Malagasy relatives of the Crown-of-Th orns (Euphorbia milii Des Moul.) are well known worldwide for their ornamental value. Malagasy taxa account for almost 10% of the genus Euphorbia L., with 110 accepted names constituting subgenus Lacanthis (Raf.) M.G.Gilbert. Th e chaotic taxonomy combined with the poor state of preservation of most herbarium specimens makes the systematic study of this huge genus a quite diffi cult task. Th is paper off ers a nomenclatural account of all the published names with a recapitulatory list citing all the accepted names in subgenus Lacanthis as a fi rst step towards the revision of the group.