''Piaranthus'' is a succulent plant genus in the subfamily

Asclepiadoideae The Asclepiadoideae are a subfamily of plants in the family Apocynaceae. Formerly, they were treated as a separate family under the name Asclepiadaceae, e.g. by APG II, and known as the milkweed family. They form a group of perennial herbs, twin ...

, in the family

Apocynaceae Apocynaceae (from ''Apocynum'', Greek for "dog-away") is a family of flowering plants that includes trees, shrubs, herbs, stem succulents, and vines, commonly known as the dogbane family, because some taxa were used as dog poison Members of the ...

. It was first described in 1810. Its name comes from Greek and is descriptive of the fleshy, succulent flowers typical of the genus (''"piar-" = fat'', ''"-anthos" = flower'').

Description

The plants typically form flat, spreading mats of multiple offsetting stems. The stems are small, compact and four-edged. Tubercles (leaf remnants) appear along the four sides. The flowers are small, fleshy, and bear five independent petals in a star shape. They appear in clusters, each flower up-turned, on a tiny inflorescence that sprouts from the tip of the stem. Each stem usually only produces a maximum of one inflorescence. The flowers of different species are in a range of colours; most emit unpleasant odours, especially the darker red or brown coloured ones. The compact, mat-forming stems are very similar to those of the related genus ''

Duvalia ''Duvalia'' is a succulent plant genus in the subfamily Asclepiadoideae, in the family Apocynaceae (dogbane). The genus was first described in 1812, named after the French physician and botanist Henri-Auguste Duval (1777-1814). Description ...

'', and the two are often confused when not in flower. However the stems of ''Piaranthus'' have four sides (in cross-section), while those of ''Duvalia'' often have more.

Distribution

The genus ''Piaranthus'' is restricted to the western part of

Southern Africa Southern Africa is the southernmost subregion of the African continent, south of the Congo and Tanzania. The physical location is the large part of Africa to the south of the extensive Congo River basin. Southern Africa is home to a number of ...

. It occurs in arid, sandy areas, in the shade of bushes. Piaranthus comptus

;Species ;formerly included species transferred to other genera ''(

Caralluma ''Caralluma'' is a genus of flowering plants in the family Apocynaceae, consisting of about 120 species. In 1795 William Roxburgh published the name '' Stapelia adscendens'' for a plant found in India. He commented that the name for the plant ...

Hoodia ''Hoodia'' (; known locally as "ghaap" or "bobbejaanghaap") is a genus of flowering plants in the family Apocynaceae, under the subfamily Asclepiadoideae, native to Southern Africa. One species of ''Hoodia'' in particular, ''Hoodia gordonii'', ...

Huerniopsis ''Huerniopsis'' is a genus of plants in the Apocynaceae family, first described in 1878. It is native to southern Africa. ;Species # ''Huerniopsis atrosanguinea'' (N.E. Br.) A.C. White & B. Sloane - N Botswana # ''Huerniopsis decipiens'' N.E.Br ...

Quaqua The genus ''Quaqua'' falls within the tribe of plants known collectively as stapeliads. All stapeliads, including ''Quaqua'', are Old World stem succulents. Species of the genus ''Quaqua'' are exceptionally varied and endemic to southwestern ...

Stisseria ''Stisseria'' is a genus of plants in the Apocynaceae, first described as a genus in 1759. ;Species accepted ;formerly included moved to other genera ''(Duvalia, Gonostemon, Hoodia, Orbea, Quaqua, Tridentea ''Tridentea'' is a genus of succ ...

)'' ;Taxonomy Phylogenetic studies have shown the genus to be monophyletic, and to be very closely related to the genera ''

Orbea Orbea is a bicycle manufacturer based in Mallabia, Spain. It is part of the Mondragón Cooperative Corporation and Spain's largest bicycle manufacturer. Orbea manufactures and assembles bikes at their own factory in Mallabia, the other models ...

'' and ''

Stapelia ''Stapelia'' is a genus of low-growing, spineless, stem succulent plants, predominantly from South Africa with a few from other parts of Africa. Several Asian and Latin American species were formerly included but they have all now been transfe ...

''. More distantly related are the genera ''

Huernia The genus ''Huernia'' (family Apocynaceae, subfamily Asclepiadoideae) consists of perennial, stem succulents from Eastern and Southern Africa and Arabia, first described as a genus in 1810.Brown, Robert. 1810. On the Asclepiadeae 11 The flowers ...

'' and ''

Tavaresia ''Tavaresia'' is a genus of plants in the family Apocynaceae, first described as a genus in 1902. It is native to southern Africa. ;Species # ''Tavaresia angolensis'' Welw. - Angola # ''Tavaresia barklyi'' (Dyer) N.E.Br. - South Africa # ''Tav ...

''.P. Bruyns, C. Klak, P. Hanacek: ''Evolution of the stapeliads (Apocynaceae-Asclepiadoideae) - repeated major radiation across Africa in an Old World group. Molecular Phylogenetics and Evolution.'' 2014. v. 77, no. 1, p. 251--263. ISSN 1055-7903.

References

{{Taxonbar, from=Q2091903 Asclepiadoideae Apocynaceae genera