally bisexual, small, and actinomorphic, with a perianth of three to six sepals. After flowering, the sepals often become thickened and enlarged around the developing fruit. Flowers lack a corolla and in some, the sepals are petal-like and colorful. The androecium is composed of three to eight stamens that are normally free or united at the base. The ovary consists of three united carpels that form a single locule, which produces only one ovule. The ovary is superior with basal or free-central placentation. The gynoecium terminates in 1 to 3 styles, each of which ends in a single stigma.[16][17][18]

Persicaria capitata AF crop
Persicaria capitata or pink knotweed


As of March 2019, Plants of the World Online accepted 56 genera:[19]

Former genera

  • Aconogonon (Meisn.) Rchb. – now included in Koenigia
  • Homalocladium (F.Muell.) L.H.Bailey – now included in Muehlenbeckia
  • Parapteropyrum A.J.Li – now included in Fagopyrum
  • Polygonella Michx. – now included in Polygonum
  • Rubrivena M.Král – now included in Koenigia


The following phylogenetic tree is based on two papers on the molecular phylogenetics of Polygonaceae.[12][13]
























Fagopyrum (including Parapteropyrum)






Rumex (including Emex)









  1. ^ a b Angiosperm Phylogeny Group (2009), "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III", Botanical Journal of the Linnean Society, 161 (2): 105–121, doi:10.1111/j.1095-8339.2009.00996.x, archived from the original on 2017-05-25, retrieved 2010-12-10
  2. ^ Antoine Laurent de Jussieu. 1789. Genera plantarum: secundum ordines naturales disposita, juxta methodum in Horto regio parisiensi exaratam. page 82. Herrisant and Barrois: Paris, France. (see External links below)
  3. ^ a b c David J. Mabberley. 2008. Mabberley's Plant-Book third edition (2008). Cambridge University Press: UK. ISBN 978-0-521-82071-4
  4. ^ Christenhusz, M. J. M.; Byng, J. W. (2016). "The number of known plants species in the world and its annual increase". Phytotaxa. Magnolia Press. 261 (3): 201–217. doi:10.11646/phytotaxa.261.3.1.
  5. ^ a b Craig C. Freeman and James L. Reveal. 2005. "Polygonaceae" pages 216-601. In: Flora of North America Editorial Committee (editors). Flora of North America vol. 5. Oxford University Press: New York, NY, USA. ISBN 978-0-19-522211-1 (see External links below)
  6. ^ a b c John Brandbyge. 1993. "Polygonaceae". pages 531-544. In: Klaus Kubitzki (editor); Jens G. Rohwer, and Volker Bittrich (volume editors). The Families and Genera of Vascular Plants volume II. Springer-Verlag: Berlin; Heidelberg, Germany ISBN 978-3-540-55509-4 (Berlin) ISBN 978-0-387-55509-6 (New York)
  7. ^ Anthony Huxley, Mark Griffiths, and Margot Levy (1992). The New Royal Horticultural Society Dictionary of Gardening. The Macmillan Press,Limited: London. The Stockton Press: New York. ISBN 978-0-333-47494-5 (set).
  8. ^ George W. Staples and Derral R. Herbst "A Tropical Garden Flora" Bishop Museum Press: Honolulu, Hawaii, USA. (2005)
  9. ^ Vernon H. Heywood, Richard K. Brummitt, Ole Seberg, and Alastair Culham. Flowering Plant Families of the World. Firefly Books: Ontario, Canada. (2007). ISBN 978-1-55407-206-4.
  10. ^ Brockington, Samuel F.; Alexandre, Roolse; Ramdial, Jeremy; Moore, Michael J.; Crawley, Sunny; Dhingra, Amit; Hilu, Khidir; Soltis, Douglas E.; Soltis, Pamela S. (2009). "Phylogeny of the Caryophyllales sensu lato: Revisiting hypotheses on pollination biology and perianth differentiation in the core Caryophyllales". International Journal of Plant Sciences. 170 (5): 627–643. doi:10.1086/597785.
  11. ^ Peter F. Stevens. 2001 onwards. Angiosperm Phylogeny Website At: Missouri Botanical Garden Website. (see External links below).
  12. ^ a b Sanchez, Adriana; Schuster, Tanja M.; Kron, Kathleen A. (2009). "A large-scale phylogeny of Polygonaceae based on molecular data". International Journal of Plant Sciences. 170 (8): 1044–1055. doi:10.1086/605121.
  13. ^ a b c Burke, Janelle M.; Sanchez, Adriana; Kron, Kathleen; Luckow, Melissa (2010). "Placing the woody tropical genera of Polygonaceae: A hypothesis of character evolution and phylogeny". American Journal of Botany. 97 (8): 1377–1390. doi:10.3732/ajb.1000022. PMID 21616890.
  14. ^ Sanchez, Adriana; Kron, Kathleen A. (2009). "Phylogenetic relationships of Afrobrunnichia Hutch. & Dalziel (Polygonaceae) based on three chloroplast genes and ITS". Taxon. 58 (3): 781–792.
  15. ^ Anjen Li, Bojian Bao, Alisa E. Grabovskaya-Borodina, Suk-pyo Hong, John McNeill, Sergei L. Mosyakin, Hideaki Ohba, and Chong-wook Park. 2003. "Polygonaceae" pages 277-350. In: Zhengyi Wu, Peter H. Raven, and Deyuan Hong (editors). Flora of China volume 5. Science Press: Beijing, China; Missouri Botanical Garden Press: St. Louis, Missouri, USA.
  16. ^ Samuel B. Jones and Arlene E. Luchsinger. 1979. Plant systematics. McGraw-Hill series in organismic biology. New York: McGraw-Hill. Page 254. ISBN 0-07-032795-5
  17. ^ Walter S. Judd, Christopher S. Campbell, Elizabeth A. Kellogg, Peter F. Stevens, and Michael J. Donoghue. 2008. Plant Systematics: A Phylogenetic Approach, Third Edition. Sinauer Associates: Sunderland, MA, USA. ISBN 978-0-87893-407-2
  18. ^ Armen L. Takhtajan (Takhtadzhian). Flowering Plants second edition (2009), pages 155-156. Springer Science+Business Media. ISBN 978-1-4020-9608-2. (see External links below)
  19. ^ "Polygonaceae Juss.". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 2019-03-01.

