Polygonum

''Polygonum'' is a genus of about 130 species of flowering plant in the buckwheat and knotweed family Polygonaceae. Common names include knotweed and knotgrass (though the common names may refer more broadly to plants from Polygonaceae). In the Middle English glossary of herbs ''Alphita'' ( 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.

''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 weeds in Europe and North America.

Description

When the genus is defined narrowly, ''Polygonum'' species are annual or perennial herbaceous plants, rarely shrubby, with much branched stems. The leaves are arranged alternately, usually less than long, with a length greater than the width. They have a membranous ochrea (a sheath around the stem nodes). The flowers are usually bisexual, rarely unisexual, and have five (occasionally four) tepals, the outer being slightly different from the inner ones. There are usually four to six stamens and three (rarely two) styles. The fruit is three-sided.

Taxonomy

The genus ''Polygonum'' was first described by Carl Linnaeus in 1754. The genus name is usually said to be from the Greek (''poly''-, 'many') and (''gonu'', 'knee' or 'joint'), in reference to the swollen jointed stem. p. 404 p. 148. However, long before Linnaeus, the name was used in Greek and Latin for a plant used medically. Discussing the plant he knew as ''polygonum'' in 1655, Matthias Martinius referred to Scribonius Largus (who wrote a list of prescriptions around 47 AD) and gave an alternative etymology, based on (''gonos'', 'offspring', 'seed'), the meaning of the name then being the Latin , i.e. 'fecund', 'with many offspring'. The ''Flora of North America'' says that a derivation meaning 'many seeds' is the "grammatically correct interpretation".

Many members of the family Polygonaceae that are now placed in separate genera were at one time or other placed in ''Polygonum'', including species of ''Fagopyrum'', ''Fallopia'', ''Persicaria'', and older sources frequently use much wider definitions of the genus. Molecular phylogenetic studies, particularly in the 21st century, have led to major changes. Clarifying the circumscription of genera split from ''Polygonum'' was described in 2015 as "still ongoing".

Classification and phylogeny

''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".

Species

Between 65 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''. Other genera, such as ''Polygonella'', have been subsumed into ''Polygonum''.

, Plants of the World Online accepted 129 species.

