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.^[1] 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.

Amphistemon
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Asterids
Order:	Gentianales
Family:	Rubiaceae
Subfamily:	Rubioideae
Tribe:	Spermacoceae
Genus:	Amphistemon Groeninckx
Type species
Amphistemon humbertii Groeninckx

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.^[1]

Distribution and habitat

It is endemic to southwestern and western Madagascar and is found in dry spiny forest-thicket and coastal bushland.^[1]

Taxonomy

According to molecular analysis of the genus, it is found to be closely related to Astiella of the species-group Hedyotis-Oldenlandia.^[1]

Species

• Amphistemon humbertii Groeninckx
• Amphistemon rakotonasolianus Groeninckx