External links

Antigonon leptopus

Antigonon leptopus, commonly known as Mexican creeper, coral vine, Coralita, bee bush (in many Caribbean islands) or San Miguelito vine, is a species of flowering plant in the buckwheat family, Polygonaceae. It is a perennial that is native to Mexico. It is a vine with pink or white flowers (Antigonon leptopus 'alba' ).

Benedictus Hubertus Danser

Benedictus Hubertus Danser (May 24, 1891, Schiedam, Netherlands – October 18, 1943, Groningen), often abbreviated B. H. Danser, was a Dutch taxonomist and botanist. Danser specialised in the plant families Loranthaceae, Nepenthaceae, and Polygonaceae.

In 1928, Danser published an exhaustive revision of the genus Nepenthes, recognising 65 species in "The Nepenthaceae of the Netherlands Indies". Today, more than 140 species of Nepenthes are known, but Danser's work is still often referenced by specialists in the field.Danser died in Groningen on October 18, 1943. The genus Dansera (Fabaceae) and the species Nepenthes danseri (Nepenthaceae), Rumex danseri (Polygonaceae) and Taxillus danseriana (Loranthaceae) are named after him.

Bistorta bistortoides

Bistorta bistortoides (American bistort, western bistort, smokeweed, mountain meadow knotweed, mountain buckwheat or mountain meadow buckwheat) is a perennial herb in the buckwheat and knotweed family Polygonaceae. The species name remains unresolved.Bistorta bistortoides is distributed throughout the Mountain West in North America from Alaska and British Columbia south into California and east into the Rocky Mountains.Bistorta bistortoides grows from foothills to above the timberline, although plants growing above 7,500 feet (2250 m) are smaller and seldom reach more than 12 inches (30 cm) in height. Plants in other areas may reach over half a meter–1.5 feet (20–60 cm) tall. The leaves are leathery and up to 40 centimeters (3 feet) long, and are mostly basal on the stem. The dense cylindrical to oblong inflorescence is packed with small white to pinkish flowers, each a few millimeters wide and with protruding stamens.American bistort was an important food plant used by Native Americans living in the Mountain West, and the roots are edible either raw or fire-roasted with a flavor resembling chestnuts. The seeds can be dried and ground into flour and used to make bread. They were also roasted and eaten as a cracked grain.


Calligonum is a genus of plants in the family Polygonaceae with about 80 species across the Mediterranean Sea region, Asia and North America.


Chorizanthe is a genus of plants in the buckwheat family known generally as spineflowers. These are small, squat, herbaceous plants with spiny-looking inflorescences of flowers. The flowers may be in shades of red or yellow to white. The bracts are pointed and sometimes tipped with a hooked awn, and the inflorescence often dries into a rounded, spiny husk. Spineflowers are found in western North America and South America.

