| Oxygonum | |
|---|---|
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| Illustration of Oxygonum alatum from Hooker's Icones Plantarum , volume 14 | |
Scientific classification  | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Order: | Caryophyllales |
| Family: | Polygonaceae |
| Subfamily: | Polygonoideae |
| Genus: | Oxygonum Burch. ex Campd. [1] |
| Species | |
See text. | |
Oxygonum is a genus of plants in the family Polygonaceae with about 30 species. It is native to eastern parts of Africa and to the Arabian Peninsula. [1]
Species of Oxygonum are annual or perennial herbaceous plants, more rarely shrubs or shrubby. Their leaves are variable between and within species. The inflorescences are long narrow racemes with bundles (fascicles) of flowers, usually one to five, but sometimes up to 15. The flowers are polygamous (i.e. there are male, female and bisexual flowers on the same plant). There are usually five tepals, arranged spirally, fused at the base to form a tube, longer in female flowers than in male ones. The eight stamens are joined at the base, with patches of nectar-bearing tissue at the base of the inner whorl. The fruit is in the form of an achene, usually three-angled, often with rows of spinelike structures. [2]
The genus Oxygonum was first published in 1819 by Francisco Campderá, who attributed the name to William John Burchell. [1] [3] Oxygonum is placed in the tribe Oxygoneae of the subfamily Polygonoideae; it is the only genus in the tribe. A 2015 molecular phylogenetic study suggested that it was the sister of all the remaining tribes. [2]
| Polygonoideae |
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As of March 2019 [update] , Plants of the World Online accepted the following species: [1]
The Polygonaceae are a family of flowering plants known informally as the knotweed family or smartweed—buckwheat family in the United States. The name is based on the genus Polygonum, and was first used by Antoine Laurent de Jussieu in 1789 in his book, Genera Plantarum. The name may refer to the many swollen nodes the stems of some species have, being derived from Greek, poly meaning 'many' and gony meaning 'knee' or 'joint'. Alternatively, it may have a different derivation, meaning 'many seeds'.
Persicaria is a genus of herbaceous flowering plants in the knotweed family, Polygonaceae. Plants of the genus are known commonly as knotweeds or smartweeds. It has a cosmopolitan distribution, with species occurring nearly worldwide. The genus was segregated from Polygonum.
The docks and sorrels, genus Rumex, are a genus of about 200 species of annual, biennial, and perennial herbs in the buckwheat family, Polygonaceae. Members of this genus are very common perennial herbs with a native almost worldwide distribution, and introduced species growing in the few places where the genus is not native.
The genus Fagopyrum is in the flowering plant family Polygonaceae. It includes some important food plants, such as F. esculentum (buckwheat) and F. tataricum. The genus is native to the Indian subcontinent, much of Indochina, and central and southeastern China. Species have been widely introduced elsewhere, throughout the Holarctic and parts of Africa and South America.
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.
Muehlenbeckia or maidenhair is a genus of flowering plants in the family Polygonaceae. It is native to the borders of the Pacific, including South and North America, Papua New Guinea and Australasia. It has been introduced elsewhere, including Europe. Species vary in their growth habits, many being vines or shrubs. In some environments, rampant species can become weedy and difficult to eradicate.
Rumex spinosus, commonly known as devil's thorn or lesser jack, is an annual herbaceous plant of the Polygonaceae. It originates in the warmer parts of the old world, but now has spread with humans to other places. It is common in disturbed areas, especially in sandy soils. It has shown some weedy behaviour in restricted areas within southern Australia.
Pteropyrum is a genus of plants in the family Polygonaceae. Plants of the World Online accepts two species, native to Iran, Oman and the Gulf States.
Oxyria is a genus of plants in the family Polygonaceae with three accepted species as of March 2019. It has a circumboreal distribution.
Koenigia is a genus of plants in the family Polygonaceae. The genus Aconogonon has been merged into Koenigia.
Knorringia is a genus of plants in the family Polygonaceae. It is native to Central Asia and Siberia.
Atraphaxis is a genus of flowering plants in the family Polygonaceae with about 40 species.
Bistorta is a genus of flowering plants in the family Polygonaceae. As of February 2019 about 40 species are accepted. It has been supported as a separate clade by molecular phylogenetic analysis. Bistorta species are native throughout much of the Northern Hemisphere, as far south as Mexico in North America and Thailand in Asia.
Pteroxygonum is a plant genus in the family Polygonaceae. As of March 2019, two species are recognized. Their native range is from Tibet to southeast China.
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.
Reynoutria is a genus of flowering plants in the family Polygonaceae. The genus is native to eastern China, Eastern Asia and the Russian Far East, although species have been introduced to Europe and North America. Members of the genus, including R. japonica and its hybrid with R. sachalinensis, are highly invasive plants.
Polygonoideae is a subfamily of plants in the family Polygonaceae. It includes a number of plants that can be highly invasive, such as Japanese knotweed, Reynoutria japonica, and its hybrid with R. sachalinensis, R. × bohemica. Boundaries between the genera placed in the subfamily and their relationships have long been problematic, but a series of molecular phylogenetic studies have clarified some of them, resulting in the division of the subfamily into seven tribes.
Duma is a genus of shrubby flowering plants in the family Polygonaceae, subfamily Polygonoideae. The genus was separated from Muehlenbeckia in 2011. The native range of the genus is Australia.