The evolutionary relationships among taxa, and how their present geographic distributions came to be, are both prominent areas of biological research. Studies of these topics fall within the fields of systematics and biogeography. Logania R.Br. are morphologically variable plants that are near-endemic to Australia, with 37 species divided between two infrageneric sections, L. sect. Logania and L. sect. Stomandra. Preliminary studies have questioned the monophyly of Logania, and the genushas a disjunct distribution corresponding to a gap at the Nullarbor Plain. Therefore, Logania are favourable candidates to gain an insight into phylogenetic relationships and how these might intersect with Earth-history events.

 We tested the monophyly of Logania and placed the genus in a broader evolutionary context using phylogenetic analyses of four molecular markers (petD, rps16, matK and rbcL). Two findings from these analyses rendered Logania non-monophyletic. We showed that L. imbricata, the only extant non-Australian Logania, belongs within Geniostoma, and that L. sect. Stomandra should be considered as a separate genus. Furthermore, we proposed two possible subgenerawithin Logania sensu stricto. Through biogeographical analyses, we found that disjunct distributions within Logania sect. Stomandra could have been caused by historical vicariant processes in the Nullarbor Plain region, but the distribution of Logania sect. Logania can only be explained by long-distance dispersal and establishment. As a result of this study, we have renamed L. imbricata to Geniostoma imbricatum and provided a formal taxonomic treatment re-classifying L. sect. Stomandra at genus level.