Polygonum is a genus of about 130 species of flowering plant in the buckwheat and knotweed family Polygonaceae. Common names include knotweed and knotgrass. In the Middle English glossary of herbs Alphita, it was known as ars-smerte. There have been various opinions about how broadly the genus should be defined. For example, buckwheat 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.
Fallopia is a genus of about 12 species of flowering plants in the buckwheat family, often included in a wider treatment of the related genus Polygonum in the past, and previously including Reynoutria. The genus is native to temperate and subtropical regions of the Northern Hemisphere, but species have been introduced elsewhere. The genus includes species forming vines and shrubs.
Polygonum arenastrum, commonly known as equal-leaved knotgrass, is a summer annual flowering plant in the knotweed family Polygonaceae. Other common names include common knotweed, prostrate knotweed, mat grass, oval-leaf knotweed, stone grass, wiregrass, and door weed, as well as many others. It is native to Europe and can be found on other continents as an introduced species and a common noxious weed. Knotweed was first seen in North America in 1809 and is now seen across much of the United States and Canada.
Reynoutria multiflora is a species of flowering plant in the buckwheat family Polygonaceae. It is known as tuber fleeceflower and Chinese knotweed. It is native to central and southern China.
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 and North America, naturalized in temperate parts of the Southern Hemisphere.
Polygonum ramosissimum is a North American species of herbaceous annual plants in the buckwheat family, widespread across much of Canada and the United States, where it is commonly called bushy knotweed. It is susceptible to downy mildew caused by the oomycete species Peronospora americana.
Persicaria cespitosa, known as tufted knotweed, is a summer annual weedy plant of the family Polygonaceae, native to eastern Asia, from China to Japan and Southeast Asia, and introduced into North America. The plant grows to 3.5 feet (105 cm) in height with elliptic to lanceolate leaves, usually 20–75 mm long. It has small pink or red flowers arranged in tight terminal spikes.
Persicaria amphibia is a species of flowering plant in the knotweed family known by several common names, including longroot smartweed, water knotweed, water smartweed, and amphibious bistort. It is native to much of North America, Asia, Europe, and parts of Africa, and it grows elsewhere as an introduced species and sometimes a noxious weed.
Fallopia baldschuanica is an Asian species of flowering plant in the knotweed family known by several common names, including Russian-vine, Bukhara fleeceflower, Chinese fleecevine, mile-a-minute and silver lace vine. It is native to Asia, and it can be found growing wild in parts of Europe and North and Central America as an introduced species.
Polygonum bidwelliae is an uncommon species of flowering plant in the knotweed family known by the common name Bidwell's knotweed. The plant was named for American suffragist Annie Bidwell, who at one time lived in the Bidwell Mansion in Chico, California. She is the person who collected the type specimen in Northern California.
Polygonum douglasii is a species of flowering plant in the knotweed family known by the common name Douglas's knotweed. It is native to much of northern and western North America, where it can be found in many types of habitat, including disturbed areas. It has been found in Canada from British Columbia north to Yukon and east as far as Québec, and in the United States as far south as California, New Mexico, Iowa, and New York.
Polygonum parryi is a species of flowering plant in the knotweed family known by the common names Parry's knotweed and prickly knotweed. It is native to the western United States from Washington to California, where it grows in several types of moist, open habitat in mountainous and coastal areas.
Persicaria punctata is a species of flowering plant in the knotweed family known by the common names dotted smartweed and dotted knotweed.
Polygonum delopyrum, the fringed jointweed or hairy jointweed, is a plant species endemic to Florida. It is found in pinelands and sandy pine barrens at elevations less than 50 m, in central and southern parts of the state.
Polygonum heterosepalum, common name dwarf desert knotweed or oddsepal knotweed, is a plant species native to the Great Basin Desert in southwestern Idaho, northern Nevada, northeastern California, and southwestern Oregon. It has been reported from 1 county in California (Modoc), 4 in Nevada, 4 in Idaho, and 5 in Oregon. The species occurs in dry, open sites in sagebrush plains and pine woodlands.
Cyperus lupulinus, the Great Plains flatsedge, is a plant species native to North America. It is widespread across southeastern Canada and the central and northeastern United States as far west as Wyoming, Colorado and New Mexico, with more isolated populations reported in Washington, Idaho and Oregon. It grows in open, sun-lit locations such as fields, prairies, roadsides, farms, etc.
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. It is also naturalized in eastern Canada and in the US State of Maine.
Polygonum patulum, called tree hogweed, is a species of flowering plant in the knotweed family. It is native to the Mediterranean region, eastern Europe, the Caucasus, Siberia, Central Asia, Mongolia, and the Province of Xinjiang in northwestern China. It has also become sparingly naturalized in scattered locations in Australia and North America.
Polygonum tenue, the slender knotweed or pleat-leaf knotweed, is a North American species of plants in the buckwheat family. it is widespread across south-central Canada (Ontario) and the eastern and central United States from Maine to Georgia, west as far as Minnesota, South Dakota, Nebraska, and Texas.
Polygonum utahense, the Utah knotweed, is an unresolved name for a putative North American species of plants in the buckwheat family. It has been found only in the States of Utah and Arizona in the southwestern United States.
