"Several genera in the Aizooideae are not monophyletic. The southern African endemics Galenia and Plinthus are nested within Aizoon. Aizoon was considered to be well circumscribed, on account of its apically depressed capsules, as opposed to a convex apex in Aizoanthemum (Chinnock, 1983; Hartmann, 2001). However, Bittrich (1990a) noted similar capsules also for most species of Galenia and Plinthus and pointed out (Bittrich 1990b) that there are no clear characters distinguishing the subgenera of Galenia or delimiting it from Aizoon. Thus, the androecial and gynoecial features used by Adamson (1956) to distinguish Galenia from Aizoon are actually shared by these two genera (Bittrich, 1990b). Characteristic for most species in the Aizoon-clade (incl. Galenia and Plinthus), are the long, often silvery hairs on the leaves, which give their leaves a silvery sheen. Although several species of Galenia (such as G. glandulifera and G. africana) do not possess “hairs”, these are possibly reduced or modified (Bittrich, 1990b). "

Klak, C., Hanáček, P., & Bruyns, P. V. (2017). Out of southern Africa: Origin, biogeography and age of the Aizooideae (Aizoaceae). Molecular Phylogenetics and Evolution, 109, 203–216. doi:10.1016/j.ympev.2016.12.016

Klak, C., Hanáček, P., & Bruyns, P. V. (2017). Disentangling the Aizooideae: New generic concepts and a new subfamily in Aizoaceae. Taxon, 66(5), 1147–1170. doi:10.12705/665.9

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