title: Amphistemon
text: # 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-' (=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 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 Groeninckx
  * Amphistemon rakotonasolianus Groeninckx
  