Polygonum oxyspermum is a coastal species of flowering plant in the buckwheat family. It is native to Europe, primarily along the shores of the Atlantic, the North Sea, and the Baltic Sea, from France and Ireland to Finland and Russia.[2] It is also naturalized in eastern Canada and in the US State of Maine.[3][4]
| Polygonum oxyspermum | |
|---|---|
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Scientific classification 
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| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Order: | Caryophyllales |
| Family: | Polygonaceae |
| Genus: | Polygonum |
| Species: | P. oxyspermum
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| Binomial name | |
| Polygonum oxyspermum | |
| Synonyms[1] | |
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Description edit
Polygonum oxyspermum is green or blue-green. Annual, stems prostrate, generally run along the surface of the ground but sometimes do rise above ground level. They can be as much as 100 cm (39 in) long. Leaves are up to 35 mm (1.4 in) long. Flowers are green, white or pink,[5] in axillary clusters.[6]
- Subspecies
Three subspecies are widely recognized, although some authors prefer to regard them as distinct species.[1]
- Polygonum oxyspermum subsp. oxyspermum – northern Europe; naturalized in Nova Scotia[7]
- Polygonum oxyspermum subsp. raii (Bab.) D.A.Webb & Chater northern Europe; naturalized in Nova Scotia, Prince Edward Island, New Brunswick, Québec, Maine, Newfoundland[8]
- Polygonum oxyspermum subsp. robertii (Loisel.) Akeroyd & D.A.Webb – Italy[9]
References edit
- ^ a b "Polygonum oxyspermum". World Checklist of Selected Plant Families. Royal Botanic Gardens, Kew – via The Plant List. Note that this website has been superseded by World Flora Online
- ^ Online Atlas of the British and Irish flora, Polygonum oxyspermum (Ray`s Knotgrass)
- ^ "Polygonum oxyspermum (Ray's knotweed)". Go Botany. New England Wildflower Society.
- ^ Wilde Planten in Nederland en België, Zandvarkensgras in Dutch with photos and global distribution map
- ^ Costea, Mihai; Tardif, François J.; Hinds, Harold R. (2005). "Polygonum oxyspermum". In Flora of North America Editorial Committee (ed.). Flora of North America North of Mexico (FNA). Vol. 5. New York and Oxford: Oxford University Press – via eFloras.org, Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
- ^ Parnell, J. and Curtis, T. 2012. Webb's An Irish Flora. Cork University Press. ISBN 978-185918-4783
- ^ "Polygonum oxyspermum". County-level distribution map from the North American Plant Atlas (NAPA). Biota of North America Program (BONAP). 2014.
- ^ "Polygonum raii". County-level distribution map from the North American Plant Atlas (NAPA). Biota of North America Program (BONAP). 2014.
- ^ Acta Plantarum, Polygonum robertii Loisel. – Poligono di Robert
External links edit
- A Photo Flora, Polygonum oxyspermum – Ray's Knotgrass (Polygonaceae Images) photos
- Flora of Northern Ireland
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