Amphistemon
Encyclopedia
Amphistemon is a genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of flowering plant
Flowering plant
The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...

s in the Rubiaceae
Rubiaceae
The Rubiaceae is a family of flowering plants, variously called the coffee family, madder family, or bedstraw family. The group contains many commonly known plants, including the economically important coffee , quinine , and gambier , and the horticulturally valuable madder , west indian jasmine ,...

 family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

. It is described by Inge Groeninckx in 2010 based on a molecular analysis of the Hedyotis
Hedyotis
Hedyotis 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. The hedyotis is native to tropical and subtropical Asia and to islands of the northwest Pacific. It comprises about...

-Oldenlandia
Oldenlandia
Oldenlandia is a genus of flowering plants in the family Rubiaceae. It is pantropical in distribution and has about 240 species. The type species for the genus is Oldenlandia corymbosa....

group. 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

It are erect perennial herbs or subshrubs with the unique feature in the Hedyotis
Hedyotis
Hedyotis 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. The hedyotis is native to tropical and subtropical Asia and to islands of the northwest Pacific. It comprises about...

-Oldenlandia
Oldenlandia
Oldenlandia is a genus of flowering plants in the family Rubiaceae. It is pantropical in distribution and has about 240 species. The type species for the genus is Oldenlandia corymbosa....

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
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of 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
Astiella is a monospecific genus of flowering plants in the Rubiaceae family. It was described by Jovet as a monospecific, herbaceous genus, endemic to Madagascar. The only species, Astiella delicatula, has several peculiar characters: it has only two calyx lobes, uni-ovulate locules, distinctly...

of the species-group Hedyotis
Hedyotis
Hedyotis 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. The hedyotis is native to tropical and subtropical Asia and to islands of the northwest Pacific. It comprises about...

-Oldenlandia
Oldenlandia
Oldenlandia is a genus of flowering plants in the family Rubiaceae. It is pantropical in distribution and has about 240 species. The type species for the genus is Oldenlandia corymbosa....

.

Species

  • Amphistemon humbertii Groeninckx
  • Amphistemon rakotonasolianus Groeninckx

External links

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