Polygonum

Polygonum
Polygonum aviculare
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Core eudicots
Order: Caryophyllales
Family: Polygonaceae
Genus: Polygonum
L.
Species

About 220 accepted species; see text

Polygonum is a genus of about 220 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.

The genus primarily grows in northern temperate regions. 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.

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

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.

Distribution and uses

Several species can be eaten cooked,[2] for example during famines.[3] The species Polygonum cognatum, known locally as "madimak",[4][5] 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.[6] Chinese medicine also uses a Polygonum multiflorum extract called Fo-Ti.

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

Reference in Literature

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's Night Dream:[7]

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

Species

Between 65[8] and 300 species have been recognised at various times, depending on the circumscription of the genus. About 200 species are currently accepted.[9] A number of species that had been included in Polygonum have been moved into several other genera, including Fagopyrum, Fallopia, Persicaria and Reynoutria.

Accepted species include:[9]

Polygonum species that have been reclassified as Fagopyrum

Polygonum species that have been reclassified as Fallopia

Polygonum species that have been reclassified as Persicaria

Flowerhead of Persicaria maculata (syn. Polygonum persicara)

Polygonum species that have been reclassified as Reynoutria

Unresolved species

References

  1. ↑ Middle English Dictionary
  2. ↑ Knotweed at NorthernBushCraft
  3. ↑ Łukasz Łuczaj (2008). "Archival data on wild food plants used in Poland in 1948". J Ethnobiol Ethnomed 4 (4): 4. doi:10.1186/1746-4269-4-4. PMC 2275233. PMID 18218132.
  4. ↑ See the preparation of one particular dish in Turkey using Polygonum cognatum: http://www.youtube.com/watch?v=DzNCO94rWXE
  5. ↑ One more dish based on "madimak" polygonum cognatum: http://www.youtube.com/watch?v=p3cJk6ChPkY
  6. ↑
  7. ↑ 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.
  8. ↑ "Polygonum". Flora of North America.
  9. 1 2 3 "The Plant List: Polygonum". Royal Botanic Gardens, Kew and Missouri Botanic Garden. 2013.

External links

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