Oscularia is a genus of succulent flowering plants in the family Aizoaceae, native to semi-arid and rocky habitats in the Western Cape of South Africa. It was previously included within the related genus Lampranthus, but was split off as a separate genus, due to differences in its fruit and flower. The species are restricted to the Western Cape Province, South Africa, where they occur only in winter rainfall areas. Their habitat is typically rocky areas of sandstone. Osculum means small mouth in Latin. Oscularia therefore means a group of small mouths and refers to the toothed leaves of Oscularia deltoides. The majority of the 22 species of Oscularia currently recognised, however, possess toothless leaves.

Oscularia caulescens, synonymously known as Lampranthus deltoides var. caulescens, Mesembryanthemum caulescens, Mesembryanthemum deltoides or Mesembryanthemum deltoides var. simplex and commonly known as Gum Toothfig in English and Dassievygie or Sandsteenvygie in Afrikaans, is a South African endemic species found in the Western Cape province, occurring exclusively on sandstone rocks, ranging along the mountains from Jonkershoek to Rooiels. Oscularia caulescens is an easy-to-grow succulent groundcover, ideal as an accent plant in especially rockeries or pots and for low-maintenance and water-wise gardens. During late spring it produces striking silky bright pink flowers.