The genus Gardenia was named in honour of Dr Alexander Garden (1730-1791) a Scottish physician who practised in South Carolina, USA, and a correspondent of Linnaeus. This species was named after Carl Thunberg, pupil of Linnaeus and a well-known 18th century botanist and traveller in South Africa.

The Afrikaans common name buffelsbal means buffalo testicles, a reference to the shape of the fruit. The Zulu name umvalasangweni means the back-gate closer and refers to the fact that it and other spiny shrubs and trees are used as the gates for cattle kraals.

Gardenia thunbergia was the first of the South African gardenias to be known to botanists, and was introduced to the Royal Botanic Gardens, Kew in London, in 1773.

The gardenia family (Rubiaceae) is a large, cosmopolitan family containing 630 genera and 10 200 species. This family's greatest claim to fame is the South American quinine tree, Cinchona, whose bark yields quinine, the first drug ever used to treat malaria. Coffee, Coffea arabica, is also a member of this family. In South Africa, the family is best known for its decorative flowering trees and shrubs: Gardenia, Rothmannia, Hyperacanthus, Alberta and Burchellia.

The genus Gardenia consists of approximately 60 species that occur in tropical and warm parts of the Old World. Six species are found in South Africa, in all provinces except the Northern and Western Cape. Gardenia thunbergia can be readily distinguished from other similar species growing in South Africa, but is possibly often confused with other species growing in Zimbabwe and further north.

It may be distinguished from G. resiniflua, the gummy gardenia, by its much larger fruits, and from G. volkensii, the Transvaal or savannah gardenia, by the fact that its fruits are not ribbed. G. cornuta, the Natal gardenia, which has un-ribbed fruits of similar size and shape can be distinguished by the fact that its fruits are orange not grey. G. ternifolia (= G. jovis-tonantis) the large-leaved Transvaal gardenia, has short hairs on both leaf surfaces, which are rough to the touch, whereas G. thunbergia leaves are smooth and hairless. Another distinguishing feature is that G. thunbergia flowers do not age yellow, as many of the other species do. Hyperacanthus amoenus (= Gardenia amoena) the spiny gardenia, has paired spines at right angles to the next pair, and pink tinged white flowers. Gardenias are also quite similar to rothmannias, but an easy way to distinguish them is by their flowers: gardenia flowers are tubular with many petals, whereas rothmannia flowers are funnel shaped with only five petals.