Bruyns P. V., Klak C., Hanáček P., Evolution of the stapeliads (Apocynaceae–Asclepiadoideae) – repeated major radiation across Africa in an Old World group, Molecular Phylogenetics and Evolution, 2014, 77:251-263, doi: 10.1016/j.ympev.2014.03.022
An analysis of 192 stapeliad species based on nuclear and plastid markers. It reconstructs repeated radiations in Africa and relationships between lineages with very different floral structures. The results challenge the monophyly of some traditionally recognised genera.