| Common knotgrass | 
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| Scientific classification | 
| Kingdom: | Plantae | 
 
| Clade: | Tracheophytes | 
 
| Clade: | Angiosperms | 
 
| Clade: | Eudicots | 
 
| Order: | Caryophyllales | 
 
| Family: | Polygonaceae | 
 
| Genus: | Polygonum | 
| Species: | P. aviculare | 
| Binomial name | 
| Polygonum aviculare 
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| Synonyms | 
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Avicularia vulgaris Didr.
Centinodium axillare Montandon
Polygonum agreste Sumner, non Polygonum agreste Sumnev.
Polygonum aphyllum Krock.
Polygonum araraticum Kom.
Polygonum berteroi Phil. 
Polygonum buxiforme Small
Polygonum ganderbalense Munshi & Javeid
Polygonum heterophyllum Lindm. 
Polygonum monspeliense Thiéb.-Bern. ex Pers. 
Polygonum neglectum Besser 
Polygonum planum Skvortsov
Polygonum polyneuron Franch. & Sav. 
Polygonum prostratum Skvortsov
Polygonum procumbens Gilib.
Polygonum retinerve Vorosch.
Polygonum rubescens Small
Polygonum scythicum Klokov
Polygonum striatum K. Koch
Polygonum uruguense H. Gross
Polygonum argenteum Ehrenb. ex Meisn.
Polygonum argenteum Skvortsov
Polygonum fusco-ochreatum Kom.
Polygonum stans Kitag.
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Polygonum aviculare or common knotgrass is a plant related to buckwheat and dock. It is also called prostrate knotweed, birdweed, pigweed and lowgrass. It is an annual found in fields and wasteland, with white flowers from June to October. It is widespread across many countries in temperate regions, apparently native to Eurasia, naturalized in temperate parts of the Southern Hemisphere.