*'' Polygonum acerosum'' Ledeb. ex Meisn.
*'' Polygonum acetosum'' M.Bieb.
*'' Polygonum achoreum'' S.F.Blake
*'' Polygonum adenopodum'' Sam.
*'' Polygonum afromontanum'' Greenway
*'' Polygonum agreste'' Sumnev.
*'' Polygonum ajanense'' (Regel & Tiling) Grig.
*'' Polygonum albanicum'' Jáv.
*'' Polygonum amgense'' Michaleva & Perfiljeva
*'' Polygonum arenarium'' Waldst. & Kit.
*'' Polygonum arenastrum'' Boreau
*''Polygonum argyrocoleon'' Steud. ex Kunze
*'' Polygonum articulatum'' L.
*'' Polygonum austiniae'' Greene
*''Polygonum aviculare'' L.
*'' Polygonum balansae'' Boiss.
*''Polygonum basiramia'' (Small) T.M.Schust. & Reveal
*'' Polygonum bellardii'' All.
*'' Polygonum biaristatum'' Aitch. & Hemsl.
*'' Polygonum bidwelliae'' S.Watson
*'' Polygonum bolanderi'' W.H.Brewer ex A.Gray
*'' Polygonum boreale'' (Lange) Small
*'' Polygonum bornmuelleri'' Litv.
*'' Polygonum bowenkampii'' Phil.
*'' Polygonum brasiliense'' K.Koch
*'' Polygonum californicum'' Meisn.
*'' Polygonum cascadense'' W.H.Baker
*'' Polygonum caspicum'' Kom.
*'' Polygonum ciliinode'' Michx. – fringed black bindweed, mountain bindweed
*'' Polygonum cognatum'' Meisn.
*'' Polygonum corrigioloides'' Jaub. & Spach
*'' Polygonum deciduum'' Boiss. & Noë
*'' Polygonum delopyrum'' T.M.Schust. & Reveal
*''Polygonum dentoceras'' T.M.Schust. & Reveal
*'' Polygonum douglasii'' Greene
*'' Polygonum effusum'' Meisn.
*'' Polygonum engelmannii'' Greene
*'' Polygonum equisetiforme'' Sm.
*'' Polygonum erectum'' L.
*'' Polygonum exsertum'' Small
*'' Polygonum fibrilliferum'' Kom.
*'' Polygonum fimbriatum'' Elliott
*'' Polygonum floribundum'' Schltdl. ex Spreng.
*'' Polygonum fowleri'' B.L.Rob.
*'' Polygonum fragile'' Sumnev.
*'' Polygonum glaucum'' Nutt.
*'' Polygonum gussonei'' Tod.
*'' Polygonum heterophyllum'' Sol. ex Meisn.
*'' Polygonum heterosepalum'' M.Peck & Ownbey
*'' Polygonum hickmanii'' H.R.Hinds & Rand.Morgan
*'' Polygonum huananense'' A.J.Li
*'' Polygonum humifusum'' C.Merck ex K.Koch
*'' Polygonum icaricum'' Rech.f.
*'' Polygonum idaeum'' Hayek
*'' Polygonum imberbe'' Sol. ex G.Forst.
*'' Polygonum inflexum'' Kom.
*'' Polygonum istanbulicum'' M.Keskin
*'' Polygonum jaxarticum'' Sumnev.
*'' Polygonum korotkovae'' Sumnev.
*'' Polygonum kudriaschevii'' Vassilkovsk.
*'' Polygonum lacerum'' Kunth
*'' Polygonum liaotungense'' Kitag.
*'' Polygonum longiocreatum'' Bartlett
*'' Polygonum longipes'' Halácsy & Charrel
*'' Polygonum majus'' (Meisn.) Piper
*'' Polygonum marinense'' T.R.Mert. & P.H.Raven
*'' Polygonum maritimum'' L.
*'' Polygonum mezianum'' H.Gross
*'' Polygonum minimum'' S.Watson
*'' Polygonum molliiforme'' Boiss.
*'' Polygonum myrtillifolium'' Kom.
*'' Polygonum nesomii'' T.M.Schust. & Reveal
*'' Polygonum nuttallii'' Small
*'' Polygonum oxanum'' Kom.
*'' Polygonum oxyspermum'' C.A.Mey. & Bunge
*'' Polygonum palastinum'' Zohary
*'' Polygonum papillosum'' Hartvig
*'' Polygonum parksii'' (Cory) T.M.Schust. & Reveal
*'' Polygonum paronychia'' Cham. & Schltdl.
*'' Polygonum paronychioides'' C.A.Mey.
*'' Polygonum parryi'' Greene
*'' Polygonum patulum'' M.Bieb.
*'' Polygonum peruvianum'' Meisn.
*'' Polygonum pinicola'' T.M.Schust. & Reveal
*'' Polygonum plebeium'' R.Br.
*'' Polygonum polycnemoides'' Jaub. & Spach
*'' Polygonum polygaloides'' Meisn.
*'' Polygonum polygamum'' Vent.
*'' Polygonum polyneuron'' Franch. & Sav.
*'' Polygonum pringlei'' Small
*'' Polygonum pulvinatum'' Kom.
*'' Polygonum ramosissimum'' Michx.
*'' Polygonum rectum'' (Chrtek) H.Scholz
*'' Polygonum recumbens'' Royle ex Bab.
*'' Polygonum rigidum'' Skvortsov
*'' Polygonum romanum'' Jacq.
*'' Polygonum rottboellioides'' Jaub. & Spach
*'' Polygonum rupestre'' Kar. & Kir.
*'' Polygonum rurivagum'' Jord. ex Boreau
*'' Polygonum sabulosum'' Vorosch.
*'' Polygonum salsugineum'' M.Bieb.
*'' Polygonum sanguinaria'' Remy
*'' Polygonum sawatchense'' Small
*'' Polygonum schistosum'' Czukav.
*'' Polygonum scoparium'' Req. ex Loisel.
*'' Polygonum sericeum'' Pall.
*'' Polygonum serotinum'' Raf.
*'' Polygonum serpyllaceum'' Jaub. & Spach
*'' Polygonum shastense'' W.H.Brewer ex A.Gray
*'' Polygonum simlense'' Royle ex Bab.
*'' Polygonum smallianum'' T.M.Schust. & Reveal
*'' Polygonum spergulariiforme'' Meisn. ex Small
*'' Polygonum striatulum'' B.L.Rob.
*'' Polygonum stypticum'' Cham. & Schltdl.
*'' Polygonum subaphyllum'' Sumnev.
*'' Polygonum tenoreanum'' E.Nardi & Raffaelli
*'' Polygonum tenue'' Michx.
*'' Polygonum tenuissimum'' A.I.Baranov & Skvortsov ex Vorosch.
*'' Polygonum thymifolium'' Jaub. & Spach
*'' Polygonum tiflisiense'' Kom.
*'' Polygonum tubulosum'' Boiss.
*'' Polygonum turgidum'' Thuill.
*'' Polygonum turkestanicum'' Sumnev.
*'' Polygonum undulatum'' (L.) P.J.Bergius
*'' Polygonum utahense'' Brenckle & Cottam
*'' Polygonum valerii'' A.K.Skvortsov
*'' Polygonum volchovense'' Tzvelev
*'' Polygonum vvedenskyi'' Sumnev.
*'' Polygonum zaravschanicum'' Zakirov

Reclassified species

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

''Polygonum'' species that have been reclassified as ''Bistorta''

