Asteropeia andPhysena are both enigmatic woody dicotyledons from Madagascar. Various taxonomic affinities have been suggested for both genera, but no consensus has been reached. An analysis of rbcL sequence data strongly supports recognition of the sister-group relationship ofAsteropeia andPhysena and their placement as the sister group to Caryophyllales. Many similarities were noted betweenAsteropeia andPhysena for stem, wood, leaf, flower, pollen, and fruit characters. The most notable differences are found in the morphology of the flowers and the anatomy of the wood rays.