Name derivation: The word Chorizanthe comes from the Greek roots chorizo and anthos meaning "to divide," and "flower," thus meaning "divided flowers," but actually used in reference to the divided calyx.

Selected species:

Chorizanthe angustifolia - narrowleaf spineflower

Chorizanthe biloba - twolobe spineflower

Chorizanthe blakleyi - Blakley's spineflower

Chorizanthe brevicornu - brittle spineflower

Chorizanthe breweri - San Luis Obispo spineflower

Chorizanthe corrugata - wrinkled spineflower

Chorizanthe cuspidata - San Francisco spineflower

Chorizanthe diffusa - diffuse spineflower

Chorizanthe douglasii - San Benito spineflower

Chorizanthe fimbriata - fringed spineflower

Chorizanthe howellii - Mendocino spineflower

Chorizanthe leptotheca - Ramona spineflower

Chorizanthe membranacea - pink spineflower

Chorizanthe obovata - spoonsepal spineflower

Chorizanthe orcuttiana - San Diego spineflower

Chorizanthe palmeri - Palmer's spineflower

Chorizanthe parryi - San Bernardino spineflower

Chorizanthe polygonoides - knotweed spineflower

Chorizanthe procumbens - prostrate spineflower

Chorizanthe pungens - Monterey spineflower

Chorizanthe rectispina - prickly spineflower

Chorizanthe rigida - devil's spineflower, rigid spineflower

Chorizanthe robusta - robust spineflower

Chorizanthe spinosa - Mojave spineflower

Chorizanthe staticoides - Turkish rugging

Chorizanthe stellulata - starlet spineflower

Chorizanthe uniaristata - one-awned spineflower

Chorizanthe valida - Sonoma spineflower

Chorizanthe ventricosa - Priest Valley spineflower

Chorizanthe watsonii - fivetooth spineflower

Chorizanthe wheeleri - Santa Barbara spineflower

Chorizanthe xanti - Riverside spineflower


Coccoloba is a genus of about 120–150 species of flowering plants in the family Polygonaceae. The genus is native to tropical and subtropical regions of the Americas, in South America, the Caribbean and Central America, with two species extending into Florida.The species are shrubs and trees, mostly evergreen. The leaves are alternate, often large (to very large in some species; up to 36 in (90 cm) wide in C. pubescens), with the leaves on juvenile plants often larger and of different shape to those of mature plants. The flowers are produced in spikes. The fruit is a three-angled achene, surrounded by an often brightly coloured fleshy perianth, edible in some species, though often astringent.There is no overall English name for the genus, although many of the individual species have widely used common names.


Eriogonum is the scientific name for a genus of flowering plants in the family Polygonaceae. The genus is found in North America and is known as wild buckwheat. This is a highly species-rich genus, and indications are that active speciation is continuing. It includes some common wildflowers such as the California buckwheat (Eriogonum fasciculatum).

The genus derived its name from the Greek word erion meaning 'wool' and gonu meaning 'knee or joint'. The author of the genus, Michaux, explained the name as describing the first named species of the genus (E. tomentosum) as a wooly plant with sharply bent stems ("planta lanata, geniculata"). Despite sharing the common name "buckwheat", eriogonum is part of a different genus than the cultivated European buckwheat and than other plant species also called wild buckwheat.

It came into the news in 2005 when the Mount Diablo buckwheat (Eriogonum truncatum, believed to be extinct) was rediscovered.


The genus Fagopyrum is in the flowering plant family Polygonaceae. It includes some important food plants, such as F. esculentum (buckwheat) and F. tataricum (Tartary buckwheat). The genus is native to the Indian subcontinent, much of Indochina, and central and southeastern China. Species have been widely introduced elsewhere, throughout the Holarctic and parts of Africa and South America.


Muehlenbeckia or maidenhair is a genus of flowering plants in the family Polygonaceae. It is native to the borders of the Pacific, including South and North America, Papua New Guinea and Australasia. It has been introduced elsewhere, including Europe. Species vary in their growth habits, many being vines or shrubs. In some environments, rampant species can become weedy and difficult to eradicate.


Persicaria is a genus of herbaceous flowering plants in the knotweed family, Polygonaceae. Plants of the genus are known commonly as knotweeds or smartweeds. It has a cosmopolitan distribution, with species occurring nearly worldwide. The genus was segregated from Polygonum.


