The genus name Didelta is derived from the Greek words di, which means ‘two’, and delta, which is ‘symbolized by a triangle’, referring to the bracts that are in 2 rows and triangular in shape. The species name spinosa is derived from the Latin spinosus, referring to the spines on the leaves.

The Afrikaans common name perdebos, translated into English as ‘horse bush’ indicates that horses apparently relish these plants as fodder. The other common name slaaibos, meaning ‘salad bush’, is an appropriate one because the soft, young, new leaves are edible and used in salads.

The genus Didelta is small, containing only 2 species, namely Didelta spinosa and D. carnosa, both in southern Africa. D. carnosa var. carnosa (dune salad bush/kusslaaibos) is a rounded shrublet up to 1 m, with fleshy leaves and attractive yellow flowers in winter and spring. The other variety Didelta carnosa var. tomentosa (hairy salad bush) is a prostrate, compact plant that is densely covered in white hairs, that give the plant a white, woolly appearance and reflect the light away from the plant, reducing transpiration. D. carnosa grows on coastal dunes and sandy flats from the Cape Peninsula in the Western Cape, through the Northern Cape, to southern Namibia.

Plant material of Didelta spinosa, and D. carnosa, was first introduced to Europe by Thunberg and Masson, in 1774. In 1781, the 2 currently recognized species of Didelta were first described by Carl Linnaeus the Younger and mistakenly placed in the genus Polymnia, an American genus. A detailed colour plate was published by Buc’hoz in 1785, in Grand Jardin de l’Univers, of a plant that had been cultivated by Trianon and named Breteuillia trianensis by him. This plant was the same as Linnaeus the Younger’s Polymnia carnosa. The genus Didelta was based on this same plant and published in 1786 in L’Heritier’s Stirpes novae as Didelta tetragoniifolia. Although the genus Breteuillia was published before Didelta, Burtt recommended that the name Didelta should be conserved because it was better known and more widely used. Later Didelta tetragoniifolia was shown by Aiton to be the same plant as Linnaeus the Younger’s Polymnia carnosa, so this species and its sibling Polymnia spinosa, were transferred to Didelta in 1789. In his monumental work De fructibus et seminibus plantarum of 1788–1792, Joseph Gaertner published the species as Favonium spinosum. Thunberg, in his 1800 work Prodromus plantarum capensium placed both Polymnia in a new genus Choristea. Gaertner and Thunberg were working independently, from Linnaeus the Younger’s work on Polymnia, and it is not known if they were aware of L’Heritier’s work on Didelta or not, but since their work is later than L’Heritier’s, his name, Didelta, stands.

The Asteraceae is one of the most familiar plant families in the world. In southern Africa it is also the largest family of flowering plants.