Polygonum

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Polygonum
Polygonum aviculare 4.JPG
Polygonum aviculare
Scientific classification e
Kingdom: Plantae
Clade: Angiosperms
Clade: Eudicots
Order: Caryophyllales
Family: Polygonaceae
Subfamily: Polygonoideae
Genus: Polygonum
L.
Species

See text.

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.[1] 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.

Description[edit]

The species are very diverse, ranging from prostrate herbaceous annual plants under 5 cm (2 in) high to erect herbaceous perennial plants growing up to 3–4 m (10–13 ft) tall to perennial woody vines growing up to 20–30 m (66–98 ft) high in trees. Several are aquatic, growing as floating plants in ponds. The smooth-edged leaves range from 1–30 cm (0.39–11.81 in) long, and vary in shape between species from narrow lanceolate to oval, broad triangular, heart-shaped, or arrowhead forms. The stems are often reddish or red-speckled. The small flowers are pink, white, or greenish, forming in summer in dense clusters from the leaf joints or stem apices.

Taxonomy[edit]

The genus name is from the Greek poly = "many" and gonu = "knee" or "joint", in reference to the swollen jointed stem.

Polygonum is placed in the tribe Polygoneae of the subfamily Polygonoideae. Within the tribe, it is most closely related to the genera Duma and Atraphaxis, forming the so-called "DAP clade".[2]

Polygoneae

Knorringia

Polygonum ciliinode (syn. Fallopia ciliinodis)

DAP clade

Duma

Atraphaxis

Polygonum

RMF clade

Reynoutria

Muehlenbeckia

Fallopia s.s.

Species[edit]

Between 65[3] and 300 species have been recognised at various times, depending on the circumscription of the genus. A number of species that had been included in Polygonum have been moved into several other genera, including Bistorta, Fagopyrum, Fallopia, Koenigia, Persicaria and Reynoutria. Other genera, such as Polygonella, have been subsumed into Polygonum.

As of February 2019, Plants of the World Online accepted 129 species.[4]

Reclassified species[edit]

Many species formerly placed in Polygonum have been moved to other genera in the subfamily Polygonoideae. Some synonyms are listed below.[5]

Polygonum species that have been reclassified as Bistorta[edit]

Polygonum species that have been reclassified as Fagopyrum[edit]

Polygonum species that have been reclassified as Fallopia[edit]

Polygonum species that have been reclassified as Koenigia[edit]

Polygonum species that have been reclassified as Persicaria[edit]

Polygonum species that have been reclassified as Reynoutria[edit]

Unresolved species[edit]

Uses[edit]

Several species can be eaten cooked,[6] for example during famines.[7] The species Polygonum cognatum, known locally as "madimak",[8][9] is regularly consumed in central parts of Turkey.

In Chinese medicine, a Polygonum extract called Rèlínqīng Kēlì (热林清颗粒) is used to treat urinary tract infections.[10] Chinese medicine also uses a Reynoutria multiflora (synonym Polygonum multiflorum) extract called Fo-Ti.

Care should be taken not to confuse Polygonum with Polygonatum – an entirely different genus of plants.

References in literature[edit]

In The Man Who Laughs Victor Hugo wrote of the Comprachicos (child-buyers) who created artificial dwarfs, formed "by anointing babies' spines with the grease of bats, moles and dormice" and using drugs such as "dwarf elder, knotgrass, and daisy juice". The idea of such use was also known to Shakespeare, as Beatrice K. Otto pointed out, quoting A Midsummer Night's Dream:[11]

Get you gone, dwarf;
You minimus, of hindering knot-grass made;

References[edit]

  1. ^ Middle English Dictionary
  2. ^ Schuster, Tanja M.; Reveal, James L.; Bayly, Michael J. & Kron, Kathleen A. (2015). "An updated molecular phylogeny of Polygonoideae (Polygonaceae): Relationships of Oxygonum, Pteroxygonum, and Rumex, and a new circumscription of Koenigia". Taxon. 64 (6): 1188–1208. doi:10.12705/646.5.
  3. ^ "Polygonum". Flora of North America.
  4. ^ "Polygonum: accepted species". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 2019-02-28.
  5. ^ "Search for Polygonum species". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 2019-02-28.
  6. ^ Knotweed at NorthernBushCraft
  7. ^ Łukasz Łuczaj (2008). "Archival data on wild food plants used in Poland in 1948". J Ethnobiol Ethnomed. 4 (1): 4. doi:10.1186/1746-4269-4-4. PMC 2275233. PMID 18218132.
  8. ^ See the preparation of one particular dish in Turkey using Polygonum cognatum: https://www.youtube.com/watch?v=DzNCO94rWXE
  9. ^ One more dish based on "madimak" polygonum cognatum: https://www.youtube.com/watch?v=p3cJk6ChPkY
  10. ^ [1]
  11. ^ Otto, Beatrice K. (2001) [2001-04-01]. "Facets of the Fool". Fools are Everywhere: The Court Jester Around the World. University Of Chicago Press. p. 29. ISBN 0-226-64091-4. Retrieved 2008-04-28.

External links[edit]