*''Polygonum amplexicaule'' → ''Bistorta amplexicaulis''
*''Polygonum bistorta'' – bistort → ''Bistorta officinalis''
*''Polygonum bistortoides'' Pursh – American bistort, western bistort, smokeweed or mountain meadow knotweed → '' Bistorta bistortoides''
*''Polygonum tenuicaule'' Bisset & S.Moore → '' Bistorta tenuicaulis''
*''Polygonum viviparum'' – alpine bistort → '' Bistorta vivipara''

''Polygonum'' species that have been reclassified as ''Fagopyrum''

*''Polygonum fagopyrum'' L. – buckwheat → ''Fagopyrum esculentum''

''Polygonum'' species that have been reclassified as ''Fallopia''

*''Polygonum aubertii'' L.Henry → '' Fallopia aubertii''
*''Polygonum baldschuanicum'' Regel – Russian vine → '' Fallopia baldschuanica''
*''Polygonum convolvulus'' L. – black bindweed, wild buckwheat → ''Fallopia convolvulus''
*''Polygonum dumetorum'' L. → '' Fallopia dumetorum''
*''Polygonum scandens'' L. → '' Fallopia scandens''

''Polygonum'' species that have been reclassified as ''Koenigia''

*''Polygonum alpinum'' → '' Koenigia alpina''
*''Polygonum campanulatum'' – lesser knotweed, bellflower smartweed → '' Koenigia campanulata''
*''Polygonum davisiae'' W.H. Brewer ex A. Gray and ''Polygonum newberryi'' Small → '' Koenigia davisiae''
*''Polygonum molle'' → '' Koenigia mollis''
*''Polygonum polystachyum'' Wall. ex Meisn. → '' Koenigia polystachya''

''Polygonum'' species that have been reclassified as ''Persicaria''

*''Polygonum alatum'' → '' Persicaria nepalensis''
*''Polygonum amphibium'' – amphibious bistort, longroot smartweed, water smartweed → '' Persicaria amphibia''
*''Polygonum capitatum'' – pinkhead smartweed → '' Persicaria capitata''
*''Polygonum chinense'' L. → '' Persicaria chinensis''
*''Polygonum coccineum'' Muhl. ex Willd. → '' Persicaria amphibia''
*''Polygonum filiforme'' Thunb. → '' Persicaria filiformis''
*''Polygonum hydropiper'' – water-pepper → '' Persicaria hydropiper''
*''Polygonum hydropiperoides'' Michx. – swamp smartweed → ''Persicaria hydropiperoides''
*''Polygonum lapathifolium'' – pale persicaria or nodding smartweed → '' Persicaria lapathifolia''
*''Polygonum longisetum'' → '' Persicaria longiseta''
*''Polygonum minus'' – small water-pepper → '' Persicaria minor''
*''Polygonum mite'' Schrank – tasteless water-pepper → '' Persicaria mitis'' (Schrank) Assenov
*''Polygonum nepalense'' → '' Persicaria nepalensis''
*''Polygonum odoratum'' Lour. – Vietnamese coriander → '' Persicaria odorata''
*''Polygonum orientale'' → '' Persicaria orientalis''
*''Polygonum pensylvanicum'' – Pennsylvania smartweed or pink knotweed or pinkweed → '' Persicaria pensylvanica''
*''Polygonum perfoliata'' – Asiatic Tearthumb → '' Persicaria perfoliata''
*''Polygonum persicaria'' – redshank or persicaria or lady's thumb → ''Persicaria maculosa''
*''Polygonum praetermissum'' → '' Persicaria praetermissa''
*''Polygonum punctatum'' Elliott – dotted smartweed → '' Persicaria punctata''
*''Polygonum runcinatum'' → '' Persicaria runcinata''
*''Polygonum sagittatum'' – arrowleaf tearthumb, American tear-thumb or scratchgrass → '' Persicaria sagittata''
*''Polygonum tinctorium'' → '' Persicaria tinctoria''
*''Polygonum virginianum'' L. → '' Persicaria virginiana''

''Polygonum'' species that have been reclassified as ''Reynoutria''

*''Polygonum multiflorum'' Thunb. → '' Reynoutria multiflora''
*''Polygonum cuspidatum'' Siebold & Zucc. – Japanese knotweed → ''Reynoutria japonica''
*''Polygonum sachalinense'' F.Schmidt – giant knotweed → '' Reynoutria sachalinensis''

Unresolved species

*''Polygonum vaccinifolium'' Wall. is an unresolved species name. '' Persicaria vaccinifolia'' may be a synonym.

Uses

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

References 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 Night's Dream'':

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

References

External links

Natural History Museum, London: Nature-navigator websiteRoyal Horticultural Society: Plant Finder section website

{{Taxonbar, from=Q271400

Polygonaceae genera
Taxa named by Carl Linnaeus