A genus of a single species, established by Grisebach in 1844, but until recently usually included in Marsdenia, which is now restricted to tropical species. Among the few woody asclepiadaceous plants occurring in Europe, Cionura erecta is most likely to be confused with Cynanchum acutum L., a species not treated in this work. But that has deeply cordate or sagittate leaves and there is a difference in the corona (crown) - the whorl of segments between the corolla and the stamens which is found in all members of the family. This consists of ten segments in Cynanchum and five in Cionura. Its near ally Periploca graeca has purplish flowers (white or yellowish in C. erecta). A detailed account of Cionura by the Polish botanist K. Browicz was published in Yearbook 12 of the Kornik Arboretum (1967), in English.