Hallianthus is a monotypic genus of flowering plants belonging to the family Aizoaceae.

[1] It only contains one species, Hallianthus planus[2] It is native to the Cape Provinces of the South African Republic.

[2] The genus name of Hallianthus is in honour of Harry Hall (1906–1986), a British-born horticulturist, botanist and succulent plant authority.

[3] The Latin specific epithet of planus refers to flat.

[4] Hallianthus planus was first described and published in Bot.