Polygonoideae is a subfamily of plants in the family Polygonaceae. It includes a number of plants that can be highly invasive, such as Japanese knotweed, Reynoutria japonica, and its hybrid with R. sachalinensis, R. × bohemica. Boundaries between the genera placed in the subfamily and their relationships have long been problematic, but a series of molecular phylogenetic studies have clarified some of them, resulting in the division of the subfamily into seven tribes.


Polygonum is a genus of about 130 species of flowering plant in the buckwheat and knotweed family Polygonaceae. Common names include knotweed, knotgrass, bistort, tearthumb, mile-a-minute, smartweed and several others. In the Middle English glossary of herbs Alphita (c. 1400–1425), it was known as ars-smerte. There have been various opinions about how broadly the genus should be defined. For example, buckwheat (Fagopyrum esculentum) has sometimes been included in the genus as Polygonum fagopyrum. Former genera such as Polygonella have been subsumed into Polygonum; other genera have been split off.

The genus primarily grows in northern temperate regions. The species are very diverse, ranging from prostrate herbaceous annual plants to erect herbaceous perennial plants and perennial woody vines growing high in trees. Several are aquatic, growing as floating plants in ponds.

Polygonum species are occasionally eaten by humans, and are used as food plants by the larvae of some Lepidoptera species – see list. Most species are considered weedy, especially in moist soils in the USA.

Rheum officinale

Rheum officinale, the Chinese rhubarb, is a rhubarb from the family Polygonaceae native to China. In the Chinese it is called yào yòng dà huáng (Chinese: 药用大黄).


The docks and sorrels, genus Rumex L., are a genus of about 200 species of annual, biennial, and perennial herbs in the buckwheat family Polygonaceae.

Members of this family are very common perennial herbs with a native almost worldwide distribution, with introduced species growing in the few places where the genus is not native.Some are nuisance weeds (and are sometimes called dockweed or dock weed), but some are grown for their edible leaves.

Rumex species are used as food plants by the larvae of a number of Lepidoptera species, and are the only host plants of Lycaena rubidus.

Rumex hymenosepalus

Rumex hymenosepalus, commonly known as canaigre, canaigre dock, ganagra, wild rhubarb, Arizona dock, and tanner's dock, is a perennial flowering plant which is native to the western United States and northern Mexico. It is a common food plant of the ruddy copper larvae.

Rumex hypogaeus

Rumex hypogaeus (synonym Emex australis), commonly known in English as southern threecornerjack, devil's thorn, or double gee (also doublegee, from the old Afrikaner name dubbeltge-doorn - 'double thorned'), is a herbaceous plant of the Polygonaceae. It occurs indigenously in South Africa and is also an invasive species in Australia & Texas in the USA.

Rumex patientia

Rumex patientia, known as patience dock, garden patience, herb patience, or monk's rhubarb, is a herbaceous perennial plant species of the genus Rumex, belonging to the family Polygonaceae. In spring it is often consumed as a leaf vegetable in Southern Europe, especially in Bulgaria, Republic of Macedonia and Serbia. It is also used in Romania in spring broths or sarmale.


Common sorrel or garden sorrel (Rumex acetosa), often simply called sorrel, is a perennial herb in the family Polygonaceae. Other names for sorrel include spinach dock and narrow-leaved dock. It is a common plant in grassland habitats and is cultivated as a garden herb or salad vegetable (pot herb).

Woody plant

A woody plant is a plant that produces wood as its structural tissue. Woody plants are usually either trees, shrubs, or lianas. These are usually perennial plants whose stems and larger roots are reinforced with wood produced from secondary xylem. The main stem, larger branches, and roots of these plants are usually covered by a layer of bark. Wood is a structural cellular adaptation that allows woody plants to grow from above ground stems year after year, thus making some woody plants the largest and tallest terrestrial plants.

Wood is primarily composed of xylem cells with cell walls made of cellulose and lignin. Xylem is a vascular tissue which moves water and nutrients from the roots to the leaves. Most woody plants form new layers of woody tissue each year, and so increase their stem diameter from year to year, with new wood deposited on the inner side of a vascular cambium layer located immediately beneath the bark. However, in some monocotyledons such as palms and dracaenas, the wood is formed in bundles scattered through the interior of the trunk.Woody herbs are herbaceous plants that develop hard woody stems. They include such plants as Uraria picta and certain species in family Polygonaceae. These herbs are not truly woody but have hard densely packed stem tissue. Other herbaceous plants have woody stems called a caudex, which is a thickened stem base often found in plants that grow in alpine or dry environments.

Under specific conditions, woody plants may decay or may in time become petrified wood.

The symbol for a woody plant, based on Species Plantarum by Linnaeus is , which is also the astronomical symbol for the planet Saturn.

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