''Oxygonum'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclu ...

s in the family

Polygonaceae 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 1 ...

with about 30

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

. It is native to eastern parts of Africa and to the Arabian Peninsula.

Description

Species of ''Oxygonum'' are

annual Annual may refer to: *Annual publication, periodical publications appearing regularly once per year ** Yearbook ** Literary annual *Annual plant *Annual report *Annual giving *Annual, Morocco, a settlement in northeastern Morocco *Annuals (band), ...

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wid ...

herbaceous plant Herbaceous plants are vascular plants that have no persistent wood, woody stems above ground. This broad category of plants includes many perennial plant, perennials, and nearly all Annual plant, annuals and Biennial plant, biennials. Definition ...

s, more rarely shrubs or shrubby. Their leaves are variable between and within species. The

inflorescence An inflorescence is a group or cluster of flowers arranged on a Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...

s 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

tepal A tepal is one of the outer parts of a flower (collectively the perianth). The term is used when these parts cannot easily be classified as either sepals or petals. This may be because the parts of the perianth are undifferentiated (i.e. of very ...

s, 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.

Taxonomy

The genus ''Oxygonum'' was first published in 1819 by

Francisco Campderá Francisco is the Spanish and Portuguese form of the masculine given name '' Franciscus''. Nicknames In Spanish, people with the name Francisco are sometimes nicknamed " Paco". San Francisco de Asís was known as ''Pater Comunitatis'' (father o ...

, who attributed the name to

William John Burchell __NOTOC__ William John Burchell (23 July 1781 – 23 March 1863) was an English explorer, naturalist, traveller, artist, and author. His thousands of plant specimens, as well as field journals from his South African expedition, are held by Ke ...

. ''Oxygonum'' is placed in the tribe Oxygoneae of the subfamily

Polygonoideae 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 ...

; it is the only genus in the tribe. A 2015 molecular phylogenetic study suggested that it was the sister of all the remaining tribes.

Species

, Plants of the World Online accepted the following species: *''

Oxygonum acetosella ''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. Description Species of ''Oxygonum'' are annual or perennial herbaceous plants, more rarely ...

'' Welw. *''

Oxygonum alatum ''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. Description Species of ''Oxygonum'' are annual or perennial herbaceous plants, more rarely ...

'' Burch. *'' Oxygonum altissimum'' Germish. *'' Oxygonum annuum'' S.Ortiz & Paiva *'' Oxygonum atriplicifolium'' (Meisn.) Martelli *'' Oxygonum auriculatum'' R.A.Graham *'' Oxygonum buchananii'' (Dammer) J.B.Gillett *'' Oxygonum carnosum'' R.A.Graham *'' Oxygonum delagoense'' Kuntze *'' Oxygonum dregeanum'' Meisn. *'' Oxygonum ellipticum'' R.A.Graham *'' Oxygonum fruticosum'' Dammer ex Milne-Redh. *''

Oxygonum gramineum ''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. Description Species of ''Oxygonum'' are annual or perennial herbaceous plants, more rarely ...

'' R.A.Graham *'' Oxygonum hastatum'' S.Ortiz *'' Oxygonum hirtum'' Peter *'' Oxygonum leptopus'' Mildbr. *'' Oxygonum limbatum'' R.A.Graham *'' Oxygonum lineare'' De Wild. *'' Oxygonum litorale'' R.A.Graham *'' Oxygonum lobatum'' R.A.Graham *'' Oxygonum maculatum'' R.A.Graham *'' Oxygonum magdalenae'' Dammer ex Peter *'' Oxygonum ovalifolium'' Robyns & E.Petit *'' Oxygonum overlaetii'' Robyns *'' Oxygonum pachybasis'' Milne-Redh. *'' Oxygonum pterocarpum'' Osborne & Vollesen *'' Oxygonum quarrei'' De Wild. *'' Oxygonum robustum'' Germish. *'' Oxygonum sagittatum'' R.A.Graham *'' Oxygonum salicifolium'' Dammer *'' Oxygonum schliebenii'' Mildbr. *'' Oxygonum sinuatum'' (Hochst. & Steud. ex Meisn.) Dammer *'' Oxygonum stuhlmannii'' Dammer *'' Oxygonum subfastigiatum'' R.A.Graham *'' Oxygonum tenerum'' Milne-Redh. *'' Oxygonum thulinianum'' S.Ortiz *'' Oxygonum wittei'' Staner

References

{{Taxonbar, from=Q7115979 Polygonaceae genera Polygonoideae