Polygonaceae

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 may refer to the many swollen nodes the stems of some species have, being derived from Greek, poly meaning 'many' and gony meaning 'knee' or 'joint'. Alternatively, it may have a different derivation, meaning 'many seeds'.[3]

Polygonaceae
Persicaria maculosa
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Caryophyllales
Family: Polygonaceae
Juss.[1]
Subfamilies

The Polygonaceae comprise about 1200 species[4] distributed into about 48 genera.[5] The largest genera are Eriogonum (240 species), Rumex (200 species), Coccoloba (120 species), Persicaria (100 species) and Calligonum (80 species).[6][7] The family is present worldwide, but is most diverse in the North Temperate Zone.

Several species are cultivated as ornamentals.[8] A few species of Triplaris provide lumber.[4] The fruit of the sea grape (Coccoloba uvifera) is eaten, and in Florida, jelly is made from it and sold commercially.[9] 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.[10]

Polygonaceae contain some of the most prolific weeds, including species of Persicaria, Rumex and Polygonum, such as Japanese knotweed.[4]

Taxonomy

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.[11] It is sister to the family Plumbaginaceae, which it does not resemble morphologically.[12]

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.[7] 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.[13] 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.[14] Afrobrunnichia might constitute a new subfamily as well.[15]

Brandbyge wrote descriptions for 43 genera of Polygonaceae in 1993.[7] 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.[6][14][16] 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.

Description
Ochrea of Persicaria maculosa

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 ochrea 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.[17][18][19]

Persicaria capitata or pink knotweed

Genera

As of March 2019, Plants of the World Online accepted 56 genera:[20]

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

Phylogeny

The following phylogenetic tree is based on two papers on the molecular phylogenetics of Polygonaceae.[13][14]

Polygonaceae
 

Symmeria

 
 
 

Afrobrunnichia

 
  Eriogonoideae  
 
 

Brunnichia

 
 

Antigonon

 
 
 
 
 

Neomillspaughia

 
 

Coccoloba

 
 
 

Podopterus

 
 

Leptogonum

 
 
 

Ruprechtia

 
 

Triplaris

 
 
 
 

Gymnopodium

 
 
 

Gilmania

 
 
 

Pterostegia

 
 
 

Eriogonum

 
 

Chorizanthe

 
 
 
 
 
 
 
  Polygonoideae  
 
 

Persicaria

 
 
 
 

Bistorta

 
 

Rubrivena

 
 
 
 

Aconogonon

 
 

Koenigia

 
 
 
 
 
 

Fagopyrum (including Parapteropyrum)

 
 
 

Calligonum

 
 

Pteropyrum

 
 

Pteroxygonum

 
 
 
 

Oxyria

 
 

Rheum

 
 

Rumex (including Emex)

 
 
 
 

Knorringia

 
 
 
 

Atraphaxis

 
 

Polygonella

 
 

Polygonum

 
 
 
 

Reynoutria

 
 

Fallopia

 
 

Muehlenbeckia

 
 
 
 
 
 
 
 

References
  1. 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
  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. Costea, Mihai; Tardif, François J. & Hinds, Harold R. "Polygonum". In Flora of North America Editorial Committee (ed.). Flora of North America (online). eFloras.org. Retrieved 2019-05-10.
  4. David J. Mabberley. 2008. Mabberley's Plant-Book third edition (2008). Cambridge University Press: UK. ISBN 978-0-521-82071-4
  5. 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.
  6. 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)
  7. 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)
  8. 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).
  9. George W. Staples and Derral R. Herbst "A Tropical Garden Flora" Bishop Museum Press: Honolulu, Hawaii, USA. (2005)
  10. 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.
  11. 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. hdl:10919/49132. S2CID 58921387.
  12. Peter F. Stevens. 2001 onwards. Angiosperm Phylogeny Website At: Missouri Botanical Garden Website. (see External links below).
  13. 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. S2CID 84694521.
  14. 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.
  15. 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. doi:10.1002/tax.583008.
  16. 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.
  17. 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
  18. 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
  19. 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)
  20. "Polygonaceae Juss.". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 2019-03-01.
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