The morphologically and phylogenetically anomalous genus Hermas is revised and nine perennial species are recognized, all endemic to mountain slopes within the Cape Floristic Region of South Africa. The new combination Hermas lanata is instated as the correct name for H. pillansii, based on the oldest available basionym. The latter species is also shown to be a very narrow endemic of the Cape Peninsula (Table Mountain to Noordhoek), not extending into the Jonkershoek Mountains as previously reported. The genus is characterized by fruits with woody endocarps, rhomboidal crystals, and pseudo-wings, all features shared with subfamily Azorelloideae, but recent phylogenetic analyses suggest that Hermas is an isolated lineage in the family, possibly sister to subfamily Apioideae s. l. An isolated position for Hermas is supported further by the unique floral morphology, viz. petaloid sepals and filiform petals, both of which are recovered as generic synapomorphies. The species may be distinguished on the basis of their habits, the size, shape, and vestiture of the leaves and involucral bracts, the synflorescence structure, the colour and venation of the sepals and petals, and the morphology and anatomy of the fruits. Species relationships are assessed in the form of a cladistic analysis of 11 morphological characters, resulting in a well-resolved phylogenetic hypothesis. A comprehensive taxonomic treatment is presented, including a key to the species, updated nomenclature, typification, descriptions, and geographical distributions.