Eggplant is a generic name encompassing several species of Solanum cultivated for their fruits, in particular the aubergine (S. melongena L.) of East Asian origin, and the two African indigenous Scarlet (S. aethiopicum L.) and Gboma (S. macrocarpon L.) eggplants. These three species are closely related to each other and share a common set of numerous wild relatives, all belonging to the megadiverse subgenus Leptostemonum Bitter (also known as the spiny solanums). As a whole, the taxonomic and phylogenetic treatment of these wild species is arduous and unstable, mostly due to their high number and the rapid evolution of the technical tools and conceptual approaches used for assessing their relationships. Large scale and carefully sampled phylogenetic studies of the last decade have dramatically improved our in-depth understanding of genus Solanum. Eggplant’s closest relatives are African and Asian species belonging to subgenus Leptostemonum; but species of the same subgenus that originate from Australia, the Pacific and the Americas also deserve attention. Here, we provide a historical survey of the last taxonomic treatments and phylogenetic analyses for genus Solanum. We hope that this will familiarise the reader with this wide topic and will ease up his/her orientation through the specialised and extensive literature. Updated inventories of eggplants and related species organised by geographical areas of origin are completed with information as to whether the species are maintained in ex situ collections. Challenges associated to ex situ eggplants germplasm conservation are also discussed. To complete the picture, other Solanum species that are sometimes allocated the generic term of eggplants are briefly mentioned.