In the present paper, the latest, very broad generic concept of the genus Mesembryanthemum L., incorporating all hitherto recognized genera of the subfamily Mesembryanthemoideae Ihlenf., Schwantes & Straka on the basis of molecular and morphological data, is critically discussed. New insights into the possible evolution of character states within the Mesembryanthemoideae based on the published data are outlined. On the basis of a new assessment of the known character states, it is proposed to return to narrower generic boundaries. A new genus, Volkeranthus Gerbaulet, with two species, is described. All accepted genera and species are listed, some of them as new combinations.