''Amphistemon'' 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 n ...

of 2 species of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. They include all forbs (flowering plants without a woody stem), grasses and grass-like plants, a vast majority of ...

s in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Rubiaceae The Rubiaceae are a family of flowering plants, commonly known as the coffee, madder, or bedstraw family. It consists of terrestrial trees, shrubs, lianas, or herbs that are recognizable by simple, opposite leaves with interpetiolar stipules ...

. It is described by

Inge Groeninckx Inge is a given name in various Germanic language-speaking cultures. In Swedish and Norwegian, it is mostly used as a masculine, but less often also as a feminine name, sometimes as a short form of Ingeborg, while in Danish, Estonian, Frisian, Ge ...

in 2010 based on a molecular analysis of the ''

Hedyotis ''Hedyotis'' (starviolet) is a genus of flowering plants in the family Rubiaceae. Many species of this genus such as ''Hedyotis biflora, H. corymbosa'' and ''H. diffusa'' are well known medicinal plants. ''Hedyotis'' is native to tropical a ...

''-''

Oldenlandia ''Oldenlandia'' is a genus of flowering plants in the family Rubiaceae. It is pantropical in distribution and has about 240 species.Inge Groeninckx, Steven Dessein, Helga Ochoterena, Claes Persson, Timothy J. Motley, Jesper Kårehed, Birgitta Bre ...

'' group.Groeninckx I, De Block P, Robbrecht E, Smets E, Dessein S. 2010. "''Amphistemon'' and ''Thamnoldenlandia'', two new genera of Rubiaceae (Spermacoceae) endemic to Madagascar." '' Botanical Journal of the Linnean Society'' 163: 447-472. The genus name is based on the Greek 'amphi-' (=double or of two kinds) and 'stemon' (=stamen) referring to the dimorphic stamen position characteristic for this genus.

Description

Amphistemon are erect perennial herbs or subshrubs with the unique feature in the ''

''-''

'' group of having stamens inserted at two distinct levels in the corolla tube, the lower stamens with filaments and anthers shorter than those of the upper stamens.

Distribution and habitat

It is endemic to southwestern and western

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

and is found in dry spiny forest-thicket and coastal bushland.

Taxonomy

According to molecular analysis of the genus, it is found to be closely related to ''

Astiella ''Astiella'' is a genus of flowering plants in the family Rubiaceae. It was described by Jovet (1941) as a monospecific, herbaceous genus, endemic to Madagascar. Later, 11 new species endemic to Madagascar were added to the genus. Species *'' A ...

'' of the species-group ''

''-''

''.

Species

* ''

Amphistemon humbertii ''Amphistemon'' is a genus of 2 species of flowering plants in the family Rubiaceae. It is described by Inge Groeninckx in 2010 based on a molecular analysis of the ''Hedyotis''-''Oldenlandia'' group.Groeninckx I, De Block P, Robbrecht E, Sm ...

'' Groeninckx * ''

Amphistemon rakotonasolianus ''Amphistemon'' is a genus of 2 species of flowering plants in the family Rubiaceae. It is described by Inge Groeninckx in 2010 based on a molecular analysis of the ''Hedyotis''-''Oldenlandia'' group.Groeninckx I, De Block P, Robbrecht E, Sme ...

'' Groeninckx

References

External links

''Amphistemon'' in the World Checklist of Rubiaceae
Rubiaceae genera Spermacoceae Endemic flora of Madagascar {{Rubioideae-stub