The genus Penaea was named by Carl Linnaeus in 1753 after Pierre Pena (1535–1605), French physician and botanist who was assistant to Matthias de L’Obel, after whom the genus Lobelia is named. The Latin specific epithet cneorum, pronounced suh-nor-um, is derived from a word of Greek origin referring to Daphne-like plants in the Thymelaeaceae, and it is also the name for a genus of shrubs, the spurge olives, in the Rutaceae. This plant was most likely given this species name due to its resemblance to species of Gnidia from the Thymelaeaceae family.

Penaea is a genus of flowering plants in the family Penaeaceae, found in southern South Africa. They have an unusual type of embryo sac development; after two rounds of mitosis, four nuclei are formed at each pole, leading to a mature embryo sac containing four polar groups each with three cells. When found in other taxa, these embryo sacs are termed Penaea-type.

Penaeaceae have been previously placed under Myrtales or close to Thymelaeaceae and in 1894 were included in this family. More recent authors agree on the placement of Penaeaceae in Myrtales, and exclude Thymelaeaceae from this order.