Amphistemon


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. The genus name is based on the Greek 'amphi-' and 'stemon' referring to the dimorphic stamen position characteristic for this genus.

Description

Amphistemon are erect perennial herbs or subshrubs with the unique feature in the Hedyotis-''Oldenlandia'' 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 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 of the species-group Hedyotis-''Oldenlandia''.

Species

Amphistemon humbertii GroeninckxAmphistemon rakotonasolianus Groeninckx